Refrigeration system, using a two or more component mixture, with at least one compressor unit

The present invention relates to a refrigeration system with at least one compressor unit, a condenser in the high pressure area, an evaporator in the low pressure area and pressure-tight connecting lines through which gas and liquid flow.

Generic systems are known in the prior art and are generally referred to as compression refrigeration systems. In general, the refrigerant in the vaporized state is brought from low to high pressure, brought from the superheated state to the wet steam inlet temperature by removing heat, liquefied at a constant wet steam temperature and possibly a little undercooled. The liquid refrigerant goes through a throttle to a low pressure level, whereby the temperature drops and some of it evaporates. Heat is now absorbed until it has completely evaporated and the cycle begins again. Refrigeration systems of this type can be used in a number of ways. Due to the supply of heat at a low temperature, they are ideally used as cooling systems. On the other hand, they are used to generate heat as heat pumps, the heat that is absorbed in the low-pressure range is also given off with the supplied compressor energy as usable heat at a correspondingly high temperature. It is ideal for double use, both for cooling and heating purposes. The efficiency of these systems is defined by the ratio of the heat absorbed in the low pressure range to the compressor energy used.

In order to keep the efficiency as high as possible, the aim is to subcool the liquid refrigerant as far as possible before it enters the throttle and thus to increase the heat absorption. Furthermore, efforts are made to keep the compressor work as low as possible. In general, it is advisable to further reduce the temperature of the liquid refrigerant before it enters the throttle by cooling in the vaporous refrigerant flow after the evaporator exit, and to accomplish the compression via one or more intercoolers. These measures require expensive heat exchangers and are therefore only rarely implemented. It must be taken into account that, no matter how good the heat exchanger design, the intercooling does not exceed the wet steam area or can take place up to the coolant temperature and the cooling of the liquid refrigerant before entering the throttle cannot take place down to the refrigerant temperature in the low pressure range, since the liquid refrigerant has about twice the heat capacity than the gaseous refrigerant.

The object of the present invention is now to create a system without the above-mentioned process-related restrictions and to achieve a comparatively improved energy yield with a compact design.

This is achieved in that the compression refrigeration system is coupled with structural units of an absorption refrigeration system. The interconnection takes place according to the invention in such a way that one or more partial flows of the refrigerant vapor are branched off from the compressor unit and each go into a system part in which an admixture of absorber takes place and complete liquefaction takes place. The decoupling of the individual partial flows from the compressor unit does not necessarily take place according to the invention at the lowest pressure level, but can take place at higher pressure levels for operational reasons. The remaining proportion of refrigerant vapor passes through the compressor unit up to the high pressure level and is directed into a mixing chamber in the expeller.

The refrigerant vapor branched off from the compressor unit before high pressure goes into at least one arrangement known from the general state of the art for absorption refrigeration systems, hereinafter referred to as an absorber unit, consisting of a mixing chamber and a heat exchanger. In the mixing chamber, condensate with a high concentration of absorber is added to the refrigerant vapor. In the subsequent heat exchanger, heat is transferred to the cooling medium until it is completely liquefied. According to the functional principle that is well known for absorption refrigeration systems, this condensate is pumped to high pressure and fed into the expeller. Usually, part of this condensate goes into the mixing chamber of the expeller, prior to which there is an exchange of heat with the exiting condensate with a high concentration of absorber agent. The remaining part goes through the deflegmator, a heat exchanger for steam cooling, into the expeller.

According to the state of the art for absorption refrigeration systems, such expeller modules basically consist of the four functional units, deflegmator, rectifier, mixing chamber and cooker. Deflegmator and rectifier are used to clean the refrigerant vapor from

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Absorbent before exiting the expeller. The mixing chamber should ideally create a balance between the liquid and gaseous phases. In the cooker, heat is supplied to evaporate the mixture of refrigerant and absorber. This supply of heat is basically the driving energy for the operation of an absorption refrigeration system. Generally there is a separation of absorber and refrigerant in the expeller. This must not be seen in the narrow sense of a complete separation, but is geared towards a focus in terms of concentration. The aim here is that, on the one hand, the purest possible refrigerant vapor and, on the other hand, a mixture with a high concentration of absorber medium leave the expeller. Usually condensate with a medium concentration ratio of refrigerant and absorber is introduced.

