DE102013110960A1 - Absorption refrigeration process and absorption chiller - Google Patents

Abstract

Shown and described is an absorption refrigeration process for providing refrigeration performance using heat (7). In order to be able to provide, in particular, small cooling capacities cost-effectively, such an absorption cooling process is proposed, in which a sorbent (36) for absorbing and / or desorbing a refrigerant (33) under reduced pressure through a sorbent channel (37) of at least one phase change module in the form of an absorber (2 , 30) and / or a desorber (3) is passed, wherein the sorbent (40) for absorbing heat absorption and / or for the delivery of Desorptionswärme in negative pressure through a heat transfer channel (39) of the at least one phase change module is passed and wherein the Sorbent (40) in at least one heat exchanger (17, 23) at least partially emits the heat of absorption to a heat transfer medium and / or at least partially absorbs the Desoptionswärme of a heat transfer medium.

Description

The invention relates to an absorption cooling process, for providing cooling capacity using useful heat, in which a sorbent for absorbing and / or desorbing a refrigerant in the negative pressure through a sorbent channel at least one phase change module in the form of an absorber and / or a desorber is passed. Furthermore, the invention relates to an absorption chiller of the type mentioned with an absorber, a desorber and a sorbent circulation between the absorber and the desorber.

Absorption refrigeration processes use existing heat to provide refrigeration capacity. The heat is transferred in a desorber to a sorbent, in which a refrigerant is absorbed. As a result of the heating of the sorbent, the refrigerant is desorbed. In this case, the refrigerant passes from the liquid phase into the gas phase and is then passed into a, for example, water-cooled, condenser, in which the refrigerant condenses with heat, that is liquefied, is. The liquefied refrigerant is released into an evaporator and evaporated therein. In this case, the refrigerant absorbs a considerable amount of heat in the form of heat of vaporization, whereby useful cooling capacity is provided at a low temperature level. The cooling capacity can be used for different cooling purposes. A particularly preferred use is the building air conditioning in the commercial and private sector.

The vaporized refrigerant is not released to the environment, but added for the purpose of recycling in an absorber again from the sorbent. The sorbent is fed to the absorber coming from the desorber. Absorption of the refrigerant in the sorbent releases heat of absorption in the absorber. However, excessive heating of the sorbent in the absorber is undesirable because it adversely affects the absorption process. To avoid excessive heating of the sorbent, the released heat of absorption must be at least partially dissipated to the environment. For this reason, the absorber is regularly water cooled or air cooled. In the absorber and the condenser, heat is dissipated at a temperature level between the temperature level of the heat for driving the absorption refrigeration process and the temperature level of the evaporator.

The sorbent is circulated by means of a pump in the sorbent circuit, the pressure side of the pump, the desorber is provided. The desorber is under a higher pressure than the absorber, since the refrigerant vapor in the desorber due to higher temperature has a higher vapor pressure. Before entering the absorber, the sorbent is depressurized via a throttle, so that the sorbent in the absorber is at a lower pressure level. In addition, the sorbent supplied to the desorber is preheated by the sorbent leaving the desorber, the sorbent leaving the desorber being simultaneously pre-cooled for absorption in the absorber. This is done in an indirect heat exchanger through which the sorbent streams flow separately.

The sorbent enriched with refrigerant in the absorber is fed to the desorber for renewed desorption of the refrigerant. In this way, both the refrigerant and the sorbent are recycled, wherein the refrigerant is passed between the absorber and the desorber together with the sorbent in the closed Sorptionsmittelkreislauf. The pressure level at which the absorption cooling process takes place depends on the sorbent (absorbent) and refrigerant (absorptive) system used. The sorbent can be in the desorber as well as in the absorber in the vacuum, d. H. at pressures below normal ambient or atmospheric pressure.

For the realization of the absorption cooling processes serve so-called absorption chillers. To operate these absorption chillers usually low-temperature heat is sufficient, which is obtained at a low temperature level and often can hardly be used on the spot makes good sense. In particular, for building air conditioning, it is preferred if the low-temperature heat is obtained as waste heat of a combined heat and power plant or as useful heat of a solar thermal system. However, it can also be used, for example, district heating or industrial process waste heat.

