US20120132399A1 - Method of operating an assembly of heat exchangers for subcritical and transcritical conditions, and an assembly of heat exchangers - Google Patents
Method of operating an assembly of heat exchangers for subcritical and transcritical conditions, and an assembly of heat exchangers Download PDFInfo
- Publication number
- US20120132399A1 US20120132399A1 US13/380,678 US201013380678A US2012132399A1 US 20120132399 A1 US20120132399 A1 US 20120132399A1 US 201013380678 A US201013380678 A US 201013380678A US 2012132399 A1 US2012132399 A1 US 2012132399A1
- Authority
- US
- United States
- Prior art keywords
- heat exchangers
- assembly
- heat exchanger
- heat
- conduit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B6/00—Compression machines, plants or systems, with several condenser circuits
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D1/00—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators
- F28D1/02—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators with heat-exchange conduits immersed in the body of fluid
- F28D1/04—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators with heat-exchange conduits immersed in the body of fluid with tubular conduits
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B41/00—Fluid-circulation arrangements
- F25B41/20—Disposition of valves, e.g. of on-off valves or flow control valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B6/00—Compression machines, plants or systems, with several condenser circuits
- F25B6/02—Compression machines, plants or systems, with several condenser circuits arranged in parallel
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B6/00—Compression machines, plants or systems, with several condenser circuits
- F25B6/04—Compression machines, plants or systems, with several condenser circuits arranged in series
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
- F25B9/002—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant
- F25B9/008—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant the refrigerant being carbon dioxide
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2309/00—Gas cycle refrigeration machines
- F25B2309/06—Compression machines, plants or systems characterised by the refrigerant being carbon dioxide
- F25B2309/061—Compression machines, plants or systems characterised by the refrigerant being carbon dioxide with cycle highest pressure above the supercritical pressure
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2500/00—Problems to be solved
- F25B2500/18—Optimization, e.g. high integration of refrigeration components
Abstract
The present invention refers to a method of operating an assembly (1) of heat exchangers (2) for subcritical and transcritical conditions, by initially arranging at least two heat exchangers (2) in parallel for the subcritical condition.
Description
- The present invention relates to a method of operating an assembly of heat exchangers for subcritical and transcritical conditions, by initially arranging at least two heat exchangers in parallel for the subcritical condition, and to an assembly of heat exchangers.
- In a conventional refrigeration system, heat release from the refrigerant is based on condensation of the refrigerant. The temperature is a critical point, which being constant during condensation. Operating an assembly of heat exchangers below the critical point is defined as subcritical mode. It is previously known to arrange heat exchangers in parallel at such subcritical mode.
- However, in heat pump and refrigeration applications using CO2 as refrigerant there is a need to operate in transcritical mode, i.e. above the critical point as well as below the critical point. Transcritical refrigeration systems with CO2 as a refrigerant are well known in the art. The critical temperature of CO2 is 31.0° C. and the critical pressure is 73.8 bar. At higher temperatures and pressures no clear distinction can be drawn between liquid and vapour, and CO2 is said to be in the so-called super-critical fluid region. The thermal conditions for these two operation modes are dramatically different. During transcritical mode the flow rates of the cold side, typically brine or water, are much lower than during subcritical mode. Thermally the process on the hot side of the refrigerant is also very different. In transcritical mode large temperature drops is required with close approach at pinch point and outlet. All together this calls for two different designs of the heat exchanger to be able to operate the system in an optimal way.
- Considering the temperature difference needed in a heat exchanger, i.e. approximate 10° C., the upper limit for heat release based on condensation of CO2 will be around 20° C. ambient temperature. Below this temperature, the CO2 stays below the critical point and the refrigeration system operates in subcritical mode. For refrigeration systems used in supermarkets, the ambient temperature will exceed 20° C. during the summer in a large part of the world. At these temperatures, cooling of the CO2 is a single-phase cooling, namely a gas cooling. CO2 is above the critical point at the high pressure side of the system, and the refrigeration system operates in transcritical mode.