According to the invention, the expeller differs from the embodiment described above by the additional possibility of introducing refrigerant vapor at high pressure. In contrast to conventional absorption refrigeration systems, with this system the heat exchanger for supplying heat, known as a cooker, can be completely omitted, and the system can only be operated by supplying technical work. In this case, as far as the performance characteristics of the system are concerned, a direct comparison with a pure compression refrigeration system is permissible. The fact that comparatively less refrigerant vapor is brought to the high pressure level means that the proportion of technical work is reduced considerably.

To further reduce the compressor output, there is the generally known method of bringing the superheated steam to saturated steam state by condensate injection between at least two compressor stages before further compression. Despite the increase in mass, this leads to a reduction in the technical work for the further compression of the steam to high pressure due to the decrease in temperature. In contrast to a compression refrigeration system with the disadvantage of not being able to branch off condensate in a process-technically favorable manner for this measure, thanks to the described compressor interconnection according to the invention, condensate can be taken from the system parts typical for absorption refrigeration systems. Ideally, condensate is removed from the expeller immediately after it leaves the rectifier. Compared to the measures for intermediate cooling in compression refrigeration systems, this effort is relatively low.

To increase the heat absorption from the medium to be cooled, referred to as brine in heat pumps, attempts are generally made to subcool the liquid refrigerant as much as possible before it enters the throttle. This can be achieved by additional cooling in the refrigerant vapor at low pressure. In the case of compression refrigeration systems according to the state of the art, this measure is not very efficient, since the mass flows of liquid and vapor which are the same when exchanging heat exist, but the refrigerant vapor only has approximately half the heat capacity. This means, on the one hand, that the liquid refrigerant cannot be cooled down too far, and on the other hand, the compressor output increases due to the overheated entry state of the vapor. Now there is the well-known method of adding condensate to increase heat absorption. Ideally, this condensate is continuously mixed in during the heat absorption for evaporation, the aim being to always be slightly in the wet steam area. This measure increases the heat absorption capacity to such an extent that the liquid refrigerant can be cooled down to almost the saturated steam temperature at low pressure. In addition, the effort for the heat exchanger with condensate injection compared to the heat exchanger with steam overheating is significantly reduced due to the better heat transfer behavior. In contrast to a compression refrigeration system with the disadvantage of not being able to branch off condensate in a process-technically favorable manner for this measure, thanks to the described compressor interconnection according to the invention, condensate can be taken from the system parts typical for absorption refrigeration systems. Ideally, the condensate that occurs after liquefaction is taken from the absorber unit, or in the case of several absorber units from the one with the lowest pressure level.

In terms of process technology, the mass fraction of the steam compressed to high pressure in relation to the mass of the steam branched off at lower pressure is precisely determined by the respective operating condition. The lower the ratio of the highest to the lowest pressure, the lower the amount of steam to be decoupled from the compressor unit for liquefaction. Since part of this condensate is used to purify the refrigerant vapor before it leaves the expeller by passing it through the deflegmator and rectifier, a

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Minimum quantity to be passed through these units. As a precise calculation shows, it makes sense to take a certain amount of the liquid refrigerant from the evaporator and mix it with the condensate that goes to the deflegmator. This essentially results in two positive effects. Since, on the one hand, more mass is passed through the deflegmator and rectifier, which has a higher concentration of refrigerant, better cleaning of the escaping refrigerant vapor from absorbent takes place in the expeller. On the other hand, the tapping of condensate from the evaporator causes a further separation of the absorber medium from the refrigerant vapor in accordance with the mass balance of the inflowing and outflowing refrigerant and absorbent, since vapor and condensate contain a different concentration of absorbent in equilibrium. While the steam contains almost exclusively refrigerant, the condensate contains a considerable amount of absorbent. Depending on the operating status, an optimal draw-off quantity can be determined. The obvious disadvantage of a smaller amount of evaporable refrigerant at low pressure, with the associated lower heat absorption capacity, is offset by the positive effects described above. The tapping measure leads to better overall system performance.

The interconnection of the compression refrigeration system according to the invention with the structural units typical for absorption refrigeration systems and the additional use of the resulting possibilities for reducing the compressor work and increasing the heat absorption capacity through the measures described above, are the essential criteria for increasing the system efficiency with relatively little additional effort in a compact design Fulfills. Compared to normal compression refrigeration systems, the additional structural effort for the connected system parts is largely compensated for by the more compact design of the steam heat exchanger with condensate injection and by the elimination of the complex Kompressorzwis chenkühlung. This system is far superior to a compression refrigeration system with the best design, especially when there are high temperature differences between heat emission and heat absorption.

