DE2336151A1 - COOLING OR COOLING MACHINE - Google Patents

Description

Cooling or chiller,

Priority: Australia from 07/17/1972

The invention relates to refrigerating machines and in particular refrigerating machines or refrigerating machines, hereinafter for the sake of simplicity called "cooling machines", of the jacket-tube type. Shell-and-tube machines are those in which the evaporator and condenser chambers are constructed in the form of elongated hollow shell formations are, with heat transfer tubes passing through in the longitudinal direction. The evaporator and condenser chambers can have separate jacket constructions or, alternatively, the evaporator and condenser chambers be formed by an insulated partition wall within a single shell structure.

To increase the capacity of refrigeration machines of the type mentioned above, two compressors connected in parallel can be

309886/0405

ORIGINAL INSPECTED

sensors are used to allow greater cooling gas flow rates in the system.

Apart from the advantage of the larger capacity, the use of two compressors enables a controlled load distribution the compressors, so that the machine operation becomes more stable and efficient. Is the load share low, it is preferable to use a single compressor operating at a relatively high load level instead of using two compressors operating at relatively low load levels because of the characteristics the compressors are worse at low load levels.

The compressors commonly used in this type of refrigeration machine are centrifugal compressors, which are normally equipped with automatic controls to reduce the gas flow therethrough so that the overall performance of the refrigeration machine can be regulated to meet machine performance requirements. It is clear that if the chiller is used for air conditioning purposes, the load requirements will vary according to the prevailing climatic conditions. Therefore, a considerable change in load can be expected during normal operation. Unfortunately, the performance curves of the centrifugal compressors are such that if the gas flow is reduced below about 90% of the maximum value, the pressure head available at the compressor can be reduced slightly. So if two centrifugal compressors are used in parallel in one refrigeration machine

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find, problems often arise in operation because the both apparently the same compressors do not have exactly the same characteristics under all load ratios have sen. Especially when a compressor is at a low fraction of its power works, then its output pressure level will not be the same as that of the other compressor and therefore it will easily get into the State of pressure drop, the so-called "stalling". This condition is well known per se and is readily recognized and recognized by those skilled in the art so-called Tumpbetrieb "of the compression disturbed compressor (with stall) accompanied what by a intermittent or pulsating operation or accompanied by a complete cessation of the flow of cooling gas will. The most unpleasant effect of the pulsating pumping condition or the pulsating, disturbed compressor delivery is a loud rattling noise that occurs at an application to air conditioning is highly undesirable. Other disadvantages of the pumping operation are Peak loads in the electrical supply when the compressors are electrically driven. Still exists the possibility of damage to the impeller or impeller blades if the pumping conditions are above a sustained for a substantial period of time. If there is a complete pressure drop or "stalling" of the compressor this means there is a risk of overheating.

In order to cope with the above problems, it has been suggested that provide separate condenser structures with associated compressors; through this arrangement however, the cost of the device becomes more significant

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Way increased, since two or more separate capacitor constructions will be required.

The main object of the invention is a refrigeration machine of the type indicated above, which takes advantage of the two compressors the construction being such as to substantially reduce the problem of "pumping" and nevertheless the need to provide separate capacitor constructions is avoided.

According to the invention, a cooling machine with an evaporator and condenser is proposed, which is characterized in that the condenser is divided into at least two condenser chambers; that a separate compressor for each condenser chamber is provided, wherein the inputs of the compressors are in connection with the evaporator and the output each is in communication with the associated condenser chamber. Of course there can be two or several capacitor sections with the associated compressors can be provided, but for most applications two is an optimum.

The evaporator and condenser can consist of separate structures or, alternatively, a single subdivided structure, the latter being preferred because of the cheaper structure. The condenser is preferably divided into separate condenser chambers by a baffle plate or baffle or baffle plates, which extend transversely to the heat transfer tubes penetrating the condenser. The condenser can be subdivided by one or more baffles in the ^{+ direction}

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the heat transfer tubes extend; in most Pällen However the former arrangement is preferred because usually, an arrangement is used with two-time pipe penetration and more uniform mean T _e ^m p ^era * ^acids ISS · ovens condenser chambers and so that a more even loading of the compressors results in parallel operation. A similar temperature mean effect can be achieved in the arrangement where the condenser is subdivided by a baffle which extends in the direction of the baffle, in which both passages of the two-pass tubes are located within one of the condenser chambers.