- The efficiency and the cooling capacity of the refrigeration system are lower in transcritical operation than in subcritical operation. It is an important disadvantage of known CO2 refrigeration systems that they have a lowered performance at elevated ambient temperatures above approximately 20° C., i.e. when a high performance is actually desired. It is an object of the present invention to provide a transcritical refrigeration system with improved performance during transcritical operation.
- It is an object of the present invention to constitute a solution to the problem, of the contradictory requirements for heat exchanger design for gas coolers and condensers. Instead of finding a design for a heat exchanger that typically is determined by subcritical conditions and then use it for transcritical operation one may use multiple heat exchangers in the system.
- According to a first aspect of the present invention, these objects are achieved by arranging at least one heat exchanger at a transcritical condition in series with the other heat exchangers, and arranging an inlet and an outlet at opposite ends of the assembly, and switching the heat exchangers between being arranged in parallel to being arranged in series by closing a first conduit, connecting said inlet to a first duct of each heat exchanger, after the first heat exchanger and between every second heat exchanger, and a second conduit, connecting said outlet to a second duct of each heat exchanger, between the other heat exchangers.
- The method include the use of multiple heat exchangers in parallel during condensation and then change to use them in serial or a combination serial and parallel during transcritical operation.
- This improves system efficiency substantially in transcritical mode as the thermal length and heat transfer increases and thus the outlet temperature of the refrigerant can be lowered.
- In addition, switching the heat exchangers between being arranged in parallel to being arranged in series by closing a first conduit, which connecting said inlet to a first duct of each heat exchanger, after the first heat exchanger and between every second heat exchanger, and a second conduit, which connecting said outlet to a second duct of each heat exchanger, between the other heat exchangers.
- By providing said heat exchangers with a dual-circuit for heat transfer between two essentially liquid media, such as a refrigerant and brine, it is an advantage of switching each circuit between being arranged in parallel to being arranged in series.
- By this the flexibility is increased and makes it possible to optimize the performance of the system both for subcritical as well as transcritical mode.
- Another aspect of the invention is an assembly of heat exchangers having an inlet and an outlet at opposite ends of the assembly, a first conduit connected to said inlet and to a first duct of each heat exchanger and a second conduit connected to said outlet and a second duct of each heat exchanger, characterised in that a valve being located in the first conduit after the first heat exchanger and between every second heat exchanger and in the second conduit between the other heat exchangers, wherein the heat exchangers being arranged in parallel having all valves in open position and in series having all valves in closed position.
- This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing a currently preferred embodiment of the invention.
-
FIG. 1 a shows a schematically view of an assembly of heat exchangers according to a first parallel arranged operating condition according to the present invention. -
FIG. 1 b shows a temperature/position chart for the operating condition according toFIG. 1 a. -
FIG. 2 a shows a schematically view of the assembly of heat exchangers according to a second serial arranged operating condition according to the present invention. -
FIG. 2 b shows a temperature/position chart for the operating condition according toFIG. 2 a. -