A favorable variant of such a system provides that the recondensation of the refrigerant enriched with absorber medium in the mixing chamber takes place at two different pressure levels. According to the invention, this can be achieved by branching off two mass flows at different pressure levels from the compressor unit. The admixture of condensate with a high concentration of absorber and the subsequent liquefaction takes place in two separate absorber units. Ideally, the condensate that occurs at higher pressure is returned to the expeller via the deflegmator and rectifier.

A particularly favorable embodiment provides for the heat exchangers in the absorber units to be designed so that the coolant can reach temperatures as high as possible. Separate condensation heat exchangers with the option of using the temperature gradient during condensation, as well as a special device for preheating the condensate before it enters the mixing chamber, are used for this purpose. According to the invention, the heating takes place in such a way that the condensate flows through the heat exchanger ducts parallel to the coolant and removes energy from the steam / condensate mixture, which it then brings back into the mixing chamber. Viewed from the outside, the energy dissipated via the coolant remains the same. It only increases the temperature difference from the start of condensation to the end of condensation and thus the possibility of maximizing the coolant outlet temperature.

According to the invention, a modification of the above variant provides for a single compressor stage to be decoupled from the main compressor unit, with no complete liquefaction taking place in the first absorber unit. Further condensation up to complete liquefaction takes place in a second absorber unit at a higher pressure. Condensate from the first pressure stage is fed into the mixing chamber of this absorber unit via a pump. The remaining steam from the first pressure stage, which has not yet condensed, is brought to a correspondingly high pressure via a further compressor unit and also introduced into this mixing chamber. In principle, this arrangement does not bring any noticeable advantage in terms of process technology compared to the embodiment described above and is structurally more complex. On the one hand, this is due to the additionally required pump and the larger design of the first absorber unit, since more steam volume passes through. The separation of this compressor unit from the main compressor unit is one of the above description of the inventive interconnection

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Compressor unit with structural units of an absorption refrigeration system, which is an obvious modification, which is basically based on the same process-shaping idea, the use of two absorber units at different pressures.

Systems of the type described above can be ideally implemented both for small systems in building services and for large systems. Due to the extraordinarily high degree of efficiency, it is particularly economical to use in cold areas as a heat pump, preferably with the two-substance mixture ammonia / water. An increased use of outside air for heat extraction is conceivable.

A favorable variant also provides for heat to be introduced into the process in addition to the technical work. The system is neither to be regarded as a compression refrigeration system nor as an absorption refrigeration system. For this purpose, as is generally the case with absorption refrigeration systems, the heat exchanger called the cooker is arranged in the expeller. Similar to condensation, there is a temperature gradient in the evaporation of the single or multicomponent mixture, which is ideally used through the appropriate structural design of the heat exchanger. The more heat is added to the process, the less steam is compressed to high pressure and sent to the mixing chamber in the expeller. In the borderline case, the system works without high pressure compression, with all the refrigerant vapor going into the absorber unit (s). The use of such systems for the use of thermal energy provided by solar collectors is ideally conceivable, whereby the usual load fluctuations of the heat supply can be ideally compensated by the possibility of the variable use of heat and technical energy. This variant, with the coupling of solar collectors, can be used particularly profitably in large systems for supplying cold for large-scale building air conditioning with simultaneous use of the dissipated heat for the operation of seawater desalination systems. Compared to the usual designs of absorption refrigeration systems, these combined systems guarantee continuous operation with compensation for fluctuations in the supplied heat. Due to the special measures to increase the heat dissipation temperature, the dissipated heat can be used beneficially for other purposes, the overall system efficiency being far above that of conventional absorption refrigeration systems.

Further features and details of the present invention emerge from the following description of the figures. It shows:

1 shows a schematic representation of a generally known compression refrigeration system with the special design of an additional heat exchanger for cooling the condensate coming from the high-pressure condenser.

2 shows a process illustration of this system in the entropy / temperature diagram.

3 shows a simple embodiment variant with coupling of the structural units, expeller and absorber unit typical for absorption refrigeration systems, to the embodiment of a compression refrigeration system shown in FIG. 1.

4 shows an expanded variant of the embodiment shown in FIG. 3 with the use of two absorber units.

Fig. 5 shows an improved variant of the embodiment shown in Fig. 4 with additional efficiency-increasing measures such as: condensate extraction from the evaporator, admixture of condensate in the steam heat exchanger, condensate injection between the compression stages, special design of the heat exchanger to raise the coolant outlet temperature. In addition, the variant in FIG. 4 is expanded by installing a heat exchanger for supplying heat from the outside.

