DE19637156C2 - Process for air conditioning with a closed absorption chiller in combination with an open sorption chiller - Google Patents

Description

The invention relates to a method for air conditioning by means of a closed absorption process and one open sorption process, the waste heat of closed absorption process for desorption in open sorption process is used, and air conditioning to carry out this procedure.

Warmth plays in the air conditioning of buildings driven cooling processes play an increasingly important role. this applies especially for southern climates with a relatively high ind degree of radialization because of the high climate need in summer at very high power peak at lunchtime zen are generated. This is especially true for U.S.A., yes pan, Korea and southern European countries.

Absorption chillers are standard for this used with the working materials LiBr / water. These are as so-called "single-effect" and "double-effect" machines available. The heat ratio of the inserted type driving heat to generated cooling or the COP is approx. 0.7 to 0.75 for single-effect systems and 1.2 to 1.25 for Double-effect systems. It has also been around for quite some time "Triple-Effect" machines developed, but not yet are on the market. Triple-effect systems leave a COP expect from 1.5 to 1.8 and would therefore have roughly the same primary energy consumption such as very good compression cooling machines (KKM). Due to corrosion problems such triple-effect systems do not yet have the Ver stage of search.  

Dehumidification and cooling systems, d. H. to the climate air with open sorption cycles, so-called called DCS (Desiccant Cooling System) are in different Executions known. Although the basic processes have been known for a long time, e.g. B. the Pennington process from US Patent 2,700,537 from 1955, have according to this Principle working air conditioning systems over negligible Market share.

The Pennington DCS known from U.S. Patent 2,700,537 is shown schematically in FIG . The warm and moist outside air is first brought into contact with activated sorbent in a sorption wheel 2 and thereby dehumidified, whereby it heats up. The dehumidified and heated air is then in a heat exchanger 4 , z. B. in the form of a regeneration wheel, cooled. The cooled and dry air is then further cooled and humidified in an adiabatic humidifier 6 . The air conditioned in this way is then supplied to the room 10 to be air-conditioned as supply air. The exhaust air from the air-conditioned room 10 is humidified and cooled in a second adiabatic humidifier 12 . The moist and cooled air from the second adiabatic humidifier 12 is used in the heat exchanger 4 in Ge countercurrent for cooling the air flowing into the room 10 ge. The heated air flowing out of the heat exchanger 4 is further heated by an external heat source 14 and then flows through the sorption wheel 2 and activates the sorbent again there before it is cooled and released into the atmosphere.

It is also already known to combine DCS with compressor refrigeration machines (KKM), ie to use the heat released in the capacitor of the KKM as a heat source 14 . Such systems are known from U.S. Patents 2,186,844, 4,887,438, 5,325,676, 5,448,895 and 5,517,828. In these systems known from the cited US patents, the dehumidification is carried out only to the desired atmospheric humidity and the air to be conditioned is subsequently cooled separately by the KKM. This concept of separation of dehumidification and cooling can accordingly be realized by using surface cooling instead of air cooling, whereby the fresh air supply can be reduced to the level determined by hygienic requirements. Since surface cooling has become very widespread recently due to greater comfort, the need to separate cooling and dehumidification is an advantage of such systems.

It has also been suggested that the Con Waste heat released by an absorption cooling system machine to drive the DCS. Such circuits are known from the following publications:

D.G. Waugaman, A. Kini, C.F. Kettleborough: A Review of Desiccant Cooling Systems, Journal of Energy Resources Technology, March 1993, vol. 115 p. 5

Saunders, J.H., Wilkinson, W.H., Landstorm, D.K., and Rutz, A.L. 19989: A Hybrid Space Conditioning System Combining a Gas-Fired Chiller and a Liquid Desiccant Dehu midifier, Proceedings of the Eleventh Annual ASME Solar Energy Conference, San Diego, Calof., Pp. 207-212

Gari, H.A., Aly S.E., and Fathalah K.A., Analysis of an Integrated Absorption / Liquid Dessicant Air Conditioning System, 1990, Heat Recovery Systems Vol. 10, No. 2, pp. 87- 98.

