EP2438367A1

EP2438367A1 - Ammonia-water absorption refrigeration unit

Info

Publication number: EP2438367A1
Application number: EP10725024A
Authority: EP
Inventors: Wolfgang STÜRZEBECHER
Original assignee: Tranter Solarice GmbH
Current assignee: Tranter GmbH
Priority date: 2009-06-04
Filing date: 2010-06-01
Publication date: 2012-04-11
Also published as: WO2010139444A1; BRPI1010951A2; DE102009023929A1; CA2763417A1; US20120073315A1

Abstract

The present invention relates to an ammonia-water absorption refrigeration unit (1) for operating temperatures even below 100°C, comprising at least one absorber (10) arranged in a coolant circuit (2), wherein the absorber (10) comprises a fully welded plate packet for an inner medium, which plate packet in turn is arranged in a jacket tube for an outer medium. The invention further relates to a method of minimal complexity for conducting media in at least one coolant circuit (2) of an ammonia-water absorption refrigeration unit (1) according to the invention, using heat exchangers which comprise a fully welded plate packet for an inner medium, which plate packet in turn is arranged in a jacket tube for an outer medium. The invention further relates to the use of an optimized absorber (10) according to the invention, comprising a fully welded plate packet for an inner medium, which plate packet in turn is arranged in a jacket tube for an outer medium, in a coolant circuit (2) of an ammonia-water absorption refrigeration unit (1) according to the invention.

Description

Ammonia-water Absorptionskälteaqqreαat

The present invention relates to ammonia-water

Absorption refrigeration units with at least one arranged in a refrigerant circuit absorber.

Furthermore, the present invention relates to a method of minimal complexity for guiding media in at least one cycle of an ammonia water absorption refrigeration unit, taking into account the thermodynamic characteristics of binary two-phase mixtures.

In addition, the use of an absorber in connection with an ammonia-water absorption refrigeration unit according to the invention and / or a method according to the invention is the subject of the present invention.

The principle of absorption refrigeration with the substance pair ammonia and water has been known for about 200 years and is now used due to the economies of scale mainly for high cooling capacities in the range of about 200 kW to about 6,500 kW. Systems of this type, as described, for example, in DE 20 2007 007 999 U1, require a complex process engineering and, at cooling temperatures below 0 ^° C., drive temperatures clearly above 100 ^° C.

Against this background, the use of currently available technologies and novel calculation methods for heat and mass transfer should provide an ammonia-water absorption refrigeration unit of minimal complexity, which enables a more economical application of the cooling principle even for cooling capacities below 100 kW. In the relevant literature, see, for example, VDI Wärmeatlas (originally published by the VDI Verlag, Dusseldorf, 10th edited and expanded edition 2006, ISBN: 978-3-540-25504-8)), no calculation methods are known. Thus, the expert is still no specific guidelines or methods for sizing known to date to dimension the individual components of ammonia water absorption refrigeration units of minimal complexity for a commercially useful ammonia water absorption chiller and select accordingly, in particular at drive temperatures of less than 100 ⁰ C cooling temperatures below 0 ⁰ C should be achievable.

For technical solution according to the invention an ammonia water absorption refrigeration unit is proposed with at least one arranged in a refrigerant circuit absorber, which is characterized in that the absorber has a fully welded plate package for an inner medium, which in turn is arranged in a jacket tube for an external medium.