6 shows a slightly modified variant of the embodiment shown in FIG. 5 with subdivision of the compressor unit.

7 shows a structural proposal for the construction of a condensation heat exchanger in an absorber unit using the temperature gradient during liquefaction.

8 shows a diagram with the heat / temperature profile of condensate and coolant.

9 shows a structural proposal for the construction of the heat exchanger for external heat supply in the expeller.

The prior art shown in Fig. 1 is a generally known refrigeration process of a compression refrigeration system with the basic functional units, compressor unit 1, condenser 2, throttle 3 and evaporator 4, and the pressure-tight lines for high pressure steam

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21, high pressure liquid 15 and low pressure steam 31. Compressor unit can be understood in the broadest sense as a unit made up of several compressors with one or more pressure stages in all possible combinations of parallel and serial connections. In this example, a steam heat exchanger 5 for cooling the high-pressure condensate 15 coming from the condenser is provided for a better understanding of the further argumentation. This heat exchanger has no particular advantage in terms of process technology, is rather uneconomical in relation to the expenditure and is usually not used at all, or only weakly designed.

In FIG. 2, the process illustrated in FIG. 1 is shown in the temperature / entropy diagram. Starting at compressor inlet a, the refrigerant vapor 31 is compressed from a to b. After the compressor exits b, heat is given off to the cooling medium, cooling from the overheated state to the point at which it enters the wet steam area c. Furthermore, a complete liquefaction takes place up to d and possibly a condensate subcooling up to e. Further cooling from e to f takes place in the steam heat exchanger 5. A throttle device 3 is used to lower the pressure from f to g, the temperature falling and part of the refrigerant evaporating. The heat is now absorbed in the evaporator 4 from h to i up to complete evaporation. After steam overheating in the steam heat exchanger 5 from i to a, the cycle begins again. As can be seen, the liquid refrigerant in the steam heat exchanger 5 cannot be cooled down too far from e to f, on the other hand the compressor work increases due to the steam overheating. The effort involved in cooling the condensate before it enters the throttle 3 results in only a slight increase in efficiency due to the associated steam overheating, even with the best heat exchanger design.

FIG. 3 shows a simple embodiment variant with coupling of the structural units typical for absorption refrigeration systems, expeller 7 and absorber unit 6, to a compression refrigeration system as shown in FIG. 1. According to the invention, a partial flow 10 is branched off from the compressor unit at a low or medium pressure level and passed on to an absorber unit 6 consisting of a mixing chamber 8 and a condensation heat exchanger 9. Ideally, as shown schematically here, several outlets for the steam branch 10 at different pressure levels are provided on the compressor unit. The remaining steam flow 11 is compressed to high pressure and passed into a mixing chamber 12 in the expeller. According to the general interconnection principle of absorption refrigeration systems, the condensate 16 from the absorber unit is brought to high pressure via a pump 32 and returned to the expeller 7. A partial flow of this condensate 18 is passed through the deflegmator 14, a heat exchanger for steam re-cooling, and further through the rectifier 13, a device for steam washing. Both devices basically serve to clean the refrigerant vapor from absorbent before it is passed on to the condenser 2. The remaining substream 17 goes, preferably after heat exchange 22 with condensate 20 that leaves the expeller, back into the mixing chamber 12 of the expeller 7. The condensate 20 from the expeller 7 has a high concentration of absorber agent and, after being introduced into the mixing chamber 8, takes effect Absorber unit 6 a considerable increase in temperature of the vapor / liquid mixture. Naturally for two- or multicomponent mixtures, the wet steam area has a temperature gradient. With an appropriate design of the condensation heat exchanger 9, this can be used to achieve the highest possible coolant outlet temperatures. The decisive factor for the functioning of the refrigeration system is the fact that the refrigerant / absorbent mixture in the liquid state has an evaporation temperature which, depending on the concentration of absorbent, is correspondingly higher than that of the pure refrigerant and thus the possibility of heat dissipation from the refrigerant up to complete condensation is given. This is the basic functional principle for absorption refrigeration systems, whereby instead of increasing the pressure, an accumulation of absorbent takes place in order to be able to release the heat to the outside at a sufficiently high temperature. While the temperature range to be managed between heat emission and heat absorption is not too high in pure absorption refrigeration systems, this disadvantage can be remedied according to the invention by diverting the refrigerant vapor 10 at a higher pressure level. The amount of refrigerant vapor 11 which passes through the high pressure compression is precisely defined in terms of process technology by the energy balance of outgoing and incoming mass flows with the corresponding enthalpies, which is ascertained via the expeller 7. After the inflowing and outflowing condensate streams 17, 18, 20, approximately equalize in terms of energy, and

