EP3835687A1 - Heat pump system - Google Patents
Heat pump system Download PDFInfo
- Publication number
- EP3835687A1 EP3835687A1 EP20206234.5A EP20206234A EP3835687A1 EP 3835687 A1 EP3835687 A1 EP 3835687A1 EP 20206234 A EP20206234 A EP 20206234A EP 3835687 A1 EP3835687 A1 EP 3835687A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- refrigerant
- usage
- heat exchanger
- side heat
- temperature
- 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.)
- Pending
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- 239000003507 refrigerant Substances 0.000 claims abstract description 218
- 230000006835 compression Effects 0.000 claims abstract description 59
- 238000007906 compression Methods 0.000 claims abstract description 59
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 110
- 238000010438 heat treatment Methods 0.000 claims description 34
- 239000007788 liquid Substances 0.000 claims description 5
- 230000002528 anti-freeze Effects 0.000 claims description 4
- 230000006866 deterioration Effects 0.000 abstract description 13
- 238000005057 refrigeration Methods 0.000 description 13
- 238000010586 diagram Methods 0.000 description 9
- 238000001514 detection method Methods 0.000 description 6
- 238000002347 injection Methods 0.000 description 6
- 239000007924 injection Substances 0.000 description 6
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000008236 heating water Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
Images
Classifications
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- 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
- F25B1/00—Compression machines, plants or systems with non-reversible cycle
- F25B1/10—Compression machines, plants or systems with non-reversible cycle with multi-stage compression
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- 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
- F25B25/00—Machines, plants or systems, using a combination of modes of operation covered by two or more of the groups F25B1/00 - F25B23/00
- F25B25/005—Machines, plants or systems, using a combination of modes of operation covered by two or more of the groups F25B1/00 - F25B23/00 using primary and secondary systems
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- 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
- F25B30/00—Heat pumps
- F25B30/02—Heat pumps of the compression type
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- 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
- F25B40/00—Subcoolers, desuperheaters or superheaters
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- 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
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- 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
- F25B2339/00—Details of evaporators; Details of condensers
- F25B2339/04—Details of condensers
- F25B2339/047—Water-cooled condensers
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- 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
- F25B2600/00—Control issues
- F25B2600/25—Control of valves
- F25B2600/2509—Economiser valves
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- 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
- F25B2600/00—Control issues
- F25B2600/25—Control of valves
- F25B2600/2513—Expansion valves
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- 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
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/17—Speeds
- F25B2700/171—Speeds of the compressor
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- 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
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/19—Pressures
- F25B2700/193—Pressures of the compressor
- F25B2700/1931—Discharge pressures
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- 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
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/21—Temperatures
- F25B2700/2115—Temperatures of a compressor or the drive means therefor
- F25B2700/21152—Temperatures of a compressor or the drive means therefor at the discharge side of the compressor
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- 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
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/21—Temperatures
- F25B2700/2116—Temperatures of a condenser
- F25B2700/21161—Temperatures of a condenser of the fluid heated by the condenser
Definitions
- the present invention relates to a heat pump system whose a high-pressure side is operated under supercritical pressure.
- the refrigerant circuit uses refrigerant whose a high-pressure side becomes supercritical pressure, and the refrigerant circuit is formed by annularly connecting, to one another through a pipe, a two-stage compressing type compressor, a heating heat exchanger which heats hot water, a cooler, a first electric expansion valve and an evaporator.
- the intermediate injection circuit branches off from the refrigerant circuit between the heating heat exchanger and the cooler.
- the intermediate injection circuit includes a second electric expansion valve and the cooler in the middle of the refrigerant circuit.
- the intermediate injection circuit returns a portion of refrigerant discharged from the heating heat exchanger to an intermediate portion between a low-pressure side and a high-pressure side of the compressor.
- This refrigeration cycle device includes a first temperature detection sensor which detects high-pressure side refrigerant discharge temperature of the compressor, a second temperature detection sensor which detects refrigerant temperature of an outlet of the heating heat exchanger, and a third temperature detection sensor which detects refrigerant temperature of an outlet of the cooler.
- a first temperature detection sensor which detects high-pressure side refrigerant discharge temperature of the compressor
- a second temperature detection sensor which detects refrigerant temperature of an outlet of the heating heat exchanger
- a third temperature detection sensor which detects refrigerant temperature of an outlet of the cooler.
- Patent Document 1 Japanese Patent Application Laid-open No. 2008-008499
- the present invention is achieved to solve the conventional problem, and it is an object of the invention to provide a heat pump system in which even if temperature of usage-side heat medium which flows into a usage-side heat exchanger rises, a high-pressure side which suppresses deterioration of COP is operated under supercritical pressure by performing appropriate control.
- the present invention provides a heat pump system including: a main refrigerant circuit formed by sequentially connecting, through a pipe, a compression mechanism composed of a compression rotation element, a usage-side heat exchanger for heating usage-side heat medium by refrigerant which is discharged from the compression rotation element and which exceeds critical pressure, an intermediate heat exchanger, a first expansion device, and a heat source-side heat exchanger; a bypass refrigerant circuit branched off from the pipe between the usage-side heat exchanger and the first expansion device, in which branched refrigerant is decompressed by a second expansion device and thereafter, heat of the refrigerant is exchanged with that of the refrigerant flowing through the main refrigerant circuit by the intermediate heat exchanger, and the refrigerant joins up with the refrigerant which is in middle of a compression operation of the compression rotation element; and a control device, wherein when temperature of the usage-side heat medium which flows into the usage-side heat exchanger rises, the control device
- Claim 1 of the present invention provides a heat pump system Including: a main refrigerant circuit formed by sequentially connecting, through a pipe, a compression mechanism composed of a compression rotation element, a usage-side heat exchanger for heating usage-side heat medium by refrigerant which is discharged from the compression rotation element and which exceeds critical pressure, an intermediate heat exchanger, a first expansion device, and a heat source-side heat exchanger; a bypass refrigerant circuit branched off from the pipe between the usage-side heat exchanger and the first expansion device, in which branched refrigerant is decompressed by a second expansion device and thereafter, heat of the refrigerant is exchanged with that of the refrigerant flowing through the main refrigerant circuit by the intermediate heat exchanger, and the refrigerant joins up with the refrigerant which is in middle of a compression operation of the compression rotation element; and a control device, wherein when temperature of the usage-side heat medium which flows into the usage-side heat exchanger rises, the control device
- the heat pump system of claim 1 further comprises a heat medium inlet temperature thermistor for detecting the temperature of the usage-side heat medium which flows into the usage-side heat exchanger, wherein when detected temperature which is detected by the heat medium inlet temperature thermistor rises, the control device operates to increase the valve opening of the second expansion device.
- the control device operates to reduce a valve opening of the first expansion device.
- the pressure of the high-pressure side of refrigerant of the main refrigerant circuit rises. Therefore, even if temperature of the usage-side heat medium which flows into the usage-side heat exchanger rises, it is possible to suppress the reduction of the enthalpy difference between the outlet of refrigerant and inlet of refrigerant in the usage-side heat exchanger.
- the heat pump system of claim 3 further includes a discharge temperature thermistor which detects temperature of the refrigerant discharged from the compressing rotation element, wherein the control device brings the temperature detected by the discharge temperature thermistor close to a target value by adjusting the valve opening of the first expansion device and the valve opening of the second expansion device.
- the heat pump system of claim 3 further includes a high pressure-side pressure detector which detects pressure of the refrigerant discharged from the compressing rotation element, wherein the control device brings a pressure value detected by the high pressure-side pressure detector close to a target value by adjusting the valve opening of the first expansion device and the valve opening of the second expansion device.