In particular, the invention makes use of the fact that with the exclusive use of fully welded tube plate heat exchangers for the absorber of an ammonia water absorption refrigeration unit with appropriate dimensioning or design cooling temperatures of below 0 ° C even at drive temperatures below 100 ° C are reachable. Ammonia-water absorption refrigeration units according to the invention are particularly suitable for solar thermal cooling systems and are hitherto unknown in the prior art. The present invention is characterized by a new simplified circuit. In the further embodiment of the invention, highly effective heat-transferring components are proposed, which go far beyond the previously known in the prior art solutions in the combinations of the invention. The prior art assumes that due to the high gas flow rate and the associated pressure losses in an absorber of an ammonia water absorption refrigeration unit effective material and heat transfer can only be achieved by using tube bundle heat exchangers. It has been found according to the invention that, with careful calculation of the numerous parameters of an ammonia-water absorption refrigeration unit, effective heat and mass transfer can be achieved precisely or specifically with tubular plate heat exchangers. It was surprisingly found that with the exclusive use of fully welded tube plate heat exchangers for the absorber of an ammonia water absorption refrigeration unit cooling temperatures below 0 ⁰ C even at drive temperatures of well below 100 ⁰ C can be achieved, especially when using a binary ammonia-water two-phase mixture.

Full-welded plate packs which can be used according to the invention for the absorber are disclosed, for example, on the part of EP 1 559 981 A2 or DE 601 12 767 T2, the disclosures of which are hereby expressly referenced.

For dimensioning or design of ammonia water absorption refrigeration units according to the invention with the aim of a particularly efficient heat and mass transfer is or is the plate geometry of the absorber used for fully welded tube-plate heat exchangers with special consideration of the thermodynamic parameters of mixtures for the leadership the media advantageously tuned to or for turbulent flow conditions with pressure losses below 0.1 MPa. Advantageously, a vote on or for turbulent flow conditions at flow rates between 0.05 m / s and 1 m / s and at pressure losses below 0.1 MPa. Under these special conditions, drive temperatures according to the invention can also be made particularly economical under 100 ^° C.

In an advantageous embodiment of the invention, the absorption takes place in the jacket tube of the absorber of the ammonia-water absorption refrigeration unit according to the invention and the resulting refrigerant-rich solution in the same upstream. According to the invention, the solution collector otherwise customary in the prior art can thus be saved according to the invention. The number of components of an absorption refrigeration unit is so reduced and it also results in a more compact design. Depending on the particular application and the required performance, an ammonia-water absorption refrigeration unit according to the invention can be implemented as required in numerous different variants and designs. In a further advantageous embodiment of the invention, an evaporator is advantageously arranged in the refrigerant circuit of the ammonia-water absorption refrigeration unit, after or behind, followed by the absorber in the refrigerant flow direction. As a result, the flow-related pressure losses are reduced and the performance of an ammonia-water absorption refrigeration unit according to the invention further improved. Advantageously, the evaporator on a fully welded plate package for an inner medium, which in turn is arranged in a jacket tube for an external medium. Here, a phase change of the liquid refrigerant into the gaseous state preferably takes place in the plate pack. In this case, the refrigerant continuously withdraws the heat from the medium in the jacket tube of the brine circulation, which is to be cooled by the absorption refrigeration unit. The flows in the plate pack and in the jacket tube of the evaporator are preferably conducted in countercurrent to one another. Full-welded plate packs which can be used in accordance with the invention for the evaporator are disclosed, for example, by EP 1 559 981 A2 or DE 601 12 767 T2, for example.