From DE-Z, sbz 8/92, pages 58 and 60, and DE-Z, Ki Air and air conditioning technology 2/1994, pages 64 and 64, are DCS or DEC systems with so-called heat wheels.

From the publication by Gari et al. is the station wagon nation of an absorption chiller with a DCS be  knows, in which the absorption refrigeration in the condenser Apparent waste heat for regeneration of the sorption is used in the DCS. This allows heat consumption achieve ratios in the range of 1.2. Primary energy considered, such a COP is still too low to to enable such systems to be implemented on the market.

It is therefore an object of the present invention the publication Gari et. al. proposed Kombinati Switching on an absorption chiller with one of to improve the sorption process in such a way that higher heat conditions can be achieved without the equipment Effort increases too much.

This problem is solved by the features of claims 1 and 21.

Because the waste heat in both the condenser / resorber as well as in the absorber in the range above 50 ° C, the Waste heat from the absorption chiller (AKM) almost complete dig to drive the open sorption process the. This measure, which appears to be the first approximation took the temperature levels of the absorption refrigerator to choose that the waste heat from both condenser / resorber So far, absorber can also be used not used because with the in the air conditioning refrigeration AKM proven material pair LiBr / water because of the crystallisa such high temperature strokes are not possible. With an air conditioning system with a combination of AKM and DCS are compared to an air conditioning system only with AKM height Evaporator temperatures here are sufficient and therefore even higher temperature strokes possible without the fabric few LiBr / water crystallization is to be feared. In order to it is possible both in the capacitor / resorber as well Coupling any waste heat generated in the absorber into the DCS. On their pairs of materials, especially water / ammonia  hitherto in air conditioning refrigeration as not economical considered.

When switching a single-Ef according to the invention fect-AKM with an open sorption process result  Thermal conditions in the range of 1.9 to 2.1, the An operating temperature of the AKM then in the range between 150 ° C and 160 ° C. If a double-effect AKM is used, the result is a quintuple effect machine with a COP in the loading range from 2.75 to 3.4. The drive temperature of the AKM is in the range of 200 ° C. Although absorption cold systems or absorption heat pumps more complex and therefore the extremely high COP of inventions can be more expensive than KKM combination according to the invention, based on primary energy also outperforms the best compressor refrigerators revolutionize the air conditioning market. See you absorption chillers because of the unfavorable efficiency where it is used an economic advantage by avoiding electricity enable peaks or where the gas price in relation to Electricity price is very low.

The air conditioning system according to the invention can be very good COP also ensure that solar cooling is economical Lich, because the doubling of the COP's halves required collector area, which is the main cost of solar cooling.

Here, when using suitable working materials re, such as water / ammonia in particular, see claim, Li I / water, mixtures of LiBr, LiI and water the tempera ture conditions in the absorption chiller len that the temperature level of the condenser is higher than the temperature level of the absorber that the temperature levels are identical or that the temperature level or Waste heat level of the absorber is higher than that of the condenser tors.

According to the advantageous embodiment of the invention (Claim 2 or 3 or 22 and 23), comprises Absorption chiller an adiabatic condenser or Resorber with condensate or solution cooler, as well as a adiabatic absorber with Lö  solution cooler. In this way, the absorber is supplied poor solution or the poor supplied to the resorber Solution or the condensate fed to the condenser strongly hypothermic. This enables a strong sliding tempera Exhaust air increase with minimal irreversibility during the heat exchange. However, be accepted additional irreversibility during the adiabatic Ab sorption, resorption or condensation. Overall, the Advantage of this design in the compact design and Effectiveness of the gas / liquid heat exchanger or Spray absorbers or spray resorbers and spray capacitors. It has been found that the Ir reversibility in the area of adiabatic absorption, Re sorption and condensation are less important than the advantages of improved heat and mass transfer and reduced irreversibility when heated the exhaust air.

The remaining sub-claims relate to others advantageous embodiments of the invention.

More single units, features and advantages result from the following description based on the drawing.

