US20040118133A1 - Heat pump and dehumidifying air-conditioning apparatus - Google Patents

Heat pump and dehumidifying air-conditioning apparatus Download PDF

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Publication number
US20040118133A1
US20040118133A1 US10/468,832 US46883203A US2004118133A1 US 20040118133 A1 US20040118133 A1 US 20040118133A1 US 46883203 A US46883203 A US 46883203A US 2004118133 A1 US2004118133 A1 US 2004118133A1
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Prior art keywords
refrigerant
evaporator
heat
pressure
air
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Kensaku Maeda
Hideo Inaba
Shunro Nishikawa
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Ebara Corp
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Individual
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Assigned to EBARA CORPORATION reassignment EBARA CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: INABA, HIDEO, MAEDA, KENSAKU, NISHIWAKI, SHUNRO
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F3/00—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems
    • F24F3/12—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling
    • F24F3/14—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling by humidification; by dehumidification
    • F24F3/1405—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling by humidification; by dehumidification in which the humidity of the air is exclusively affected by contact with the evaporator of a closed-circuit cooling system or heat pump circuit
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F3/00—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems
    • F24F3/12—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling
    • F24F3/14—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling by humidification; by dehumidification
    • F24F3/153—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling by humidification; by dehumidification with subsequent heating, i.e. with the air, given the required humidity in the central station, passing a heating element to achieve the required temperature
    • 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
    • F25B5/00—Compression machines, plants or systems, with several evaporator circuits, e.g. for varying refrigerating capacity

Definitions

  • the present invention relates to a heat pump and a dehumidifying air-conditioning apparatus, and more particularly to a heat pump with a high coefficient of performance (COP) and a dehumidifying air-conditioning apparatus which has such a heat pump and a high moisture removal per energy consumption.
  • COP coefficient of performance
  • FIG. 10 is a flow diagram of a conventional air-conditioning system.
  • a dehumidifying air-conditioning apparatus having a compressor 201 for compressing a refrigerant, a condenser 202 for condensing the compressed refrigerant with outside air OA, an evaporator 204 for depressurizing the condensed refrigerant with an expansion valve 203 and evaporating the refrigerant to cool process air from an air-conditioned space 100 to a temperature lower than its dew point, and a reheater 205 for reheating the process air, which has been cooled to a temperature lower than its dew point, at the downstream side of the condenser 202 with the refrigerant upstream of the expansion valve 203 .
  • the refrigerant is condensed in the condenser 202 and the reheater 205 .
  • a heat pump HP is constituted by the compressor 201 , the condenser 202 , the reheater 205 , the expansion valve 203 , and the evaporator 204 .
  • the heat pump HP pumps heat from the process air which flows through the evaporator 204 into the outside air OA which flows through the condenser 202 .
  • FIG. 11 is a Mollier diagram in the case where HFC134a is used as the refrigerant in the conventional dehumidifying air-conditioning apparatus.
  • a point a represents a state of the refrigerant evaporated by the evaporator 204 , and the refrigerant is in the form of a saturated vapor.
  • the refrigerant has a pressure of 0.34 MPa, a temperature of 5° C., and an enthalpy of 400.9 kJ/kg.
  • a point b represents a state of the vapor drawn and compressed by the compressor 201 , i.e., a state at the outlet port of the compressor 201 . In the point b, the refrigerant is in the form of a superheated vapor.
  • the refrigerant vapor is cooled in the condenser 202 and reaches a state represented by a point c in the Mollier diagram.
  • the refrigerant is in the form of a saturated vapor and has a pressure of 0.94 MPa and a temperature of 38° C. Under this pressure, the refrigerant is cooled and condensed to reach a state represented by a point d.
  • the refrigerant is in the form of a saturated liquid and has the same pressure and temperature as those in the point c.
  • the saturated liquid has an enthalpy of 250.5 kJ/kg.
  • the refrigerant liquid is depressurized by the expansion valve 203 to a saturation pressure of 0.34 MPa at a temperature of 5° C. and reaches a state represented by the point e.
  • the refrigerant at the point e is delivered as a mixture of the refrigerant liquid and the vapor at a temperature of 5° C. to the evaporator 204 , in which the mixture removes heat from process air and is evaporated to reach a state of the saturated vapor, which is represented by the point a in the Mollier diagram.