With regard to absorption chillers, there is a need for small, on-demand mobile, lower power units. This can for example be in the range of 100 W to 10 kW. A disadvantage of such absorption chillers, however, are the high specific equipment costs. Therefore, there is currently a desire to reduce the volume and weight of corresponding absorption chillers. This can be achieved, for example, by plate absorbers and / or plate-type deserts, which can be constructed as modules and combined to form so-called stacks or stacks, similar to fuel cell stacks. In this way, the volume, weight and, ultimately, the cost of absorption chillers can be reduced.

The modules in the form of an absorber and / or desorber have a sorbent channel for absorption or desorption, through which sorbent flows. In addition, a heat transfer channel is provided, which is flowed through, for example, by warm or cold water. In this case, only a thin partition wall is provided for a favorable heat transfer between the heat carrier channel and the sorbent channel. It would be desirable to make the channels and the partition as narrow as possible or thin, in order to provide a stack that has very many absorber modules and / or Desorbermodule at low height and thus allows high specific power.

In practice, however, it has been shown that the modules can not be reduced arbitrarily. Neither the partition nor the sorbent channel or the heat transfer channel can be made arbitrarily narrow. The thinner the partition is formed, the easier the partition wall can be deformed by the pressure differences of the media, resulting in uneven flow cross sections in the sorbent channel and / or in the heat transfer channel. In addition, it should be taken into account that even small deformations of the dividing wall have the greater effect on the corresponding flow cross sections, the narrower the sorbent channel and / or the heat transfer channel is formed. An uneven flow through the sorbent channel and / or the heat transfer channel reduces the performance of a phase change module and thus the specific power of the stack.

Against this background, there is still a need for optimization with regard to the structural design of the absorption chillers for increasing the specific performance of corresponding stacks. Attempts are currently being made to suitably stabilize the partition in itself or to support it by other components of the modules. This has proven to be effective, but not yet fully satisfactory.

Therefore, the present invention has the object, the absorption cooling process and the absorption refrigeration machine of the type mentioned in each case to design and further, that in particular small cooling capacities can be provided at a lower cost.

The object is achieved according to claim 1 by an absorption cooling process of the type mentioned, in which the sorbent for absorbing heat absorption and / or for the delivery of Desorptionswärme in negative pressure through a heat transfer channel of the at least one phase change module is passed and in which the sorbent in at least one heat exchanger at least partially emits the heat of absorption to a heat transfer medium and / or at least partially absorbs the Desoptionswärmung of a heat transfer medium.

In addition, the above object is achieved by an absorption chiller according to the preamble of claim 12, characterized in that in the sorbent circuit, a heat exchanger for emitting heat of absorption to a separate heat transfer medium and / or for receiving Desorptionswärme is provided by a separate heat transfer medium.

The invention has therefore recognized that higher specific refrigeration capacities can be realized with smaller absorption refrigeration machines and thus with correspondingly lower costs, if in the absorber and / or desorber instead of a separate heat transfer medium for supplying Desorptionswärme to Soprtionsmittel and / or for dissipating heat of absorption from the sorbent Also, the heat transfer channel is flowed through by the sorbent. This makes it possible to compensate for the pressure difference between the Sorptionsmittelkanal and the heat transfer channel of the same phase change module or substantially cancel or set to a low value without having to operate a very high control engineering effort, which in turn would adversely affect the manufacturing cost. Pressure differences between the sorbent channel and the heat carrier channel can be so lifted in particular to minimal pressure differences, which result from the different flow resistance during flow through the sorbent channel on the one hand and the heat transfer channel on the other.

Since according to the invention, the heat transfer channel of the absorber and / or the desorber is flowed through with sorbent, it requires for the actual heat supply to the absorption cooling process and / or for the actual heat dissipation from the absorption cooling process of another heat exchanger, which allows a heat exchange with a separate heat transfer medium. This heat exchanger is provided in the sorbent circuit between the absorber and the desorber. This also means that the design effort of the absorption chiller is higher than in the prior art. According to the invention, however, it has surprisingly been recognized that this additional design effort is more than compensated for by the increase of the specific power to be achieved thereby.

The advantage achieved by the invention can be achieved both with respect to the absorber and to the desorber. However, this will be particularly preferred for the absorber, since this is usually operated at a still somewhat lower pressure level than the desorber. In other words, the heat carrier channel of the desorber can be flowed through directly with a separate, the heat-providing heat transfer medium, such as in the form of warm water. In this case, however, both the sorbent channel and the heat transfer channel of the absorber are flowed through by sorbent in order to remove the heat of absorption from the sorbent channel. The absorption heat is thus transferred from the sorbent stream absorbing the refrigerant to the sorbent stream passing through the heat transfer channel. To remove the heat of absorption of the heat transfer medium passing through the sorbent stream is fed to another heat exchanger in which the heat of absorption is at least partially released to another medium. This can be in gaseous form (eg air) or liquid (eg cooling water). The latter, however, will be preferred to reduce the space. The heat exchange is also due to the negative pressure of the sorbent preferably indirectly, ie without direct contact of the heat exchanging media with each other, take place.