1 shows a block diagram of a first game in embodiment of the invention, wherein the Tem is above the peraturniveau of the capacitor of the absorber of the absorption refrigerator.

FIG. 2 shows a second embodiment, which differs from the embodiment in FIG. 1 in that the temperature level of the absorber is above that of the condenser;

Fig. 3 is an embodiment corresponding to Figure 1 with adiabatic condensation and absorption.

FIG. 4 shows the process control of the third embodiment according to FIG. 3 in a Dühr diagram;

Fig. 5 shows a fourth embodiment corresponding to Fig 2 with adiabatic Kondesation and absorption.

FIG. 6 shows the process control of the fourth embodiment according to FIG. 5 in a Dühr diagram; and

Fig. 7 is a DCS according to the prior art.

In the following description of the various embodiments of the invention, the same reference numerals are used for identical or corresponding components to the Pennington DCS according to FIG. 7.

Fig. 1 shows a first embodiment in the block diagram. Warm and moist outside air supplied from the atmosphere is first brought into contact with activated sorbent in a sorption wheel 2 and thereby heated and dehumidified. The dehumidified and heated air is then cooled in a heat exchanger 4 in the form of a regeneration wheel. The cooled and dried air can then be further cooled and humidified if necessary in a first adiabatic humidifier 6 . The already pre-cooled air from the first adiabatic humidifier 6 is cooled in an evaporator 8 of an absorption refrigerator 9 to the desired final temperature and the air cooled in this way is supplied as a supply air to a room to be air-conditioned. The exhaust air from room 10 is first fed to a second adiabatic humidifier 12, where it is humidified and cooled (cold recovery). The moist and cooled air from the second adiabatic humidifier 12 is heated in the regeneration wheel 4 by heat that is extracted from the outside air also flowing through the regeneration wheel. The air heated in the regeneration wheel 4 is then supplied to an absorber 16 of the absorption refrigerator 9 and takes up the waste heat accumulating in the absorber 16 of the absorption refrigeration system 9 and is further heated. The air then flows through a condenser 18 of the absorption refrigerator 9 . The air there absorbs the waste heat generated in the condenser 18 of the absorption refrigerator and is further heated. The air heated in this way is then fed back to the sorption wheel 2 and activates the sorbent there again. The cooled and humidified air in the sorption wheel 2 is fed into the atmosphere as exhaust air.

The absorption refrigerator 9 also has, in a known manner, a regenerator or generator 20 , in which the drive heat from a heat source 14 is injected. The regenerator 20 is connected in a known manner via a solution circuit 22 to the absorber 16 and via a steam line 24 to the condenser 18 . Also in a known manner, the condenser 18 is connected to the evaporator 8 via a condensate line 26 , into which an expansion valve 28 is connected. The evaporator 8 is finally connected to the absorber 16 via a steam line 30 .

In this first embodiment of the invention, the temperature conditions of the absorption refrigeration machine are selected so that the waste heat released in the absorber 16 is at a lower temperature level than the waste heat released in the condenser.

Fig. 2 shows a second embodiment of the invention, which differs from the first embodiment according to FIG. 1 only in that the waste heat in the condenser is released at a lower temperature level than the waste heat in the absorber and thus the arrangement of absorber 16 and condenser 18 is exchanged in the exhaust air flow.

Fig. 3 shows a third embodiment of the invention, which corresponds to the temperature ranges of the Absorptionskäl system machine of the embodiment of FIG. 1, but an adiabatic absorber 16 'with solution cooler 17 and an adiabatic condenser 18 ' with condensate cooler 19 summarizes. As can be seen from Fig. 3, the exhaust air first flows through the solution cooler 17 and then the condenser sat cooler 19 before it is fed to the sorption wheel 2 . The solution circuit 22 between the regenerator 20 and the absorber 16 'is passed through the solution cooler 17 . The poor solution is subcooled in the solution cooler 17 and sprayed under cool into the spray absorber 16 ', where it absorbs incoming refrigerant vapor from the evaporator 8 via line 30 . The abge led through the condensate line 26 passes through the condensate cooler 19 , so that the condensate is supercooled. After the condensate cooler 9 branches off from the line 26, a line 32 with which part of the supercooled condensate is fed back into the spray absorber 18 ', where it is used to condense the refrigerant vapor flowing through the line 24 from the regenerator 20 . Otherwise, this third embodiment of the invention corresponds to the embodiment according to FIGS. 1 and 2.