FIGS. 1 a and 2 a shows anassembly 1 ofheat exchangers 2. Theheat exchangers 2 each have a dual-circuit for heat transfer between two essential liquid media, such as a refrigerant and brine. However, the present invention is also applicable in heat exchangers with only one liquid media. Theassembly 1 ofheat exchangers 2 having an inlet A, e.g. from a compressor (not shown) in a refrigerant circuit, and an outlet B, e.g. to an expansion valve (not shown), at opposite ends of theassembly 1. Theassembly 1 having a corresponding inlet C and outlet D for the brine circuit at opposite ends of theassembly 1. In addition, theassembly 1 having afirst conduit 4 connected to said inlet A and to afirst duct 5 of eachheat exchanger 2, and asecond conduit 6 connected to said outlet B and asecond duct 7 of eachheat exchanger 2. Further, avalve 3 being located in thefirst conduit 4, after thefirst heat exchanger 2 and between everysecond heat exchanger 2, and in thesecond conduit 6 between theother heat exchangers 2, wherein theheat exchangers 2 being arranged in parallel having allvalves 3 in open position, as shown inFIG. 1 a, and in series having allvalves 3 in closed position, as shown inFIG. 2 a. - In
FIG. 1 a theheat exchangers 2 are arranged in parallel for the subcritical condition, i.e. at a temperature below the condensing condition of the refrigerant. The heat transfer is shown inFIG. 1 b, wherein the upper curve corresponds to the temperature drop from inlet A to outlet B of the refrigerant, which during condensation having a more or less constant temperature, and the lower curve corresponds to the temperature rise from inlet C to outlet D of the brine. InFIG. 2 a theheat exchangers 2 are arranged in series with each other at a transcritical condition, i.e. at a temperature above condensing condition of the refrigerant. The heat transfer is shown inFIG. 2 b, wherein the upper curve corresponds to the temperature drop from inlet A to outlet B of the refrigerant, and the lower curve corresponds to the temperature rise from inlet C to outlet D of the brine. Theheat exchangers 2 are switched between being arranged in parallel to being arranged in series byclosing valves 3 arranged alternating in afirst conduit 4, connected to afirst duct 5 of eachheat exchanger 2, between each second heat exchanger and in asecond conduit 6, connected to asecond duct 7 of eachheat exchanger 2, between theother heat exchangers 2. - The brine circuit (not shown) having a corresponding conduit 8 and a
conduit 9, communicating with the inlet C and the outlet D, respectively, andvalves 10. The brine circuit may likewise be switched between being arranged in parallel to being arranged in series. Thevalves 10 being located in the conduit 8, after thefirst heat exchanger 2 referred to the inlet C and between everysecond heat exchanger 2, and in thesecond conduit 9 between theother heat exchangers 2, wherein theheat exchangers 2 being arranged in parallel having allvalves 10 in open position, as shown inFIG. 1 a, and in series having allvalves 10 in closed position, as shown inFIG. 2 a. - The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. For example only one circuit of the dual-circuit heat exchanger may be operated according to the present invention.
Claims (4)
1. A method of operating an assembly of heat exchangers for subcritical and transcritical conditions, by initially arranging at least two heat exchangers in parallel for the subcritical condition, comprising: arranging at least one heat exchanger at a transcritical condition in series with the other heat exchangers, and arranging an inlet and an outlet at opposite ends of the assembly, and switching the heat exchangers between being arranged in parallel to being arranged in series by closing a first conduit connecting said inlet to a first duct of each heat exchanger, after the first heat exchanger and between every second heat exchanger, and a second conduit connecting said outlet to a second duct of each heat exchanger, between the other heat exchangers.
2. The method according to claim 1 , further comprising: providing said heat exchangers with a dual-circuit for heat transfer between two essentially liquid media, such as a refrigerant and a brine, and switching each circuit between being arranged in parallel to being arranged in series.
3. The method according to claim 1 or claim 2 , further comprising: arranging all heat exchangers in series at a transcritical condition.