In a further advantageous embodiment of the invention, a desorber is advantageously arranged in the refrigerant circuit of the ammonia-water absorption refrigeration unit, advantageously comprising a fully welded plate pack for an inner medium, which in turn is arranged in a jacket tube for an external medium. In the desorber, a phase change of the refrigerant-containing solution from the liquid to the gaseous state preferably takes place in the plate package. In this case, the refrigerant-containing solution is continuously supplied with heat from a medium in the jacket tube of the heating circuit, which drives or is intended to drive the absorption refrigeration unit. The flows in the plate pack and in the jacket tube of the desorber are preferably conducted in countercurrent to one another. Advantageously, the desorber is arranged downstream of the absorber in the direction of refrigerant flow. By these measures according to the invention, individually and / or in combination with one another, in particular the performance of an ammonia-water absorption refrigeration unit according to the invention is further improved. Full-welded plate packs which can be used according to the invention for the desorber are disclosed in the manner of example by EP 1 559 981 A2 and DE 601 12 767 T2. In a further advantageous embodiment of the invention, a capacitor is advantageously arranged in the refrigerant circuit of the ammonia-water absorption refrigeration unit, advantageously comprising a fully welded plate package for an inner medium, which in turn is arranged in a jacket tube for an external medium. In the condenser, a phase change of a refrigerant-containing vapor from the gaseous to the liquid state preferably takes place in the jacket tube, wherein the resulting refrigerant-containing condensate is stored upstream in the same. As a result, the otherwise common in the art in absorption refrigeration units refrigerant accumulator can be saved. The number of components of an ammonia-water absorption refrigeration unit according to the invention is reduced and a more compact design is made possible. In this case, the refrigerant-containing vapor continuously dissipates heat to a medium in the plate pack of the recooling circuit, which serves as the heat sink for the ammonia-water absorption refrigeration unit according to the invention. The flows in the plate pack and in the jacket tube of the condenser are preferably conducted in countercurrent to one another. Preferably, the condenser is arranged in the direction of refrigerant flow in front of the evaporator of an ammonia-water absorption refrigeration unit according to the invention. By these measures according to the invention, individually and / or in combination with one another, in particular the performance of an ammonia-water absorption refrigeration unit according to the invention is further improved.

Fully welded plate packs which can be used according to the invention are disclosed in the manner of example by EP 1 559 981 A2 and DE 601 12 767 T2, respectively.

In a further advantageous embodiment of the invention, a solution heat exchanger is advantageously arranged in the refrigerant circuit of the ammonia-water absorption refrigeration unit, advantageously comprising a fully welded plate package for an inner medium, which in turn is arranged in a jacket tube for an external medium. In the solution heat exchanger, a refrigerant-containing solution to be supplied to the desorber is already internally preheated. The flows in the plate pack and in the jacket tube of the solution heat exchanger are preferably conducted in countercurrent to one another. This reduces the external heat input in the desorber and further improves the performance of an ammonia-water absorption refrigeration unit according to the invention. Is preferred the solution heat exchanger arranged in the refrigerant flow direction between the absorber and desorber. By these measures according to the invention, individually and / or in combination with one another, in particular the performance of an ammonia-water absorption refrigeration unit according to the invention is further improved. Fully welded plate packs which can be used according to the invention for the solution heat exchanger are disclosed, for example, by EP 1 559 981 A2 or DE 601 12 767 T2, for example.

In a further advantageous embodiment of the invention in the refrigerant circuit of the ammonia-water absorption refrigeration unit at drive temperatures above 100 ⁰ C advantageously arranged a dephlegmator, advantageously comprising a fully welded plate package for an inner medium, which in turn is arranged in a jacket tube for an external medium. In the dephlegmator, preferably in the plate pack, a refrigerant-containing vapor to be supplied to the condenser dissipates heat to a medium in the jacket tube, whereby a portion of the refrigerant-containing vapor is already condensed. This ensures that get with the refrigerant-containing vapor only small amounts of solvent vapor in the condenser. Preferably, the dephlegmator is arranged upstream of the condenser in the direction of refrigerant flow. By these measures according to the invention, individually and / or in combination with one another, in particular the performance of an ammonia-water absorption refrigeration unit according to the invention is further improved.

Full-welded plate packs which can be used according to the invention for the dephlegmator are disclosed, for example, on the part of EP 1 559 981 A2 or DE 601 12 767 T2.