AT 410 482 B superheated refrigerant vapor 11 flows in with a high specific enthalpy, while refrigerant vapor 21 leaves the expeller in the saturation state with a significantly lower specific enthalpy, it can be seen that the amount of superheated, high-energy refrigerant vapor 11 to be introduced is less than that of the refrigerant vapor 21 exiting. Since the compressor work is the decisive factor for the expenditure of technical energy, there are significantly better performance data compared to the compression refrigeration system shown in FIG. 1. The measure of cooling the liquid refrigerant with the associated steam overheating in the steam heat exchanger 5 does not lead to any significant increase in the compressor work, since it means that less mass has to be compressed to high pressure. In contrast to the one in Fig. 1 Compression refrigeration system described, the use of the steam heat exchanger 5 leads here to a decisive process improvement.

According to the invention, FIG. 4 shows an expanded variant of the embodiment shown in FIG. 3 with the use of two absorber units 6 and 26. The mass flows 10 and 23 are decoupled at different pressure levels. The condensate 18 from the absorber unit 26 with the higher pressure is returned to the expeller 7 via deflegmator 14 and rectifier 13, while the condensate 16 from the absorber unit 6 with the lower pressure returns to the mixing chamber 12 of the expeller 7. The two-stage condensation measure enables the system to cope with higher temperature differences between heat transfer to the cooling medium and heat absorption from the brine, with the compressor work being kept as low as possible. In this embodiment, three outputs at different pressure levels are provided for the steam extraction 10 to the individual absorber units, it being possible for the optimum level to be opened depending on the operating requirements. In terms of process technology, it is particularly advantageous that the condensate 23 from the absorber unit 26 with the higher pressure level has a lower concentration of absorber agent and is better suited for rectification. In addition, as the balance of the mass flows of absorber medium and refrigerant entering and leaving the expeller shows, the condensate 20 leaving the expeller 7 has a lower concentration of absorber agent, which leads to lower temperatures in the expeller 7. A related temperature limit can be important if it is to be prevented that the refrigerant mixture undergoes chemical changes, which can be possible above a certain limit temperature. A further advantage is given if a heat exchanger Fig. 5, 35 is provided in the expeller 7 for a heat supply from the outside, since this heat supply can take place at a lower temperature.

Fig. 5 shows an improved variant of the embodiment shown in Fig. 4 with additional efficiency-increasing measures such as, condensate extraction from the evaporator 4, admixture of condensate 27 in the steam heat exchanger 5, condensate injection between the compression stages 34, special version 28 of the condensation heat exchanger 9 to increase the Coolant outlet temperature and additional heat recovery exchanger 25. A special variant in addition to Fig. 4th provides a heat exchanger 35 for the purpose of supplying heat from the outside.

In short, the condensate extraction serves to clean the refrigerant vapor 30 in the evaporator 4 from absorbent, even if only to a small extent. Since even the smallest proportions of absorbent cause a strong increase in the evaporation temperature, the process reacts extremely sensitively to this contamination of the absorbent and requires a corresponding pressure reduction in the evaporator 4 in order to be able to absorb the heat from the brine. This leads to an increased compressor performance and thus poorer performance data of the system. Since even very small amounts drawn off have a great cleaning effect, the disadvantage that this means that less condensate is available for evaporation and that less heat can be extracted from the brine is by far eliminated by the positive effect. Another very efficient measure to improve the performance data of the system consists in injecting condensate 27 into the steam heat exchanger 5. With this additional heat of evaporation, the high-pressure condensate 15 can be cooled further and thus more heat can be extracted from the brine. In addition, there is the advantage in terms of process technology that the steam enters the compressor unit 1 in the saturated steam state, which reduces the compressor work despite the increase in mass. An additional possibility of reducing the compressor work results from further condensate injection between the higher pressure levels.