In the present case, a sorbent stream is understood to mean the stream of sorbent, irrespective of the concentration of the refrigerant absorbed in the sorbent. The refrigerant may form a separate refrigerant flow between the desorber and the absorber. The sorbent stream fed to the sorbent channel of a phase change module is preferably identical to the sorbent stream withdrawn from the sorbent channel of the phase change module, even if it has more or less refrigerant or in other words is enriched or depleted with refrigerant. However, it is different when a sorbent stream is divided into two or more streams. In this case, each of the partial flows is preferably considered to be the same sorbent stream until it is divided again or combined with other sorbent streams.

The design effort can be reduced for example by the fact that the heat exchanger sorbent from several absorbers or absorber modules of a stack of an absorption chiller is supplied. The heat exchanger can then also be made sufficiently robust, so that the pressure difference between the media streams leads to no appreciable deformation of the partition wall between the media streams.

Alternatively or in addition to the absorber can be flowed through in the desorber both the sorbent channel and the heat transfer channel of sorbent, preferably useful heat from a separate heat transfer medium, such as warm water, is transferred to the heat transfer medium flowing through the sorbent stream, in a separate heat exchanger. This is also preferably be provided for indirect heat exchange with a liquid heat transfer medium. Alternatively or additionally, this heat exchanger may be designed to simultaneously transmit useful heat for a plurality of desorber or desorber modules of a stack of an absorption refrigeration machine. In this case, a larger sorbent stream is preferably passed together through the heat exchanger and then split to be fed to the various desorbers.

In the case of absorption refrigeration machines with a stack of absorbers and / or desorbers, it is generally preferred if the absorber modules and / or the desorber modules are designed to be similar, preferably of identical construction. In principle, the absorbers and / or desorber, for example by stacking, can be combined into stacks to provide a high mass and heat exchange surface. However, to reduce the design effort, the condenser, the evaporator, the at least one pump and the at least one heat exchanger may be provided only once and associated with the stack of absorber modules and desorber modules or the stacks of either absorber modules or desorber modules. In this case, it is generally preferred if the absorbers and / or the desorbers are connected in parallel, and thus through which sorbents are flowed through in parallel with one another, preferably the same. Additionally or alternatively, a plurality of sorbent channels and / or heat transfer channels may be provided in each absorber and / or desorber.

In a first preferred embodiment of the absorption cooling process and the absorption chiller, the sorbent is circulated between the at least one heat carrier channel and the at least one heat exchanger. The sorbent is thus not only circulated in the actual sorbent cycle between the absorber and the desorber. There is also at least one additional partial circuit, which leads sorbent between the absorber or the desorber and the associated heat exchanger in a circle. If the partial circuit is assigned to the desorber, the partial circuit is not passed through the absorber. If the partial circuit is assigned to the absorber alternatively or additionally, the partial circuit is not passed through the desorber. This allows an efficient operation of the absorption cooling process, because then expedient heat dissipated and / or heat can be supplied. It is however, the at least one partial circuit is preferably not decoupled from the actual sorbent circuit between the absorber and the desorber. Rather, an exchange of sorbent between the Sorptionsmittelkreislauf and the at least one partial circuit is possible or provided. In this way, it is ensured that the respective subcircuit and the sorbent circuit have substantially the same pressure at least with respect to the absorber and / or the desorber, which may have different pressures.

The coupling of the sorbent circuit and the at least one partial circuit can be carried out in a simple and procedurally expedient manner if the sorbent is at least partially mixed after leaving the heat transfer channel and the sorbent channel. This applies to both phase change modules in the form of an absorber and a desorber, preferably a corresponding separate partial circuit can be assigned to both phase change modules. However, such a partial cycle can also be assigned only to the absorber or only to the desorber. The two sorbent streams from the respective heat carrier channel and the respective sorbent channel are thus preferably brought together after flowing through the heat carrier channel and the sorbent channel.