- the heat pump system of any one of claims 1 to 5 further includes a usage-side heat medium circuit which includes a conveying device and which circulates the usage-side heat medium by the conveying device.
- the usage-side heat medium is water or antifreeze liquid.
- Fig. 1 is a block diagram of a heat pump system according to the embodiment of the invention.
- the heat pump system is composed of a refrigeration cycle device 9 which is a supercritical vapor compressing type refrigeration cycle, and a usage-side heat medium circuit 30.
- the refrigeration cycle device 9 is composed of a main refrigerant circuit 10 and a bypass refrigerant circuit 20.
- the main refrigerant circuit 10 is formed by sequentially connecting, through a pipe 16, a compression mechanism 11 which compresses refrigerant, a usage-side heat exchanger 12 which is a radiator, an intermediate heat exchanger 13, a first expansion device 14 and a heat source-side heat exchanger 15 which is an evaporator.
- Carbon dioxide (CO2) is used as refrigerant.
- the compression mechanism 11 is composed of a low stage-side compression rotation element 11a and a high stage-side compression rotation element 11b.
- the usage-side heat exchanger 12 heats usage-side heat medium by refrigerant discharged from the high stage-side compression rotation element 11b.
- a volume ratio of the low stage-side compression rotation element 11a and the high stage-side compression rotation element 11b which configure the compression mechanism 11 is constant, these rotation elements use a common driving shaft (not shown), and the rotation elements are composed of a single compressor placed in one container.
- This embodiment is described using a two-stage compression mechanism 11 in which the compression rotation element is composed of the low stage-side compression rotation element 11a and the high stage-side compression rotation element 11b, but the present invention can be applied also to a single compression mechanism in which the compressing rotation element is not divided into the low-stage side compressing rotation element 11a and the high-stage side compressing rotation element 11b.
- a position where refrigerant from the bypass refrigerant circuit 20 joins up is defined as a middle position of being compressed by the compression rotation element
- a portion of the compression rotation element up to a position where refrigerant from the bypass refrigerant circuit 20 joins up is defined as the low stage-side compression rotation element 11a
- a portion of the compression rotation element after the position where the refrigerant from the bypass refrigerant circuit 20 joins up is defined as the high stage-side compression rotation element 11b.
- the low-stage side compressing rotation element 11a and the high-stage side compressing rotation element 11b may be a two-stage compression mechanism 11 which is composed of independent two compressors.
- the bypass refrigerant circuit 20 branches off from the pipe 16 between the usage-side heat exchanger 12 and the first expansion device 14, and is connected to the pipe 16 between the low stage-side compression rotation element 11a and the high stage-side compression rotation element 11b.
- the bypass refrigerant circuit 20 is provided with a second expansion device 21.
- a portion of high pressure refrigerant after it passes through the usage-side heat exchanger 12, or a portion of high pressure refrigerant after it passes through the intermediate heat exchanger 13 is decompressed by the second expansion device 21, and becomes intermediate pressure refrigerant and after that, this refrigerant is heat-exchanged with high pressure refrigerant which flows through the main refrigerant circuit 10 by the intermediate heat exchanger 13, and the refrigerant joins up with refrigerant between the low stage-side compression rotation element 11a and the high stage-side compression rotation element 11b.
- the usage-side heat medium circuit 30 is formed by sequentially connecting the usage-side heat exchanger 12, a conveying device 31 which is a conveying pump, and the heating terminal 32a through a heat medium pipe 33. Water of antifreeze liquid is used as the usage-side heat medium.
- the usage-side heat medium circuit 30 in this embodiment includes a hot water storage tank 32b in parallel to the heating terminal 32a.
- the usage-side heat medium circuit 30 circulates the usage-side heat medium through the heating terminal 32a or a hot water storage tank 32b by switching between a first switching valve 34 and a second switching valve 35.
- the usage-side heat medium circuit 30 may include any one of the heating terminal 32a and the hot water storage tank 32b.
- High temperature water produced by the usage-side heat exchanger 12 radiates heat in the heating terminal 32a and is utilized for heating a room, and low temperature water whose heat is radiated in the heating terminal 32a is again heated by the usage-side heat exchanger 12.
- High temperature water produced by the usage-side heat exchanger 12 is introduced into the hot water storage tank 32b from an upper portion of the hot water storage tank 32b, low temperature water is sent out from a lower portion of the hot water storage tank 32b and heated by the usage-side heat exchanger 12.
- a hot water supplying heat exchanger 42 is placed in the hot water storage tank 32b, and the hot water supplying heat exchanger 42 exchanges heat between supplied water from a water supplying pipe 43 and high temperature water in the hot water storage tank 32b. That is, if a hot water supplying plug 41 is opened, water is supplied from the water supplying pipe 43 into the hot water supplying heat exchanger 42, the water is heated by the hot water supplying heat exchanger 42, temperature of the water is adjusted to predetermined temperature by the hot water supplying plug 41, and hot water is supplied from the hot water supplying plug 41.
- Water is supplied from the water supplying pipe 43 and heated by the hot water supplying heat exchanger 42, and hot water supplied from the hot water supplying plug 41 and high temperature water in the hot water storage tank 32b are not mixed with each other, and they are indirectly heated.
- the hot water supplying heat exchanger 42 is a water heat exchanger using a copper pipe or stainless steel pipe as a heat transfer pipe, and the water supplying pipe 43 extending from a water supplying source (running water) and the hot water supplying plug 41 are connected to the hot water supplying heat exchanger 42 as shown in Fig. 1 .
- the water supplying pipe 43 sends normal temperature water into a lower end of the hot water supplying heat exchanger 42, i.e., into a lower portion in the hot water storage tank 32b.
- the normal temperature water sent into the hot water supplying heat exchanger 42 from the water supplying pipe 43 draws heat from the high temperature water in the hot water storage tank 32b while moving upward in the hot water storage tank 32b from downward, and the normal temperature water becomes high temperature heated water and is supplied from the hot water supplying plug 41.
- the hot water storage tank 32b is provided with a plurality of hot water storage tank temperature thermistors, e.g., a first hot water storage tank temperature thermistor 55a, a second hot water storage tank temperature thermistor 55b and a third hot water storage tank temperature thermistor 55c.
- a first hot water storage tank temperature thermistor 55a e.g., a first hot water storage tank temperature thermistor 55a
- a second hot water storage tank temperature thermistor 55b e.g., a third hot water storage tank temperature thermistor 55c.
- the normal temperature water which enters the hot water supplying heat exchanger 42 from the water supplying pipe 43 draws heat from high temperature water in the hot water storage tank 32b while moving upward in the hot water storage tank 32b from downward. Therefore, temperature of hot water in the hot water storage tank 32b naturally becomes high at an upper portion and lower at a low portion in the hot water storage tank 32b.
- the main refrigerant circuit 10 is provided with a high pressure-side pressure detector 51 and a discharge temperature thermistor 52 in the pipe 16 on the discharge side of the high stage-side compression rotation element 11b.
- the high pressure-side pressure detector 51 is provided in the main refrigerant circuit 10 from a discharge side of the high stage-side compression rotation element 11b to an upstream side of the first expansion device 14. It is only necessary that the high pressure-side pressure detector 51 can detect pressure of high pressure refrigerant in the main refrigerant circuit 10.
- the discharge temperature thermistor 52 is also provided in the main refrigerant circuit 10 from the discharge side of the high-stage side compressing rotation element 11b to the upstream side of the first expansion device 14. It is also only necessary that the discharge temperature thermistor 52 can detect temperature of the high pressure refrigerant of the main refrigerant circuit 10.
- the usage-side heat medium circuit 30 includes a heat medium inlet temperature thermistor 54 for detecting temperature of usage-side heat medium which flows into the usage-side heat exchanger 12.
