US20120073315A1

US20120073315A1 - Ammonia-water absorption refrigeration unit

Info

Publication number: US20120073315A1
Application number: US13/309,226
Authority: US
Inventors: Wolfgang Stuerzebecher
Original assignee: Individual
Current assignee: Tranter GmbH
Priority date: 2009-06-04
Filing date: 2011-12-01
Publication date: 2012-03-29
Also published as: CA2763417A1; WO2010139444A1; BRPI1010951A2; DE102009023929A1; EP2438367A1

Abstract

An ammonia water absorption chiller unit for drive temperatures of also less than 100° C. with at least one absorber arranged in a refrigerant cycle, wherein the absorber includes a fully welded packet of plates for an inner medium which is in turn placed in a casing for an outer medium. A method of minimum complexity for leading media in at least one refrigerant cycle of the ammonia water absorption chiller unit using heat exchangers which include a fully welded packet of plates for an inner medium which is in turn arranged in a casing for an outer medium. A use of an absorber which includes a fully welded packet of plates for an inner medium which is in turn arranged in a casing for an outer medium in a refrigerant cycle of the ammonia water absorption chiller unit.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of pending International patent application PCT/EP2010/003301 filed on Jun. 1, 2010 which designates the United States and claims priority from German patent application 10 20009 023 929.4 filed on Jun. 4, 2009, the content of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to ammonia water absorption chiller units comprising at least one absorber arranged in a refrigerant cycle. The present invention furthermore relates to a method of minimum complexity for leading media in at least one cycle of an ammonia water absorption chiller unit in consideration of the thermodynamic particularities of binary diphase mixtures.

BACKGROUND OF THE INVENTION

The use of an absorber in connection with an ammonia water absorption chiller unit according to the invention and/or a method according to the invention is furthermore a subject of the present invention.
The principle of absorption refrigeration by means of the substance combination of ammonia and water has been known for about 200 years and is mainly used for high refrigerating capacities in the range comprised between about 200 kW and about 6,500 kW today for reducing costs. Installations of this kind, such as for example described in DE 20 2007 007 999 U1 require a complex process technology and drive temperatures of clearly more than 100° C. for cooling temperatures beneath 0° C.
Based upon these facts, an ammonia water absorption chiller unit of minimum complexity shall be provided by using presently available technologies and new calculation methods for the heat and substance transfer, which chiller unit permits a more economic application of the cooling principle also for refrigerating capacities of less than 100 kW. In the literature relevant to the subject, see for example VDI Wärmeatlas (originally published by VDI-Verlag, Düsseldorf. 10^threvised and enlarged edition 2006, ISBN: 978-3-540-25504-8), no calculation methods are known for this. Thus, up to the present the man skilled in the art does not know any concrete dimensioning guide-lines or methods in order to dimension the individual components of ammonia water absorption chiller units of minimum complexity for an industrially usable ammonia water absorption refrigerating machine and to select them correspondingly, wherein cooling temperatures beneath 0° C. shall be in particular achievable with drive temperatures of less than 100° C.