If the partial circuit is assigned to the absorber, this preferably takes place only after the adsorber leaving the sorbent channel of the absorber and having been enriched with refrigerant passes the desorber and at least partially discharges the previously received refrigerant there. In other words, the sorbent flowing from the desorber to the absorber is mixed with the sorbent flowing from the heat carrier channel of the absorber. If, however, the subcircuit is assigned to the desorber alternatively or additionally, the sorbent emerging from the heat carrier channel and the sorbent channel is merged, after the sorbent having been depleted with refrigerant leaving the sorbent channel of the desorber has passed through the absorber where it has again been enriched with refrigerant. In other words, the sorbent flowing from the absorber to the desorber is mixed with the sorbent flowing out of the heat carrier channel of the desorber.

It is particularly preferred in this context if the sorbent medium flowing through the sorbent channel is at least partially mixed with the sorbent flowing through the heat carrier channel of the first phase change module only after it has flowed through, preferably the sorbent channel of a second phase change module. It can thus be provided that the sorbent stream flowing through the sorbent channel of the absorber is first passed through the sorbent channel of the desorber before the sorbent stream is at least partially mixed with the sorbent stream flowing through the heat carrier channel of the absorber, or vice versa. This has the advantage that the sorbent stream enriched with refrigerant in the absorber is used only in the desorber, instead of depleting the concentration of the refrigerant beforehand by backmixing with another sorbent stream. Alternatively or additionally, it may be achieved that the sorbent stream leaving the desorber, which is low in refrigerant, is first used for the recovery of refrigerant in the absorber, instead of enriching the refrigerant concentration in the sorbent by backmixing with the sorbent of the corresponding subcircuit.

Alternatively or additionally, it may be provided that the sorbent streams are separated prior to entering the sorbent channel and the heat transfer channel of the absorber and / or desorber, preferably after passing through a heat exchanger for heating or cooling the sorbent. Prior to the separation of the sorbent streams, these can be guided into a common sorbent stream, for example in a line section of a sorbent circuit provided for this purpose. Thus, it can be ensured in a simple manner that the sorbent streams before entering the sorbent channel and the heat transfer channel of the desorber and / or absorber have at least substantially the same pressure and / or substantially the same temperature.

Since it is generally preferred to operate the absorber at a low temperature level and the desorber at a higher temperature level, it makes sense if the coming of the desorber, passed through the at least one heat exchanger sorbent is then divided into a plurality of partial streams to in the to be passed at least one sorbent channel and in the at least one heat transfer channel at least one absorber. Then, in the case of an absorber, both the at least one sorbent channel and the sorbent stream fed to the at least one heat carrier channel are then cooled. In the case of a subcircuit associated with the desorber, alternatively or additionally, both the sorbent stream fed to the sorbent channel and to the heat carrier channel of the desorber are heated.

Against this background, it is particularly advantageous from a constructive point of view if the partial streams of the sorbent from the respective subcircuit and the actual sorbent circuit are first brought together and then passed jointly through the at least one heat exchanger. If the heat exchanger also sorbent streams from several absorbers or more desorbers of a common stack of absorber and / or Desorbermodulen is supplied together, the design complexity is further reduced.

As a result of the balance between the pressure in the Sorptionsmittelkanal and the pressure in the heat transfer channel of the respective phase change module, it offers to reduce the height of a mode when the sorbent channel and the heat transfer channel by a release agent, preferably in the form of a sheet or foil of metal and / or Plastic, are separated from each other. Since there is sorbent both in the sorbent channel and in the heat transfer channel, a lesser effort must also be driven to avoid leaks. In the case of minor leaks in the separation of sorbent channel and heat transfer channel, some sorbent will pass from one channel to the other. Although this can lead to a corresponding change in the concentration of refrigerant, it is otherwise less critical for the absorption refrigeration process.

The advantages of the absorption cooling process are obtained in particular if the negative pressure of the sorbent in the sorbent channel and in the heat transfer channel of the corresponding phase conversion module is at least 50 mbar (relative), in particular at least 100 mbar (relative). These pressures are relative pressures, ie the negative pressure compared to the ambient pressure or normal air pressure. In the case of pressure data without a special note or with the addition (absolute), these are absolute pressures. Underpressures of 50 mbar (relative) or 100 mbar (relative) in the sorbent channel would already be sufficient to deform partitions between the Sorptionsmittelkanal and the heat transfer channel, such as when through the heat transfer medium medium under ambient pressure or normal air pressure or caused by further pump overpressure would flow. This is the case, in particular, if a sheet metal or a foil of metal and / or plastic is used as the dividing wall.