According to a particularly advantageous embodiment of the invention, there is the possibility of reducing previously considered necessary or necessary in the prior art components. It was found that at drive temperatures below 100 ⁰ C, the proportion of vaporous solvent in the refrigerant-containing vapor is usually less than 5%, so that according to the invention, in particular a dephlegmator can be saved. In a further advantageous embodiment of the invention, a refrigerant subcooler is arranged in the refrigerant circuit of the ammonia-water absorption refrigeration unit, advantageously comprising a fully welded plate package for an inner medium, which in turn is arranged in a jacket tube for an external medium. In the refrigerant subcooler, the temperature of the condensed refrigerant to be supplied to the evaporator is lowered below the boiling point. As a result, it is achieved according to the invention that, on the one hand, no premature evaporation takes place in the case of pressure losses, and, on the other hand, the amount of enthalpy of evaporation is increased, which further improves the performance of an ammonia-water absorption refrigeration unit according to the invention. The flows in the plate pack and in the jacket tube of the refrigerant subcooler are preferably conducted in countercurrent to one another. Preferably, the refrigerant subcooler is arranged in the refrigerant flow direction on the one hand between the evaporator and the condenser and on the other hand between the evaporator and the absorber. Full-welded plate packs which can be used according to the invention for the refrigerant subcooler are disclosed, for example, by EP 1 559 981 A2 or DE 601 12 767 T2, for example.

According to a particularly advantageous embodiment of the invention, there is the possibility of reducing previously considered necessary or necessary in the prior art components. It has been found that with a cooling capacity of the evaporator of less than 100 kW, the refrigerant subcooler can be saved, especially because at a cooling capacity of the evaporator of less than 100 kW, the contribution of a refrigerant subcooler to increase the performance of an ammonia water absorption refrigeration unit according to the invention the technical effort - and the associated cost expenditures - not justifiable for efficient use.

Preferably, the refrigerant contained in the refrigeration cycle is ammonia or has ammonia. Preferably, the solvent contained in the refrigeration cycle is water or has water.

In a further advantageous embodiment of the invention, the feed and / or discharge lines are provided in the refrigerant flow direction to the condenser and / or absorber with a pressure equalization line. This will be Reduces pressure losses and allows a more even heat transfer. As a result of this measure, which is otherwise not customary in the state of the art, the efficiency of the absorption of refrigerant into the sorbent and hence the mode of action of an ammonia-water absorption refrigeration unit according to the invention are further improved overall.

The invention further relates to ammonia-water absorption refrigeration units having an absorption refrigeration process of minimal complexity for guiding media in at least one refrigerant circuit using heat exchangers comprising a fully welded inner medium plate package, which in turn is disposed in a jacket tube for an outer medium. Fully welded plate packs which can be used according to the invention are disclosed in the manner of example by EP 1 559 981 A2 and DE 601 12 767 T2.

According to the invention, it is proposed that the plate geometry, with special consideration of the thermodynamics of mixtures of substances for the guidance of the media for the purpose of particularly efficient heat and mass transfer, be tuned to turbulent flow conditions with pressure losses below 0.1 MPa. Advantageously, a vote on or for turbulent flow conditions at flow rates between 0.05 m / s and 1 m / s and at pressure losses below 0.1 MPa. According to the invention, this simultaneously results in the possibility of a compact construction of ammonia-water mixtures according to the invention.

Absorption refrigeration units. Depending on the particular application and required performance, the inventive design can be implemented in numerous different variants, as needed. The method can be used due to the present invention carried out modular grading and tuning fully welded tube-plate heat exchanger with cooling power from the kilowatt range into the megawatt range inside, and thus advantageously contribute significantly to the rational use of energy.

The invention consequently also relates to the embodiment of an absorber as a fully welded plate pack for an internal medium, which in turn is arranged in a jacket tube for an external medium, in a refrigerant circuit of an ammonia-water mixture according to the invention. Absorption refrigeration units, in particular with one or more of the aforementioned features.

The embodiments of the invention and the results obtained with these allow optimization of the individual tube-plate heat exchangers, lead to a high efficiency and allow a hitherto unknown in the prior art and not accessible compact design of ammonia-water absorption refrigeration units.

Further details, features and advantages of the invention will be explained in more detail with reference to the embodiment of the invention shown in the figure of the drawing. Showing:

1 shows a block diagram of an embodiment of an inventive ammonia water absorption refrigeration unit.

1 shows an ammonia-water absorption refrigeration unit 1 with an absorber 10, evaporator 20, condenser 30, desorber 40, solution heat exchanger 50, dephlegmator 60 and a refrigerant subcooler 70 arranged in a refrigerant circuit 2. Further, pressure compensation lines 80, 90 establish a connection in FIG Refrigerant flow direction 3 between inlet and outlet of the absorber 10 and condenser 30 ago to reduce pressure losses and to allow a more uniform heat transfer.

The refrigerant contained in the refrigerant circuit 2 flows into the refrigerant flow direction 3 symbolically represented by an arrow and is conveyed by a pump 100 into the desorber 40. The basic mode of operation of an absorption refrigeration unit is assumed to be known in the present case (cf., in particular, Handbook of Refrigeration, Volume 7, Sorption Refrigeration Machines, Wilhelm Niebergall, 1959). The drive energy is via a heating medium in the desorber 40 through the terminals 41 and 42 and derived. The cooling capacity is transmitted by means of a refrigerant medium in the evaporator 20 through the terminals 21 and 22. The cooling of the ammonia water absorption chiller 1 is carried out by a heat transfer medium in the absorber 10 through the terminals 11 and 12 and in the condenser through the terminals 31 and 32. The execution of the heat exchanger with a fully welded plate package for an inner medium, which in turn a jacket tube for an external medium is arranged, in principle follows the disclosures of EP 1 559 981 A2 and DE 601 12 767 T2, the disclosures of which are hereby expressly referenced. The plate geometry for a fully welded plate package according to the invention is advantageously with particular consideration of the thermodynamics of mixtures for the guidance of the media for particularly efficient heat and mass transfer to turbulent flow conditions at flow rates between 0.05 m / s and 1 m / s at pressure drops below 0, 1 MPa tuned.

The development of the invention relates in the present case to a hitherto in the prior art not considered possible or feasible held reduction of components of an absorption refrigeration unit, which have been considered necessary and necessary according to the prior art. The results and calculations of the present invention show that the dephlegmator 60 can be saved at drive temperatures below 100 ^° C. The same applies to the refrigerant subcooler 70 at a cooling capacity of the evaporator of less than 100 kW. Under these conditions, ammonia-water absorption refrigeration units 1 of minimal complexity, which allow economical application of the cooling principle for cooling capacities below 100 kW, at drive temperatures below 100 ⁰ C and cooling temperatures below 0 ° C.

The illustrated in the figure of the drawing and described in connection with these embodiments of the invention are only illustrative of the invention and are not limiting for this.

LIST OF REFERENCES:

1 absorption refrigeration unit

2 refrigerant circuit

3 refrigerant flow direction

10 absorbers

11 connection

12 connection

20 evaporators

21 connection

22 connection

30 capacitor

31 connection

32 connection

40 desorber 1 connection 2 connection

50 solution heat exchangers

60 Dephlegmator

70 refrigerant subcooler

80 pressure compensation line

90 pressure compensation line

100 pump

Claims

Claims:

1. ammonia water absorption refrigeration unit (1) having at least one in a refrigerant circuit (2) arranged absorber (10), characterized in that the absorber (10) has a fully welded plate package for an inner medium, which in turn in a casing tube for a outer medium is arranged.

2. ammonia water absorption refrigeration unit (1) according to claim 1, characterized by a in the refrigerant circuit (2) arranged evaporator (20), comprising a fully welded plate package for an inner medium, which in turn is arranged in a jacket tube for an external medium.

3. ammonia water absorption refrigeration unit (1) according to claim 2, characterized in that the absorber (10) in the refrigerant flow direction (3) after the evaporator (20) is arranged.

4. ammonia water absorption refrigeration unit (1) according to one or more of claims 1 to 3, characterized by a in the refrigerant circuit (2) arranged desorber (40), comprising a fully welded plate package for an inner medium, which in turn in a casing tube for an outer medium is arranged.

5. ammonia water absorption refrigeration unit (1) according to claim 4, characterized in that the desorber (40) in the refrigerant flow direction (3) after the absorber (10) is arranged.