- the control device 60 controls operation frequencies of the low-stage side compressing rotation element 11a and the high-stage side compressing rotation element 11b, a valve opening of the first expansion device 14, a valve opening of the second expansion device 21 and a conveying amount of the usage-side heat medium conveyed by the conveying device 31 based on detected pressure detected by the high pressure-side pressure detector 51, detected temperature detected by the discharge temperature thermistor 52 and detected temperature detected by the heat medium inlet temperature thermistor 54.
- Fig. 2 is a pressure-enthalpy diagram (P-h diagram) under the ideal condition concerning the refrigeration cycle device in the embodiment.
- Points a to e and points A and B in Fig. 2 correspond to points in the refrigeration cycle device shown in Fig. 1 .
- high pressure refrigerant (point a) discharged from the high stage-side compression rotation element 11b radiates heat in the usage-side heat exchanger 12 and after that, the high pressure refrigerant branches off from the main refrigerant circuit 10 at a refrigerant branch point (point A), the high pressure refrigerant is decompressed to intermediate pressure by the second expansion device 21 and becomes intermediate pressure refrigerant (point e), and the intermediate pressure refrigerant is heat-exchanged by the intermediate heat exchanger 13.
- the high pressure refrigerant which flows through the main refrigerant circuit 10 after it radiates heat by the usage-side heat exchanger 12 is cooled by intermediate pressure refrigerant (point e) which flows through the bypass refrigerant circuit 20, and the high pressure refrigerant is decompressed by the first expansion device 14 in a state (point b) where enthalpy thereof is reduced.
- refrigerant enthalpy of refrigerant (point c) which flows into the heat source-side heat exchanger 15 after it is decompressed by the first expansion device 14 is also reduced. Dryness (weight ratio occupied by gas phase component to the entire refrigerant) of refrigerant when it flows into the heat source-side heat exchanger 15 is reduced and liquid component of refrigerant is increased. Therefore, this contributes to evaporation in the heat source-side heat exchanger 15, a refrigerant ratio is increased and an endothermic energy amount from outside air is increased, and it returns to the suction side (point d) of the low stage-side compression rotation element 11a.
- refrigerant of an amount corresponding to gas phase component which does not contribute to evaporation in the heat source-side heat exchanger 15 is made to bypass by the bypass refrigerant circuit 20, and becomes low temperature intermediate pressure refrigerant (point e), the refrigerant is heated by high pressure refrigerant which flows through the main refrigerant circuit 10 in the intermediate heat exchanger 13, and the refrigerant reaches a refrigerant joining point B located between the low stage-side compression rotation element 11a and the high stage-side compression rotation element 11b in a state where refrigerant enthalpy is increased.
- the control device 60 determines that high temperature water is insufficient in the hot water storage tank 32b.
- the control device 60 operates the low stage-side compression rotation element 11a and the high stage-side compression rotation element 11b and heats low temperature water by the usage-side heat exchanger 12.
- the control device 60 operates the conveying device 31 such that detected temperature detected by the heat medium outlet temperature thermistor 53 which is heating producing temperature becomes equal to the target temperature.
- the control device 60 operates the low stage-side compression rotation element 11a and the high stage-side compression rotation element 11b and heats circulated water by the usage-side heat exchanger 12, and the control device 60 operates the conveying device 31 such that a temperature difference, which is the temperature difference of the circulated water, between detected temperature detected by the heat medium outlet temperature thermistor 53 and detected temperature detected by the heat medium inlet temperature thermistor 54 becomes equal to a target temperature difference.
- high temperature water produced by the usage-side heat exchanger 12 radiates heat in the heating terminal 32a and is utilized for heating a room, and low temperature water whose heat is released by the heating terminal 32a is again heated by the usage-side heat exchanger 12.
- control since control is performed such that a temperature difference between detected temperature detected by the heat medium outlet temperature thermistor 53 and detected temperature detected by the heat medium inlet temperature thermistor 54 becomes equal to the target temperature difference.
- control is performed such that a temperature difference between detected temperature detected by the heat medium outlet temperature thermistor 53 and detected temperature detected by the heat medium inlet temperature thermistor 54 becomes equal to the target temperature difference. Therefore, the detected temperature detected by the heat medium outlet temperature thermistor 53 and the detected temperature detected by the heat medium inlet temperature thermistor 54 increase gradually.
- a solid line is a pressure-enthalpy diagram when temperature of the usage-side heat medium which flows into the usage-side heat exchanger 12 rises with respect to broken lines.
- inlet temperature (point a) of refrigerant toward the usage-side heat exchanger 12 moves to an increasing direction (point a') of enthalpy.
- outlet temperature (point A) of refrigerant from the usage-side heat exchanger 12 moves to the increasing direction (point A') of enthalpy.
- outlet temperature (point B) of refrigerant from the bypass refrigerant circuit 20 of the intermediate heat exchanger 13 also moves to the increasing direction (point B') of enthalpy.
- inlet temperature (point e) of refrigerant toward the bypass refrigerant circuit 20 of the intermediate heat exchanger 13 also moves to the increasing direction (point e') of enthalpy.
- control device 60 must control the valve opening of the second expansion device 21 such that a temperature difference between the outlet temperature (point B') of refrigerant from the bypass refrigerant circuit 20 of the intermediate heat exchanger 13 and the inlet temperature (point e') of refrigerant toward the bypass refrigerant circuit 20 to the intermediate heat exchanger 13 does not become as small as possible in the intermediate heat exchanger 13.
- a ratio of an amount of refrigerant which flows through the bypass refrigerant circuit 20 to an amount of refrigerant which flows on the side of the main refrigerant circuit 10 of the intermediate heat exchanger 13 is increased.
- valve opening of the second expansion device 21 is increased and a ratio of an amount of refrigerant which circulates through the bypass refrigerant circuit 20, the high-stage side compressing rotation element 11b and the usage-side heat exchanger 12 to an amount of refrigerant which circulates through the main refrigerant circuit 10 is increased.
- the enthalpy difference between the high pressure refrigerant (point a') discharged from the high-stage side compressing rotation element 11b and the refrigerant (point A') of a branch point of refrigerant after heat is released at the usage-side heat exchanger 12 is equal to a total of an enthalpy difference between refrigerant (point B') on the suction side of the high-stage side compressing rotation element 11b and the intermediate pressure refrigerant (point e') which flows through the bypass refrigerant circuit 20 and an enthalpy difference of the high-stage side compressing rotation element 11b.
- the high-stage side compressing rotation element 11b and the usage-side heat exchanger 12 Since the amount of refrigerant which circulates through the bypass refrigerant circuit 20, the high-stage side compressing rotation element 11b and the usage-side heat exchanger 12 is increased, it is possible to suppress the deterioration of the heating ability in the usage-side heat exchanger 12.
- the control device 60 operates to reduce the valve opening of the first expansion device 14. According to this, since pressure on the high-pressure side of refrigerant of the main refrigerant circuit 10 rises, even if temperature of the usage-side heat medium which flows into the usage-side heat exchanger 12 rises, it is possible to suppress the reduction of the enthalpy difference (point a' to point A') between the outlet of refrigerant and the inlet of refrigerant in the usage-side heat exchanger 12.
- the control device 60 adjusts the valve opening of the first expansion device 14 and the valve opening of the second expansion device 21. According to this, temperature detected by the discharge temperature thermistor 52 is brought close to a target value.
- the target value of discharge temperature is preset in the control device 60.
- the control device 60 adjusts the valve opening of the first expansion device 14 and the valve opening of the second expansion device 21. According to this, a pressure value detected by the high pressure-side pressure detector 51 is brought close to a target value.
- the compressing rotation element may be a single compressing rotation element which is not divided into the low-stage side compressing rotation element 11a and the high-stage side compressing rotation element 11b. If the single compressing rotation element is employed, a position where refrigerant from the bypass refrigerant circuit 20 joins up is defined as a middle position of being compressed by the compression rotation element.
- the heat pump system of the present invention whose high-pressure side is operated under supercritical pressure, even if temperature of usage-side heat medium which flows into a usage-side heat exchanger rises, deterioration of COP is suppressed by performing appropriate control. Therefore, the heat pump system is suitable for refrigerating equipment, an air conditioner, a hot water supply system, heating equipment and the like.
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Heat-Pump Type And Storage Water Heaters (AREA)
Abstract
Description
- The present invention relates to a heat pump system whose a high-pressure side is operated under supercritical pressure.
- As conventional refrigeration cycle devices of this kind, there is one including a refrigerant circuit and an intermediate injection circuit. The refrigerant circuit uses refrigerant whose a high-pressure side becomes supercritical pressure, and the refrigerant circuit is formed by annularly connecting, to one another through a pipe, a two-stage compressing type compressor, a heating heat exchanger which heats hot water, a cooler, a first electric expansion valve and an evaporator. The intermediate injection circuit branches off from the refrigerant circuit between the heating heat exchanger and the cooler. The intermediate injection circuit includes a second electric expansion valve and the cooler in the middle of the refrigerant circuit. The intermediate injection circuit returns a portion of refrigerant discharged from the heating heat exchanger to an intermediate portion between a low-pressure side and a high-pressure side of the compressor.
- This refrigeration cycle device includes a first temperature detection sensor which detects high-pressure side refrigerant discharge temperature of the compressor, a second temperature detection sensor which detects refrigerant temperature of an outlet of the heating heat exchanger, and a third temperature detection sensor which detects refrigerant temperature of an outlet of the cooler. When detected temperature which is detected by the first temperature detection sensor is within a first predetermined temperature range, control is performed such that an opening degree of the first electric expansion valve is maintained, and when a difference between detected temperature detected by the second temperature detection sensor and detected temperature detected by the third temperature detection sensor is within a second predetermined temperature range, control is performed such that an opening degree of the second electric expansion valve is maintained. According to this, a circulation amount of refrigerant which flows into the intermediate injection circuit is suppressed within a constant range, and an expected refrigerant circuit can be formed.
- If a heating load of a heating appliance is reduced, returning temperature of water to a heating heat exchanger from a hot water circuit rises, and refrigerant discharge temperature of high-stage side rotation compressing element also rises. Therefore, control is performed such that the refrigerant discharge temperature of the high-stage side rotation compressing element is lowered by opening the first electric expansion valve (see
patent document 1 for example). - [Patent Document 1]
Japanese Patent Application Laid-open No.2008-008499 - However, according to the conventional configuration, in the refrigeration cycle device whose high-pressure side is under supercritical pressure and having the heating heat exchanger which heats hot water and the intermediate injection circuit, there is a problem that COP of the refrigeration cycle device is lowered when the returning temperature of water to the heating heat exchanger rises, but technique for suppressing this phenomenon is not disclosed.
- The present invention is achieved to solve the conventional problem, and it is an object of the invention to provide a heat pump system in which even if temperature of usage-side heat medium which flows into a usage-side heat exchanger rises, a high-pressure side which suppresses deterioration of COP is operated under supercritical pressure by performing appropriate control.
- To solve the conventional problem, the present invention provides a heat pump system including: a main refrigerant circuit formed by sequentially connecting, through a pipe, a compression mechanism composed of a compression rotation element, a usage-side heat exchanger for heating usage-side heat medium by refrigerant which is discharged from the compression rotation element and which exceeds critical pressure, an intermediate heat exchanger, a first expansion device, and a heat source-side heat exchanger; a bypass refrigerant circuit branched off from the pipe between the usage-side heat exchanger and the first expansion device, in which branched refrigerant is decompressed by a second expansion device and thereafter, heat of the refrigerant is exchanged with that of the refrigerant flowing through the main refrigerant circuit by the intermediate heat exchanger, and the refrigerant joins up with the refrigerant which is in middle of a compression operation of the compression rotation element; and a control device, wherein when temperature of the usage-side heat medium which flows into the usage-side heat exchanger rises, the control device controls a valve opening of at least the second expansion device, and increases a ratio of an amount of the refrigerant which flows through the bypass refrigerant circuit to an amount of the refrigerant which flows on the side of a main refrigerant circuit of the intermediate heat exchanger.
- According to this, even if temperature of the usage-side heat medium which flows into the usage-side heat exchanger rises, since an amount of refrigerant which circulates through the bypass refrigerant circuit, the high-stage side compressing rotation element and the usage-side heat exchanger is increased, it is possible to suppress deterioration of heating ability in the usage-side heat exchanger.
- Further, even if temperature of the usage-side heat medium which flows into the usage-side heat exchanger rises, since a heat exchanging amount between high pressure refrigerant which flows through the main refrigerant circuit and intermediate pressure refrigerant which flows through the bypass refrigerant circuit in the intermediate heat exchanger is increased, it is possible to suppress the reduction in an enthalpy difference between an outlet of refrigerant and an inlet of refrigerant in the usage-side heat exchanger.
- Hence, even if temperature of usage-side heat medium which flows into a usage-side heat exchanger rises, it is possible to provide a heat pump system whose high-pressure side which suppresses deterioration of COP is operated under supercritical pressure.
- According to the present invention, it is possible to provide a heat pump system whose high-pressure side which suppresses deterioration of COP is operated under supercritical pressure by performing appropriate control even if temperature of usage-side heat medium which flows into a usage-side heat exchanger rises.
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Fig. 1 is a block diagram of a heat pump system according to an embodiment of the present invention; -
Fig. 2 is a pressure-enthalpy diagram (P-h diagram) of a refrigeration cycle device in the embodiment of the invention; and -
Fig. 3 is a pressure-enthalpy diagram (P-h diagram) of the refrigeration cycle device when temperature of usage-side heat medium which flows into a usage-side heat exchanger rises in the heat pump system in the embodiment of the invention. -
Claim 1 of the present invention provides a heat pump system Including: a main refrigerant circuit formed by sequentially connecting, through a pipe, a compression mechanism composed of a compression rotation element, a usage-side heat exchanger for heating usage-side heat medium by refrigerant which is discharged from the compression rotation element and which exceeds critical pressure, an intermediate heat exchanger, a first expansion device, and a heat source-side heat exchanger; a bypass refrigerant circuit branched off from the pipe between the usage-side heat exchanger and the first expansion device, in which branched refrigerant is decompressed by a second expansion device and thereafter, heat of the refrigerant is exchanged with that of the refrigerant flowing through the main refrigerant circuit by the intermediate heat exchanger, and the refrigerant joins up with the refrigerant which is in middle of a compression operation of the compression rotation element; and a control device, wherein when temperature of the usage-side heat medium which flows into the usage-side heat exchanger rises, the control device controls a valve opening of at least the second expansion device, and increases a ratio of an amount of the refrigerant which flows through the bypass refrigerant circuit to an amount of the refrigerant which flows on the side of a main refrigerant circuit of the intermediate heat exchanger. - According to this, even if temperature of usage-side heat medium which flows into the usage-side heat exchanger rises, since a heat exchanging amount between high pressure refrigerant which flows through the main refrigerant circuit and intermediate pressure refrigerant which flows through the bypass refrigerant circuit in the intermediate heat exchanger increases, it is possible to suppress the reduction of an enthalpy difference between an outlet and an inlet of refrigerant in the usage-side heat exchanger.