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Ideally, that condensate 34 is taken immediately when it exits the rectifier 13. The special designs 28 of the condensation heat exchangers 9 in the absorber units 6, 26 are used to achieve higher coolant outlet temperatures and do not lead to a direct increase in the performance data of the refrigeration system, but to one better usability of the dissipated heat. Under certain operating conditions, especially when there are large differences between the condensation temperature in the condenser 2 and the evaporation temperature in the evaporator 4, it makes sense to use a heat exchanger 25 with heat extraction from the condenser 2 to heat the condensate 19 before it enters the expeller 7. This heat exchanger 25, like the heat exchanger 22, serves for energy recovery and lowers the energy requirement to be introduced into the system. In the case of smaller temperature differences, it should be noted that less steam is extracted from the compressor unit and, as a result, a smaller amount of condensate can be passed through deflegmator 14 and rectifier. This results in the problem that the condensate heating 25 makes the re-cooling in the deflegmator 14 very poor and the overall process can become worse instead of better as a result of this measure. Depending on the intended use, it can be useful to provide a system variant with a heat exchanger 35 in the expeller 7. This enables mixed operation with more or less compressor work with a corresponding supply of heat. This can go so far that the system can be operated mainly with thermal energy with little or no compressor work.

FIG. 6 shows a modified variant of the embodiment shown in FIG. 4 with separate compressor units, which are each designated by 1 with regard to the consideration as a total compressor unit. In terms of process technology, the two-stage condensation at different pressure stages pursues exactly the same goal as in FIG. 5 with the associated advantages mentioned above. From a structural point of view, there is no discernible advantage, but rather an additional expense due to the additional pump 36. This interconnection is basically based on the same principle according to the invention, the decoupling of refrigerant vapor from a compressor unit and forwarding it to an absorber unit. In this case, the absorber unit consists of two sub-units, 6 and 26, each with a mixing chamber and a condensation heat exchanger. These two sub-units are interconnected in such a way that part of the condensate 16 and the remaining steam 23 are passed from the first unit 6 into the second unit 26, where further complete liquefaction takes place. Since there is a pressure difference between the absorber subunits 6 and 26, a compressor 1 and a pump 36 are interposed.

7 shows a possible embodiment of a condensation heat exchanger 9. The main aim is to transfer the heat to the cooling medium at the highest possible temperature. To achieve this, in order to ensure the equilibrium of the phases, the vapor / condensate mixture must always be well mixed during the condensation and must not be mixed back into a previous condensation stage. As is generally customary, the steam / condensate mixture passes through a large number of floors, where it gives off the heat to the baffles 42, which pass this heat on to the tube bundle 43 with the cooling medium. These tube bundle units 43, which are connected to the guide plates, together with distributors and collectors, are usually accommodated in a pressure vessel 41. The special feature of this heat exchanger is that two different cooling media are passed through separate tube bundle units 43 with the corresponding distributor and collector units 44, 45. While the cooling medium from the heating rail runs through a closed circuit and leaves the pressure vessel again via the outlet nozzle 47, the second medium, a condensate from the expeller with a high concentration of absorber medium, goes into the mixing chamber 8 directly above it The absorber medium serves as a cooling medium for the condensation process, with higher energy being introduced into the mixing chamber 8 as a result of the heating. Since the heat release now begins in the wet steam area at a higher energy level, more heat must be extracted for complete liquefaction, the temperature being higher at the start of condensation. The amount of heat that actually goes to the outside remains unchanged according to the energy balance, since the additional heat of condensation is brought back into the mixing chamber 8 via the condensate. The real advantage of this interconnection according to the invention is that the cooling medium can be brought from the heating rail to a higher outlet temperature.

8 shows a diagram with the heat curve of condensate and coolant. This is a

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Heat exchangers without the inventive condensate preheating with the temperature b 'at the start of condensation and one with the corresponding interconnection with the temperature b at the start of condensation considered. As you can see, the special interconnection allows the coolant outlet temperature to be raised from d 'to d.

9 shows the possible design of a heat exchanger for the evaporation of two- or multi-component mixtures, the concentration and the associated temperature changes being used in a targeted manner during the evaporation in order to be able to accomplish the supply of heat at the lowest possible temperatures. In the case of evaporation, it is essentially a question of not letting the separated vapor pass into the condensate of a previous evaporation stage. This is achieved in that the condensate is passed over an arrangement of trays 52 with condensate collecting devices 56, the steam flowing out at the edge to the container jacket 51 and mixing with the steam that separated further below. A reflux into the heat exchanger channels further above is not possible with this arrangement. The heat dissipation to the guide plates 52 takes place via tube bundles 53 with collector and distributor units 54. This, as shown in FIG. 9 The heat exchanger shown is particularly suitable for use in refrigeration systems using the absorption principle and, instead of the usually built-in cooker, a heat exchanger with a heating device located directly in the boiling condensate without corresponding use of the temperature gradient is arranged in the expeller 7.

In the case of the features according to the invention shown schematically in all the figures, it should be pointed out that the individual components and supply lines can be manufactured in all possible different design variants known in the prior art.