SUMMARY OF THE INVENTION

For technically solving the problem, the invention proposes an ammonia water absorption chiller unit comprising at least one absorber arranged in a refrigerant cycle, which is characterized in that the absorber comprises a fully welded packet of plates for an inner medium which is in turn placed in a casing for an outer medium.
Herein, the invention makes in particular use of the knowledge that if fully welded tube plate exchangers are exclusively used for the absorber of an ammonia water absorption chiller unit, cooling temperatures of beneath 0° C. can be achieved even with drive temperatures of less than 100° C. with a corresponding dimensioning. Ammonia water absorption chiller units according to the invention are especially suitable for solar thermal cooling systems and have been unknown hitherto in the state of the art. Herein, the present invention is stamped by a new simplified circuit. In another embodiment of the invention, highly efficient heat transmitting components are proposed, the combinations of which according to the invention go far beyond the solutions which have been hitherto known in the state of the art. The present state of the art proceeds on the assumption that due to the high gas flow rate and the pressure losses related thereto, an efficient substance and heat transfer in an absorber of an ammonia water absorption chiller unit can only be obtained by using tubular heat exchangers. According to the invention it has been found that if the numerous parameters of an ammonia water absorption chiller unit are carefully calculated, an efficient heat and substance transfer can be just or especially be achieved by means of tube plate exchangers. Herein, it has surprisingly been found that if fully welded tube plate exchangers are exclusively used for the absorber of an ammonia water absorption chiller unit, cooling temperatures of beneath 0° C. can be obtained even with drive temperatures of clearly less than 100° C., in particular if a binary ammonia water diphase mixture is used.
Fully welded packets of plates which can be used according to the invention for the absorber are typically disclosed in for example EP 1 559 981 A2 or DE 601 12 767 T2, the disclosures of which are explicitly referenced herewith.
For dimensioning ammonia water absorption chiller units according to the invention with the object of a highly efficient heat and substance transfer, the plate geometry of fully welded tube plate exchangers used for the absorber is advantageously adapted to or for turbulent flow conditions with pressure losses of less than 0.1 MPa in particular consideration of the thermodynamic parameters of substance mixtures for leading the media. An adaptation to or for turbulent flow conditions is advantageously realized with flow rates comprised between 0.05 m/s and 1 m/s and with pressure losses of less than 0.1 MPa. Under these special conditions, drive temperatures beneath 100° C. can also be made usable in an economic way according to the invention.
In an advantageous embodiment of the invention, the absorption takes place in the casing of the absorber of the ammonia water absorption chiller unit according to the invention and the generated solution which is high in refrigerant is pre-stored in the same one. Thus, the solution collector which is otherwise common in the state of the art can be saved according to the invention. The number of building components of an absorption chiller unit can thus be reduced and furthermore a compact structure is achieved. In dependence on the respective application and the required capacity, an ammonia water absorption chiller unit according to the invention can be realized in numerous different variants and embodiments, according to the respective need.
In another advantageous embodiment of the invention an evaporator is advantageously arranged in the refrigerant cycle of the ammonia water absorption chiller unit, after or behind which evaporator, the absorber follows in flow direction. Thereby the flow dependent pressure losses are reduced and the efficiency of an ammonia water absorption chiller unit according to the invention is further improved. The evaporator advantageously comprises a fully welded packet of plates for an inner medium, which is in turn arranged in a casing for an outer medium. In the packet of plates, a change of phases of the liquid refrigerant into the gaseous state preferably occurs. Herein, the refrigerant constantly withdraws the heat from the medium in the casing of the refrigerating agent cycle which shall be cooled by means of the absorption chiller unit. The currents in the packet of plates and in the casing of the evaporator are preferably guided in reverse currents with respect to each other. Fully welded packets of plates which can be used according to the invention for the evaporator are typically disclosed by for example EP 1 559 981 A2 or DE 601 12 767 T2.
In another advantageous embodiment of the invention, a desorber (desorption unit) is advantageously arranged in the refrigerant cycle of the ammonia water absorption chiller unit, advantageously comprising a fully welded packet of plates for an inner medium which is in turn arranged in a casing for an outer medium. In the desorber, preferably in the packet of plates, a change of phases of the refrigerant bearing solution from the liquid into the gaseous state occurs. Herein, the refrigerant bearing solution is constantly supplied with heat by a medium in the casing of the heating cycle which drives or shall drive the absorption chiller unit. The currents in the packet of plates and in the casing of the desorber are preferably guided in reverse currents with respect to each other. The desorber is advantageously arranged after the absorber in the refrigerant flow direction. Thanks to these measures according to the invention, taken individually or in combination with each other, the efficiency of an ammonia water absorption chiller unit will be further improved. Fully welded packets of plates which can be used according to the invention for the desorber are typically disclosed by for example EP 1 559 981 A2 or DE 601 12 767 T2.
In another advantageous embodiment of the invention, a condenser is advantageously arranged in the refrigerant cycle of the ammonia water absorption chiller unit, advantageously comprising a fully welded packet of plates for an inner medium which is in turn arranged in a casing for an outer medium. In the condenser, preferably in the casing, a change of phases of a refrigerant bearing vapor from the gaseous into the liquid state occurs, wherein the generated refrigerant bearing condensate will be pre-stored in the same one. Thereby, the refrigerant collector which is otherwise common in absorption chiller units according to the state of the art can be saved. The number of building components of an ammonia water absorption chiller unit is thus reduced and a compact structure is enabled. Herein, the refrigerant bearing vapor constantly conveys heat to a medium in the packet of plates of the recooling cycle which serves as heat sink to the ammonia water absorption chiller unit according to the invention. The currents in the packet of plates and in the casing of the condenser are preferably guided in reverse currents with respect to each other. The condenser is advantageously arranged before the evaporator of an ammonia water absorption chiller unit according to the invention in the refrigerant flow direction. Thanks to these measures according to the invention, taken individually or in combination with each other, in particular the efficiency of an ammonia water absorption chiller unit will be further improved. Fully welded packets of plates which can be used according to the invention for the condenser are typically disclosed by for example EP 1 559 981 A2 or DE 601 12 767 T2.