  • the saturated vapor is drawn into the compressor 201 again, and the above cycle is repeated.
  • FIG. 12 is a psychrometric chart showing an air-conditioning cycle in the conventional dehumidifying air-conditioning apparatus.
  • the alphabetical letters K, L, M correspond to the encircled letters in FIG. 10.
  • air (in a state K) from the air-conditioned space 100 is cooled to a temperature lower than its dew point to lower the dry bulb temperature thereof and lower the absolute humidity thereof, and reaches a state L.
  • the state L is on a saturation curve in the psychrometric chart.
  • the air in the state L is reheated by the reheater 205 to increase the dry bulb temperature thereof and keep the absolute humidity thereof constant, and reaches a state M. Then, the air is supplied to the air-conditioned space 100 .
  • the state M is lower in both of absolute humidity and dry bulb temperature than the state K.
  • the present invention has been made in view of the above drawbacks. It is therefore an object of the present invention to provide a heat pump with a high coefficient of performance (COP) and a dehumidifying air-conditioning apparatus which consumes a small amount of energy per amount of moisture removal.
  • COP coefficient of performance
  • a heat pump comprising: a pressurizer for raising a pressure of a refrigerant; a condenser for condensing the refrigerant to heat a high-temperature heat source fluid; an evaporator for evaporating the refrigerant to cool a low-temperature heat source fluid; a refrigerant path branched into a plurality of branched refrigerant paths between the condenser and the evaporator; a first heat exchanging portion disposed in the branched refrigerant path between the condenser and the evaporator for evaporating the refrigerant under an intermediate pressure between the condensing pressure of the condenser and the evaporating pressure of the evaporator to cool the low-temperature heat source fluid by evaporation of the refrigerant under the intermediate pressure; a second heat exchanging portion disposed in the branched ref
  • a dehumidifying air-conditioning apparatus comprising: a pressurizer for raising a pressure of a refrigerant; a condenser for condensing the refrigerant to heat a high-temperature heat source fluid; an evaporator for evaporating the refrigerant to cool process air to a temperature lower than its dew point; a refrigerant path branched into a plurality of branched refrigerant paths between the condenser and the evaporator; a first heat exchanging portion disposed in the branched refrigerant path between the condenser and the evaporator for evaporating the refrigerant under an intermediate pressure between the condensing pressure of the condenser and the evaporating pressure of the evaporator to cool the process air by evaporation of the refrigerant under the intermediate pressure; a second heat exchanging portion disposed in the branched refriger
  • the low-temperature heat source fluid can be precooled in the first heat exchanging portion prior to cooling in the evaporator.
  • the low-temperature heat source fluid can be heated in the second heat exchanging portion after cooling in the evaporator with use of the heat in precooling.
  • process air is used as the low-temperature heat source and is cooled to a temperature lower than its dew point by the evaporator, it is possible to provide a dehumidifying air-conditioning apparatus which consumes a small amount of energy per amount of moisture removal.
  • the operative temperature of the refrigerant can gradually be changed to achieve a high efficiency of heat exchange.
  • the efficiency ⁇ of heat exchange is defined by
  • the temperature of the high-temperature fluid at the inlet of the heat exchanger is represented by TP 1
  • the temperature of the low-temperature fluid at the inlet of the heat exchanger is represented by TC 1
  • the temperature thereof at the outlet of the heat exchanger by TC 2 is defined by
  • the branched refrigerant paths extend through the interior of the evaporator in parallel, respectively, and are joined to each other at the downstream side of the evaporator.
  • an ejector on a branched refrigerant path for a refrigerant which exchanges heat with process air having a high temperature for pressurizing a refrigerant which exchanges heat with process air having a low temperature by a refrigerant which has passed through the branched refrigerant path.
  • FIG. 1 is a schematic view showing a whole arrangement of an air-conditioning system according to a first embodiment of the present invention
  • FIG. 2 is a flow diagram of a dehumidifying air-conditioning apparatus according to the first embodiment of the present invention
  • FIG. 3 is an enlarged view showing branched refrigerant paths in a heat exchanger of the dehumidifying air-conditioning apparatus shown in FIG. 2;
  • FIG. 4A is a perspective view showing a heat exchanger and an evaporator in the case where a refrigerant path is not branched, as viewed from a front side;
  • FIG. 4B is a perspective view showing a heat exchanger and an evaporator in the case where a refrigerant path is not branched, as viewed from a rear side;
  • FIG. 5 is a Mollier diagram of a heat pump included in the dehumidifying air-conditioning apparatus shown in FIG. 2;
  • FIG. 6 is a psychrometric chart showing an air-conditioning cycle in the dehumidifying air-conditioning apparatus shown in FIG. 2;
  • FIG. 7 is a graph showing the relationship between the number of branched refrigerant paths and the temperature efficiency in a dehumidifying air-conditioning apparatus according to the present invention.