- Further, since an amount of refrigerant which circulates through the bypass refrigerant circuit, the high-stage side compressing rotation element and the usage-side heat exchanger increases, it is possible to suppress deterioration of heating ability in the usage-side heat exchanger.
- Hence, even if temperature of the usage-side heat medium which flows into the usage-side heat exchanger rises, it is possible to provide a heat pump system whose high-pressure side which suppress the deterioration of COP is operated under supercritical pressure.
- According to claim 2, the heat pump system of
claim 1 further comprises a heat medium inlet temperature thermistor for detecting the temperature of the usage-side heat medium which flows into the usage-side heat exchanger, wherein when detected temperature which is detected by the heat medium inlet temperature thermistor rises, the control device operates to increase the valve opening of the second expansion device. - According to this, even if temperature of the usage-side heat medium which flows into the usage-side heat exchanger rises, since the amount of refrigerant which circulates through the bypass refrigerant circuit, the high-stage side compressing rotation element and the usage-side heat exchanger increases, it is possible to suppress the deterioration of the heating ability in the usage-side heat exchanger.
- According to claim 3, in the heat pump system of claim 2, the control device operates to reduce a valve opening of the first expansion device.
- According to this, the pressure of the high-pressure side of refrigerant of the main refrigerant circuit rises. Therefore, even if temperature of the usage-side heat medium which flows into the usage-side heat exchanger rises, it is possible to suppress the reduction of the enthalpy difference between the outlet of refrigerant and inlet of refrigerant in the usage-side heat exchanger.
- According to claim 4, the heat pump system of claim 3 further includes a discharge temperature thermistor which detects temperature of the refrigerant discharged from the compressing rotation element, wherein the control device brings the temperature detected by the discharge temperature thermistor close to a target value by adjusting the valve opening of the first expansion device and the valve opening of the second expansion device.
- According to this, it is possible to increase the heat exchanging amount between the high pressure refrigerant which flows through the main refrigerant circuit and the intermediate pressure refrigerant which flows through the bypass refrigerant circuit in the intermediate heat exchanger, and to increase the amount of refrigerant which circulates through the bypass refrigerant circuit, the high-stage side compressing rotation element and the usage-side heat exchanger while preventing excessive rise or reduction of discharge temperature of refrigerant which is discharged from the compressing rotation element.
- Hence, it is possible to realize the discharge temperature of stable refrigerant, and even if temperature of the usage-side heat medium which flows into the usage-side heat exchanger rises, it is possible to suppress the reduction of the enthalpy difference between the outlet of refrigerant and inlet of refrigerant in the usage-side heat exchanger, and suppress deterioration of the heating ability in the usage-side heat exchanger.
- According to claim 5, the heat pump system of claim 3 further includes a high pressure-side pressure detector which detects pressure of the refrigerant discharged from the compressing rotation element, wherein the control device brings a pressure value detected by the high pressure-side pressure detector close to a target value by adjusting the valve opening of the first expansion device and the valve opening of the second expansion device.
- According to this, it is possible to prevent excessive rise or reduction of pressure of refrigerant which is discharged from the compressing rotation element, and even if temperature of the usage-side heat medium which flows into the usage-side heat exchanger rises, it is possible to suppress the reduction of the enthalpy difference between the outlet of refrigerant and the inlet of refrigerant in the usage-side heat exchanger.
- According to claim 6, the heat pump system of any one of
claims 1 to 5 further includes a usage-side heat medium circuit which includes a conveying device and which circulates the usage-side heat medium by the conveying device. - According to this, even if temperature of the usage-side heat medium which flows into the usage-side heat exchanger rises, it is possible to suppress the deterioration of COP, and to provide a heat pump system capable of utilizing high temperature usage-side heat medium and whose high-pressure side is operated under supercritical pressure.
- According to claim 7, in the heat pump system of any one of
claims 1 to 6, the usage-side heat medium is water or antifreeze liquid. - According to this, it is possible to store high temperature water in the hot water tank, and to provide a heat pump system whose high-pressure side which heats a room using the high temperature water is operated under supercritical pressure.
- An embodiment of the present invention will be described below with reference to the drawings. The invention is not limited to the embodiment.
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Fig. 1 is a block diagram of a heat pump system according to the embodiment of the invention. The heat pump system is composed of arefrigeration cycle device 9 which is a supercritical vapor compressing type refrigeration cycle, and a usage-sideheat medium circuit 30. Therefrigeration cycle device 9 is composed of a mainrefrigerant circuit 10 and abypass refrigerant circuit 20. - The main
refrigerant circuit 10 is formed by sequentially connecting, through apipe 16, acompression mechanism 11 which compresses refrigerant, a usage-side heat exchanger 12 which is a radiator, anintermediate heat exchanger 13, afirst expansion device 14 and a heat source-side heat exchanger 15 which is an evaporator. Carbon dioxide (CO2) is used as refrigerant. - The
compression mechanism 11 is composed of a low stage-sidecompression rotation element 11a and a high stage-side compression rotation element 11b. The usage-side heat exchanger 12 heats usage-side heat medium by refrigerant discharged from the high stage-side compression rotation element 11b. - A volume ratio of the low stage-side
compression rotation element 11a and the high stage-side compression rotation element 11b which configure thecompression mechanism 11 is constant, these rotation elements use a common driving shaft (not shown), and the rotation elements are composed of a single compressor placed in one container. - This embodiment is described using a two-
stage compression mechanism 11 in which the compression rotation element is composed of the low stage-sidecompression rotation element 11a and the high stage-side compression rotation element 11b, but the present invention can be applied also to a single compression mechanism in which the compressing rotation element is not divided into the low-stage sidecompressing rotation element 11a and the high-stage side compressing rotation element 11b. - Here, when a single compression mechanism is employed, a position where refrigerant from the
bypass refrigerant circuit 20 joins up is defined as a middle position of being compressed by the compression rotation element, a portion of the compression rotation element up to a position where refrigerant from thebypass refrigerant circuit 20 joins up is defined as the low stage-sidecompression rotation element 11a, and a portion of the compression rotation element after the position where the refrigerant from thebypass refrigerant circuit 20 joins up is defined as the high stage-side compression rotation element 11b. - The low-stage side compressing
rotation element 11a and the high-stage side compressing rotation element 11b may be a two-stage compression mechanism 11 which is composed of independent two compressors. - The
bypass refrigerant circuit 20 branches off from thepipe 16 between the usage-side heat exchanger 12 and thefirst expansion device 14, and is connected to thepipe 16 between the low stage-sidecompression rotation element 11a and the high stage-side compression rotation element 11b. - The
bypass refrigerant circuit 20 is provided with asecond expansion device 21. A portion of high pressure refrigerant after it passes through the usage-side heat exchanger 12, or a portion of high pressure refrigerant after it passes through theintermediate heat exchanger 13 is decompressed by thesecond expansion device 21, and becomes intermediate pressure refrigerant and after that, this refrigerant is heat-exchanged with high pressure refrigerant which flows through themain refrigerant circuit 10 by theintermediate heat exchanger 13, and the refrigerant joins up with refrigerant between the low stage-sidecompression rotation element 11a and the high stage-side compression rotation element 11b. - The usage-side
heat medium circuit 30 is formed by sequentially connecting the usage-side heat exchanger 12, a conveyingdevice 31 which is a conveying pump, and theheating terminal 32a through aheat medium pipe 33. Water of antifreeze liquid is used as the usage-side heat medium. - The usage-side
heat medium circuit 30 in this embodiment includes a hotwater storage tank 32b in parallel to theheating terminal 32a. The usage-sideheat medium circuit 30 circulates the usage-side heat medium through theheating terminal 32a or a hotwater storage tank 32b by switching between a first switching valve 34 and asecond switching valve 35. The usage-sideheat medium circuit 30 may include any one of theheating terminal 32a and the hotwater storage tank 32b. - High temperature water produced by the usage-
