REFRIGERANT DRYER

• US 20110061409A2
• Filed: 10/14/2009
• Published: 03/17/2011
• Est. Priority Date: 10/15/2008
• Status: Active Grant

• Current Assignee: Kaeser Kompressoren AG
• Original Assignee: Kaeser Kompressoren GmbH
• Inventors: FEISTHAUER, Michael, FOERSTER, Andreas, KOBELT, Klaus-Ulrich, FREDENHAGEN, Andreas, DERING, Kristian
• Granted Patent: US 8,857,207 B2
• Time in Patent Office: Days
• US Class Current: 062/115.000
• CPC Class Codes: B01D 53/265 by refrigeration (condensation)
• CPC Class Codes: F25B 2400/24 Storage receiver heat
• CPC Class Codes: F28D 20/02 using latent heat
• CPC Class Codes: Y02E 60/14 Thermal energy storage

Abstract

A refrigerant dryer, in particular a compressed air refrigerant dryer, is provided for drying a gaseous fluid while cooling the gaseous fluid using a refrigerant. The dryer includes a pressure fluid-refrigerant agent-heat exchanger (30) in which a cooling of the gaseous fluid takes place directly or indirectly by a refrigerant conveyed in a primary loop (16), one or more refrigerant compressor/compressors (24) for operating the primary loop, and a cold accumulator (13) with an accumulator-side heat exchanger (20) which couples an accumulator discharge fluid to a cold accumulator medium (14). The pressure fluid-refrigerant agent-heat exchanger (30) and the cold accumulator (13) are fluidically connected or can be brought into fluidic connection via a discharge loop (15) for an accumulator discharge fluid. The cold accumulator (13) is arranged, relative to gravity, above the pressure fluid-refrigerant agent-heat exchanger (30), in such a manner that the heated accumulator discharge fluid is conveyed through the discharge loop (15) for cooling in the cold accumulator (13), is cooled there, and subsequently re-conveyed to the pressure fluid-refrigerant agent-heat exchanger (30).

Claims

1. A refrigerant dryer, in particular a compressed air refrigerant dryer, for drying a gaseous fluid while cooling the gaseous fluid using a refrigerant, the dryer comprising:

a pressure fluid-refrigerant agent-heat exchanger (30) in which a cooling of the gaseous fluid takes place directly or indirectly by a refrigerant conveyed in a primary loop (16),

one or more refrigerant compressor/compressors (24) for operating the primary loop, and

a cold accumulator (13) having an accumulator-side heat exchanger (20) which couples an accumulator discharge fluid to a cold accumulator medium (14),

wherein the pressure fluid-refrigerant agent-heat exchanger (30) and the cold accumulator (13) are fluidically connected or may be brought into fluidic connection via a discharge loop (15) for an accumulator discharge fluid, in such a manner that the accumulator discharge fluid having an increased heat content is conveyed through the discharge loop (15) for heat emission to the cold accumulator (13), emits heat there, and subsequently, having a reduced heat content, is again conveyed to the pressure fluid-refrigerant agent-heat exchanger (30).

2. The refrigerant dryer according to claim 1, wherein the connection is such that and the accumulator discharge fluid is selected so that the accumulator discharge fluid condenses in the accumulator discharging loop while emitting heat to the cold accumulator (13) and evaporates in the pressure fluid-refrigerant agent-heat exchanger (30) while absorbing heat.

3. The refrigerant dryer according to claim 1, wherein the discharge loop is driven by convection of the accumulator discharge fluid, in particular in a gravity-induced manner, by arranging the cold accumulator (13) above the pressure fluid-refrigerant agent-heat exchanger (30) and/or by drive means such as a pump.

4. The refrigerant dryer according to claim 1, wherein the discharge loop (15) is essentially only active during operating phases in which the refrigerant compressor/compressors (24) is/are switched off or is/are driven at a reduced power.