However, the advantages are all the greater if the pressure of the sorbent in the sorbent channel and in the heat transfer channel is less than 0.8 bar (absolute), preferably less than 0.5 bar (absolute), more preferably less than 0.25 bar (absolute), especially less than 0.1 bar (absolute). If the sorption processes occur at such low pressures, a medium present in the heat transfer channel under ambient or atmospheric pressure would be able to deform even relatively massive partitions between the sorbent channel and the heat transfer channel. Alternatively or additionally, even the smallest leaks in this case would require an immense transfer of heat transfer medium into the sorbent channel.

The at least one phase change module is preferably an absorber and / or a desorber for the reasons mentioned. It can also be provided that an entire stack of, preferably stacked, absorbers and / or desorbers is provided. The absorber modules and / or the desorber modules are then preferably similar. Further preferably, the absorber modules and / or Desorbermodule are formed substantially identical, for example, to use a large number of identical parts. It is particularly preferred if the at least one phase change module is a membrane absorber and / or a membrane desorber. These modules can namely be made very space-saving. In the case of membrane absorbers or membrane desorbers, the sorbent channel is separated by a semipermeable membrane, which is permeable to the refrigerant, from a vapor space to which the refrigerant is supplied in vapor form (absorber) or from which the refrigerant is removed in vapor form (desorber). The refrigerant is thus expelled in the membrane desorber over the membrane in the vapor space and withdrawn from the vapor space. In the membrane absorber, the refrigerant is conducted in the vapor space and absorbed through the membrane in the sorbent. In the case of membrane absorbers or membrane desorbers preferably flat membranes and no hollow fiber membranes are used to dissipate heat in a simple manner parallel to the sorption or to be able to supply heat.

The advantages of the invention can be attained to a particular degree if lithium bromide (LiBr) solution, preferably an aqueous lithium bromide (LiBr) solution, and / or preferably water, an alcohol or the like is used as the sorbent. Then the absorption cooling process is preferably carried out at low pressures. For example, in the case of corresponding material systems, these are preferably less than 100 mbar (absolute). Good results were achieved especially at pressures of less than 50 mbar (absolute).

With regard to the absorption chiller, it is preferably consistent with the absorption cooling process described with respect to the absorption chiller preferably when the at least one heat exchanger is provided in at least a partial circuit of sorbent and wherein the at least one partial circuit includes the absorber and / or the desorber. The subcircuit of the absorber thus leads - if available - to bypass the desorber, while the subcircuit of the desorber - if present - to bypass the absorber. Thus, undesirable accumulation or depletion of the sorbent with respect to the refrigerant is avoided.

Alternatively or additionally, the partial circuit may be connected to a line via which the partial circuit is connected to a sorbent channel of the absorber or desorber. This line is preferably used for supplying sorbent from the subcircuit to the sorbent channel. It can therefore be diverted from the subcircuit via the corresponding line a sorbent stream. This sorbent stream can then be directed into the sorbent channel of the phase change module to which the subcircuit is associated. Thus, a pressure equalization and a concentration balance between the sorbent in the sorbent channel and in the heat transfer channel can be achieved.

Alternatively or additionally, a line connecting the partial circuit with a sorbent channel of the absorber or desorber may be provided. This can serve to feed sorbent from the sorption channel to the subcircuit. It is further preferred in this context if the sorbent from the sorbent channel of the absorber is fed to the subcircuit of the desorber or the sorbent from the sorbent channel of the desorber to the subcircuit of the absorber. This leads to a pressure equalization of the two partial flows while avoiding a significant change in the concentration of refrigerant in the sorbent.

The at least one heat exchanger of the corresponding subcircuit associated with the absorber and / or the desorber can be arranged between the lines connected to the subcircuit for supplying sorbent to the subcircuit and for discharging sorbent from the subcircuit. Then, the common sorbent stream can be cooled or heated in the heat exchanger. Subsequently, the sorbent stream can be divided into then preferably equal tempered sorbent streams. For this purpose, the heat exchanger is preferably provided in the flow direction of the sorbent after the line for supplying sorbent to the partial circuit and before the line for supplying sorbent to the sorbent channel of the absorber or desorber.

The invention will be explained in more detail with reference to a drawing illustrating only embodiments. In the drawing shows

1 a process flow diagram of an absorption refrigeration process and an absorption refrigeration machine according to the prior art in a schematic representation,

2 a process flow diagram of a first absorption cooling process according to the invention and a first absorption refrigeration machine according to the invention in a schematic representation,

3 a process flow diagram of a second absorption cooling process according to the invention and a second absorption refrigeration machine according to the invention in a schematic representation and

4 an absorber of an absorption chiller of the absorption chillers 2 and 3 in a schematic cross-sectional view.

In the 1 an absorption cooling process known from the prior art is shown schematically. The absorption chiller 1 for performing the absorption refrigeration process has an absorber 2 , a desorber 3 , a capacitor 4 and an evaporator 5 on. Between the absorber 2 and the desorber 3 there is a sorbent circuit 6 in which sorbents are circulated by the absorber 2 to the desorber 3 and is returned. The sorbent cycle 6 is in the desorber 3 warmth 7 supplied via warm water, whereby the sorbent is heated and the absorbent absorbed in the sorbent refrigerant is partially desorbed. The refrigerant then enters the condenser 4 where the refrigerant condenses. This is done by the refrigerant in the condenser 4 via a water cooling by means of cooling water heat 8th withdrawn. The now liquid refrigerant is then in the evaporator 5 evaporated. In this case, the refrigerant cools considerably, which is why the environment about for the purpose of building cooling heat 9 can be withdrawn at a relatively low temperature level. The refrigerant is then re-absorbed in the sorbent. This is done by releasing heat of absorption 10 in the absorber 2 that the absorber 2 is extracted via cooling water. The refrigerant is therefore also in circulation 11 guided, wherein the sorbent circulation 6 and the refrigerant circuit 11 between the absorber 2 and the desorber 3 overlap, as in the sorbent circuit 6 Also in the sorbent absorbed refrigerant is circulated.

In the sorbent circuit 6 is a pump 12 provided for circulating the sorbent. Pressure side to the pump 12 is the desorber 3 and on the suction side of the absorber 2 arranged. The desorber 3 returning sorbent is by means of a throttle 13 relaxed. To preheat the desorber 3 fed sorbent exchanges this sorbent stream in a heat exchanger 14 Indirect heat with the desorber 3 leaving and therefore warmer sorbent stream. This simultaneously leads to pre-cooling of this sorbent stream before it enters the absorber 2 , To evaporate the refrigerant, this is done by a throttle 15 in the evaporator 5 guided.

In the 2 an absorption refrigeration process is shown which is based on the same process principle as in 1 illustrated absorption refrigeration process is based. The same components therefore bear the same reference numerals. To avoid unnecessary repetition, therefore, only the differences between the absorption refrigeration processes will be discussed below. These differences essentially relate to an additional partial circulation of the sorbent comprising an additional heat exchanger 17 as well as the absorber 2 , The absorber 2 As in the prior art, has a sorbent channel through which sorbent flows to absorb refrigerant. In addition, a heat transfer channel is provided, via which during the absorption of the refrigerant absorption heat can be dissipated in the sorbent, so that the sorbent for receiving the refrigerant is not heated too much. Unlike in the prior art, however, both the sorbent channel and the heat transfer channel of sorbent are flowed through, previously in the supplementary heat exchanger 17 through a cooling medium 18 , in particular cooling water, is cooled.

The sorbent cycle 6 between the absorber 2 and the desorber 3 and the subcircuit associated with the absorber are placed before the supplementary heat exchanger 17 and in the illustrated and insofar preferred absorption cooling process before the pump 12 merged to circulate the sorbent to after leaving the heat exchanger 17 to be separated from each other again. When in the 2 shown interconnection can be on a supplementary pump in the subcircuit 16 of the absorber 2 be waived. This is in the sorbent cycle 6 as well as in the partial cycle 16 a throttle 13 . 19 provided, but this is not mandatory. About the throttle 19 If necessary, a small pressure difference between the heat carrier channel and the sorbent channel of the absorber 2 be set to impart a desired shape, position or curvature of the thin partition between sorbent channel and the heat transfer channel. Alternatively or additionally, about the same purpose in the sorbent circulation 6 and in the partial cycle 16 each between the heat exchanger 17 and the absorber 2 Chokes are arranged to control the pressures in both channels of the absorber 2 independent of each other. The sorbent in the partial cycle 16 is the heat transfer channel of the absorber 2 fed while the sorbent of the sorbent circuit 6 through the sorbent channel of the absorber 2 and then to the desorber 3 is directed.

In the 3 a further absorption refrigeration process is shown schematically, in which the corresponding absorption chiller 21 in comparison with the absorption chiller 20 according to 2 a second subcircuit 22 for the sorbent. This second subcircuit 22 points like the first part cycle 16 an additional heat exchanger 23 and an additional pump 24 on. The sorbent is after the preheating of the sorbent by the desorber 3 coming sorbent stream through the pump 24 and then through the heat exchanger 23 directed.

In the heat exchanger 23 the sorbent stream gets through the heat 7 heats providing heat transfer medium. In the illustrated and so far preferred absorption cooling process, the heat transfer medium is warm water. After heating the sorbent in the heat exchanger 23 becomes the second subcircuit 22 separated and so the heat transfer channel of the desorber 3 Sorptionsmittel fed, while the remaining sorbent stream via an optional throttle 25 for setting a small differential pressure between the sorbent channel and the heat transfer channel of the desorber 3 in the sorbent channel of the desorber 3 where the sorbent releases refrigerant by desorption. The heat removed from the sorbent of the sorbent channel is at least partially replaced by the sorbent flowing through the heat transfer channel transferring heat to the sorbent in the sorbent channel. The refrigerant depleted sorbent from the sorbent channel then flows in the direction of the absorber 2 while the sorbent from the heat transfer channel through a throttle 26 and back to the pump 24 for conveying the sorbent to the desorber 3 and through the second subcircuit 22 flows. A small pressure difference between the sorbent channel and the heat transfer channel can be used or adjusted to impart a desired shape, position or curvature of the thin partition between the sorbent channel and the heat transfer channel.

At the absorbers 2 and the desorbers 3 according to 2 and 3 these are in particular membrane absorber modules and membrane desorber modules. Their structure corresponds to each other. The processes occurring therein and the material flows are merely inversely to one another. The processes are based on a schematic cross-section of a membrane absorber according to 4 explained. The absorber 30 has several steam rooms with porous structures 32 are filled. In the porous structures 32 enters the vaporized refrigerant 33 in which it is in the illustrated and so far preferred absorber 30 is about water. The refrigerant 33 passes through a semipermeable membrane 34 in the illustrated and so far preferred absorber module on a support grid 35 can rest in the sorbent 36 passing through a very narrow sorbent channel 37 flows. The refrigerant 33 is from the sorbent 36 absorbed. The released heat of absorption is at least partially via a partition wall 38 in the form of a sheet or foil of metal and / or plastic to the through the heat transfer channel 39 flowing sorbents 40 issued. The heat transfer channel 39 is in the illustrated and so far preferred absorber 30 much wider than the sorbent channel 37 or the adjacent sorbent channels 37 , Through the heat transfer channel 39 also flows much more sorbent 40 as through the adjacent sorbent channel 37 or the adjacent sorbent channels 37 to the sorbent 36 in at least one sorbent channel 37 to cool sufficiently.

When in the 4 shown phase change module are several steam rooms 31 , Sorbent channels 37 and heat transfer channels 39 intended. However, this is not necessarily the case.

Because the sorbent 36 . 40 in the heat transfer channel 39 and in the sorbent channel 37 has substantially the same pressure, the sorbent channel 37 and the heat transfer channel 39 be very thin and can also be a very thin film as a partition 38 for separating the sorbent channel 37 from the heat transfer channel 39 be used. The resulting phase change module is thus very shallow and thus can be used together with similar modules to form a flat stack.

Claims (16)

Absorption refrigeration process, for providing refrigeration capacity using heat ( 7 ) in which a sorbent ( 36 ) for the absorption and / or desorption of a refrigerant ( 33 ) under reduced pressure through a sorbent channel ( 37 ) at least one phase change module in the form of an absorber ( 2 . 30 ) and / or a desorber ( 3 ), in which the sorbent ( 40 ) for absorbing heat of absorption and / or for discharging desorption heat in the negative pressure through a heat transfer channel ( 39 ) of the at least one phase change module is passed and wherein the sorbent ( 40 ) in at least one heat exchanger ( 17 . 23 ) at least partially emits the heat of absorption to a heat transfer medium and / or absorbs the heat of desorption at least partially from a heat transfer medium. An absorption refrigeration process according to claim 1, wherein the sorbent ( 40 ) in the circuit between the at least one heat transfer channel ( 39 ) and the at least one heat exchanger ( 17 . 23 ) to be led. An absorption refrigeration process according to claim 1 or 2, wherein the sorbent ( 36 . 40 ) after leaving the heat transfer channel ( 39 ) and the sorbent channel ( 37 ) is at least partially mixed. An absorption refrigeration process according to claim 3, wherein the sorbent channel ( 37 ) by flowing sorbents ( 36 ) after flowing through a second phase change module with the heat carrier channel ( 39 ) of the first phase change module by flowing sorbent ( 40 ) is at least partially mixed. An absorption refrigeration process according to any one of claims 1 to 4, wherein a stream of sorbent ( 36 . 40 ) by the at least one heat exchanger ( 17 . 23 ), then the stream of sorbent ( 36 . 40 ) is divided into several sub-streams and in which a partial flow into the sorbent channel ( 37 ) and a partial flow in the heat transfer channel ( 39 ). Absorption cooling process according to claim 5, wherein the partial streams of the sorbent are combined and subsequently passed through the at least one heat exchanger. An absorption refrigeration process according to any one of claims 1 to 6, wherein the sorbent ( 36 . 40 ) in the sorbent channel ( 37 ) and in the heat transfer channel ( 39 ) by a partition wall ( 38 ), preferably in the form of a film, are separated from each other. Absorption cooling process according to one of claims 1 to 7, wherein the negative pressure of the Sorbent ( 36 . 40 ) in the sorbent channel ( 37 ) and in the heat transfer channel ( 39 ) is at least 50 mbar (relative), in particular at least 100 mbar (relative). An absorption refrigeration process according to any one of claims 1 to 8, wherein the pressure of the sorbent ( 36 . 40 ) in the sorbent channel ( 37 ) and in the heat transfer channel ( 39 ) is less than 0.8 bar (absolute), preferably less than 0.5 bar (absolute), more preferably less than 0.25 bar (absolute), in particular less than 0.1 bar (absolute). Absorption cooling process according to one of Claims 1 to 9, in which the at least one phase change module is an absorber ( 2 . 30 ), preferably a membrane absorber, and / or a desorber ( 3 ), preferably a membrane sorber. Absorption cooling process according to one of Claims 1 to 10, in which the sorbent ( 36 . 40 ), preferably an aqueous, lithium bromide (LiBr) solution and / or as a refrigerant ( 33 ) Water is used. Absorption chiller ( 20 . 21 ) for providing refrigeration power using heat ( 7 ), preferably according to one of claims 1 to 11, with an absorber ( 2 . 30 ), a desorber ( 3 ) and a sorbent circulation ( 6 . 22 ) between the absorber ( 2 . 30 ) and the desorber ( 3 ), characterized in that in the sorbent circulation ( 6 . 22 ) a heat exchanger ( 17 . 23 ) is provided for delivering absorption heat to a separate heat transfer medium and / or for receiving desorption heat from a separate heat transfer medium. Absorption refrigerating machine according to claim 12, characterized in that the heat exchanger ( 17 . 23 ) in at least one partial cycle ( 16 . 22 ) of sorbent ( 36 . 40 ) is provided and wherein the partial circuit ( 17 . 22 ) the absorber ( 2 . 30 ) and / or the desorber ( 3 ). Absorption refrigerating machine according to claim 12 or 13, characterized in that one of the subcircuit ( 16 . 22 ) with a sorbent channel ( 37 ) of the absorber ( 2 . 30 ) or desorber ( 3 ) connecting line for supplying sorbent ( 36 ) from the subcircuit ( 16 . 22 ) to the sorbent channel ( 37 ) is provided. Absorption chiller according to one of claims 12 to 14, characterized in that a partial circuit ( 16 . 22 ) with a sorbent channel ( 37 ) of the absorber ( 2 . 30 ) or desorber ( 3 ) connecting line for supplying sorbent ( 36 ) from the sorption channel ( 37 ) to the partial cycle ( 16 . 22 ) is provided. Absorption refrigerating machine according to one of claims 12 to 15, characterized in that the heat exchanger ( 17 . 23 ) between those with the subcircuit ( 16 . 22 ), and, preferably, that the heat exchanger ( 17 . 23 ) in the flow direction of the sorbent ( 36 . 40 ) after the line for feeding sorbent ( 36 . 40 ) to the partial cycle ( 16 . 22 ) and before the line for supplying sorbent ( 36 ) to the sorbent channel ( 37 ) of the absorber ( 2 . 30 ) or desorber ( 3 ) is provided.

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