  • FIG. 8 is a flow diagram of a dehumidifying air-conditioning apparatus according to a second embodiment of the present invention.
  • FIG. 9 is a Mollier diagram of a heat pump included in the dehumidifying air-conditioning apparatus shown in FIG. 8;
  • FIG. 10 is a flow diagram of a conventional dehumidifying air-conditioning apparatus
  • FIG. 11 is a Mollier diagram of a heat pump included in the conventional dehumidifying air-conditioning apparatus.
  • FIG. 12 is a psychrometric chart showing an air-conditioning cycle in the conventional dehumidifying air-conditioning apparatus.
  • FIG. 1 is a schematic view showing a whole arrangement of an air-conditioning system according to the first embodiment of the present invention
  • FIG. 2 is a flow diagram of a dehumidifying air-conditioning apparatus according to the first embodiment of the present invention.
  • the dehumidifying air-conditioning apparatus in the first embodiment serves to cool process air to a temperature lower than its dew point for dehumidifying the air.
  • the dehumidifying air-conditioning apparatus includes a heat pump HP 1 therein.
  • the dehumidifying air-conditioning apparatus lowers the humidity of the process air to maintain a comfortable environment in an air-conditioned space 100 supplied with the process air.
  • the dehumidifying air-conditioning apparatus mainly comprises an indoor unit 10 and an outdoor unit 20 installed outside of the air-conditioned space 100 (outdoor).
  • the indoor unit 10 in the dehumidifying air-conditioning apparatus comprises a refrigerant evaporator 1 for evaporating a refrigerant, a heat exchanger 2 for exchanging heat between the refrigerant and the process air, and an air blower 3 for circulating the process air.
  • the heat exchanger 2 performs a heat exchange between process air flowing into the evaporator 1 and process air flowing out of the evaporator 1 , indirectly with the refrigerant.
  • the heat exchanger 2 has a first heat exchanging portion 21 for evaporating the refrigerant to cool the process air, and a second heat exchanging portion 22 for condensing the refrigerant to heat the process air.
  • the outdoor unit 20 in the dehumidifying air-conditioning apparatus comprises a pressurizer (compressor) 4 for raising a pressure of the refrigerant, a refrigerant condenser 5 for cooling and condensing the refrigerant, and an air blower 6 for circulating the cooling air.
  • Process air paths which are paths for circulating process air, include a path 30 connecting the air-conditioned space 100 and the first heat exchanging portion 21 in the heat exchanger 2 , a path 31 connecting the first heat exchanging portion 21 and the evaporator 1 , a path 32 connecting the evaporator 1 and the second heat exchanging portion 22 in the heat exchanger 2 , a path 33 connecting the second heat exchanging portion 22 and the air blower 3 , and a path 34 connecting the air blower 3 and the air-conditioned space 100 .
  • the first heat exchanging portion 21 in the heat exchanger 2 , the evaporator 1 , and the second heat exchanging portion 22 in the heat exchanger 2 are connected in the order named by the process air paths.
  • Refrigerant paths include a path 40 connecting the evaporator 1 and the compressor 4 , a path 41 connecting the compressor 4 and the condenser 5 , and a path connecting the condenser 5 and the evaporator 1 .
  • the path connecting the condenser 5 and the evaporator 1 is branched into a plurality of branched refrigerant paths at the downstream side of the condenser 5 .
  • three branched refrigerant paths 42 , 43 , 44 are formed at the downstream side of the condenser 5 .
  • the branched refrigerant paths 42 , 43 , 44 are joined to one path 45 at the upstream side of the evaporator 1 .
  • Outside air OA is introduced as cooling air through the path 46 into the condenser 5 .
  • the outside air OA removes heat from the refrigerant which is condensed, and the heated outside air OA is drawn through the path 47 into the air blower 6 , from which the air is discharged through the path 48 as exhaust air EX.