4. An assembly of heat exchangers having an inlet and an outlet at opposite ends of the assembly, a first conduit connected to said inlet and to a first duct of each heat exchanger and a second conduit connected to said outlet and a second duct of each heat exchanger, wherein a valve is located in the first conduit after the first heat exchanger and between every second heat exchanger and in the second conduit between the other heat exchangers, and wherein the heat exchangers are arranged in parallel having all valves in an open position and in series having all valves in a closed position.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SE0950507-4 | 2009-06-30 | ||
SE0950507A SE533859C2 (en) | 2009-06-30 | 2009-06-30 | Method for operating a system of heat exchangers for subcritical and transcritical states, as well as a system of heat exchangers |
PCT/SE2010/050717 WO2011002401A2 (en) | 2009-06-30 | 2010-06-23 | Method of operating an assembly of heat exchangers for subcritical and transcritical conditions, and an assembly of heat exchangers |
Publications (1)
Publication Number | Publication Date |
---|---|
US20120132399A1 true US20120132399A1 (en) | 2012-05-31 |
Family
ID=43411645
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US13/380,678 Abandoned US20120132399A1 (en) | 2009-06-30 | 2010-06-23 | Method of operating an assembly of heat exchangers for subcritical and transcritical conditions, and an assembly of heat exchangers |
Country Status (9)
Country | Link |
---|---|
US (1) | US20120132399A1 (en) |
EP (1) | EP2449330A2 (en) |
JP (1) | JP2012532303A (en) |
KR (1) | KR20120036899A (en) |
CN (1) | CN102472588A (en) |
CA (1) | CA2765853A1 (en) |
RU (1) | RU2012103008A (en) |
SE (1) | SE533859C2 (en) |
WO (1) | WO2011002401A2 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20150075196A1 (en) * | 2012-04-23 | 2015-03-19 | Mitsubishi Electric Corporation | Refrigeration cycle system |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN107631512A (en) * | 2017-09-04 | 2018-01-26 | 广东美的暖通设备有限公司 | Multiple on-line system |
CN111336707B (en) * | 2020-02-29 | 2021-09-03 | 同济大学 | Carbon dioxide heat pump heating system with topologic homoembryo circulation |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH10170081A (en) * | 1996-12-11 | 1998-06-26 | Toshiba Corp | Air conditioner |
JPH10267494A (en) * | 1997-03-25 | 1998-10-09 | Mitsubishi Electric Corp | Cooler |
JP2006097978A (en) * | 2004-09-29 | 2006-04-13 | Denso Corp | Refrigerating cycle |
US7908881B2 (en) * | 2005-03-14 | 2011-03-22 | York International Corporation | HVAC system with powered subcooler |
KR100865093B1 (en) * | 2007-07-23 | 2008-10-24 | 엘지전자 주식회사 | Air conditioning system |
-
2009
- 2009-06-30 SE SE0950507A patent/SE533859C2/en not_active IP Right Cessation
-
2010
- 2010-06-23 RU RU2012103008/06A patent/RU2012103008A/en not_active Application Discontinuation
- 2010-06-23 US US13/380,678 patent/US20120132399A1/en not_active Abandoned
- 2010-06-23 KR KR1020117031414A patent/KR20120036899A/en not_active Application Discontinuation
- 2010-06-23 CA CA2765853A patent/CA2765853A1/en not_active Abandoned
- 2010-06-23 EP EP10766360A patent/EP2449330A2/en not_active Withdrawn
- 2010-06-23 WO PCT/SE2010/050717 patent/WO2011002401A2/en active Application Filing
- 2010-06-23 JP JP2012517456A patent/JP2012532303A/en active Pending
- 2010-06-23 CN CN2010800301916A patent/CN102472588A/en active Pending
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20150075196A1 (en) * | 2012-04-23 | 2015-03-19 | Mitsubishi Electric Corporation | Refrigeration cycle system |
US9822994B2 (en) * | 2012-04-23 | 2017-11-21 | Mitsubishi Electric Corporation | Refrigeration cycle system with internal heat exchanger |
Also Published As
Publication number | Publication date |
---|---|
EP2449330A2 (en) | 2012-05-09 |
CA2765853A1 (en) | 2011-01-06 |
CN102472588A (en) | 2012-05-23 |
WO2011002401A3 (en) | 2011-06-09 |
WO2011002401A2 (en) | 2011-01-06 |
JP2012532303A (en) | 2012-12-13 |
SE533859C2 (en) | 2011-02-08 |
RU2012103008A (en) | 2013-08-10 |
KR20120036899A (en) | 2012-04-18 |
SE0950507A1 (en) | 2010-12-31 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: ALFA LAVAL CORPORATE AB, SWEDEN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:CHRISTENSEN, ROLF;REEL/FRAME:027625/0294 Effective date: 20120113 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |