CA1114622A - Internal combustion engines integrated with heat recuperators - Google Patents

Abstract

ABSTRACT
More than 60 % of the heating value of the fuel consumed in the usual internal combustion engines is wasted past remedy. The present invention, which is applicable in combination with any type of internal combustion engine, is devised to reduce the heat losses and to improve the ef-ficiency of the thermodynamic cycles by making practicable an increase of the compression ratio, while suppressing knocking. Besides, a reduction in the emission of pollu-tants is achieved.
The invention embodies apparatus to generate super-heated steam, comprising a water preheater, a forced - cir-culation steam generator, a steam separator, a steam super-heater which forms the actual jacketed cooling system of the engine, and a feasibly complete thermal insulation sys-tem. Said apparatus is integrated with the internal combus-tion engine, its steam generating constituent parts being arranged in countercurrent to the flow of the combustion products generated by the engine's process.
The superheated pressure steam is utilized as mo-tive power for an injector-compressor serving to pre-com-press the combustion air for compression-ignition or other fuel injection engines, or to supercharge the air-fuel mix-ture in the case of carburetor engines. In all cases, the compressed gaseous intake, incorporating the injected su-perheated steam, enters the engine's working space with in-creased enthalpy. If superheated steam is produced in excess of the demand of the compressor, it will be fed directly into the working space with appropriate timing.
The invention offers the convenience of reducing the usual heat losses to the only heat being rejected with the cooled exhaust gases.

Description

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GE~RA~ DISCUSSI0 ~ his invention refers to internal combustion engines of any kind, including engines which currently have been usin~ water or aqueous ~ixtures as a coolant. ~he object of the invention is to minImize the heat loss experienced with usual internal combustion engines, whereby superheat-ed pressure steam is generated and usefully consumed.
~ wo major heat losses are encountered in the oper-ation of the conventional engines: the first one derives from the necessity to cool the metallic parts which come into contact with, and contain the working substance while it develops the thermodynamic process, the second one is due to the inevitable evscuation from the working space of the combustion products while they still contain a substan-tial portion of the heat of co~bustion. If we consider thatthe walls of the combustion chamber may be exposed to com-~ bu~tion temperatures of 1500 to 2200C, and that the evac--, uated products may enter the exhaust manifold with a tem-perature of 400 to 800C, we realize that a considerable 1 20 waste of valuable energy may be caused by said heat losses.
; Steps have been devised and occasionally put to work to regain in some measure these losses; nevertheless a distinction should be made regarding the scope and object of such endeavors. ~hose instances where the recovered en-ergy is used for purposes independent from, and not affect-i ~ng the operation of the engines, shculd not be related to the present invention. ~or example, the warm cooling fluid or the hot exhaust gaseR may be fed to installations which do not form a functional part of the internal combustion engine. ~he recovered energy represents still a loss forthe engine, however useful the operation of said instal-lations might be. In the section dealing with the prior art, only tho~e applications that are integrated in the function of the engines and are devised to improve their efficiency shall be taXen into consideration. ~ -Notwithstanding remarkable advancements in the design of the engines, other di~advantages apart from the mentioned heat losses 8t~11 persist. ~or instance, limita- -tions are imposed to the compression ratio because of pos-sible ~nocking. It iB evident that attaining higher tem-perature levels of combustion, under higher pressures, and without inducing knocking, will result in impro~ed thermo-dynamic cycles. Increasing the compression ratio may be ac- `;
complished by supercharging or pre-compressine the combus-tion air, or the air-fuel mi~ture, before they are ~ntro- ; ~ ~*
duced into the engine's ¢ombustion space. ~his step has been adopted only in limited cases for spark-ignition en-gines with pistone. Of course, most compression-ignition en-gines and all eas turbines must be equipped with compressing apparatus for the air supply. It is, however, apparent that providing internal ¢ombustion engines, in general, with pre-oompressing devices will improve their performance, on con-dltion that said device~ be not wasteful energy-wise.
An inconvenience, lnherent to the currently used ~ackoted cooling systems, derives from the relatively cold metallic surfaces enclosing the combustion process. ~here results a quenching of the combustion in the layer ad~acent to the metallic surface, yielding produ~ts of incomplete com-bustion. Dis~ociation of some nitric oxides, produced in the hot zone~ is also prevented by the sudden cooling. ~hese by-products of the combustion are the pollutants currently be-ing emitted by the engines. A remedy would consist in fea-sibly increase the temperature of the walls confining the process of combustion. ~oteworthy, the ~anadian patent of ` ~~

1915, Water Jac~eting Process1 165954, to J.B.Meriam, claims efficiently utilizing the fuel by maintaining the cooling ~ -water at a temperature of about 135C while producing steam under the pressure of 2.5 k ~ cm2ga. A pressure of similar magnitude, whereby the coola~t may attain a similar temper-ature has been adopted for the cooli~g systems of modern engines; such pressurized systems are, however, not devised as steam generab~, but are rather intended to prevent boiling of the water inside the cooling jackets.
It cannot be maintained that the comparatively small increase of the coolant 1 8 temperature, as related here, would eliminate the production of pollutants. Even putting into prsctice the system proposed in the Canadian ;~
patent 157796 of 1914, to W.J.Still, Internal Combustion En-gine, whereby circulating cooling water is caused to boil !i under a pressure of about 15 k ~ cm2ga, the temperature dif-ference between the e~olving ¢ombustion and the coolant having the corresponding ~aturation temperature Or about 1935, would not ~be significantly dimini~hed, and conse-quently the quenching of the working substance would not be ~ubstantially reduced. It ~hould be noted that a metallic wall through which heat i8 being transferred will attain a mean temperature nearer to that of the fluid presenting the greater convection coefficient. In ~acketed cooling systems with circulating liquid coolants, mostly water, the walls confining the combustio~ process will have a mean temper-ature near to that of the coolant, the heat convection being much more active from wall to said coolant.
PRIOR AR~
Many attempts have been devised to recuperate heat that is usually wasted in the operation of internal combus-tion engines. Consideration will be given here to specific endea~ors which might be related to the present in~ention.I"
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~he Canadian patent 157796 mentioned in the pre- `
ceding section may be included in the prior art because it repre~ents a~ attempt to recover waste heat by generating steam to be used in the engine. ~he saturated pressure steam would be introduced into the engine's cylinder, under the piston, thus transformIng the engine into a hybrid ma-chine, operating as an internal combu~tion eng me above the piston, and as a steam engine under the same piston. ~ *
In the Canadian patent 412278 o~ 1943, to C.K.~ew-`~
combe, ~iquid Cooling Sy~tems, vapor produced in the engine ~acket is compressed by means of an injector-type heat pump and delivered with increased pressure and temperature to a high pr~snre condenser (radiator). The high pressure con-densate i~ retur~ed to the cooling jacket through an expan-sion ~alve. ~he hiBh pressure steam to be used as motive power in the heat pump is obtaine~ from a by-pass stream of the hi~h pressure condensate whi¢h i8 oirculated through a ~aoket enolosing the exhaust manifold, or throuBh a pipe ooiled around ~aid manifold. A variant arrangement is des-cribed, where usual cooling medium i~ ciroulated through the engine Jacket and i9 discharged through a heat-ex-i changer where it i8 cooled while heating and vaporizing a highly volatile refrigerant.
Another invention having a similar ob~ect has been patented in Canada in 1954 (Patent 505611, Engine Cool-ing System Utilizing Waste Heat, to ~.C.Harbert and W.C.
Corey). ~he cooling liquid i8 circulated through the engine ~acket whereby it i9 heated to ~ubstantially vaporizing temperatures and is discharged into a steam separator. ~he ~eparated steam is used to drive a l~w pressure turbine having a fan mounted on its output shaft. ~he ~an ~roduces ~ 2.~

an air current which activates the cooling effect of a condenser wherein the exhaust ~team from the turbine i8 condensed. Remarkably, the in~entors stress upon the ad-vantages derived from maintaining the cooling fluid at higher temperatures, omittIng, however, to indioate the magnitude of the "~ub~tantially vaporizing temperatures". ~
The Canadian patent 5236g2 of 1956, to R.R.Hull, ~ ~-~ rtually an alternative to patent 505611. It presents mainly an improvement to the vapor separator included in the cooling circu~t. ~he turbine, an essential feature in the preceding patent, has been abandoned. A solution to the problem of removing the temporary hardne~ from the make-up water is proposeds the salts precipitated in the separator will be periodically blown out.
~he ~anadian patents 392846 of 1940, Steam ~arbu-retor, to ~h.Bibeau, and 700185 of 1964, Vapor Generating Apparatus, to G.C.3erger, both having for ob~ect humidify-ing the combu~tion air or the air-fuel intake to the en-gine, comprise small vapor generating devices mounted on 4~
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~he engine's exhaust manifold. Apparently the steam supply ;
for the intended application is assumed to be very small, accordingly the recovery of waste heat is minimal.
A number of inventions and adaptation~ have been devised whereby liquid water is admixed, in~ected, or in-troduced in some other way into the worXing substance or into the components thereof, before, during, or after combus-tion o¢curs. Some of these designs specify the added fluid as a combustion modifying liquid ingredient such as water, or a mixture of water with alcohol, etc. ~he admitted pur-pose of the water injection is to control the strength of fuel mixture in supercharged engines, or to control the in- -take pressure of ths air-fuel mixture, or to prevent knocX-ing in supercharged engines. The Canadian patent 693772 of 1964, Internal Combustion Engine, to ~.T.Barnes, describes means for in~ecting water into the engine cylinder durlng the power stroke. ~he water i8 converted into superheated steam and supposedly contribute3 to pushing the piston.
Substantial gain in thermal efficiency i9 claimed in the Canadian patent 901901 of 1972, E~gine System And ~hermogenerator ~herefor, to G.L.Ginter, describing a sys-tem which combines internal combust~on with external combus-tlon in a single engine. The working substance would be supplied at nearly constant pressure and temperature. ~he compression and the expansion strokes take place in sepa-rate cylinders, the ~olumetric capacity of the expansion cylinders being twice as large as that of the compression cylinders. The doubling of the ~olume of the working sub-stance is obtained by inject~ng water into the separately ~0 pro~ided combustion chamber, whereby the ideal rate of water to be injected should equal, in weight, the combined weight of the fuel and compressed air input. In terms of ~4~
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usual air to fuel ratios, this means that about l9 kg of water would be injected for every kg of fuel consumed. To minimize the heat dissipation into the ambient atmosphere, the engi~e is completely enclosed in thermal insulation.
For the record, it should be noted that the maxi~
mum rate of modifying liquid injected in turbo-jet engines, consisting approximately of 75~ water and 25~ alcohol, is 5 weight units of the liquid to one weight unit of fuel.
The techniques of supercharging the inta~e of in-ternal combustion engines and, in general, of pre-compres-sing the combustion air, which are at present in use, con-Biet of centrifugal compressors or of inje¢tor-type com-pressor~, the latter utilizing compressed air as motive power. The oentrifugal superchargers may be driven by the engines, either directly or through appropriate gearing;
i they may also be driven by gas turbines which use exhaust ;~
gases from the engines as motive power. The compressed a~r needed for the in~ector-type compressors must be furnished by separate mechanically driven compressors. In~ector-com-pressor~ u~ing steam as motive power have been proposed for boosting the pressure of coolant vapors, as was men-tioned in relation with Canadian patent ~12278, but no such steam in~ector-compressor has been used until now as super-charger, or as intake air compresFor, in combination with internal combustion engines.
CONC~USIO~S TO THE PRIOR ART
~ he described attempts to recover the heat Io85e9 by raising steam or vapor from the cooling liquid, and by causing the produced vapor to perform useful work, shall be evaluated with a view to the following two questions~ fir~t, how large a portion of the heat that would otherwise be wasted i8 being recuperated; second, in what measure is the !

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engine's efficiency affected by putting to work the recov-ered enrgy. - ~-Reco~ering a more or less substantial portion of the waste heat may be attained by mea~s already Imown. An i 5 average-to-good recuperation could be expected by imple-menting the Canadian patents 157796, 165954, 412278, 505611, 523692, which take advantage of an acti~re heat con~rection from metal to ¢oola~t, and of possibly extended heat trans- 1~ ;
fer surfaces. Only poor recuperation might be achieved in 10 other casee, where the heat tran~fer surface is rather lim-ited, or the water i~ stagnant, etc.
In the present state of the art, and with a view to the above second que~tion, the results obtained by uti-lizing the recovered energy,through the vehicle of steam 15 genera$ed from waste heat, are questionable. ~or instance, in the application Or the Canadian patents 412278 and 505611 an improveme~t in the specific function of the radiator~ or oondensers is achieved, resulting in a more intensive dis-sipation into the atmosphere of the heat removed from the 20 thermodynamic process. l~o improvement in the engine' 9 fuel consumption is thereby intended or accomplished. No benefit to the engine operation iB derived from the generated ~team when implementing those other invention~ where the stesm i8 used elsewhere. ~he same applies to the inventions where 25 the generated steam is condensed without performing work.
~ he parameters of the produced steam are important for its possible utilization. In most patents relative to steam generating cooling system~ low pre~ures seem to be preferred. ~he Canadian patent 157796, having for ob~ect 30 the already mentioned steam-internal combu~tion engine, is an exception inasmuch a~ it specifies steam of about 15 kg/cm2ga.

In all known vaporizers or generators usIng waste heat from internal combustion engines, the steam, or vapor, - ~-produced is in the ~aturated state, it being separated from the liquid phase either when it leaves the boiler, or in r~
distinct separators through which the liquid-vapor mixture i8 circulated. ~he saturation temperature, assoaiated with the steam pre~sure, is significant because of its possible effect in preventing cold metallic walls. AB was shown in . .
the General Discu~sion, however, coolants at saturation temperatures in the range of 193O would not reduce substan-tially the quenching of the working substance.
It will be shown now that the utilization of the ~aturated steam, as devised and practised in the prior art iB une¢onom~cal.
We shall consider in the first instance those sy~- ;
tems where the ~team is used as working substance in a steam engine of the reciprocating or of the rotating type.
~he steam enBine shall, of course,form an integral part of the internal combu~tion engine and shall contribute, as such, to it~ efficient operation.
~ et U8 aesume that in a waste heat recovery system of a known type, about 1/3 (approximately 3000 kcal) of the heating power of 1 kg fuel (rated at 9500 kca ~ ~g) is used to generate steam at 15 k ~ cm2ga. Ideally about 4.5 kg of stoam having an enthalpy of 662 kcal/kg might be produced.
Putting thi~ fluid to work in a steam engine, from which it would be exhau~ted under a pressure of at least 1.25 ata, its quality would drop to about 0.92. Taking into account minimal thermal and mechanical losses, the equivalent of the work regained could not exceed 50 kcal per kg steam u~ed, totaling about 225 kcal out of the 3000 kcal being recovered.
Should the steam be generated under a lower _ g _ 6Z~; ~
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pressure, the useful work to be gained would be even les~
In the second instance, we shall con~ider the pos-sible effect regarding the performance of internal combus-tion engines if ~aturated steam is admixed to the combustian products in their working space.
An increa3e in the output of mechanical work W8S
expected as a consequence of the retarded combustion, when injecting ~aturated steam into the wor~ng cylinders during the power stroke. ~he expected increase of the produced work is, however, not likely to occur.
~et U8 assume that the following favorable condi- ;
tions prevail:
- A steam generator, recovering a sufficient portion of the waste heat is prov~ded, ~aid generator being similar to those known i~ the prior art but being capable to raise steam having a pre~sure between 10 and 15 k ~cm2ga, which would have an enthalpy of 657 to 662 kca~ kg. Doubtless the steam pre~s~re haq to be higher than the pressure of the ; working substance at the time of the injection into the cyl-inder (or working spa¢e);
- Steam is generated and in~ected at a rate of approx-imately 4.5 kg per kg fuel con~umed by the engine;
- ~he internal combustion engine is operated with a min~mum of excess air.
When it i9 introduced into the working space and mixed with the products of the combustion, the steam attains the ~tate of one component in a mixture of several gaseous components. Its pre~sure drops to the partial value corre-sponding to the Mol ratio f ~2 to the other components ~0 present in the working space. It can be proved that at the assumed rate of steam injection with an average fossil fuel, burnt efficiently, the partial pressure of the (total) water z~ :

vapors present will be equal to about ~9% of the pressure ~ -of the mixture. ~ecause of the heat interchange with the hot combu~tion products and its drop in pressure, the steam becomes superheated. ~he superheat being achieYed at the expense of the combustion heat and the specific heat of the steam bei~g higher than that of the other gaseous components present, a certa m down toning and slowing of the combus~
tion will ta~e place. Irrespective of the way the process develops after the injection, the steam will continue to be ;`
superheated until it i8 evacuated with the combustion pro-ducts from the working space. It is convenient to use the term "combined exhaust gases" to denote the steam enriched ~ -evacuated gases. Conditions and parameters of the gases evacuated from internal combustion engines vary widely de-pending on the type and mode of operation of the engines, on the back-pressure prevailing in the exhaust manifolds, etc. ~ack-pressures of 1.3 to 1.7 k ~cm2abs may be reason-ably assumed: the corresponding partial pressure of the steam will range from 0.51 to 0.66 k ~cm2abs. Statistical data from testing of various engines show values of ex-haust temperatures ranging from 400 to over 800C, but even if the temperature of the combined exhaust gases would drop below 400C the steam in the mixture would still be super-heated. Actually, under the assumed partial pressures, it would be so at any temperature above 90C. ~he enthalpy of superheated steam with the parameters of 0.51 to 0.66 k ~ cm2 abs and, say, 300C is about 735 kcal/kg. It becomes evident that in such circumstances additional combu~tion heat will be wasted, namely at a rate of about 735 - 662 = 73 kcal for every kg of saturated steam generated and fed into the working space of the engine.
Consideration has been given to various systems, i$ ~4G

wherein liquid water i8 injected or sprayed, or introduced in some other way into the working substance of internal combustion engines. ~he purpose of admixing water to the working æubstance may be to make the operation of the en-gines more flexible. Prevention of detonation may also beattained. Whatever the advantages claimed, no gain in the mechanical work produced i8 likely to result . ~he water ;
will vaporize and the vapor will be superheated, all of ,.
this being obtained at the e~pense of the combustion heat.
~he superheated steam will parti~ipate to the further evo-lution of the working substance, being evacuated from the engine as a component of the combined exhaust gases. ~8 was shown above, the evacuated low pressure superheated ; ~team may have an enthalpy exceeding 700 kcal/kg, almost all of which would be ~ubtracted from the thermodynamic process,to be dissipated into the surround~ng atmosphere.
It ~ con~equent~y evident that increasing the mass of the working substan¢e in the engine, by addition of sat-urated steam or of llquid water, will not result ~n a gain in the energy balance of the process.
Since the combustlon products evacuated from the worki~g space may contain a substant~al portion of the com-bustion heat, adaptation~ of the exhaust system have been made in order to possibly recuperate some of the heat. ~he embodiment of the Canadian patent 157796 includes a heat-exchanger equipped with a bank of tubes through which the exhaust gases flow, gi~ing up heat that generatessteam. Tn other inventions only a part of the exhaust manifold is adapted as a vapor generator. ~he saturated steam obtained from the engine's ~ackets and the adapted exhaust sy~tem, or from the latter alone, is eventually used in the opera-tion of the engine. It is obvious, howe~er, that for the - 12 _ .. -... . . - - . . ~-........ - . ~ - . -62~

generated steam to be useful, at all, a minimum value of the saturation pressure would be required. ~his sets a lim- -~
it to the lowest temperature at which the exhaust gases should leave the vapor generator, in order that heat might 5 be transferred. ~he preceding analyæi~ was based on the ; ~;~
desire to raise s~eam havIng a saturation pressure of 10 to 15 k ~ cm2ga with saturation temperatures ranging from 183 to 193~, in which case the temperature of the exhau~t gases should not drop below 220 to 230C. Although it might be argued that steam at a pressure of, say, 3 k ~cm2ga, having a saturation temperature of 142C, could still be ussble, the exhaust gases could not practically be cooled below about 170C. But if this low pres~ure steam, having an enthalpy of 652 k¢a ~ kg i8 fed into the internal combus-tion process and finds its way into the exhaust system, itwill terminate its supposed useful funct~on as low pressure superheated ~team with increased enthalpy. At a partial pressure of about 0.5 ~ ~cm2 abs and at a temperature of about 170~ (which would be required for the process to be feasible~ the steam enthalpy would amount to 671 kca~ kg, contributing to increase the heat content of the combined exhaust gases, instead of recovering some waste energy. In the same way~ if steam of higher pressures is generated, higher temperatures of the exhaust gases would be required

2~ to produce it, resulting in a still higher heat 1O8g.
~ inally, the result attained by using the exhaust gases as motive power in a gas turbine, which would drive a centrifugal supercharger, shall be considered. Turbo-chargers are used to boost the intake pressure at a ratio of ~0 1,5/1 to 3/1 or more. ~o make the system operative, the gases shall enter the turbine at a measurably higher pressure than the back-pressure maintained in the usual exhaust systems.

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Reckoning with a reasonable efficiency of the turbine-turbocompressor combination, a back-pressure of at least 4.5 k ~ cm2abs at the exhaust valves of the engine would be --re~uired, while the turbine outlet pres~ure could be kept at 103 kg/cm2abs. ~he increase of the bac~-pressure auto-matically re~ults in an increase of the temperature of the ¢ombustion ga~es at the end of the expansion stroke. In -any case, the temperature of the exhaust gases fed to the turbine might well be at a level of 600C. With a near-adi-abatic expansion of this working substa~ce, the exhaust gases w~ll leave the turbine at a temperature of about 300C
which is well above the previously assumed exit temperature ;~
Or 170O.
In aonclusion, whether evacuated directly or after performing some useful service, as practised in the present state of the art, the exhaust gases still have a relatively high enthalpy.
In the once-throu4h participation of the steam or of the in~ected water, meaning by this that the generated steam or the vaporized in~ected water is eliminated after going once through the thsrmodynamic process, a big disad-vantage has to be considered. Make-up water has to be sup-plied at the set proportion to the consumed fuel. In the in-ventions related to the vaporizing cooling fluid discussed hereinbefore, the engine jackets form the essential elements of the steam generators. It must be realized that procuring water which is free from dis~olved minerals would be quite expensive, not to say prohibitive, especially whsn the re-quired quantity is a multiple of the quantity of fuel con-sumed. Mud and scale build-up is inevitable when commonly available fresh water is vaporized. The prob1em becomes serious if deposit3 form in the intricate pa~ses of the 6~
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cooling jacket~ of mo~ern e~gine~. Removing the coating ;~
formed on the outside surfa~e of the pipes arranged in a bundle inside a heat-exchanger may also be an almost impoe-sible task. Similar trouble may be experienced when liquid water i8 in~ected or sprayed, or even introduced as an emul-sion with the fuel, to be vaporized ln the combustion cham~
bers, in the cylinders, or in the attached pa~sages, leav-ing depo~ita that will obatruct the operation of the eng~ne~.
An attempt to deal with the problem has been made in the Canadian patent 523692. ~hi~ patent, however, does not relate to a once-through util~zation of the steam and the quantity of make-up water is rather small. ~he solution proposed provides ror the fre~h water to be fed into the swirling ourrent produaed in the ~team separator, where the ~ ;
hardness forming minerals would preaipitate. The precipitate would be bl~wn off periodically, presumably without be~ng entrained in the vaporization circuit.
Regarding the supercharging by the procedures used ln the present state of the art, it should be remarked that these prooedures consume u~eful energy, either by di~erting a part of the power from the crankshaft, or by converting some other form of usable energy. It has been already shown that dri~ing a turbocharger by a gas turbine utilizing the engine~s exhau~t gases i~ relati~ely uneconomical. It i8 to bo noted aleo that increasing the engine's compression by pre-oompre~ing the ¢harge without using a combustion modi-fier might bring about knocking.
GENERA~ DESCRIPTION OF HE I~VE~TION
In thie disclosure superheated steam with a pre~sure of 10 to 15 k ~ cm2ga and a temperature of 360 to 400C has been assumed as a desirable working medium, said medium to --- be generated by the heat recuperators.

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In thi~ invention, heat that would be otherwise wasted i~ recovered by genersting ~uperheated steam having relat~vely high parameters and the fluid 90 produced iB -~
utilized in apparatus integrated with the engines, to im~
prove their operation and their efficiency.
The #uperheated pressure ~team i~ produced in three ~uccessi~e steps, achieved in distinct device~, ar~
ranged in countercurrent to the flow of the combustion producte.
In the fir~t s*~p the feed water is preheated from its storage temperature to a temperature nearing, but appr~-priately below, its vaporization temperature, while being pumped and maintained at a pressure appropriately above the pre-#elected worklng pre#sure of the ~team. ~he preheated water i~ tran~ferred to the next step at such a rate as to make up for the produced (and consumed) steam.
I~ the second ~tep the water i~ subjected to vapor-lzstion while being kept in forced circulation, the water-steam mixture being di~charged in a separator from where practically dry saturated steam flows to the third step.
~he effluent water from the separator returns to the vapori-zation circuit, incorporating on its way the preheated make-up water.
In the thlrd ~tep the saturated steam 1~ ~uper-heated to a pre-~elected temperature, after which it i9 uti-lized to raise the potential of the internal com~u~tion process .
In the reverse order, considering the flow of the oombustion products, the third step includes the combustion proce~6 taking place at high te~perature in the working space of the engine. The hot products of the combustion give up part of their heat to the steam which flows through .... . . . .. . . .. .. ... ... . . ....

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a one-way system of cooling jackets provided around said working space, including the e~haust manifold, whereby the steam is superheated. It must b~ ~tressed upon that the primary funtion of the flow offluid in the jackets system i~ to continuously cool and maintain the metallic walls confin~ng the working space and the exhaust passages at a temperature level compatible with the construction and the operation of the engines. ~he superheating of the steam, whlch i8 essential to the successful recovery of waste heat, actually repre~ents a con~enient secon~ary function of the system.
In the ~econd step, the s~ill hot e~haust gases enter a heat-exchanger wherein the vaporization of the circulating water is achieved. In order that heat might 15 be transferred, the gases shall leave this heat-exchanger ~ , with a suitably higher temperature thAn the saturation temperature corresponding to the pre-selected stsam pres-sure.
In continuation, the e~haust gases are led to another heat-exchanger, where the first ~tep of heat re-covery take~ place. While the water is preheated, the tem-perature of t~e gases drop to a feasibly low final level, making thus available for a useful purpose a portion of the residual heat that, in different circumstances, would be dissipated. Cooling the exhaust gases to about 120 C, or below, is ~uite feasible in this way.
~ he superheated steam is used as motive power in an injector-compressor, by means of which the air, or fuel-air mixture, required for the operation of the engin~ is ~0 compressed or superchareed.
Particularly, when being di~charged through the steam nozzle of the injector-compressor, part of the -- 1~ --~4~2~ :

enthalpy of th~ superheated steam will supply the naeded mechanical work bg being converted into kineti¢ ~nergy.
~ecau~e of the relatively low efficiency of a proce~s based on the momentum of masse~, not all the capa¢ity for 5 producing mechanical work will be utilized in achie~ing the ~ ~ .
compression, but the unused kinetic energy as well as that portion of unconverted enthalpy of the injected ~team will not be wasted. In fact, the involved fluids will ~ix and their temperatures will equalize in the diffu~er a~d in the following passsges including the inta~e msnifold, thu~ sup-plying the engine with a working substance of increased po-tential energy. As will be shown hereinafter, euf*icient steam may be generated in the described syetem to meet the demand for boosting the intake pressure of a~y type of in-ternal combu~tion engine. In most ca~es the ~uperheatedste~m produced may actually exceed the quantity required ~or sald purpose. ~hie invention includes means providing for the utillzation of the excess eteam by feeding it with ap- ¦
propriate tim~ng into the working ~pace of the engine. In opposition to the energy lose exper~enced when introducing saturated steam into the combustion proce~s, in~ectine superheated steam with an enthalpy of about 770 kcal/kg will rèsult in an aotual gain in the engine's heat balance.
~he metallic walls confining the working space o~
the enelne will be maintained at higher temperatures than thoee prevailing with the customary cooling systems. In the reglon of the engine where the hot thermodynamic process takes place, the steam used as a cooling medium will reach a temperature nearing 400C, i.e. at_least 200 degrees higher than the temperature of the usual liquid coolants. However the temperature of said metallic wall3 will be prevented to ri~e above ~et limit~ by means pro~ided to achieve an active ~5 ~46~

heat convection from metal to the steam being superheated, thereby keeping the metal temperature C108e to that of the s~eam. ~aid mean~ consist of a succession of pas~es through which the steam i8 forced to flow at high speed, it be~ng guided 80 as to avoid stagnant pockets. ~he surface of the hot metallic walls, in co~tact with the ~uperheating ~team, ie provided with fins whi¢h have the double function of au genting the heat transferrin~ surface and of increasing the Reynolds number of the steam flow.
~esides, in this Invention, less heat will be di-verted ~rom the thermodynamic process by way of cooling be-cause Or the narrower temperature gap between said proces~ !
and the confining metallic wall~. On the other hand, the higher temperature of said walls will reduce the quenching of the ~ombustion and the emis~lon of pollutants.
Using steam for a coolant has the important advan-tage of avolding the buid up of scale and obstructions in the Ja¢ket sy~tem.
~ he minerals making up the hardness of the fresh water will precipitate mainly in the preheating heat-ex-changer, whlls the remainder will settle in the vaporizi~g heat-exchanger. ~y mean~ of speclal devices provided at the outlet headers of both heat-exchangers, the precipitates will be blown off automatlcally in the form of a sludge.
~oteworthy, in both heat-exchangers, the water flow~ through straight and easily cleanable tubes.
With the devised heat recoYery system, which is com-pletely integrated with the internal combustion engine, there i8 no need to dissipate heat until the exhaust gases ~0 reach the outlet of the exhaust 8y8tem. Conse~uently, the outer sùrface of all metallic parts which confine or carry .~
, . .

.4 ' the hot fl~ ids usefully employed m the operation, i~ pro-tected from losing heat by a ~uitable thermal insulation.
~he invention comprises Injector-compressors to ~ -supply the intaXe gaseous fluid~ with ~ncreased pres~ure.
The pre-compressed air, or air-fuel mixture, is supplied to reciprocating engine~ through their i~take manifold which includes a larger than usual distribution chamber, haYing the function of equalizing the supply to the s~ngle cyli~-der~. In the case of gas turbines, the pre compressed medi-um is conveyed through a tube forming the actual combustorof the engine.
The in~reased water~content of the combustible mixture, as a consequence Or being compressed through the in~ector-compressor by mean~ of ~team, will act as an effec-tlve k~ocking suppressor, making it possible to adopt higher compre~sion ratios. Accordingly, the combustion will take place at hi~her pres~ures than have been usea until now, re~ulting i~ more complete combustion reactions with a mini-mum of excess air.
On the other hand, because of their higher water vapor content, the mean specifi¢ heat of the combustion pro-ducts will increase. This will have the effect of lowering the peak temperature of the combustion, ~otwithstanding the oppo~ite tendency due to the higher pressure, and to the higher enthalpy of the supplied combustion air, or air-fuel mixture.
Iraintaining the intake manifolds under pressure will eliminate the intake suction work inthe four-stroke process, as well as the crankca3e pumping in the two-stroke process. These conditions will effect a change i~ the indi-cated diagram , by which the area representing the useful work will be augmented.

1~46Z~

~he economic result of the invention may be illus- ~
trated by the fol~ow~ng e~ample. ;
In the hypothe~is made hereinbefore, that the pro-duced steam should have the parameters of 15 k ~ a and 400C, the following heat amounts shall be exchanged in the ~ystem. A6suming that the stored feed water already con-tains about 20 kcal/kg and limiting its preheat to a tem-perature of at least 20 degrees below the vaporization tem-psrature, about 160 kc ~ kg will havc to be supplied in the heat-e~changer Q~ the first step. In the eecond step heat-èx¢hanger, where the vapori~ation occurs, about 482 kcal/kg will be supplied, making up for the enthalpy of 662 kcal/Xg of the saturated steam. In the third step l~L8 kcal/~g sha~l be transferred to the saturated steam, while it flows through the ~ackete syst~m. Adequate heat transfer areas will be pro~ided to suit these rsquirements.
If the ~yBtem i8 designed to produce that kind of superheated steam (having an enthalpy of about 780 ~cal/k~
at a rate of 4.5 kg for one kg o* fuel consumed, the heat recuperated and reintroduced into the thermodynamic cycle wlll amount to about ~420 kcal per kg fuel consumed. Of course, not all the heat recovered will represent a gal~, since after going through the proce~s, the steam will be evacuated at low pressure (at a partial pressure of about 0.51 to 0.66 k ~cm2abs) but stlll in the superheated state.
At 0.66 k ~cm2abs and at a temperature of 120C, which can be reasonably assumed for the combined exhaust gases being evacuated, the steam wlll have an enthalpy of 650 kcal/kg, resulting in a net gain, in the recuperation, of 110 kcal per kg of steam. This compares fsvorably with the net loss experienced with all prior sy~tems which generate saturated steam. ~he g8in 0~ 110 X 4.5 ~ 495 kcal representing 5.2 462;~; -:, of the heating value of one kg fuel i9 not negligible. ~ut the invention offers al~o the advantage of concentrating both major heat losses, experienced with all known internal combustion engines, in one single, substantially reduced - 5 heat waste. It can be demonstrated that the heat content of the combined exhaust gases evacuated from the engine, in the assumed conditions, will amou~t to about, or less than, -~
3600 kcal for one kg fuel consumed, reducing the total heat l~ss to about 38 %. In all existing types of engines this 10 lose i8 rated at 60 % or more.
~ here is no special reason to set the rate of steam produ¢tion at 4.5 kg per kg of fuel: an optimal rate might be determined after all relevant factor~ havs been investi- -gated. The amount of steam to be supplied to the injector-compressor depend~ on the engine characteristics, such as thermodynamic cycle, de~ired pre-compression, excess of com-bustion air, etc.Rates of 1.5 to 4.5 kg steam per kg of fuel are plausible. Adopting too low rates may result in rather ineffectual operations regardine the heat recuperation and the indicated diagram. Capabilities of steam production some-what higher than stri¢tly required shall be provided, but not to a degree as might be wasteful through largely in-crea~ed heat re~ection.
~he optimal rate of steam production shall match the normal power output of the eng~ns. With a variable power output, variations in the production of steam will occur.
Within limits, an adequate operation of the engine can be maintained by the means of control described hereinafter.
If the power output rises above the value set as normal, there will be more disposable heat converted into steam enthalpy. ~onversely a fall in the output will reduce the amount of would-be waste heat. There is a built-in .. .. . . . . . . . . . . ..

1~462~

inertia of the system which will take care of short-time fluctuation~ of the ~ariables. The provided controlling -means will react to more austained ~ariations, their purpose being to adapt the ~y~tem to changes in the englne output.
In consequence o~ an increased heat ~upply, one of the ~ollowing alternative~ i9 likely to occur: either the temperature of the superheated steam will tend to rise above the design limit becau~e the heat tn~fer from the combus- ;~
tio~-eYpansion process exceeds the heat amount required by 10 the saturated steam beinB produced in the ~aporizing heat- ' -exchanger, or the superheat temperature will drop substan-tially because steam i9 being generated in excess of the capability of superheating it.
A decrease in the heat supply may have opposite but similar effects. ~lther the temperature of the superheated steam will fall muoh below the normal value because insuffi-alent heat i8 transferred from the combustion- expansion prooess, or the superheat will sUrpass the pre-set limit be-; cause of the reduced steam production in the eecond step heat-exchanger.
To be noted that while a drop of the superheat in the range Or 20 to 30 deBrees C m~ght be accepted, a rise in tb~ temperature above the design limit should be avoided.
; A throttling device is mounted inthe passage Or the gases between the exhaust manifold and the vaporizlng heat-exchanger. Its function is to regulate the pressure with which the eases are evacuated from the working space at the end of the expansion. It is ob~ious that this device cannot control the quantity of gases flowing out of the exhaust manifold but by regulating the back-pressure exerted on the engine, it will influence the tem~ature of the exhaust gases. The throttling valve i8 actuated by a servomechanism z~

taking the impulse from a temperature sensor, located in the transfer pipe Or the superheated steam. If the superheat tends to rise above a set limit, the throttle reduces the free section of flow, causing the bac~-pressure to rise.
The temperature (and the anthalpy) of the exhaust gase~ will increase, augmenting the heat supply to the vaporizing heat-e~changer. ~he throttling valve is adjusted i~ ~uch a way that, in normal operating conditions, it will take an inter-mediate position between the most restricted section and the full open mg of the gas passage. Should the superheat fall below t~e acceptable limit, the throttle will increase its opening, causing a drop in the back-pre~ure. The tem- ~ `~
perature (and the enthalpy) of the exhaust gases will also arop and, consequelltl~, le~s water will be vaporized. It can be asserted that, in all the alternatives considered, the eguilibrlum between the interdependent variables of vaporlzation and superheat, will be restored by the action of the throttling de~ice.
Another variable to be considered i9 the temper-ature of the preheated water. A two-way damper, controlled by a thermostat, is inserted in the passage of the gases between the vaporizing heat-exchanger and the preheatin~
heat-exch~ngèr. If the water temperature rises abo~e a pre-set level, the thermostat causes the damper to rotate 80 as to di~ert part Or the heating gases through a tube, by-passing the preheating exchanger. ~he heat supply to the preheater can thus be reduced (and in exceptional circum-sta~ces, completely cut off). Should the temperature Or the preheated water fall off, no action would be required. ~he ~aporizing heat-e~changer will assume the task of heatin~
up the water and any reduction in the steam production will set into motion the described mechanism of adaptation of 4~2;~

the variables.
~ flow regulating valve, located in the efflux pipe of the preheating heat-exchanger, keeps the supply of make-up water in balance with the steam delivered by the ~ystem.
~he valve i8 linked with a liquid level controller mounted on the steam separator.
~ o facilitate starting the engine from a cold state (while no stBam i9 yet being generated) a suitable starting apparatus shall be provided, comprising a cranking motor coupled with an air compresqor. ~he delivered air shall have pressure just sufricient to entrai~ the intake air or air-fuel mi~ture through the injector compressor. A drive pin-ion, known as a Bendix drive, will crank the engine until the internal combustion process becomes operative, whèn said pinion w~ll di~engage. ~he starti~g motor will contin-ue to run, maintaining the supply of compressed air. Mean-w~ile all steam ~upply to the in~ector-compressor and to ; the engine's working space will be shut off by automatic de~ice~. When a pre-set minimum steam pressure has built up in the ~yetem, the starting motor will stop and the com-preseed air ~upply will cease. The steam will ~tart flowing through the in~ector-compressor, putting gradually the en-~ine on stream.
~he pre-compre~sion of the gaseous intake to the engine is controlled by a valve which regulates the flow of ~uperheated steam to the injector-compressor. The valve is actuatsd by a pressurs sensor mounted on the distribution chamber of the intake manifold. Concurrent or opposing im-pulses may be fsd through another transducsr to the servo-~0 me¢hanism of the valve. ~his maXes it possible to achievevariable compression rate in internal combustion engines without having recourse to expensive mechanisms.

. .. ..

~4~;Z~ :
;`:
DETAIIæD D~S~RIP~IO~ OF ~HE INVE~ION
A detailed description of thi~ i~vention will now be presented in connection with the accompanying drawings, ~ 't which illustrate some of its possible embodiments, and in 5 which: ~
~igure 1 is a flow diagram of an 1nternal combus- .
tion engine integrated with heat recuperator3; ::
~igure 2 i8 a sectional view of a heat-e~changer having the function of preheat~ng the feed water; :`
~igure 3 i~ a cross-sectional view taken along the line I-I of ~ig. 2 ;
~ igure 4 i8 a sectional view of a heat-exchanger, wherein the vaporization of the water takes place;
Flgure 5 i8 a cross-sectional view taXen along the line II-II o~ ~iB- 4 ;
~igure 6 is a fragmentary sectional:.view of a pre-oompressing (or supercharging) apparatus, comprising an in~ector-compres~or, the intaXe-manifold distribution chRmber, and pertaining control fittings;
Figure 7 is a fragmentary sectional view of a cylinder block showing the succes~ive passeQ of the ~ackets system throu~h which the flowing steam iB euperheated, while oooling the block;
Figure 8 is a sectional view taken along the line III-III of ~ig. 7 ;
Figure 9 is a v~ew of a ~acketed exhaust manifold with part of the shell removed;
Figure 10 i8 a cross -~ectional view taken along the line IY-I~ of Fig. 9 ;
~0 Figure ll is a fragmentary elevational view of a stea~ separating and water circulating and replenishing sub-system, including the pertzining regulating fitt~ngs;

1~146Z~:
~ igure 12 is a fragmentary elevational view of a make-up water supply apparatus;
~ igure 13 i8 a fragmentary sectional view showing a possible organization of the cylinder heads of a recipro-cating engine, integrated with heat recuperators;
~ igure 14 i3 a partial sectional view of the cyl~
inders head taken along the line ~-Y of ~ig. 1~ ;
Figure 15 i8 a fragmentary sectional view of a cy~der ~ a two-at~e en~i~e; :;
~igure 16 i8 a diagrammatic frag~entary view of a gaa turb~ne integr~ted wtt~ heat recuperator~, e~uipped w~h a two-stag~ pre-c~mpreu~i~g appa~atu~;
~igure 17 ie the ~iew, partly represented in per- ;
specti~e, of V-8 engine integrated with the heat recuper-ating 8y8tem, showing als~ the theTD~ ln~ulation to be in-stalled on the hot surfaces of the metallic parts.
In all rigures, identical or similar components or parts are designated by the ssme reference numerals.
It should be noted that thi~ invention is by no mea~s re~trioted to the embodiments represented in the ac-companying drawings, it being applicable also in other ways consistent wlth it~ stipulated principle~.
Reverting to Figure 1 , it can be seen that feed water from the storage tPnk 11 1~ pumped by the positi~e displacement pump 12 through the hest-exchanger 1 , where it iB preheated ~and from where it is conveyed to ~oin the va-porlzing circuit, under control of the flow regulating valYé 14 . ~he circulating pump 22 , taking suction from the steam separator 21 , maintains the separator's llquid efflux in a continuous flow to which the controlled amount of make-up water i8 added, the joint stream being forced to flow through the heat-exchanger 2 , where steam i8 generated.

~4~2~

A watsr-steam mixture *lows out of the heat-exchanger through a transfer line which dis~harges ~t into the steam separator 21 . The regulating valve 14 i~ linked with the liquid level controller 25 attached to the steam separator and haYing the function of maintaining feasibly constant the volume of water within the ~aporizing circuit. Depend-ing on the steam quantity being produced, water in excess may be discharged by the pump 12 , resulting in a pressure increase above the pre-set value in the preheating appara-tus. ~he relief val~e 13 will then open the way through aby-pass pipe, allowing the excess water to return to the storage tanX. During the preheatIng and furthermore during the vaporization process, the temporary hardness constitu-tinB minerals di~solved in the feed water precipitate and are entrained into the outlet headers Or the heat -exchPn-8er~ 1 and 2 , settling as a sludge in the bottom sectlon of said headers. Special blow-off devices 16 eliminate the sludge thus collected.
Practically dry saturated steam flows out of the steam separator through a vapor line equipped with the pressur6 regulating valve 26 . Said valve maints~ns the pressure in the vaporization apparatus substantially con-stant. ~he saturated steam enters the superheatlng system, flowing first through a finned tube ~ac~eted by the en~ine's ; 25 exhaust manifold 31 ~ then through the successive passes of the en~ine's Jsc~eting system 4 , attaining in the end the required supsrheat. A main transfer pipe conveys the super-he~ted steam to the injector-compressor 33 , to which it i9 supplied in the needed amount while being controlled by the regulating valve 34 . ~his valve is actuated by impulses from a pressure sen~or attached to the distribution chamber 36 of the intake manifold, into which the pre-compressed , 4~

air or air-fuel mixture i9 discharged. ~rom chamber 36 the gaseou~ medium i9 distributed through appropriate inta~e passages to the working space (or to the single working space~) ~ of the engine.
- 5 If the amount of superheated steam produced by the system exoeeds the demand of the injector, as regulated by the ~alve 34 , the pressure in the main tran~r pipe will increase. ~he pressure control valve 35 w~ll then ope~ the pa~sage for the excess steam i~to the secondary distributor 37 , from where it will be fed to the work~ng space 3 with suitable timing, and through separate intake devices.
The arrow 32 stand~ for the mechanical work pro-duced by the engine.
Heat is transferred to the saturated ~team being superheated,from the hot combustion gases through the wa1ls confining the work~ng space 3 ; then through the wall of the fi~ned tube located inside the exhaust manifold 31 .
~eaving this manifold, the ~till hot gases are conducted to the vaporizing heat-exchanger 2 . The throttling device .20 23 , installed in the duct between the engine and the ex-changer 2 , acts aB an enthalpy regulator of the exhaust ga~es, as was explained in the preceding ~sneral Descrip-tion. ~rom heat-exchanger 2 , the gase~ are conducted to the preheating heat-exchanger l through a duct provided with a by-pas~ and a two-way damper 15 . A thermostat, inserted into the preheated water outlet, controls the position of the damper, allowing for part of the exhaust gases to be diverted directly to the evacuation pipe, if 80 required.
~he preheating heat-exchanger 1 , ~hown in Fig-ures 2 and 3 , consists of a bundle o~ straight tubes en-closed in a cylindrical shell provided at both ends with ~46~ .

strong tube sheets into which the tube~ are tightly expand-ed. The make-up water i8 pumped into the inlet header lOl from where it flows through the pipes 105 , it being pre-heated by the exhaust gases flowing in the oppo~ite direc-tion outside the pipes. The preheated water leaves theheat-exchanger by way of the outlet header 102 .
~ he vaporizing heat-exchanger 2 , shown in ~igures 4 and 5 , co~prises æimilareLementa to those of heat-ex-changer 1 namelys one bundle of tubes with the ends expand-ed into tube sheets and enclosed in an elongated shell,having two headers attached ~t it3 ends, etc. ~he vapori-zing fluid stream, composed of the saturated water being re-cyoled from the steam separator and of the relati~ely cool-er preheated water coming from heat-exchanger l , i9 fed into the inlet header 201 whence it runs through the pipes 205 . ~rom the exhau~t gases, flowing in countercurrent out61de the pipes, heat is transferred in sufficient amount to restore the liqu1d enthalpy to saturation, and then to generate the reguired quantity of saturated steam. $he water-steam mixture thus obtained leavee the vaporizer via the outlet header 202 .
The size, number and length of the tubes in each bundle shall be 90 selected as to achieYe the de~ired heat transfer from the heating gases to the heated fh~ds. Speede of the heated fluid~ of at least 3 or 4 ~ sec are ad~isable in order to promote entrainment of the ste~m bubbles in the vaporizing exchanger and to avoid settlement of obstructions in the tubes of both heat-exchangers.
Heating will bring about the precipitation of dis-solved minerals, the precipitates bein~ carried by the cur-rent into the outlet headers 102 and 202 . Owing to the sudden ~lowing of the current when entering the much larger ~46Z~ ~:

section of flow, and to the upwards turn of its course, the i~
precipitates will ~ink to the bottom of the outlet headers.
The baffles 106 and 206 will prevent stirring of ~he col-le~ted sludge, which will be automatically e~aeuated by the 5 blow-off ~alve 16 . The ou~er ends of the headers are pro- -~ided with bolted ¢overs 103 and 104 , respectively 20~ and 204 , which can be removed for cleaning and maintenance purposes. ~ ~
While the headers 101 , 102 , 201 , 202 will be de- i signed to withstand a pressure of 20 k ~ cm2 ga, t~us allowing ;;
for ample eafety respecting the selected pressures of the water preheating and of the vaporiz m g systems, the shells being subjected to a pressure of less than 2 k ~¢m2 ga will be made of thinner metal plate. S1nce the shells are heated by the exhaust ga~es while the pipes are cooled by the flutds being heated, there results a difference in thermal expan~ion cau~ing strain in the shells' metal plate. ~o relie~e such ~train, the ~hells are provided with pre-formed expansion ;~
oorrugatlons 107 , respectively 207 . Depending on the over-all length of the tube bundles, one to three baffle plate~
108 , respectively 208 , are mounted inside the ~hells wlth the ob~eot of for~ing the flow of the heating gase~ to follow a ~inuous path through and across the bundles. Movement (oon-~ tra¢tion) o~ the pipes will not be hindered by the baffles, ; 25 these be~ng provided w~th oversize tube holes. ~o be noted, althou~h the ~igures 3 and 5 show the shells as having a cir-oular cross-~ection, any shape of croas-section suitabl~ a¢-commodating the array of tubes might be adopted.
Figure 2 shows that the duct 17 which conveys the eYhau~t gases to the heat-exchanger 1 , branchee off into the inlet paseage to the heat-exchanger and into the by-pass duct 18 . The by-pa~s rejoins the outlet psssage of . ~ .

L5 462;~

the gase~ from the heat-exchanger, combining into the evacu-ation duct 19 . The d2mper 15 mounted at the ~unct~on be-tween the inlet passage and the ducts 17 and 18 is actuated by the trsnsducer 152 , commanded by the thermo~tat 151 in-serted into the preheated water outlet nozzle. ~he functionof this damper has been explained in the General Description.
~ he tube 311 shown in ~igure 4 conducts the gases from the exhaust manifold of the engine to the throttling device 23 , which controls the enthalpy of said gases and consequently the heat supply to th~ heat-exchanger 2 , this important function having been explained in the General Description. From the throttline device the heatlng gases go through the intake passage 24 into the shell of the e~chan-ger 2 and, after completing the run therein, flow to the ex-c~anger 1 by way of duct 17 .
F~gures 4 and 16 offer a schematic illustration ofthe throttling device 23 , comprising a telescopic valve ac-tuated hydraulically or pneumatically by an automatic con-trol system. ~ald control system is based on the well known princ~ples and technologg used in the d~sign of such servo-mechanisms. ~he governing temperature of the superheated steam ie measured by a sensor located in the respective transfer line and ~hown a~ a dot in Figure 1 . Other types of throttles, actuated by feed-back control systems may be used to perform the described function.
~he evacuation of the precipitates mentioned in the previous description will be achieved by mesns of the auto- -matlc blow-off æystem shown diagrsmmatically in the Figures 2 and 4 . A control de~ice 161 is pro~ided in each of the drainage tubes connecting the outlet headers 102 and 202 with the ~alves 16. ~hese valves are operated by solenoid actuators 162 . ~he control device 161 consists of an elec-. . - . ~ . , . ,-tronic circuit, known as an optical isolator. ~he two main component~ of the isolator, namely a light emitter and a photocell, are mounted on opposite sideæ of the drainage tube facing each other. A~ sludge seeps in the water filled drain, down to the blow-off valve, gradually increasing the -~luid's turbidity, the intensity of the light beam falling on the photocell diminishes. ~he photocell, which is actu-ally a light depending resistor,will bé linked with the ele¢trical circuit of the solenoid in such a way as to cause the valve to open, given a sufficient dimming of the light and to close it again when the fIuid has become acceptably ; olear. A calibrated spring,integrated in the actuator 162 , will suitably counterbalance the solenoid action.
lhe saturated water-steam mixture is transferred in .*
a continuous forced etream from the vaporizing heat-exchan-ger to ~he steam separator 21 , a schematic detail of which 1~ shown in ~igure 11 , ~he misture i8 introduced tangen-tially through the inlet nozzle 211 into the annular space of the upper portion of the separator. ~he centr~fugal force resulting from the produced swirl separates the water, pro-Jecting it onto the outer wall of the separator drum, form-ing a layer which flows downwards, while the ~team rises in the central bell-shaped compartment 212 with slowed down mo-tion. A number of suitably arranged bafrles 213 guide the steam in a tortuous path, furthering the separation of the water droplets which might be entrained. ~rom the separator, the dried saturated steam flows through the nozzle 260 , the pressure regulating valve 26 and the vapor line 262 to the steam superheating syste~ (see also ~igures 1 and 17).
~0 Valve 26 i8 actuated by the transaucer 261 commanded by a pressure sensor. ~he satursted water collected in the en-larged section of the separator flows out through the pipe ... ~

~14Ç;~

218 which i8 actually the suction pipe of the circulating pump 22 . Beside~ separating the two phases of the circu-lating fluid, the separator maintains a feasibly constant reserve of saturated water in the system. The liquid level controller 25 , communicating with the steam separator through a liquid line 252 and a vapor line 253 , lets the float 251 to follow any sustained variation of the level occuring inside the separator. The baffle 214 will pre~ent disturbances in the movements of the float by the turbu-le~ce of the water. Through the correlated movements of the external forksd arm 254 , which are converted into driving forces by the transdueer 140 , the variations of the llquid level inside the separator will regulate the flow of the preheated make-up water through the ~alve 14 .
~he saturated water drawn by the pump 22 is dis-charged through the pipe 221 where it is mixed with the make-up water discharged through the convergent pipe 142 .
To prevent a backwards flow into the preheating system, a checkvalve 141 is provided between valve 14 and discharge pipe 142 .
~he steam trap 215 (of a suitable commercial type) will prevent flooding of the steam system, in 8C far as it will evacuate the water automatically, should the liquid level rise above the open end of the pipe 216 . Otherwise the steam trap will ~hut off any outflow of vapor.
~he pipe 217 will conduct the water evacuated by the steam trap back to the storage tanX 11 , as indicated in ~igure 12 . ~his figure includes some details of the feed-water system. ~he positi~e displacement pump 12 draws the wa-ter from tank 11 through the strainer 121 and discharges it under pressure through pipe 122 , which fseds the preheating heat-exchanger. As described above, the flow of the preheated 6~ ~
water, out of the preheating system, is regulated by the valve 14 . Depending on the steam consumption, the flow might be more or less restricted, bringing about pressure increases in the preheating circuit which will rebound in the discharge pressure at pump 12 . This will put into ac-tion the relief system consisting of the by-pass loop 123 comprising the relief valve 13 , whereby the pressure ex-¢eeding a pre-set value will be measured and converted by the specially designed transducer 131 into an impulse ac-tuating the relief valve through the line 132 . Should apersistent pressure increase occur, the transducer 131 will actuate, through the secondary line 133 , a switch that will stop the operation of the pump 12 . ~he pump will be auto-matically switched on, as soon as the pressure will drop to the normal operating value.
~igures 7 , 8 , 9 and 10 exemplify a steam super-heatinB system adapted to a multi-cylinder engine. Generally the ~team i9 guided through the system from the less hot to the hottest regions of the engine. Figures 9 and 10 show an exhaust mani~old 31 connected with the exhaust ports 49 (Fi6 7) through the passages 310 . The gases flow through the an-nular space formed around the steam carrying finned pipe 314 and leave through the tube 3~1 on their way to the above des-cribed throttling device 23 and to the following heat-ex-changers. ~ike the shell of the heat-exchangers, the body of the manifold 31 i8 made of thinner metal plate and is pro-vided with at least two corrugations 313 to compensate the strain due to the difference in thermal expansion between said body and the pipe 314 . Removable covers 312 give ac-cess to the annular s~ace for inS2ection, etc. ~he steampipe is equipped with several groups of longitudinal fins 315 , so arranged as to allow the uniform distribution of - ~5 -462~

the exhaust gas~ as they enter the annular space throu~h the passages 310 ; but otherwi~e increasing the area of con-tact between exhaust gases and metal and intensifying the heat transfer to the steam flowing inside the finned tube.
The ~team will become partlg superheated, meaning that it will attain an intermediate temperature between the tempera-ture of saturation, assumed at about 190C, and the final temperature of ~uperheat, assumed at about 400C. ~he devised system can be built to obtain a partial superheat of 250-~OCC.
The partly superheatcd steam is conducted through the inlet nozzle 41 into the engine's jacketing system 4 shown in Fig-ures 7 and 8 , where it attains the final superheat while serving as a coolant for the working space and the hot pas-sages of the engine. The illustrated jacketing system i8 par-titioned in three successi~e pas~es; a different number ofsubdi~isions ¢an be adoptsd if required to optimize the heat conv~ction. The metallic surface being swept by the steam is pro~ided with parallel fin~ 42 which guide the flow, and with trans~eree ridge~ 43 and 44 which ensure the uniform distri-bution of the flowing steam around the cylinder~, preventingalso stagnant pookets between ad~acent cylinders.
Casting of a cylinder bank as exemplified in the drawings, will require exact posit~Ling of the elaborate cores and their firm holding during the casting pro¢es~.
This is made po~sible by providing suitable openings in the lateral walle Or the block. These openings w~ll al~o permit frittering and removing o~ the cores after casting. The open-ings are closod with co~ers 46 , securily fastened to the structure of the lateral walls.
~0 Sturdy posts 45 will be part of this lateral struc-ture , serving also to guide the flow inside the jac~et.
Studbolts 47 will be screwed into the posts 45 for ~oining ~1462~ ~

the cylinders' head with the cylinders' block.
~ imilar details 3 , 4 , 42 , 46 , 47 may-be seen in the Figures 13 , 14 and 15 .
The ~uperheated steam leaves the jacket6 system through the outlet nozzle 48 which i9 connected with the main transfer pipe 340 (see ~igures 6 and 13).
Figure 6 exemplifies a pre-compressing or super- ;
charging appsratus, adapted to multi-cylinder engines. ~he in~ector-compressor 33 will perform the function ofs pre- ;~
compressing the combustion air in the case of compression-ignition engines; supercharging the air-fuel mixture i~ the case of carburetor engines; supercharging the air in the case of fuel-injectio~, spark ignition engines. In all ca~es the gaseous intake fluid (air or air-fuel) i9 drawn into the suotion chamber 333 through the nozzle 335 which is connec-ted with an approprlate induction pipe. ~he needed amount Or superheated steam is supplied through the transfer pipe 340 and the flow regulating valve 34 0 The needle 331 ser~es to adjust the steam flow through the inJector 332 in so far a~ it reduoes the inlet section of the injector, while being lengthened bythermal expansion when the superheat ri~e~, 2nd it enlarge~ said section while being contracted when the superheat drops. ~he steam ~et mixes with the ga~eous intake in the Yenturi tube 334 , the mixture being discharged with increased pressure into the distribution chamber of the in-take manifold 36 . ~he relati~ely large volume of this cham-ber and the baffle 361 placed in front of the inflow open-ing ensure the uni~orm ~upply to the single cylinders by way of the intake passages 362 .
~he steam supply to the injector-compressor i~ reg-ulated to mainta~n a pre-set constant pressure in the in-take manifold. To this effect valve 34 is linked in a feed-~i14~2~
back system with the transducer 341 mounted on the ma~ifold chambsr 36 . A æeparate l;nk 343 , connecting the servomotor of valve 34 with a pres~ure control unlt mounted on the en-gine's command panel, will be used either to modify at will the pre-set pressure, or to shut the regulati~g val~e in order to cut the s~ea~ supply during the start up procedure, as described in the General De~cription of the invention.
~he compressed air used for starting the ~ngine will be sup-plisd to th~ injector 332 throug~ the pipe 342 .
It should be ~oted that the wa~te heat recovery 8ystem i8 generally designed to produce s-team at a rate to ~atisfg the maximum demand of motive power of the injector-compressor. ~otal consumption of the steam thus produced will result in a basic pre~sure prevailing in the main trans-fer line 340 . Should the consumption be partially reduced, a~ a consequence of an intentional eteam overproduction, or of a transitory reduction of the steam demand, the pre~sure in the llne 340 will increase over the basic Yalue, signal- ¦
ing that 8urplu6 steam i~ available.
Figure3 13 and 14 illustrate details related to a multi-oylinder 4-stroke internal combustion engine. Besides the ¢omponents 36 and 362 of the intake manifold ~lready described, ~igure 13 exemplifies means for feeding directly into the working apace the superheated steam wh~ch may be produced in excese of the quantity consumed by the inieotor-oompressor. A c~oss-over pipe, integral with the flow con-trol valve 35 , branched off the transfer line 340 , supplie~
the superheated steam to the ~econdary intake manifold 37 which distributes it to the single cylinders by way of the intake duct~ 371 . The vslve 35 is governed by a pressure sensor mounted on the line 340 . ~eacting to the signal~ of . the pre~sure sensor, the valve 35 will open and stay so, as A

4Ç~

long a~ the pressure in line 340 i9 above the basic value.
~he ducts 371 convey the superheated steam into suitably shaped passage6 located in the cylinder head, from where it ~ ;~
is fed with appropriate timing ~to the cylinder6 through the secondary inlet valves 373 . ~he regular engine's intake and exhaust ~alves may be operated by a single cam~haft ~60 whiah iB continuously dr~vsn in a fixed relation with the rotation of the crankshaft. ~he secondary inlet valves are operated by a separate camshaft ~74 , which although being precisely liiked, as to timing, with the kinematic sy~tem of the engine, is set into motion by an automati¢ clutch which keeps lt in motion while steam is flowing through the valve 35 . ~he a~mshaft 374 shall be arranged 80 that the opening of the ~alves oommence at moments of time when the pressure in tho cylinders has dropped well below the pressure of the superheated steam. ~a~ellar val~es 372 are provided at the entran¢e to the steam passages, which will check any possl-ble baok-flow ~ the combusti~n gases i~to the steam system.
Spar~ plugs , or in~ection nozzles for compression-ignitlon enginee, will be installed in the ports 38 shown in the ~igure 14 (see also Figure 16). In the case of fuel-in~ectlon spark ignltion engines, another port shall be pro-~ided. All other numerals in ~igures 13 and 14 designate elements already aescribed.
~igure 15 shows some details re}ated to a cylinder of a two-strake en~ine, integrated with the waste heat re-co~ery apparatus. Here, the compressed medium is delivered through the centrally located intake ~alve, while the e~-panded ¢ombustion products are e~acuated ~ia the lower ex-haust ports. ~he superheated steam feeding valves are loca-ted on the side of the cylinder. ~he inlet valves 373 will discharge through port~ which will ~ta~ cov~ere~.when the , . . .

combustion process develops the highest temperature and pressure inside the cylinder. It should be noted that lo-cating laterally the inlet port for the superheated steam may be advantageous also i~ the case of four-stroke en-gine~
~ igure 16 shows the diagram of a gas turbine inte-grated with the de~ised waste heat recovery sy~tem. ~he turbine is completely jacketed. ~or convenience in the as-sembling of this type of engine, its ca~ing must be split along a plane containing the shaft axis. Each half of the ca3ing shall consist in turn of two separate parts joined together along a plane adjacent to the exhaust face of the rotor. When a~sembled, the ~acketing system 4 will consist of two ringli~e compartments, one of which will cover the exhau~t gases collector, while the other one will encase the stationary and rotating blsde systems and the distributor of combu~tion gases with attached combustor. The saturated ~team being fed by way of the vapor line 262 flows first through the compartment enclosing the exhaust collector, whereby it beco~es partially superheated, then it crosses o~er to the oompartment encasing what actually forms the hot working ~pace of the engine, where it completes its super-heating oycle. The steam serves throughQut the turbine as a coolant for the hot metallic walls. The inlet of th~ satu-rated steam, the crossover 316 which allows the passage be-tween the two compartments,and the outlet of the superheated steam are conveniently located, so that the steam being su-perheated follows a one-way path, feasibly in countercurrent with the flow of the hot wor~ing substance. The superhe~ted steam is admitted through the flow regulating valve ~4 and the connected supply lines to both the injectors of the two-stage compressor. ~he first-stage suction chamber is con--~146~
nected with an induction tube supplying the gaseous medium ~ ;
to be pre-compr~ssed (air or air-fuel mixture). ~he Venturi tube 33 of the first stage discharges into the suction chamber of the second stage of the compressor. ~he second-ætage Venturi tube 330 discharges directly into the combus-tor of the gas turbine. ~onverging ports 38 , located near the intake end of the combustor, are used for the seating of sparXplugs and/or of fuel injecting device~, as may be required by the particular internal combustion process beinB adopted. Similarly to the valve designated by the same numeral in Figure 6 , the regulating valve 34 is actuated by a pre~sure transducer with the difference that, in the case of gas turbines, the governing parameter i8 the pres-sure attained in the combustor after the combustion has taken place. The servomotor of the valve 34 is also connect-ed with an additional line 343 transmitting adeguate signPl8 from the command panel of the engine which may modify, at will, the prevailing pressure in the combustor, and also may cut off the communication between the superheated steam system and the in~ector-compressor during the starting up of the turbine. aompressed air for starting will be supplied in the previously descr~bed manner through the nozzle ~42 .
The exhaust gases are led out of the turbine by way of the duot 311 through the throttling device 23 , the function of which has alre~dy been explained.
A~ in all other type~ of internal combustion en-gines integrated with waste heat recovery systems described as forming the ob~ect of the pre~ent invention, the ga~ tur-bines will be pro~ided with suitable thermal insulation that will minim~ze the heat dissipation into the atmosphere.
The numerals 51 , 54 , 621designate some of the types of insulation which will be described hereinafter.

_ 41 -4~2~:
~igure 17 exemplifies the embodiment of the inven~
tion in a V-8 internal combustion engine. lhe engine proper ;-is represented in axonometric projection, while the other ~ -components are shown separated and spread out for the sake of clarity. ~or obvious reasons not all the numerals desig-nating previously described parts have been reproduced. ~he drawing shows how, in this case, the vapor line 262 divides into two lines 314 , each supplying the saturated steam to one of the two jacketed exhaust manifolds of the engine.
10 ~his i8 not the case in ~ig>ure 16 , where the vapor line -262 delivers the steam directly to the inlet of the jacket system.
As was mentioned in the General Description, the in-vention ~ncludes a thermal insulating system devised to feasibly reduce the heat dissipation into the surrounding atmosphere. ~hermal insulation is applied over the exposed surface of the metallic parts, or else encases single de-vices, which confine or carry the hot substances contribu ting usefullg to the operation of the engine. ~he insula-ting materials and components shall comply with the follow-ing requirements: efficient heat conservation, stability at the operating temperature, and resistance to repeated dis-mantling and rea~sembling of the parts. Compliance with the last requirement i9 achieved by seleCting quitable in-sulation textures and by adequate desi~n of its protectivecovering. Relative to the other two required properties, efficiency and stability, it is considered that the three following grades, or classes, of insulation will suitably correspond to the intended application of the inventior,:
high temperature insulation gOoa to about 1000C, medium-high t~erature insulation good to about 550C, medium-low temperature insulation good to about ~50C.

`:
:

In Figure 17 the numeral 51 designates the insula- -~
tion which covers the jacketing system. It consists of in~
sulating blankets, good to 550C, held in place and protec-ted by sheet metal coverings. ~he same type of insulation, -5 designated by numeral 59 , shall be used for the heat-ex-changer 1 ; while the insulation 60 , covering the heat-exchanger 2 , shall have blankets good to 1000C. Similar insulation but of lesser ouality (35~C) designated by the numerals 57 , 58 , will be provided respectively for the steam ssparator 21 and the liquid level controller 25 .
l~olded insulations 52 ard 53 made of high tempera-ture quality material (1000~), provided with hard protec- `
tive oovering, shall enclose the exhaust manifold 31 and the exhaust passages 310 . Similar molded components 55 and 56 made of medium-high temper&ture insulation (550C) enclose the distribution chamber 36 and the secondary manyfold ~7 .
Single devices will be enclosed in metal boxes pad-ded with suitable insulating materials, said boxes being designed for easy dismantling with a view to inspection and maintenance. Such insulating components are designated with the numerals 54,61 and 632 and serve to insulate re-spectively the in~ector-compressor 33 , the recycling pump 22 , and the throttl~ng device 23 . Similar insulating boxes designated with the nu~eral 63 will enclose various control and regulating valves; while components marked 631 will insulate the valves 34 and 35 , handling the super-heated steam.
Most piping and the exhaust gases duct 17 will be provided with medium-lo~Y tem~erature in~ulation, numerals 62 , respectiYely 65 , mPde o~ mineral wool wrapped in shock resistant covering. A sirilar type of insulation, 1~4~

of medium-high temperature quality~ indicative 621 , will be used for the pipes 340 and 371 carrying superheated ~;
steam; while the tubes 311 and the duct 24 , conducting hot eYhaust gases, shall be insulated with high temperature fibrous material, numerals 622 and 64 .
Heat insulating pads, indicative 66 , made of high temperature material and having the upper side protected by a metall~c sheet, shall be installed on top of the cyl-inder heads. ~he sealing gaskets 67 ~hall also offer ade-quate insulating properties to brea~ the heat conductionbetween the cylinder blocks and the underlying casings or metal bases.
As was disclosed in the foregoing description, vari-ous controlling devices contribute to the operation of the engines integrated with heat recovery apparatus. The relief, control and regulating devices, as well as the transducers and actuating mechanisms may be available as commercial products, or they may be designed to suit specific require-ments but still conforming to known models. Included are, however, other accessories which, though similar to de-vices already in use, will require basic adaptations in order to perform new functions, consequently qualifying as innovations. Examples of such innovations are the throt-tling device 23 (~igures 4 , 16 ) and the two-way damper 2~ 15 (Figure 2 ) 0 ~he dual controlling function of the trans-ducer apparatus 131 , 132 , 133 (~i~ure 12 ), and the dual link actuating the valve 34 (~i~ures 6 , 16 ) illustrate other innovative ideas. It should be noted that the auto-matic blow-off device 16 , 161 , 162 , as represented dia-grammatically in ~igures 2 and 4 , complemented by the re-spective description, is to be considered a characteristic part o~ the invention, although it has in its composition Çi2~ :
devices used in known applications. ~ -Note: ~he term 'working space' used in the present .
disclosure and in the following claims is understood to define the engine's confined space wherein the fuel com- ;
bustion and the subsequent expansion of the combustion products take place.

Claims (21)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In combination with internal combustion engines of any known type, and functionally integrated with the same, apparatus recuperating heat that would otherwise be wasted, whereby liquid water is stepwise heated, vaporized and superheated in countercurrent with the flow of the combustion products, the superheated steam thus generated being operatively used in the said engines, said apparatus comprising means to supply make-up water at a pressure ap-propriately higher than the selected working pressure of the produced steam, a heat-exchanger wherein the make-up water is preheated to a temperature nearing but appropri-ately below its saturation temperature, means to convey and discharge at a controlled rate the preheated water into a circulating stream of saturated water, a vaporizing heat-exchanger wherein heat is transferred to the mixture of circulating saturated water with the relatively cooler pre-heated water to restore the saturation enthalpy of the liq-uid and also to generate steam whereby a saturated water-steam mixture is delivered through a transfer pipe in a continuous forced stream, a steam separator having the func-tion of separating the two phases composing the mixture transferred from the vaporizing heat-exchanger whereby dry saturated steam is obtained while saturated water is drawn by a circulating pump, means to maintain a constant liquid level inside the separator by which an adequate supply of make-up water in relation to the steam produced is attained, means to blow-off automatically, in the form of a sludge, the hardness constituting minerals which precipitate and collect in both the preheating and vaporizing heat-exchangers, a superheating apparatus consisting of a heat transferring element jacketted by the engine's exhaust manifold wherein the saturated steam is partially superheated, and of a one-way sequence of jacketing compartments, provided around the engine's working space, wherein the partially superheated steam is superheated to the desired final temperature while serving as a coolamt for the engine, an apparatus for pre-compressing the combustion air or the air-fuel mixture that form the gaseous intake of internal combustion engines, com-prising an injector-compressor or, in the case of a gas tur-bine, comprising a two-stage compressor consisting of two injectors mounted in series, means to supply the superheated steam as motive power to said injector-compressor, or to said two-stage compressor, means by which superheated steam, that might be produced in excess of the quantity demanded as motive power by the pre-compressing apparatus, is supplied to the working space of the engine with appropriate timing, means to regulate the back-pressure in the exhaust manifold thereby controlling the enthalpy of the combustion products evacuated from the engine's working space and consequently controlling the heat supply to the vaporizing heat-exchanger, means to control the supply of warm exhaust gases to the preheating heat-exchanger in relation with the temperature of the preheated water, apparatus to start the cold engine while no steam is yet available comprising a cranking motor coupled with an air compressor, said compressor to supply temporary motive power to the injectors of the pre-com-pressing apparatus, and a thermal insulating system that will prevent heat dissipation from the metallic parts con-fining or carrying the hot substances usefully employed in the operation of the engine.

2. In combination and functionally integrated with internal combustion engines, apparatus recuperating heat that otherwise would be wasted, by means of which liquid water is preheated, vaporized and superheated in distinct steps and through separate constituent means, arranged in countercurrent with the flow of the combustion products, whereby the superheated steam thus generated is used in the operation of said engines, said apparatus comprising a make-up water storage tank, a positive displacement pump pumping water from said tank through a preheating heat-exchanger equipped with tubes through which the water flows and is preheated by exhaust gases flowing in countercurrent outside the tubes, a flow regulating valve discharging the preheated make-up water, at a controlled rate, through convergent piping into a stream of recycling saturated water, a thermo-stat operated two-way damper allowing for part of the ex-haust gases to by-pass the preheating exchanger and thus con-trolling the heat supply to the water being preheated, a vaporizing heat-exchanger equipped with tubes through which the joint stream of said recycling saturated water and pre-heated make-up water is maintained in continuous forced cir-oulation while, from exhaust gasses flowing in countercurrent outside the tubes, enough heat is transferred to restore the saturation liquid enthalpy and to generate steam in the needed guantity whereby a steam-water mixture is produced, a throttling device located in the duct leading the exhaust gases to the vaporizing heat-exchanger and having the func-tion of regulating the back-pressure in the exhaust mani-fold of the engine, thereby controlling the enthalpy of the exhaust gases and consequently the heat supply to said heat-exchanger, a steam separator to which the produced steam-water mixture is conducted from the vaporizing heat-exchanger and into which said mixture is intoduced tangen-tially being separated by the resulting centrifugal effect into saturated water which collects in the bottom section of the separator, and saturated steam which, after undergo-ing further drying, leaves the separator through a vapor line, a pressure regulator mounted in said vapor line, a circulating pump taking suction from the separator's bottom section, serving to recycle the saturated water, a liquid level controller attached to the steam separator, which con-trols through a servomechanism the aforementioned flow reg-ulating valve discharging the preheated water, a check valve to prevent backwards flow from the recycling circuit into the preheating system, a by-pass loop provided with a relief valve connecting the discharge pipe of the aforemen-tioned positive displacement pump with the water storage tank, an automatic blow-off system to evacuate the hardness form-ing minerals which precipitate in the preheating heat-ex-changer and accumulate as a sludge in the outlet header thereof, said system comprising an optical isolator and a solenoid actuated blow-off valve, an identical blow-off sys-tem for the vaporizing heat-exchanger, a superheating appa-ratus composed of a finned tube located inside the engine's exhaust manifold, wherein the saturated steam flowing from the steam separator is partially superheated and of a one-way sequence of Jacketing compartments enclosing the engine's working space, wherein the steam is further superheated to the desired temperature while serving as a coolant for the hot walls and the passages of said working space, a main transfer pipe through which the superheated steam flows out of the superheating apparatus, a sensor which measures the temperature of the superheated steam mounted on said trans-fer pipe, said sensor governing the afore-mentioned throt-tling device, a pre-compressing apparatus consisting of an injector-compressor or, if a higher compression is needed as in the case of gas turbines, consisting of a two-stage compressor comprising two injectors mounted in series, said apparatus serving to pre-compress the gaseous intake to the engines, whereby the pre-compressed intake is discharged into a distribution chamber functioning as intake manifold for multi-cylinder engines, or into the combustors of the gas turbines, a flow regulating valve supplying the super-heated steam as motive power to the injectors of the pre-compressing apparatus, a pressure sensor mounted on the dis-tribution chamber or on the turbine's combustor to govern said regulating valve, secondary intake valves to feed di-rectly and with appropriate timing superheated steam into the engine's cylinders if such steam is produced in excess of the demand of the described pre-compressing apparatus, a pipe branched off the main steam transfer pipe to supply the surplus superheated steam to said secondary intake valves through a flow control valve and a secondary intake manifold, said control valve being governed by a pressure sensor set on the main transfer pipe, a check valve provided in the pas-sage of each secondary intake valve to prevent back-flow of combustion gases, a steam trap mounted on the aforementioned steam separator to prevent flooding of the steam system if the liquid level in said separator tends to rise above a pre-set limit, and a thermal insulating system to minimize heat loss from the hot substances that are useful in the op-eration of the engines.

3. In combination with internal combustion engines, apparatus recuperating heat according to claim 1 , whereby superheated steam having controlled pressure-temperature parameters is generated at predetermined rates in relation to the consumed fuel, the superheated steam parameters ranging from 10 to 15 kg/cm2ga and from 360 to 400°C, and the steam production rate ranging from 1.5 to 4.5 kg per 1 kg of fuel consumed.

4. Apparatus recuperating heat according to claim 2 , wherein make-up water is preheated while flowing through the tubes of a first heat-exchanger, and wherein the preheated water is added at a controlled rate to a re-cycling stream of saturated water, the joint stream of preheated and saturated water being forced to circulate through the tubes of a second heat-exchanger wherein it is subjected to further heating and to vaporization, both preheating and heating-vaporization being accomplished by heat transferred from exhaust gases flowing in countercur-rent outside the tubes of the heat exchangers, each of said heat-exchangers being equipped with an inlet header and an outlet header through which the water flows in and out of said tubes.