In another advantageous embodiment of the invention, a solution heat exchanger is advantageously arranged in the refrigerant cycle of the ammonia water absorption chiller unit, advantageously comprising a fully welded packet of plates for an inner medium which is in turn arranged in a casing for an outer medium. In the solution heat exchanger, a refrigerant bearing solution which shall be supplied to the desorber will be internally pre-heated. The currents in the packet of plates and in the casing of the solution heat exchanger are preferably guided in reverse currents with respect to each other. Thereby, the external heat supply will be reduced in the desorber and the efficiency of an ammonia water absorption chiller unit according to the invention will be further improved. The solution heat exchanger is preferably arranged between the absorber and the desorber in the refrigerant flow direction. Thanks to these measures according to the invention, taken individually or in combination with each other, in particular the efficiency of an ammonia water absorption chiller unit according to the invention will be further improved. Fully welded packets of plates which can be used according to the invention for the solution heat exchanger are typically disclosed by for example EP 1 559 981 A2 or DE 601 12 767 T2.
In another advantageous embodiment of the invention, a dephlegmator is advantageously arranged in the refrigerant cycle of the ammonia water absorption chiller unit at drive temperatures of more than 100° C., advantageously comprising a fully welded packet of plates for an inner medium which is in turn arranged in a casing for an outer medium. In the dephlegmator, preferably in the packet of plates a refrigerant bearing vapor which shall be supplied to the condenser conveys heat to a medium in the casing, wherein a part of the refrigerant bearing vapor already condenses. Thereby it is achieved that only small quantities of solvent vapor reach the condenser. The dephlegmator is preferably arranged before the condenser in the refrigerant flow direction. Thanks to these measures according to the invention, taken individually or in combination with each other, in particular the efficiency of an ammonia water absorption chiller unit according to the invention will be further improved. Fully welded packets of plates which can be used according to the invention for the dephlegmator are typically disclosed by for example EP 1 559 981 A2 or DE 601 12 767 T2.
According to an especially advantageous embodiment of the invention it is possible to omit building components which have been hitherto assumed as necessary or required in the state of the art. It has been found that at drive temperatures of less than 100° C. the portion of vaporous solvent in the refrigerant bearing vapor is usually less than 5%, such that according to the need in particular a dephlegmator can be saved according to the invention.
In another advantageous embodiment of the invention, a refrigerant supercooling unit is arranged in the refrigerant cycle of the ammonia water absorption chiller unit, advantageously comprising a fully welded packet of plates for an inner medium which is in turn arranged in a casing for an outer medium. In the refrigerant supercooling unit, the temperature of the condensed refrigerant which shall be supplied to the evaporator is reduced beneath the boiling point. Thereby it is achieved according to the invention that, on the one hand, no premature evaporation occurs with pressure losses and, on the other hand, the amount of the evaporation enthalpy is increased which further improves the efficiency of an ammonia water absorption chiller unit according to the invention. The currents in the packet of plates and in the casing of the refrigerant supercooling unit are preferably guided in reverse currents with respect to each other. The refrigerant supercooling unit is preferably arranged between the evaporator and the condenser, on the one hand, and between the evaporator and the absorber, on the other hand, in the refrigerant flow direction. Fully welded packets of plates which can be used according to the invention for the refrigerant supercooling unit are typically disclosed by for example EP 1 559 981 A2 or DE 601 12 767 T2.
According to an especially advantageous embodiment of the invention it is possible to omit building components which have been hitherto assumed as necessary or required in the state of the art. It has been found that with a cooling capacity of the evaporator of less than 100 kW, the refrigerant supercooling unit can also be saved, in particular since with a cooling capacity of the evaporator of less than 100 kW the contribution of a refrigerant supercooling unit to increasing the efficiency of an ammonia water absorption chiller unit according to the invention does not justify the technical expenditure and the costs related thereto for an efficient use.
The refrigerant contained in the refrigeration cycle is preferably ammonia or comprises ammonia. The solvent contained in the refrigeration cycle is preferably water or comprises water.
In another advantageous embodiment of the invention, the feeding pipes and/or draining pipes to the condenser and/or the absorber in the refrigerant flow direction are provided with a pressure compensation pipe. Thereby, pressure losses are reduced and a more uniform heat transfer is enabled. Thanks to this measure which is unusual in the state of the art the efficiency of the absorption of refrigerant in sorbent and thus the efficiency of an ammonia water absorption chiller unit according to the invention will be further improved.
The invention furthermore relates to ammonia water absorption chiller units comprising an absorption refrigeration method of minimum complexity for leading media in at least one refrigerant cycle using heat exchangers which comprise a fully welded packet of plates for an inner medium which is in turn arranged in a casing for an outer medium. Fully welded packets of plates which can be used according to the invention are typically disclosed by for example EP 1 559 981 A2 or DE 601 12 767 T2.
According to the invention, it is proposed that in particular consideration of the thermodynamic of substance mixtures for leading the media the plate geometry is adapted to turbulent flow conditions with pressure losses of less than 0.1 MPa for a particularly efficient heat and substance transfer. An adaptation to or for turbulent flow conditions is advantageously realized with flow rates comprised between 0.05 m/s and 1 m/s and with pressure losses of less than 0.1 MPa. According to the invention, it becomes simultaneously possible thereby to obtain a compact construction of ammonia water absorption chiller units according to the invention. In dependence on the respective application and the required capacity, the embodiment according to the invention can be realized in numerous different variants, according to the respective need. Herein, the modular graduation and adaptation of fully welded tube plate exchangers permits to use the method with cooling capacities comprised between the kilowatt range and the megawatt range and the method can thus considerably contribute to an economic use of energy advantageously.
Logically, the invention furthermore relates to an absorber which is configured as fully welded packet of plates for an inner medium which is in turn arranged in a casing for an outer medium, in a refrigerant cycle of an ammonia water absorption chiller unit according to the invention in particular having one or more of the above mentioned characteristics.
The embodiments according to the invention and the knowledge gained by them permit an optimization of the individual tube plate exchangers, lead to a high efficiency and allow a compact construction of ammonia water absorption chiller units which has been hitherto unknown and inaccessible in the state of the art.