The process control with the temperature and pressure ratios in this third embodiment are shown schematically in Fig. 4 in a Dühring diagram. A Düh ring diagram essentially corresponds to a pT diagram; instead of the pressure, the dew point temperature assigned to the respective pressure is plotted. This results in straight line equations for the isosteres.

Fig. 5 shows a fourth embodiment of the invention, which differs from the embodiment of FIG. 3 only because that the condensate cooler 19 and the solution cooler 17 have swapped places. As can be seen from the temperature and heat conditions shown schematically in FIG. 6, the waste heat of the absorber is at a higher temperature level than that of the capacitor, so that the adiabatic absorber 16 'associated solution cooler 17 is warmer than that Condensate cooler 19 assigned to adiabatic condenser 18 ′.

As working materials for the absorption chiller com Men especially lithium bromide (LiBr) and water, ammonia and water, as well as lye and water in question. Have here especially mixtures of NaOH and KOH by weight ratio of 40/60 to 60/40 found advantageous poses. Both a solid and a sorpti can be used for the DCS Onsmittel be used, as in the exemplary Embodiments is the case, as well as a liquid Sorbent or absorbent z. B. in the form of a Mi LiCl and water.

When using lye mixtures for the Absorp chiller is a much higher temperature rise than possible with lithium bromide. This also allows the waste heat delivered at standard evaporator temperatures above 60 ° C can be. An integration of this system in climate center len with an existing cold water network is also possible.

Another advantageous embodiment results through the use of ammonia / water as a material system. According to the invention, the condenser pressure is the Ab sorption machine by adding water to the refrigerant Reduced ammonia to a manageable pressure.

In the exemplary embodiments of the invention according to FIGS . 1 to 6, the absorption refrigerator is each designed as a one-stage system. It is of course also possible to use multi-stage absorption chillers or absorption heat pumps to drive the open sorption circuit.

With multi-stage AKM, a triple ef can also be used fect machine with a COP in the range of 1.9 to 2.1  be built. The advantage here is that the higher external evaporator temperature much higher temperature Differences in the heat exchangers are available. At a gas-fired machine can thus the price by we significantly reduced heat exchanger surfaces significantly reduced be tied. This makes it an inexpensive too highly efficient air conditioning provided.

Claims (40)