5. The refrigerant dryer according to claim 1, wherein the primary loop (16) and the discharge loop (15) are in fluidic connection at least in case to case, in particular within the pressure fluid-refrigerant agent-heat exchanger (30), so that the accumulator discharge fluid of the discharge loop (15) and the refrigerant of the primary loop (16) are formed by the same refrigerant.

6. The refrigerant dryer according to claim 5, wherein the discharge loop (15) forms in parts of the primary loop (16) from case to case and is thus delimited by the flow ducts of the primary loop.

7. The refrigerant dryer according to claim 1, wherein the primary loop (16) and the discharge loop (15) are configured as loops which, in terms of fluid technology, are separated from each other and are in thermal interaction with each other through a primary loop-transfer-heat exchanger (52).

8. The refrigerant dryer according to claim 1, wherein the cold accumulator (13) is spatially separated from the pressure fluid-refrigerant agent-heat exchanger (30).

9. The refrigerant dryer according to claim 1, wherein the accumulator-side heat exchanger (20) and the pressure fluid-refrigerant agent-heat exchanger (30) are integrated into one common component (12).

10. The refrigerant dryer according to claim 1, wherein the gaseous fluid flows in a direction of flow through an air-air-heat exchanger (49) upstream and downstream of the pressure fluid-refrigerant agent-heat exchanger (30), in such a manner that the gaseous fluid cooled down in the pressure fluid-refrigerant agent-heat exchanger (30) pre-cools the gaseous fluid flowing into the pressure fluid-refrigerant agent-heat exchanger (30), wherein the pressure fluid-refrigerant agent-heat exchanger (30) and the air-air-heat exchanger (49) are integrated into one common component, and wherein the accumulator-side heat exchanger (20) is realized as a separate individual component or is integrated into one common component together with the air-air-heat exchanger (49) and the pressure fluid-refrigerant agent-heat exchanger (30).

11. The refrigerant dryer according to claim 1, wherein heat is extracted from the cold accumulator (13) in a charge state by an accumulator-side heat exchanger (20) or a separate loading heat exchanger (48) by an accumulator charging fluid which may be identical to or separate from the accumulator discharge fluid.

12. The refrigerant dryer according to claim 1, wherein, in the charge state, the cold accumulator (13) is in active communication with the refrigerant of the primary loop (16) through the accumulator-side heat exchanger (20) and/or a separate loading heat exchanger (48) for reducing the heat content of the cold accumulator medium (14).

13. The refrigerant dryer according to claim 1, wherein the thermal capacity of the cold accumulator (13), the cold accumulator medium (14) respectively, is increased in that the cold accumulator medium (14) performs a phase transition in its operating range.

14. The refrigerant dryer according to claim 1, wherein the cold accumulator medium (14) is selected such that its operating range is between −

8°

C. and 4°

C., preferably about 2°

C. for structural configurations in which the accumulator-side heat exchanger (20) and the pressure fluid-refrigerant agent-heat exchanger (30) are integrated into one common component (12), and/or about −

3°

C. for structural configurations in which the cold accumulator (13) is spatially separated from the pressure fluid-refrigerant agent-heat exchanger (30).

15. The refrigerant dryer according to claim 1, wherein means for increasing the thermal conductivity are provided on the accumulator-side heat exchanger (20) and/or on an optional additionally provided loading heat exchanger (48) of the cold accumulator (13) and/or in the cold accumulator (13) itself, in order to effect a most efficient coupling possible of the accumulator discharge fluid and/or the accumulator charge fluid with the cold accumulator medium (14) of the cold accumulator (13).

16. The refrigerant dryer according to claim 1, wherein the means for increasing the thermal conductivity in the cold accumulator (13) are formed in that substances, particles or fibers having high thermal conductivity are incorporated in the cold accumulator medium for improving effective thermal conductivity in the cold accumulator medium.