side heat exchanger 12 radiates heat in theheating terminal 32a and is utilized for heating a room, and low temperature water whose heat is radiated in theheating terminal 32a is again heated by the usage-side heat exchanger 12. - High temperature water produced by the usage-
side heat exchanger 12 is introduced into the hotwater storage tank 32b from an upper portion of the hotwater storage tank 32b, low temperature water is sent out from a lower portion of the hotwater storage tank 32b and heated by the usage-side heat exchanger 12. - A hot water supplying heat exchanger 42 is placed in the hot
water storage tank 32b, and the hot water supplying heat exchanger 42 exchanges heat between supplied water from awater supplying pipe 43 and high temperature water in the hotwater storage tank 32b. That is, if a hotwater supplying plug 41 is opened, water is supplied from thewater supplying pipe 43 into the hot water supplying heat exchanger 42, the water is heated by the hot water supplying heat exchanger 42, temperature of the water is adjusted to predetermined temperature by the hotwater supplying plug 41, and hot water is supplied from the hotwater supplying plug 41. - Water is supplied from the
water supplying pipe 43 and heated by the hot water supplying heat exchanger 42, and hot water supplied from the hotwater supplying plug 41 and high temperature water in the hotwater storage tank 32b are not mixed with each other, and they are indirectly heated. - The hot water supplying heat exchanger 42 is a water heat exchanger using a copper pipe or stainless steel pipe as a heat transfer pipe, and the
water supplying pipe 43 extending from a water supplying source (running water) and the hotwater supplying plug 41 are connected to the hot water supplying heat exchanger 42 as shown inFig. 1 . Thewater supplying pipe 43 sends normal temperature water into a lower end of the hot water supplying heat exchanger 42, i.e., into a lower portion in the hotwater storage tank 32b. - The normal temperature water sent into the hot water supplying heat exchanger 42 from the
water supplying pipe 43 draws heat from the high temperature water in the hotwater storage tank 32b while moving upward in the hotwater storage tank 32b from downward, and the normal temperature water becomes high temperature heated water and is supplied from the hotwater supplying plug 41. - To measure temperature of hot water at a plurality of different height positions, the hot
water storage tank 32b is provided with a plurality of hot water storage tank temperature thermistors, e.g., a first hot water storage tank temperature thermistor 55a, a second hot water storagetank temperature thermistor 55b and a third hot water storagetank temperature thermistor 55c. - The normal temperature water which enters the hot water supplying heat exchanger 42 from the
water supplying pipe 43 draws heat from high temperature water in the hotwater storage tank 32b while moving upward in the hotwater storage tank 32b from downward. Therefore, temperature of hot water in the hotwater storage tank 32b naturally becomes high at an upper portion and lower at a low portion in the hotwater storage tank 32b. - The main
refrigerant circuit 10 is provided with a high pressure-side pressure detector 51 and adischarge temperature thermistor 52 in thepipe 16 on the discharge side of the high stage-side compression rotation element 11b. - The high pressure-
side pressure detector 51 is provided in the mainrefrigerant circuit 10 from a discharge side of the high stage-side compression rotation element 11b to an upstream side of thefirst expansion device 14. It is only necessary that the high pressure-side pressure detector 51 can detect pressure of high pressure refrigerant in the mainrefrigerant circuit 10. - Further, the
discharge temperature thermistor 52 is also provided in the mainrefrigerant circuit 10 from the discharge side of the high-stage side compressing rotation element 11b to the upstream side of thefirst expansion device 14. It is also only necessary that thedischarge temperature thermistor 52 can detect temperature of the high pressure refrigerant of the mainrefrigerant circuit 10. - The usage-side
heat medium circuit 30 includes a heat mediuminlet temperature thermistor 54 for detecting temperature of usage-side heat medium which flows into the usage-side heat exchanger 12. - The
control device 60 controls operation frequencies of the low-stage sidecompressing rotation element 11a and the high-stage side compressing rotation element 11b, a valve opening of thefirst expansion device 14, a valve opening of thesecond expansion device 21 and a conveying amount of the usage-side heat medium conveyed by the conveyingdevice 31 based on detected pressure detected by the high pressure-side pressure detector 51, detected temperature detected by thedischarge temperature thermistor 52 and detected temperature detected by the heat mediuminlet temperature thermistor 54. -
Fig. 2 is a pressure-enthalpy diagram (P-h diagram) under the ideal condition concerning the refrigeration cycle device in the embodiment. - Points a to e and points A and B in
Fig. 2 correspond to points in the refrigeration cycle device shown inFig. 1 . - First, high pressure refrigerant (point a) discharged from the high stage-side compression rotation element 11b radiates heat in the usage-
side heat exchanger 12 and after that, the high pressure refrigerant branches off from the mainrefrigerant circuit 10 at a refrigerant branch point (point A), the high pressure refrigerant is decompressed to intermediate pressure by thesecond expansion device 21 and becomes intermediate pressure refrigerant (point e), and the intermediate pressure refrigerant is heat-exchanged by theintermediate heat exchanger 13. - The high pressure refrigerant which flows through the main
refrigerant circuit 10 after it radiates heat by the usage-side heat exchanger 12 is cooled by intermediate pressure refrigerant (point e) which flows through thebypass refrigerant circuit 20, and the high pressure refrigerant is decompressed by thefirst expansion device 14 in a state (point b) where enthalpy thereof is reduced. - According to this, refrigerant enthalpy of refrigerant (point c) which flows into the heat source-
side heat exchanger 15 after it is decompressed by thefirst expansion device 14 is also reduced. Dryness (weight ratio occupied by gas phase component to the entire refrigerant) of refrigerant when it flows into the heat source-side heat exchanger 15 is reduced and liquid component of refrigerant is increased. Therefore, this contributes to evaporation in the heat source-side heat exchanger 15, a refrigerant ratio is increased and an endothermic energy amount from outside air is increased, and it returns to the suction side (point d) of the low stage-sidecompression rotation element 11a. - On the other hand, refrigerant of an amount corresponding to gas phase component which does not contribute to evaporation in the heat source-
side heat exchanger 15 is made to bypass by thebypass refrigerant circuit 20, and becomes low temperature intermediate pressure refrigerant (point e), the refrigerant is heated by high pressure refrigerant which flows through the mainrefrigerant circuit 10 in theintermediate heat exchanger 13, and the refrigerant reaches a refrigerant joining point B located between the low stage-sidecompression rotation element 11a and the high stage-side compression rotation element 11b in a state where refrigerant enthalpy is increased. - Therefore, on the suction side of the high stage-side compression rotation element 11b (point B), since refrigerant pressure is higher than that on the suction side of the low stage-side
compression rotation element 11a (point d), refrigerant density is also high, and refrigerant which joins up with refrigerant discharged from the low stage-sidecompression rotation element 11a is sucked, further compressed by the high stage-side compression rotation element 11b and is discharged. Therefore, a flow rate of the refrigerant which flows into the usage-side heat exchanger 12 is largely increased, and ability of heating water which is usage-side heat medium is largely enhanced. - A case where the hot
water storage tank 32b is used in the usage-sideheat medium circuit 30 will be described below. - Among the plurality of hot water storage tank temperature thermistors, if detected temperature detected by the first hot water storage tank temperature thermistor 55a which is placed at the highest position in the hot
water storage tank 32b is lower than a predetermined value, thecontrol device 60 determines that high temperature water is insufficient in the hotwater storage tank 32b. - The
control device 60 operates the low stage-sidecompression rotation element 11a and the high stage-side compression rotation element 11b and heats low temperature water by the usage-side heat exchanger 12. Thecontrol device 60 operates the conveyingdevice 31 such that detected temperature detected by the heat mediumoutlet temperature thermistor 53 which is heating producing temperature becomes equal to the target temperature. - With this, low temperature water which is sent out from the lower portion of the hot
water storage tank 32b is heated by the usage-side heat exchanger 12. According to this, high temperature water is produced, and the high temperature water is introduced into the hotwater storage tank 32b from the upper portion of the hotwater storage tank 32b. - Since high temperature water is gradually stored in the hot
water storage tank 32b from the upper portion, detected temperature detected by the heat mediuminlet temperature thermistor 54 gradually increases. - A case where the
heating terminal 32a is used in the usage-sideheat medium circuit 30 will be described. - The