5. Apparatus according to claim 2 , wherein satu-rated steam, after being partially superheated by heat trans-ferred from the engine's combustion products while it flows through a finned tube located inside a collector functioning as exhaust manifold, is conducted into the engine's jacket-ing system wherein it flows in a one-way path from the less hot regions to the hottest regions of the engine thereby be-coming superheated to a pre-set final temperature, heat for this purpose being supplied by the hot metallic walls con-fining the engine's working apace and by the attached hot passages, whereby the steam being superheated serves as a coolant for said metallic walls and said passages.

6. Apparatus according to claim 5 , wherein the metallic walls confining the engine's working space are cooled by pressure steam being superheated, whereby said walls and the surfaces thereof which are in contact with the thermodynamic process are maintained at temperatures corresponding to the steam superheat by means that inten-sify the heat convection from metal to steam, thereby lessening the quenching of the combustion within the working space of the engine.

7. Apparatus according to claim 5 , wherein steam serving as a cooling medium flows through the engine's jacket, said jacket being partitioned into successive compartments, whereby the surface of the hot metallic walls being swept by said cooling medium is provided with fins projecting inside the jacket and with transverse protuberances or ridges which guide the cooling medium and are arranged so as to prevent the forming of stagnant pockets, in multi-cylinder engines also between adjacent cylinders, the number of the successive compartments and the fins and ridges being so designed as to obtain best suited speeds of the steam flow and best conditions for the heat convection from metal to steam.

8. Apparatus according to claim 5 , wherein a pipe provided with external longitudinal fins arranged in groups, is located inside an elongated body made of thinner metal plate, which body is connected with the engine's exhaust ports to form an exhaust manifold, and is provided with at least two corrugations to relieve the strain due to dif-ferences in thermal expansion between said body and the finned pipe, said finned pipe carrying saturated steam which is being partially superheated by the exhaust gases flowing in countercurrent through the annular space around the pipe, the groups of longitudinal fins being arranged to allow for an uniform distribution of the exhaust gases in the annular space, and otherwise to activate the heat transfer from exhaust gases to steam.

9. Apparatus according to claims 2 and 4 , wherein heat from exhaust gases is transferred to the make-up water being preheated and to the circulating water being heated and vaporized, by means of separate heat-exchangers con-sisting, each, of a bundle of straight tubes enclosed in an elongated shell provided at both ends with tube sheets into which the tubes are tightly expanded, and with two outer com-partments attached to the tube sheets forming the inlet and outlet headers of the heat-exchangers, the inlet header having an inlet nozzle at its bottom and the outlet header having an outlet nozzle at its top, both headers being pro-vided with removable covers for cleaning the tubes, the out-let header being also provided with a drainage tube located at its bottom and with a baffle to shield said drainage from trubulence, the headers being designed to withstand a pres-sure of up to 20 kg/cm2 ga, while the shell enclosing the tube bundle, being subjected to a pressure of less than 2 kg per cm2ga, is made of thinner metal plate, said shell being provided with pre-formed expansion corrugations and with appropriate inlet and outlet passages for the exhaust gases, whereby, depending on the length of the shell, one to three baffle plates are mounted inside the shell to guide the flow of the exhaust gases through and across the tube bundle, the size and number of the tubes composing the tube bundle in each heat-exchanger as well as the overall length of the shell and tube bundle system being designed to achieve the adequate conditions for the required heat transfer.

10. Apparatus according to claim 4 , whereby dis-solved minerals, forming the hardness of the make-up water, precipitate in the tubes of the heat-exchangers during the preheating and furthermore during the vaporization taking place therein, the precipitates being carried by the fluids flowing at speeds of 3 to 4m/sec, into the outlet headers wherein , owing to sudden change of direction and slowing of the current, they separate and collect as a sludge in the bottom section of said headers, from where aid sludge is evacuated by means of automatic blow-off systems.

11. Apparatus according to claim 4 , wherein each heat-exchanger is equipped with an automatic blow-off system, said system being composed of an electronic control device consisting of a light emitter and a photocell mounted on opposite sides of a drainage tube and facing each other thus forming an optical isolator, and of a solenoid actuated blow-off valve, the electrical circuit of the solenoid being linked with the optical isolator 80 as to cause the valve to open when the turbidity of the fluid , due to the col-lected sludge, has reached a given intensity, and to close again when the fluid has become clear, the solenoid action being balanced by an appropriate spring.

12. Apparatus according to claim 2 , wherein a throt-tling device is mounted in the duct leading the exhaust gases from the exhaust manifold, or from the exhaust system of the engine, to the vaporizing heat-exchanger, said device serving to regulate the back-pressure in the exhaust mani-fold, or system, thereby controlling the pressure and the enthalpy of the combustion products being evacuated from the engine, and consequently regulating the heat supply to said heat-exchanger, the throttling device being actuated by a servo-mechanism comprising a temperature sensor located in the transfer pipe of the superheated steam, said mecha-nism causing the heat supply for the vaporization to in-crease by closing the throttle when the temperature of the steam exceeds a pre-set value, and conversely causing the heat supply to be reduced by opening the throttle when said temperature drops below a pre-set limit.

13. Apparatus according to claim 2 , wherein the heat-exchanger serving to preheat the make-up water is equipped with a two-way damper mounted at the junction of the exhaust gases duct with the inlet passage to the heat-exchanger and with a by-pass duct, said damper controlling the heat supply to said heat-exchanger by allowing for part of the exhaust gases to flow through the by-pass, the damp-er being actuated by a transducer including a thermostat located in the outlet nozzle of the heat-exchanger.

14. Apparatus according to claim 5 , wherein the exterior walls of the jacketing compartments are provided with suitably shaped and sized openings to facilitate the exact positioning and firm holding of the cores during the pouring of the molten metal, and the frittering and removal of said cores after completed casting, said openings being tightly closed with bolted covers, when in use.

15. Apparatus according to claim 2 , comprising a steam separator composed of an upper cylindrical section and of a lower larger section joined together by a widening sec-tion, enclosing in its upper section a bell-shaped compartment providing an annular space into which the saturated steam-water mixture, being transferred from the vaporizing heat-exchanger, is introduced tangentially through a nozzle near the top of the separator whereby the centrifugal force re-sulting from the produced swirl separates the water, projec-ting it onto the outer wall of said annular space and build-ing up a layer which flows downwards to collect in the larger bottom section of the separator, while the steam rises through the bell shaped central compartment wherein it is forced to follow a tortuous path formed by a series of baffles furthering the separation of water droplets that might be entrained, the dried saturated steam flow-ing out through a nozzle located at the top of the sepa-rator, a stream of saturated water being drawn by a pump through a nozzle located at the bottom of the separator, whereby a constant volume of vater is maintained in the separator by means of a liquid level controller communi-cating with the steam separator through a liquid line and a vapor line, said liquid level controller actuating through a servo-mechanism the flow regulating valve which discharges the preheated make-up water into the stream of pumped saturated water, the high level of the water in the separator being also limited by a pipe which can eva-cuate the excess water through a steam-trap.

16. Apparatus recuperating heat according to claim 1 wherein superheated pressure steam is used as motive power in a pre-compressing apparatus comprising one injector-com-pressor, or two injector-compressors mounted in series, wherein part of the enthalpy of said steam is converted into kinetic energy through nozzles producing steam jets, whereby the gaseous intake of the engine, being drawn by the suction of the steam jets, is discharged from said pre-compressing apparatus mixed with steam and with increased pressure and temperature, thus supplying the engine with a gaseous intake having an increased potential energy, and whereby the water vapor mixed with the engine's working sub-stance acts as a knocking suppressor and, besides, by in-creasing the mean specific heat of the combined combustion products, lowers the peak temperature of the combustion, notwithstanding the higher potential of the gaseous intake.

17. Apparatus according to claim 1 , wherein an in-jector-compressor performs the function of pre-compressing or supercharging the combustion air , or the air-fuel mixture, that forms the gaseous intake of the internal com-bustion engines, and discharges said gaseous mixture into a recipient forming the intake manifold of a reciprocating engine or the combustor of a gas turbine, whereby super-heated steam, which is produced by recuperating heat that would otherwise be wasted, is supplied as motive power to said injector-compressor, the superheated steam supply being controlled by a flow regulating valve so as to main-tain a pre-set pressure in said recipient, said valve being actuated by a servo-motor which is connected in a feed-back system with a pressure sensor mounted on the respective recipient, the servo-motor being also connected with a separate pressure control device serving to modify at will the value of the pre-set pressure governing the regulating valve, and to cut off the steam supply during the engines' starting-up procedure, an additional adjustment of the flow of superheated steam as motive power being achieved by means of the expansion or contraction of a needle reducing or enlarging the inlet gap of the steam injectors in res-ponse of variations in the temperature of the steam.

18. Apparatus according to claim 1 , wherein means are provided to dispose of the superheated steam that might be produced in excess of the quantity demanded as motive pow-er by the compressing apparatus, whereby the pressure in the main pipe supplying the superheated steam increases beyond a pre-set value, said means comprising a pipe which is branched off said main pipe and which is equipped with a flow control valve, a pressure sensor mounted on the main pipe actuating said flow control valve by keeping it open as long as surplus superheated steam is available as a con-sequence of the increased pressure, a secondary intake system including a manifold feeding the available super-heated steam to the cylinders through suitable passages, which are located either in the cylinders head or on the side of the cylinders, secondary inlet valves lodged in said passages and operated with appropriate timing by a secondary camshaft, said camshaft being set into motion by a clutch and being kept moving only while steam is being fed through the flow control valve, the timing of the second-ary inlet system being so arranged that the opening of the valves commence when the pressure in the cylinders is well below the pressure of the superheated steam, whereby in order to prevent back-flow of combustion gases into the steam system a check valve is provided in each secondary inlet passage.

19. Apparatus according to claim 2 , comprising a feed water system composed of a storage tank, a positive displacement pump taking suction from said tank and dis-charging into the feed pipe of the preheating heat-ex-changer, a by-pass loop between the pump discharge and the storage tank including a pressure relief valve, a transdu-cer controlling the discharge pressure of the positive-dis-placement pump by opening the relief valve and establishing a flow back to the storage tank, when said pressure exceeds temporarily the selected value of the working pressure of the water preheating system, while if no make-up water is needed and a persistent pressure increase occurs, a secondary trans-ducer line will switch off the driving motor of said pump.

20. Apparatus according to claim 1 , wherein means are provided to start the engine from a cold state, while no steam is yet available and all admission ways of the steam to the compressing apparatus and to the engine's working space are automatically closed, said means consisting of a starting motor coupled with an air compressor, said compres-sor delivering air as temporary motive power to the said com-pressing apparatus, and with a driving pinion by means of which the engine will be cranked until the combustion process becomes operative, when said driving pinion will disengage automatically, whereby however the starting motor will con-tinue to run, thus maintaining the supply of compressed air until a pre-set steam pressure has built up in the steam generating system, when the starting motor will be switched off, while steam will start flowing through the compressing apparatus putting the engine gradually on stream.

21. Apparatus according to claim 1 , wherein there being no need to dissipate heat until the exhaust gases reach the outlet of the exhaust system, a feasibly complete thermal insulating system is provided which will minimize the heat loss into the surrounding atmosphere through the metallic walls and other parts confining or carrying the hot substances contributing usefully to the operation of the engine, whereby the only major heat loss of the internal combustion engine will be the reduced amount of heat being rejected with the cooled exhaust gases.