17. The refrigerant dryer according to claim 1, wherein the dryer splits a refrigerant guide into sections of two parallel tracks in the primary loop (16), namely a compressed air-side track (41) and an accumulator-side track (42), wherein the compressed air-side track (41) is guided across the pressure fluid-refrigerant agent-heat exchanger (30) and the accumulator-side track (42) is guided across the cold accumulator (13).

18. The refrigerant dryer according to claim 17, wherein a separate expansion element (26, 26′

) and/or similar adjustment elements (36) is/are respectively allocated to the compressed air-side track (41) and the accumulator-side track (42) to achieve different evaporation pressures.

19. The refrigerant dryer according to claim 1, wherein flow paths of the discharge loop (15) are partially or exclusively used for reducing the heat content of the cold accumulator (13) by the refrigerant of the primary loop (16).

20. The refrigerant dryer according to claim 19, wherein continuous refrigerant ducts (17) constitute sections of the discharge loop (15) and extend at least substantially over an entire height of the common component (12) formed by the accumulator-side heat exchanger (20) and the pressure fluid-refrigerant agent-heat exchanger (30).

21. The refrigerant dryer according to claim 20, wherein in the discharge state, a convection-induced circulation is created within the refrigerant ducts (17) in the pressure fluid-refrigerant agent-heat exchanger (30), so that the refrigerant absorbs heat in the lower area of the refrigerant ducts (17) by the gaseous fluid to be cooled in the compressed air ducts (18), the refrigerant evaporates and rises toward the cold accumulator (13) with an increased heat content, emits heat there and condenses, and then descends again under the influence of gravity, after heat emission within the cold-conducting ducts (17), in order to again cool the gaseous fluid there in the compressed air ducts (18).

22. The refrigerant dryer according to claim 20, wherein the cold accumulator medium (14) is separately accommodated within a plurality of sealed chambers (19) which are each formed to be terminally closed duct portions, or the plurality of chambers (19) are fluidically connected to each other by at least one terminally arranged collecting vessel (50) which preferably includes one or more opening(s) (51) for filling and emptying, respectively.

23. The refrigerant dryer according to claim 20, wherein the common component (12) comprising the accumulator-side heat exchanger (20) and the pressure fluid-refrigerant agent-heat exchanger (30) is formed to be a plate-type heat exchanger or an aluminum block-type heat exchanger.

24. A method for cold-drying a gaseous fluid in a refrigerant dryer, in particular a compressed air refrigerant dryer, wherein the refrigerant dryer comprises:

a pressure fluid-refrigerant agent-heat exchanger (30) in which a cooling of the gaseous fluid takes place directly or indirectly by a refrigerant conveyed in a primary loop (16),

one or more refrigerant compressor/compressors (24) for operating the primary loop, and

a cold accumulator (13) with an accumulator-side heat exchanger (20) which couples an accumulator discharge fluid to a cold accumulator medium (14),

the method comprising the following steps;

reducing the heat content of the cold accumulator (13) by excess cooling capacity of the refrigerant of the primary loop in operating states in which the cooling of the gaseous fluid does not require any or only a fraction of available cooling capacity, and

discharging the cold accumulator (13) and cooling the gaseous fluid using the accumulator discharge fluid by a heat or cold transfer between the pressure fluid-refrigerant agent-heat exchanger (30) and the cold accumulator (13) in operating states in which the cooling of the gaseous fluid is not or is only partially caused by cooling capacity of the primary loop, wherein during circulation of the accumulator discharge fluid, the accumulator discharge fluid is subjected—

if necessary influenced by control elements—

to cyclic phase transitions between liquid and vapor at a substantially equal pressure level.

25. The method according to claim 24, wherein the cooling of the gaseous fluid is effected exclusively or partially by the cold accumulator upon interruption or switching off or a stepped or continuous power reduction of the primary loop, wherein the convective heat or cold transfer between the cold accumulator (13) and the pressure fluid-refrigerant agent-heat exchanger starts automatically or is regulated or controlled, in particular by valves.