control device 60 operates the low stage-sidecompression rotation element 11a and the high stage-side compression rotation element 11b and heats circulated water by the usage-side heat exchanger 12, and thecontrol device 60 operates the conveyingdevice 31 such that a temperature difference, which is the temperature difference of the circulated water, between detected temperature detected by the heat mediumoutlet temperature thermistor 53 and detected temperature detected by the heat mediuminlet temperature thermistor 54 becomes equal to a target temperature difference. - According to this, high temperature water produced by the usage-
side heat exchanger 12 radiates heat in theheating terminal 32a and is utilized for heating a room, and low temperature water whose heat is released by theheating terminal 32a is again heated by the usage-side heat exchanger 12. At that time, since control is performed such that a temperature difference between detected temperature detected by the heat mediumoutlet temperature thermistor 53 and detected temperature detected by the heat mediuminlet temperature thermistor 54 becomes equal to the target temperature difference. - Since the heating load is gradually reduced, control is performed such that a temperature difference between detected temperature detected by the heat medium
outlet temperature thermistor 53 and detected temperature detected by the heat mediuminlet temperature thermistor 54 becomes equal to the target temperature difference. Therefore, the detected temperature detected by the heat mediumoutlet temperature thermistor 53 and the detected temperature detected by the heat mediuminlet temperature thermistor 54 increase gradually. - A case where temperature of the usage-side heat medium which flows into the usage-
side heat exchanger 12 in the usage-sideheat medium circuit 30, i.e., a case where detected temperature detected by the heat mediuminlet temperature thermistor 54 rises will be described below usingFig. 3 . - In
Fig. 3 , a solid line is a pressure-enthalpy diagram when temperature of the usage-side heat medium which flows into the usage-side heat exchanger 12 rises with respect to broken lines. - In
Fig. 3 , if temperature of the usage-side heat medium which flows into the usage-side heat exchanger 12 rises, inlet temperature (point a) of refrigerant toward the usage-side heat exchanger 12 moves to an increasing direction (point a') of enthalpy. Further, outlet temperature (point A) of refrigerant from the usage-side heat exchanger 12 moves to the increasing direction (point A') of enthalpy. - Similarly, outlet temperature (point B) of refrigerant from the
bypass refrigerant circuit 20 of theintermediate heat exchanger 13 also moves to the increasing direction (point B') of enthalpy. Further, inlet temperature (point e) of refrigerant toward thebypass refrigerant circuit 20 of theintermediate heat exchanger 13 also moves to the increasing direction (point e') of enthalpy. - In a state where pressure exceeds critical pressure, if temperature moves to the increasing direction of enthalpy, inclination of isothermal line with respect to pressure also becomes steep.
- Hence, even if temperature of the usage-side heat medium which flows into the usage-
side heat exchanger 12 rises, to suppress the deterioration of COP of therefrigeration cycle device 9, thecontrol device 60 must control the valve opening of thesecond expansion device 21 such that a temperature difference between the outlet temperature (point B') of refrigerant from thebypass refrigerant circuit 20 of theintermediate heat exchanger 13 and the inlet temperature (point e') of refrigerant toward thebypass refrigerant circuit 20 to theintermediate heat exchanger 13 does not become as small as possible in theintermediate heat exchanger 13. - Further, even if temperature of the usage-side heat medium which flows into the usage-
side heat exchanger 12 rises, it is necessary that heating ability of the usage-side heat medium is not deteriorated as small as possible by refrigerant which is discharged from the high-stage side compressing rotation element 11b in the usage-side heat exchanger 12. - More specifically, a ratio of an amount of refrigerant which flows through the
bypass refrigerant circuit 20 to an amount of refrigerant which flows on the side of the mainrefrigerant circuit 10 of theintermediate heat exchanger 13 is increased. - That is, the valve opening of the
second expansion device 21 is increased and a ratio of an amount of refrigerant which circulates through thebypass refrigerant circuit 20, the high-stage side compressing rotation element 11b and the usage-side heat exchanger 12 to an amount of refrigerant which circulates through the mainrefrigerant circuit 10 is increased. - According to this, even if temperature of the usage-side heat medium which flows into the usage-
side heat exchanger 12 rises, the heat exchanging amount between the high pressure refrigerant which flows through the mainrefrigerant circuit 10 and the intermediate pressure refrigerant which flows through thebypass refrigerant circuit 20 in theintermediate heat exchanger 13 is increased. - Hence, it is possible to suppress the reduction of an enthalpy difference (point a' to point A') between the outlet of refrigerant and the inlet of refrigerant in the usage-
side heat exchanger 12. - The enthalpy difference between the high pressure refrigerant (point a') discharged from the high-stage side compressing rotation element 11b and the refrigerant (point A') of a branch point of refrigerant after heat is released at the usage-
side heat exchanger 12 is equal to a total of an enthalpy difference between refrigerant (point B') on the suction side of the high-stage side compressing rotation element 11b and the intermediate pressure refrigerant (point e') which flows through thebypass refrigerant circuit 20 and an enthalpy difference of the high-stage side compressing rotation element 11b. - Hence, in order to increase the enthalpy difference (point a' to point A') between the outlet of refrigerant and the inlet of refrigerant in the usage-
side heat exchanger 12, it is necessary to increase the enthalpy difference (point B' to point e') of thebypass refrigerant circuit 20 of theintermediate heat exchanger 13. - Since the amount of refrigerant which circulates through the
bypass refrigerant circuit 20, the high-stage side compressing rotation element 11b and the usage-side heat exchanger 12 is increased, it is possible to suppress the deterioration of the heating ability in the usage-side heat exchanger 12. - The
control device 60 operates to reduce the valve opening of thefirst expansion device 14. According to this, since pressure on the high-pressure side of refrigerant of the mainrefrigerant circuit 10 rises, even if temperature of the usage-side heat medium which flows into the usage-side heat exchanger 12 rises, it is possible to suppress the reduction of the enthalpy difference (point a' to point A') between the outlet of refrigerant and the inlet of refrigerant in the usage-side heat exchanger 12. - The
control device 60 adjusts the valve opening of thefirst expansion device 14 and the valve opening of thesecond expansion device 21. According to this, temperature detected by thedischarge temperature thermistor 52 is brought close to a target value. The target value of discharge temperature is preset in thecontrol device 60. - According to this, it is possible to prevent the discharge temperature of refrigerant discharged from the high-stage side compressing rotation element 11b from being excessively increased or reduced, it is possible to increase the heat exchanging amount between the high pressure refrigerant which flows through the main
refrigerant circuit 10 and the intermediate pressure refrigerant which flows through thebypass refrigerant circuit 20 in theintermediate heat exchanger 13, and it is possible to increase the amount of refrigerant which circulates through thebypass refrigerant circuit 20, the high-stage side compressing rotation element 11b and the usage-side heat exchanger 12. - The
control device 60 adjusts the valve opening of thefirst expansion device 14 and the valve opening of thesecond expansion device 21. According to this, a pressure value detected by the high pressure-side pressure detector 51 is brought close to a target value. - According to this, it is possible to prevent pressure of refrigerant discharged from the high-stage side compressing rotation element 11b from being excessively increased or reduced. Even if temperature of the usage-side heat medium which flows into the usage-
side heat exchanger 12 rises, it is possible to suppress the reduction of the enthalpy difference (point a' to point A') between the outlet of refrigerant and the inlet of refrigerant in the usage-side heat exchanger 12. - The compressing rotation element may be a single compressing rotation element which is not divided into the low-stage side
compressing rotation element 11a and the high-stage side compressing rotation element 11b. If the single compressing rotation element is employed, a position where refrigerant from thebypass refrigerant circuit 20 joins up is defined as a middle position of being compressed by the compression rotation element. - By using water or antifreeze liquid as usage-side heat medium, it is possible to use the usage-side heat medium in the
heating terminal 32a or high temperature water can be stored in thehot water tank 32b. - As described above, according to the heat pump system of the present invention whose high-pressure side is operated under supercritical pressure, even if temperature of usage-side heat medium which flows into a usage-side heat exchanger rises, deterioration of COP is suppressed by performing appropriate control. Therefore, the heat pump system is suitable for refrigerating equipment, an air conditioner, a hot water supply system, heating equipment and the like.