According to a particularly advantageous embodiment of the Invention includes the cooling device:

An elongated hollow structure that divides lengthways to form evaporator and condenser sections is; first and second heat transfer tubes extending through the evaporator or condensate sections; two compressors, their inputs in connection with the evaporator chamber and their outputs each in connection with separate of two separate condenser chambers within the condenser section stay in contact. Here, according to the invention, the chambers are formed by a baffle which extends across the condenser section to form substantially gas-tight partitions between the chambers to accomplish; return means are also provided, which remove the condensed cooling fluid from each chamber of the condenser section return to the evaporator section.

Preferably the elongated hollow structure is in essentially elliptical in cross-section and during normal operation According to the invention, a major axis of the ellipse may be vertical. The evaporator and condenser sections may be defined as a pair of spaced apart plates that are close to and parallel to the minor axis of the ellipse are arranged in any cross-section along the length of the hollow structure.

Preferably the two compressors are mounted on the hollow structure and are longitudinally spaced arranged on this. The compressors have impeller or impulse wheels that revolve around the horizontal axes turn, whose inlets are in communication with the evaporator section through inlet openings in the upper Part of the hollow structure are provided; the first heat exchanger tubes are arranged near the lower part of the evaporator section. The outputs of the compressors are preferably in communication with the separate chambers via outlet openings in the side of the hollow structure are provided; the second heat transfer tubes are arranged in the upper part of the separate chambers. More than two compressors can be provided and in this package there would be an equal number of Baffles required to create separate chambers for the compressors.

An example embodiment of the invention is intended will now be explained in more detail with reference to the accompanying drawings, in which:

Fig. 1 is a partial view of a refrigerator according to the invention;

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Pig. Fig. 2 is a partial section along line A-A in Pig. 1.

The refrigerating machine generally indicated by the reference numeral 2 comprises an elongated hollow shell construction 4 and two centrifugal compressors 6 and 8, which are arranged on the shell structure 4. The jacket construction 4 is made of sheet steel or steel plates and is essentially in cross section at vertical main axis elliptical.

The jacket structure 4 is supported in the longitudinal direction by a pair of parallel plates 12 arranged at a distance and 14 subdivided, which evaporator and condenser sections 16 and 18 form. The distance between the Plates 12 and 14 provide thermal insulation between the evaporator and condenser sections 16 and 18. An insulating jacket not shown in the drawings would normally be around the portion of the outer perimeter the jacket structure 4 arranged around and provides thermal insulation for the evaporator section 16. In the illustrated embodiment of a machine, the evaporator section 16 is above of the capacitor section 18 arranged; however, this is not absolutely necessary. A variety in the Spaced parallel heat transfer tubes 20 extend through the evaporator section 16 in FIG regular arrangement, but are provided near the lower part of the evaporator section 16. The pipes include with and without ribs or fins provided copper tubing in the end walls 22 and the construction 4 are carried. When the refrigerator is installed, the heat transfer tubes 20 became one Form part of a primary heat transfer circuit in which

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a heat transfer fluid (usually water) as Cooling medium is used. In a typical installation the chiller 2 would be used to keep the water cool, which circulates in an air conditioning system. The design is such that the water in the pipes 20 via an inlet manifold 26 and a Outlet manifold 28 emerges in the vicinity of the end walls 22 and 24 of the jacket structure 4, respectively are arranged. In some cases, provisions can be made to reduce the heat transfer fluid passes through a number of tubes 20 before it passes through outlet manifold 28 and the remaining part of the primary heat transfer circuit is returned.

Of course, when the tubes 20 are filled with water, they are quite heavy and additional support can be provided be required on the intermediate parts along their length. In the machine 2 shown there is such a carrier provided by a pair of perforated plates 30 and 30a mounted on plate 14. The pipes 20 pass through an array of perforations provided in plates 30 and 30a.