BRIEF DESCRIPTION OF THE DRAWINGS

Other details, characteristics and advantages of the invention will be explained in detail in the following by means of the exemplary embodiment of the invention which is represented in the FIGURE of the drawing. Herein:

FIG. 1 is a block diagram which shows an exemplary embodiment of an ammonia water absorption chiller unit according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows an ammonia water absorption chiller unit 1 comprising an absorber 10, an evaporator 20, a condenser 30, a desorber 40, a solution heat exchanger 50, a dephlegmator 60 and a refrigerant supercooling unit 70 which are arranged in a refrigerant cycle 2. Furthermore, pressure compensation pipes 80, 90 realize a connection in the refrigerant flow direction 3 between the feeding and draining pipe of the absorber 10 or the condenser 30 in order to reduce pressure losses and to permit a more uniform heat transfer.
The refrigerant contained in the refrigerant cycle 2 flows into the refrigerant flow direction 3 which is symbolically represented by means of an arrow and is supplied by means of a pump 100 into the desorber 40. The principal functioning of an absorption chiller unit is presently taken for granted (cf. in particular Handbuch der Kältetechnik, vol. 7, sorption refrigerating machines, Wilhelm Niebergall, 1959). The drive energy is introduced and discharged via a heating medium through the connections 41 and 42 into or from the desorber 40. The cooling effect is transferred by means of a refrigerant medium in the evaporator 20 through the connections 21 and 22. The recooling of the ammonia water absorption chiller unit 1 is realized by a heat transfer medium in the absorber 10 through the connections 11 and 12 as well as in the condenser through the connections 31 and 32. The design of the heat exchanger which comprises a fully welded packet of plates for an inner medium which is turn arranged in a casing for an outer medium principally follows the disclosures of EP 1 559 981 A2 or DE 601 12 767 T2, the disclosures of which are explicitly referenced herewith. The plate geometry of a fully welded packet of plates according to the invention is advantageously adapted to turbulent flow conditions with flow rates comprised between 0.05 m/s and 1 m/s and with pressure losses of less than 0.1 M Pa in particular consideration of the thermodynamic of substance mixtures for leading the media for a particularly efficient heat and substance transfer.
The improvement of the invention presently refers to a reduction of components of an absorption chiller unit which has been hitherto regarded as impossible or unrealizable in the state of the art and which components have been hitherto regarded as required and necessary. The results and calculations of the present invention show that the dephlegmator 60 can be saved with drive temperatures of less than 100° C. The same is true for the refrigerant supercooling unit 70 with a cooling capacity of the evaporator of less than 100 kW. Under these circumstances, ammonia water absorption chiller units 1 of minimum complexity are obtained which allow an economic application of the cooling principle also for cooling capacities of less than 100 kW, at drive temperatures of less than 100° C. and cooling temperatures of less than 0° C.
The exemplary embodiments of the invention represented in the FIGURE of the drawing and described in connection with this one only serve for explaining the invention and are not limiting to this one.