-
- 9
- refrigeration cycle device
- 10
- main refrigerant circuit
- 11
- compression mechanism
- 11a
- low stage-side compression rotation element
- 11b
- high stage-side compression rotation element
- 12
- usage-side heat exchanger
- 13
- intermediate heat exchanger
- 14
- first expansion device
- 15
- heat source-side heat exchanger
- 16
- pipe
- 20
- bypass refrigerant circuit
- 21
- second expansion device
- 30
- usage-side heat medium circuit
- 31
- conveying device
- 32a
- heating terminal
- 32b
- hot water storage tank
- 33
- heat medium pipe
- 34
- first switching valve
- 35
- second switching valve
- 41
- hot water supplying plug
- 42
- hot water supplying heat exchanger
- 43
- water supplying pipe
- 51
- high pressure-side pressure detector
- 52
- intermediate pressure-side pressure detector
- 53
- heat medium outlet temperature thermistor
- 54
- heat medium inlet temperature thermistor
- 55a
- first hot water storage tank temperature thermistor
- 55b
- second hot water storage tank temperature thermistor
- 55c
- third hot water storage tank temperature thermistor
- 60
- control device
Claims (7)
- A heat pump system comprising:a main refrigerant circuit (10) formed by sequentially connecting, through a pipe (16), a compression mechanism (11) composed of a compression rotation element (11a, 11b), a usage-side heat exchanger (12) for heating usage-side heat medium by refrigerant which is discharged from the compression rotation element (11a, 11b) and which exceeds critical pressure, an intermediate heat exchanger (13), a first expansion device (14), and a heat source-side heat exchanger (15);a bypass refrigerant circuit (20) branched off from the pipe (16) between the usage-side heat exchanger (12) and the first expansion device (14), in which branched refrigerant is decompressed by a second expansion device (21) and thereafter, heat of the refrigerant is exchanged with that of the refrigerant flowing through the main refrigerant circuit (10) by the intermediate heat exchanger (13), and the refrigerant joins up with the refrigerant which is in middle of a compression operation of the compression rotation element (11a, 11b); anda control device (60), whereinwhen temperature of the usage-side heat medium which flows into the usage-side heat exchanger (12) rises, the control device (60) controls a valve opening of at least the second expansion device (21), and increases a ratio of an amount of the refrigerant which flows through the bypass refrigerant circuit (20) to an amount of the refrigerant which flows on a side of the main refrigerant circuit (10) of the intermediate heat exchanger (13).
- The heat pump system according to claim 1, further comprising a heat medium inlet temperature thermistor (54) for detecting the temperature of the usage-side heat medium which flows into the usage-side heat exchanger (12), wherein when detected temperature which is detected by the heat medium inlet temperature thermistor (54) rises, the control device (60) operates to increase the valve opening of the second expansion device (21).
- The heat pump system according to claim 2, wherein the control device (60) operates to reduce a valve opening of the first expansion device (14).
- The heat pump system according to claim 3, further comprising a discharge temperature thermistor (52) which detects temperature of the refrigerant discharged from the compressing rotation element (11a, 11b), wherein the control device (60) brings the temperature detected by the discharge temperature thermistor (52) close to a target value by adjusting the valve opening of the first expansion device (14) and the valve opening of the second expansion device (21) .
- The heat pump system according to claim 3, further comprising a high pressure-side pressure detector (51) which detects pressure of the refrigerant discharged from the compressing rotation element (11a, 11b), wherein the control device (60) brings a pressure value detected by the high pressure-side pressure detector (51) close to a target value by adjusting the valve opening of the first expansion device (14) and the valve opening of the second expansion device (21) .
- The heat pump system according to any one of claims 1 to 5, further comprising a usage-side heat medium circuit (30) which includes a conveying device (31) and which circulates the usage-side heat medium by the conveying device (31) .
- The heat pump system according to any one of claims 1 to 6, wherein the usage-side heat medium is water or antifreeze liquid.
Applications Claiming Priority (1)
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JP2019223863A JP7390605B2 (en) | 2019-12-11 | 2019-12-11 | heat pump system |
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EP3835687A1 true EP3835687A1 (en) | 2021-06-16 |
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EP20206234.5A Pending EP3835687A1 (en) | 2019-12-11 | 2020-11-06 | Heat pump system |
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Citations (4)
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JP2008008499A (en) | 2006-06-27 | 2008-01-17 | Sanyo Electric Co Ltd | Refrigerating cycle device and heat pump type water heater |
WO2009091401A1 (en) * | 2008-01-17 | 2009-07-23 | Carrier Corporation | Capacity modulation of refrigerant vapor compression system |
US20100115975A1 (en) * | 2007-04-24 | 2010-05-13 | Carrier Corporation | Refrigerant vapor compression system and method of transcritical operation |
DE112016004544T5 (en) * | 2015-10-05 | 2018-06-21 | Denso Corporation | Refrigeration cycle device |
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Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4269323B2 (en) * | 2004-03-29 | 2009-05-27 | 三菱電機株式会社 | Heat pump water heater |
JP7233845B2 (en) * | 2018-03-27 | 2023-03-07 | 株式会社富士通ゼネラル | air conditioner |
JP6986675B2 (en) * | 2018-05-31 | 2021-12-22 | パナソニックIpマネジメント株式会社 | Supercritical vapor compression refrigeration cycle and liquid heating device |
-
2019
- 2019-12-11 JP JP2019223863A patent/JP7390605B2/en active Active
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2020
- 2020-11-06 EP EP20206234.5A patent/EP3835687A1/en active Pending
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2008008499A (en) | 2006-06-27 | 2008-01-17 | Sanyo Electric Co Ltd | Refrigerating cycle device and heat pump type water heater |
US20100115975A1 (en) * | 2007-04-24 | 2010-05-13 | Carrier Corporation | Refrigerant vapor compression system and method of transcritical operation |
WO2009091401A1 (en) * | 2008-01-17 | 2009-07-23 | Carrier Corporation | Capacity modulation of refrigerant vapor compression system |
DE112016004544T5 (en) * | 2015-10-05 | 2018-06-21 | Denso Corporation | Refrigeration cycle device |
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JP2021092358A (en) | 2021-06-17 |
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