The heat transfer fluid in the tubes 20 is through the ability to evaporate and expand cooling fluid emanating from a plurality of nozzles 32 exits, cooled. The nozzles 32 extend longitudinally in three rows across the evaporator chamber 16 in the vicinity of the plate 14. The cooling fluid is in liquid form to the nozzles 32 via a supply channel 34 delivered centrally to and between the plates

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and 14 is arranged. A row of nozzles is located located directly above the feed channel 34 and the other rows are arranged on either side and are supplied with cooling liquid via a plurality of tubes 36 which extend laterally to the Supply channel 34 extend. The nozzles 32 are arranged so that they vaporize and expand Discharge cooling fluid in a direction substantially parallel to plate 14 for better circulation of the cooling gas around the heat transfer tubes 20 so that heat is extracted more efficiently from the heat transfer fluid therein can be. A larger volume flow of evaporating and expanding cooling fluid in the evaporator section means that a greater amount of heat from Heat transfer fluid is discharged in the tubes 20. Therefore, the output capacity of the machine can be regulated by adjusting the flow of cooling fluid to meet the amount required by the compressors. As mentioned above, would Set undesired modes of operation when the flow of cooling fluid should be regulated by the two Compressors 6 and 8 would be adjusted independently of one another without any special measure in the capacitor section, as will be described below, would be incorporated.

The evaporated cooling fluid is released from the evaporator section by means of inlet ports 38 and 40 against the centrifugal compressors 6 or 8 collected. According to the state of the art, a group or arrangement of eliminator

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"or separator plates 42 are provided to ensure that only cooling fluid in the gaseous state and not cooling fluid droplets can reach the compressor input.

The one leaving the centrifugal compressors 6 and 8 Eühlfluid is in the £ ompressorabschnitt 18 by means of Discharge lines 44 and 46 discharged. An important feature of the invention is a partition to effectively reduce the capacitor section 18 to be divided into the two chambers 50 and 52.

The partition wall 48 is provided with a group or arrangement of perforations that form a group or arrangement of heat conducting tubes 54, which penetrate the perforations and on their respective periphery are sealed against the partition wall 48. The outlet ports 44 and 46 are each in communication with the chambers 50 and 52 of the condenser section 18.

The heat conducting tubes 54 are provided in the upper part of the condenser chamber section 18 and extend between the end walls 22 and 24 of the jacket structure 4. The tubes 54 form part of a secondary Heat transfer line in which the heat transfer medium is located and enters the tubes 54 through an inlet manifold 56 which is adjacent the end wall 22 and is adjacent via an outlet manifold 58 the end wall 24 emerges. The tubes 54 may or may not be finned or finned provided copper pipes, which over their length through the end wall 22, a pair of per-

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Required carrier plate *! 6O ₃ 6Oa ₃ file Srennwand 4-8 and the end wall 24 are supported.

As can best be seen from Fig. 2, there are oil outlet ports 44 and 46 in communication with the respective chambers 50 and 52 of the condenser 18 via openings 62 and 64 in the side of the shell construction 4. The cooling fluid carried out of the outlet ports 44 and 46 alis "is at a relatively higher temperature because of the compression process and is like that led that it circulates around the tubes 54. In this way, the heat transfer fluid is absorbed in the secondary circuit Heat from the cooling gas. The secondary circuit usually includes an atmospheric heat sink for dissipation unwanted warmth. After the cooling fluid has lost sufficient heat, it condenses on the Tubes 54 or on the inside of the peripheral walls of chambers 50 and 52. The "condensed" cooling fluid can then drain into cooling sumps 66 and 68 ". Feed pipes 70 and 72 are provided to allow liquid cooling fluid to flow through them from the sumps into the feed channel 34 can step from which as freely from the ranks can emerge from nozzles 32. The coolant flow through the supply pipes 70, 72 is controlled by float valves, respectively. 74, 76 regulated, the mode of operation of which is regulated by the level of the cooling fluid in the sumps.

It is not essential that the partition 48 be absolute gastight connection zv / i see the two chambers 50 and 52 has. So if the seal between the Sections 50 and 52 is imperfect, and capacitors 6 and 8 under different load conditions work, then it is most likely that the pressure

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in the chambers 50 and 52 will differ and thus a certain flow of cooling fluid between the chambers will be established. The proportion of cooling fluid flow between the two chambers will in practice be insignificant compared to the amount of cooling fluid in the cooling machine, which may be very large and, in addition, the pressures reached (depending on the cooling gas used) in the condenser chambers are only of the order of magnitude - from about 9 to 10 pounds per inch (square meter) (overpressure, equivalent to 0.63 to 0.70 atmospheres) and so a large pressure differential is unlikely. If the two compressors 6 and 8 are set to operate so that the load is equally shared, the presence of a small flow of cooling fluid from one chamber to the other may be considered beneficial because it tends to more evenly reduce the Distribute load between the two capacitors. In practice it would be difficult to ensure a completely gas-tight seal at the points where the tubes 54 penetrate the baffle or baffle 48; however, as previously mentioned, some gas permeation can be tolerated. The main effect of the baffle or baffle 48 for dividing the condenser section into the two separate chambers is to be seen in the fact that the pressure in one chamber is essentially independent of the pressure in the other chamber and that therefore the mode of operation of the one compressor is essentially independent of the other's mode of operation. The probability that one of the compressors will have a pressure drop or a disturbed compressor delivery

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so-called "stalling" experiences, is essentially reduced.

Although the invention has been described with reference to only a single embodiment, it is not based on limited to this. Many modifications are within the scope of the invention to those skilled in the art possible. So are the primary and secondary heat exchanger circuits in the embodiment described only "single pass circles", that is, the heat transfer fluid migrates over the Length of the evaporator and condenser sections each once. Of course, they can also be designed in this way be that multiple passes can be provided according to known practices.

Expectations; -14 -

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Claims (12)

- 14 [ij cooling or refrigerating machine with an evaporator and condenser, characterized in that the condenser (18) is divided into at least two condenser chambers (50; 52), a separate compressor (6; 8) for each condenser chamber (50; 52), wherein the inputs of the compressors (6; 8) are in communication with the evaporator (16) and the output of each is in communication with the associated condenser chamber (50; 52). 2. Machine according to claim 1, characterized in that the evaporator and condenser (16; 18) by a separation are formed within a single construction. 3- machine according to one of claims 1 or 2, characterized by two condenser chambers, which are formed by a baffle, which the condenser divided into equal parts, with the baffle across the condenser with respect to the continuous heat transfer tubes extends. 4. Cooling machine with an elongated section divided to form evaporator and condenser sections Hollow structure, first and second heat transfer tubes passing through evaporator and condenser sections each go, two compressors, whose inputs are in connection with the evaporator section and their outputs in connection with separate of the two separate condenser chambers within the - 15 309886 / 0A05 Condenser section, characterized in that the chambers are formed by a guide plate (48), which extends across the condenser section and has substantially gas-tight partitions forms between the chambers; and by recirculation means removing the condensed cooling fluid from each Return the chamber of the condenser section to the evaporator section. 5. Machine according to claim 4, characterized in that the hollow structure is essentially elliptical in cross section with a vertical major axis, the subdivision of the hollow structure takes place in a horizontal plane which includes the minor axis of the hollow structure ₃ 6. Machine according to claim 4 or 5 _S, characterized in that the Yerdampferabschnitt is located above the condenser section. 7. Machine according to one of! Claims 4 to 6, characterized characterized in that the two compressors are of equal fit and that the baffle extends through a center plane of the capacitor section, the two capacitor sections being the same 7 volumes and an equal number of second transfer tubes through each of the two separate condenser chambers extends " 8. Machine according to claim 5 »6 or 7, characterized in that a pair of spaced apart parallel longitudinal plates is used to make the hollow Construction in evaporator and condenser sections too 309886/0405 - 16 - . - 16 - divide, with the space above the top plate the evaporator section and the space below the lower plate is the capacitor section and where the space between the spaced parallel plates serves as a conduit for condensed cooling fluid, that to the evaporator section through the return devices is returned. 9. Machine according to one of the preceding claims, characterized in that the separate condenser chambers have separate facilities to condensed Return cooling fluid to the evaporator section. 10. Machine according to claim S _1, characterized in that the separate devices each supply condensed cooling fluid to the space between the plates. 11. Machine according to claim 10, characterized in that the upper plate of the spaced apart Plates with a number of tubes or bones (bones) is provided on the top of the plates terminate in a series of nozzles to discharge condensed cooling fluid to the evaporator section. 12. Cooling machine essentially as described with reference to the drawings. PATENl ANW ALTh FINaCtDIPL-INC MPLrING-S-STAMSK 309886/0405 ι ^Λ ·. Blank page