LIST OF REFERENCE NUMERALS

- 1 absorption chiller unit
- 2 refrigerant cycle
- 3 refrigerant flow direction
- 10 absorber
- 11 connection
- 12 connection
- 20 evaporator
- 21 connection
- 22 connection
- 30 condenser
- 31 connection
- 32 connection
- 40 desorber
- 41 connection
- 42 connection
- 50 solution heat exchanger
- 60 dephlegmator
- 70 refrigerant supercooling unit
- 80 pressure compensation pipe
- 90 pressure compensation pipe
- 100 pump

Claims

1. An ammonia water absorption chiller unit comprising at least one absorber arranged in a refrigerant cycle, characterized in that the absorber comprises a fully welded packet of plates for an inner medium which is in turn placed in a casing for an outer medium.

2. The ammonia water absorption chiller unit according to claim 1, characterized by an evaporator arranged in the refrigerant cycle, comprising a fully welded packet of plates for an inner medium which is in turn placed in a casing for an outer medium.

3. The ammonia water absorption chiller unit according to claim 2, characterized in that the absorber is arranged after the evaporator in the refrigerant flow direction.

4. The ammonia water absorption chiller unit according to claim 1, characterized by a desorber arranged in the refrigerant cycle, comprising a fully welded packet of plates for an inner medium which is in turn placed in a casing for an outer medium.

5. The ammonia water absorption chiller unit according to claim 4, characterized in that the desorber is arranged after the absorber in the refrigerant flow direction.

6. The ammonia water absorption chiller unit according to claim 1, characterized by a condenser arranged in the refrigerant cycle, comprising a fully welded packet of plates for an inner medium which is in turn placed in a casing for an outer medium.

7. The ammonia water absorption chiller unit according to claim 1, characterized in that the condenser is arranged before the evaporator in the refrigerant flow direction.

8. The ammonia water absorption chiller unit according to claim 1, characterized by a solution heat exchanger arranged in the refrigerant cycle, comprising a fully welded packet of plates for an inner medium which is in turn placed in a casing for an outer medium.

9. The ammonia water absorption chiller unit according to claim 8, characterized in that the solution heat exchanger is arranged between the absorber and the desorber in the refrigerant flow direction.

10. The ammonia water absorption chiller unit according to claim 1, characterized in that at drive temperatures of more than 100° C. a dephlegmator which is arranged in the refrigerant cycle and comprises a fully welded packet of plates for an inner medium which is in turn placed in a casing for an outer medium is present.

11. The ammonia water absorption chiller unit according to claim 10, characterized in that the dephlegmator is arranged before the condenser in the refrigerant flow direction.

12. The ammonia water absorption chiller unit according to claim 10, characterized in that the dephlegmator is cancelled at drive temperatures of less than 100° C.

13. The ammonia water absorption chiller unit according to claim 1, characterized by a refrigerant supercooling unit arranged in the refrigerant cycle, comprising a fully welded packet of plates for an inner medium which is in turn placed in a casing for an outer medium.

14. The ammonia water absorption chiller unit according to claim 13, characterized in that the refrigerant supercooling unit is cancelled with a cooling capacity of the evaporator of less than 100 kW.

15. The ammonia water absorption chiller unit according to claim 13, characterized in that the refrigerant supercooling unit is arranged between the evaporator and the condenser, on the one hand, and between the evaporator and the absorber, on the other hand, in the refrigerant flow direction.

16. The ammonia water absorption chiller unit according to claim 1, characterized in that the refrigerant cycle comprises at least one refrigerant, preferably ammonia.

17. The ammonia water absorption chiller unit according to claim 1, characterized in that the refrigerant cycle comprises at least one solvent, preferably water.

18. The ammonia water absorption chiller unit according to claim 1, characterized in that the feeding pipes and/or draining pipes to the condenser and the absorber in the refrigerant flow direction contain pressure compensation pipes.

19. A method of minimum complexity for leading media in at least one refrigerant cycle of an ammonia water absorption chiller unit, preferably an ammonia water absorption chiller unit according to claim 1, using heat exchangers which comprise a fully welded packet of plates for an inner medium which is in turn arranged in a casing for an outer medium.

20. The method according to claim 19, characterized in that for leading the media the plate geometry of the heat exchangers is adapted to turbulent flow conditions for a particularly efficient heat and substance transfer.

21. The method according to claim 20, characterized by an adaptation of the plate geometry of the heat exchangers to or for turbulent flow conditions with flow rates comprised between 0.05 m/s and 1 m/s as well as with pressure losses of less than 0.1 MPa.

22. A use of an absorber which comprises a fully welded packet of plates for an inner medium which is in turn arranged in a casing for an outer medium, in a refrigerant cycle of an ammonia water absorption chiller unit, preferably an ammonia water absorption chiller unit preferably using a method according to claim 19.