1. A method for air conditioning with an absorption refrigerator ( 9 ), which has a closed working medium circuit, in which heat is coupled in at an upper temperature range (T2, T2 '), the waste heat at a medium temperature range (T1, T1') and released by absorption of heat at a lower temperature range (T0) provides cooling capacity, and a sorption chiller ( 2 , 4 , 6 , 12 ) which extracts heat and moisture from the air to be cooled in an open sorption process, the desorption by the waste heat of the absorption chiller ( 9 ) takes place, the sorption chiller latent and possibly sensitive cooling loads and the absorption chiller covers sensitive cooling loads, characterized in that the temperature range (T1, T1 ') of the waste heat is in the range above 50 ° C and that the waste heat of the absorption chiller ( 9 ) completely for desorption in we use the sorption chiller ( 2 , 4 , 6 , 12 ) d. 2. The method according to claim 1, characterized in that the absorption takes place in an adiabatic absorber ( 16 ') and the adiabatic absorber ( 16 ') in a first solution cooler ( 17 ) supercooled poor solution, and that the condensation in an adiabatic Condenser ( 18 ') takes place and condensate discharged from the adiabatic condenser ( 18 ) is subcooled in a condensate cooler ( 19 ) and is partially returned to the adiabatic condenser ( 19 ). 3. The method according to claim 1, characterized in that absorption takes place in an adiabatic absorber and  the adiabatic absorber in a first solution cooler supercooled poor solution is supplied, and that the Condensation or absorption in an adiabatic Resorber takes place and the adiabatic resorber in one second solution cooler supplied supercooled poor solution becomes. 4. The method according to at least one of the preceding claims, characterized in that water is used as the working medium for the absorption refrigerator ( 9 ). 5. The method according to claim 4, characterized in that a mixture of NaOH and KOH in the weight ratio 40/60 to 60/40 is used as the sorbent for the absorption refrigerator ( 9 ). 6. The method according to claim 5, characterized in that CsOH is contained in the sorbent. 7. The method according to at least one of the preceding claims 1 to 3, characterized in that ammonia is used as Ar beitsmittel for the absorption refrigerator ( 9 ). 8. The method according to claim 7, characterized in that water is used as the sorbent for the absorption refrigerator ( 9 ). 9. The method according to claim 8, characterized in that Substances that lower vapor pressure in ammonia be added. 10. The method according to claim 9, characterized in that water is used as a vapor pressure reducing substance.   11. The method according to claim 9, characterized in that salt solutions are used as vapor pressure reducing substances become. 12. The method according to claim 11, characterized in that LiBr is used as salt. 13. The method according to at least one of the preceding claims, characterized in that a single-stage absorption refrigerator ( 9 ) is used. 14. The method according to at least one of the preceding claims 1 to 12, characterized in that a multi-stage absorption refrigerator ( 9 ) is used. 15. The method according to at least one of the preceding claims, characterized in that a solid is used as the sorbent in the sorption refrigerator ( 2 , 4 , 6 , 12 ). 16. The method according to claim 15, characterized in that a Penning ton DCS with a sorption wheel ( 2 ) and a regeneration wheel ( 4 ) is used as a sorption refrigerator ( 2 , 4 , 6 , 12 ). 17. The method according to claim 15 or 16, characterized records that the exhaust air flow between regeneration wheel and sorption wheel first a first heat exchanger and then a second heat exchanger or vice versa returns that poor in the first heat exchanger Solution from the generator through the air to be heated of the sorption chiller and then the Adiabatic absorber is supplied, and that in the two th heat exchanger poor solution from the adiabatic resor Via the air to be warmed the sorption refrigeration  seem supercooled and then to the adiabatic resorber is returned. 18. The method according to claim 15 or 16, characterized in that the exhaust air flow between the regeneration wheel ( 4 ) and sorption wheel ( 2 ) first passes through a first heat exchanger ( 17 ) and then a second heat exchanger ( 19 ) or vice versa that in that he most heat exchanger ( 17 ) poor solution from the generator ( 20 ) subcooled by the air to be heated in the sorption refrigeration machine and then fed to the adiabatic absorber ( 16 '), and that in the second heat exchanger ( 19 ) condensate from the adiabatic condenser ( 18 ') is subcooled by the air to be heated in the sorption refrigerator and a partial stream thereof is then returned via a line ( 32 ) to the adiabatic condenser ( 18 '). 19. The method according to at least one of the preceding claims 16 to 18, characterized in that the cooling capacity provided in the evaporator ( 8 ) of the absorption refrigerator ( 9 ) at least partially covers the cooling load from cold blankets. 20. The method according to at least one of the preceding claims 16 to 19, characterized in that the supply air after the regeneration wheel ( 4 ) is cooled by evaporative cooling. 21. Air conditioning system for carrying out the method according to one of the preceding claims, with an absorption refrigerator ( 9 ), in which heat is coupled in at an upper temperature range (T2, T2 '), the waste heat is emitted at a medium temperature range (T1, T1') and cooling power is provided by absorbing heat at a lower temperature range (T0), and