6. ammonia water absorption refrigeration unit (1) according to one or more of claims 1 to 5, characterized by a in the refrigerant circuit (2) arranged capacitor (30), comprising a fully welded plate package for an inner medium, which in turn in a casing tube for an outer medium is arranged.

7. ammonia-water absorption refrigeration unit (1) according to one or more of claims 2 to 6, characterized in that the capacitor (30) in the refrigerant flow direction (3) in front of the evaporator (20) is arranged.

8. ammonia water absorption refrigeration unit (1) according to one or more of claims 1 to 7, characterized by a in the refrigerant circuit (2) arranged solution heat exchanger (50), comprising a fully welded plate package for an inner medium, which in turn in a casing tube for an outer medium is arranged.

9. ammonia water absorption refrigeration unit (1) according to claim 8, characterized in that the solution heat exchanger (50) in the refrigerant flow direction (3) between the absorber (10) and desorber (40) is arranged.

10. ammonia-water absorption refrigeration unit (1) according to one or more of claims 1 to 9, characterized in that at drive temperatures above 100 ⁰ C in the refrigerant circuit (2) arranged dephlegmator (60), comprising a fully welded plate package for an internal Medium, which in turn is arranged in a jacket tube for an external medium, is present.

11. ammonia water absorption refrigeration unit (1) according to claim 10, characterized in that the dephlegmator (60) in the refrigerant flow direction in front of the condenser (30) is arranged.

12. ammonia water absorption refrigeration unit (1) according to claim 10 or claim 11, characterized in that the dephlegmator (60) is omitted at drive temperatures below 100 ⁰ C.

13. ammonia water absorption refrigeration unit (1) according to one or more of claims 1 to 12, characterized by a in the refrigerant circuit (2) arranged refrigerant subcooler (70), comprising a fully welded plate package for an inner medium, which in turn in a jacket tube for an outer medium is arranged.

14. ammonia water absorption refrigeration unit (1) according to claim 13, characterized in that the refrigerant subcooler (70) at a cooling capacity of the evaporator (20) of less than 100 kW is omitted.

15. ammonia water absorption refrigeration unit (1) according to claim 13 or claim 14, characterized in that the refrigerant subcooler (70) in the refrigerant flow direction (3) on the one hand between the evaporator (20) and condenser (30) and on the other hand between the evaporator (20) and Absorber (10) is arranged.

16. ammonia water absorption refrigeration unit (1) according to one or more of claims 1 to 15, characterized in that the refrigerant circuit (2) at least one refrigerant, preferably ammonia.

17. ammonia water absorption refrigeration unit (1) according to one or more of claims 1 to 16, characterized in that the refrigerant circuit comprises at least one solvent, preferably water.

18. ammonia water absorption refrigeration unit (1) according to one or more of claims 1 to 17, characterized in that the feed and / or discharges in the refrigerant flow direction (3) to the condenser (30) and absorber (10) contain pressure equalization lines.

19. A process of minimal complexity for guiding media in at least one refrigerant circuit (2) of an ammonia water absorption refrigeration unit (1), preferably an ammonia water absorption refrigeration unit (1) according to one or more of claims 1 to 18, using heat exchangers comprising a fully welded inner medium plate package, which in turn is disposed in an outer medium jacket tube.

20. The method according to claim 19, characterized in that the plate geometry of the heat exchanger for the management of the media for the purpose of particularly efficient heat and mass transfer to turbulent flow conditions is tuned.

21. The method according to claim 20, characterized by a vote of the plate geometry of the heat exchanger on or for turbulent flow conditions at flow rates between 0.05 m / s and 1 m / s and at pressure losses below 0.1 MPa.

22. Use of an absorber (10), which has a fully welded plate package for an inner medium, which in turn is arranged in a jacket tube for an external medium, in a refrigerant circuit (2) of an ammonia-water Absorptionskälteaggregates (1), preferably a Absorptionskälteaggregates (1) according to one or more of claims 1 to 18, preferably using a method according to any one of claims 19 to 21.