a sorption chiller ( 2 , 4 , 6 , 12 ) which extracts heat and moisture from the air to be cooled in an open sorption process, the desorption taking place through the waste heat of the absorption chiller ( 9 ), the sorption chiller having latent and possibly sensitive cooling loads and the absorption chiller sensitive cooling loads covers,
wherein the temperature range (T1, T1 ') of the waste heat is in the range above 50 ° C and that the waste heat of the absorption refrigerator ( 9 ) is used completely for desorption in the sorption refrigerator ( 2 , 4 , 6 , 12 ). 22. Air conditioning system according to claim 21, characterized in that the absorption refrigerator ( 9 ) an evaporator ( 8 ), an adiabatic absorber ( 16 ') with a first solution cooler ( 17 ), a generator ( 20 ) and an adiabatic condenser ( 18 ') with a condensate cooler ( 19 ). 23. Air conditioning system according to claim 21, characterized in that the absorption refrigerator has an evaporator, egg an adiabatic absorber with a first solution cooler, a generator and an adiabatic resorber with one has second solution cooler. 24. Air conditioning system according to at least one of the preceding claims 21 to 23, characterized in that the working medium of the absorption refrigerator ( 9 ) is water. 25. Air conditioning system according to claim 24, characterized in that the sorbent of the absorption refrigerator ( 9 ) is a mixture of NaOH and KOH in a weight ratio of 40/60 to 60/40. 26. Air conditioning system according to claim 25, characterized in that CsOH is contained in the sorbent. 27. Air conditioning system according to at least one of the preceding claims 21 to 23, characterized in that the working medium of the absorption refrigerator ( 9 ) is ammonia. 28. Air conditioning system according to claim 27, characterized in that the sorbent of the absorption refrigerator ( 9 ) is water. 29. Air conditioning system according to claim 28, characterized in that the ammonia vapor pressure reducing substance fe are mixed. 30. Air conditioning system according to claim 29, characterized in that vapor pressure reducing substances is water. 31. Air conditioning system according to claim 29, characterized in that the vapor pressure reducing substances are salt solutions. 32. Air conditioning system according to claim 30, characterized in that the salt is LiBr. 33. Air conditioning system according to at least one of the preceding claims 21 to 32, characterized in that the absorption refrigerator ( 9 ) is single-stage. 34. Air conditioning system according to at least one of the preceding claims 21 to 32, characterized in that the absorption refrigerator ( 9 ) is multi-stage. 35. Air conditioning system according to at least one of the preceding claims 21 to 34, characterized in that the sorption refrigerator ( 2 , 4 , 6 , 12 ) has a solid as a sorbent. 36. Air conditioning system according to claim 35, characterized in that the sorption refrigerator ( 2 , 4 , 6 , 12 ) is a Penning ton DCS with a sorption wheel ( 2 ) and a regeneration wheel ( 4 ). 37. Air conditioning system according to claim 35 or 36, characterized records that the exhaust air flow between regeneration wheel and sorption wheel first a first heat exchanger and then a second heat exchanger or vice versa returns that poor in the first heat exchanger Solution from the generator through the air to be heated of the sorption chiller and then the Adiabatic absorber is supplied, and that in the two th heat exchanger poor solution from the adiabatic resor Via the air to be warmed the sorption refrigeration seem supercooled and then to the adiabatic resorber is returned. 38. Air conditioning system according to claim 35 or 36, characterized in that the exhaust air flow between the regeneration wheel ( 4 ) and sorption wheel ( 2 ) first passes through a first heat exchanger ( 17 ) and then a second heat exchanger ( 19 ) or vice versa, in that he most heat exchanger ( 17 ) poor solution from the generator ( 20 ) subcooled by the air to be heated in the sorption refrigeration machine and then fed to the adiabatic absorber ( 16 '), and that in the second heat exchanger ( 19 ) condensate from the adiabatic condenser ( 18 ') is subcooled by the air to be heated in the sorption refrigerator and a partial stream thereof is then returned via a line ( 32 ) to the adiabatic condenser ( 18 '). 39. Air conditioning system according to at least one of the preceding claims 36 to 38, characterized in that the cooling capacity provided in the evaporator ( 8 ) of the absorption refrigerator ( 9 ) at least partially covers the cooling load from cold blankets. 40. Air conditioning system according to at least one of the preceding claims 36 to 39, characterized in that the supply air after the regeneration wheel ( 4 ) is supplied to an adiabatic humidifier ( 6 ) for evaporative cooling.