  • An evaporating section 51 for evaporating the refrigerant to cool the process air which flows through the first heat exchanging portion 21 is provided in the first heat exchanging portion 21 of the heat exchanger 2 .
  • a condensing section 52 for condensing the refrigerant to heat (reheat) the process air which flows through the second heat exchanging portion 22 is provided in the second heat exchanging portion 22 of the heat exchanger 2 .
  • Restrictions 11 , 12 , 13 are disposed on the respective branched refrigerant paths 42 , 43 , 44 at the upstream side of the first heat exchanging portion 21 .
  • Restrictions 14 , 15 , 16 are disposed on the respective branched refrigerant paths 42 , 43 , 44 at the downstream side of the second heat exchanging portion 22 .
  • the restrictions 11 - 16 may comprise orifices, capillary tubes, expansion valves, or the like.
  • FIG. 3 is an enlarged view showing the branched refrigerant paths 42 , 43 , 44 in the heat exchanger 2 of the dehumidifying air-conditioning apparatus shown in FIG. 2.
  • the refrigerant paths including the evaporating section 51 and the condensing section 52 penetrate the first heat exchanging portion 21 and the second heat exchanging portion 22 in the heat exchanger 2 , alternately and repeatedly. Specifically, as shown in FIG.
  • the refrigerant path 42 has an evaporating section 61 a , a condensing section 62 a , a condensing section 62 b , an evaporating section 61 b , an evaporating section 61 c , and a condensing section 62 c .
  • the refrigerant path 43 has an evaporating section 63 a , a condensing section 64 a , a condensing section 64 b , an evaporating section 63 b , an evaporating section 63 c , and a condensing section 64 c .
  • the refrigerant path 44 has an evaporating section 65 a , a condensing section 66 a , a condensing section 66 b , an evaporating section 65 b , an evaporating section 65 c , and a condensing section 66 c.
  • the heat exchanger 2 has the first heat exchanging portion 21 for allowing the process air before flowing through the evaporator 1 to pass therethrough, and the second heat exchanging portion 22 for allowing the process air after flowing through the evaporator 1 to pass therethrough.
  • the first heat exchanging portion 21 and the second heat exchanging portion 22 form respective separate spaces, each in the form of a rectangular parallelepiped.
  • the evaporator 1 is disposed between the first heat exchanging portion 21 and the second heat exchanging portion 22 .
  • FIGS. 4A and 4B show the arrangement of a heat exchanger and an evaporator in the case where a refrigerant path is not branched, for reference.
  • FIG. 4A is a perspective view as viewed from the front side
  • FIG. 4B is a perspective view as viewed from the rear side.
  • the first heat exchanging portion 21 and the second heat exchanging portion 22 have a plurality of substantially parallel heat exchange tubes as refrigerant passages in each of a plurality of planes which lie perpendicularly to the flow of the process air.
  • Tubes 67 are provided across the evaporator 1 between the corresponding sections, for example, the evaporating section 61 a and the condensing section 62 a , the evaporating section 61 b and the condensing section 62 b , and the evaporating section 61 c and the condensing section 62 c (see FIG. 4B).
  • the corresponding evaporating and condensing sections are connected to each other.
  • the ends of the evaporating sections 61 b , 61 c , the ends of the evaporating sections 63 b , 63 c , and the ends of the evaporating sections 65 b , 65 c are connected to each other by a U tube 68 .
  • the ends of the condensing sections 62 a , 62 b , the ends of the condensing sections 64 a , 64 b , and the ends of the condensing sections 66 a , 66 b are connected to each other by a U tube 69 (see FIG. 4A).
  • the refrigerant flowing in one direction from the evaporating section 61 a to the evaporating section 62 a is introduced into the condensing section 62 b by the U tube 69 .
  • the refrigerant introduced into the condensing section 62 b then flows into the evaporating section 61 b , from which the refrigerant flows into the evaporating section 61 c via the U tube 68 and further flows into the condensing section 62 c .
  • the refrigerant passages are provided as a group of meandering thin pipes.
  • a group of meandering thin pipes pass through the first heat exchanging portion 21 and the second heat exchanging portion 22 , and are held in alternate contact with the process air which has a higher temperature and the process air which has a lower temperature.
  • a drain pan 7 is provided in the indoor unit 10 of the dehumidifying air-conditioning apparatus.
  • the drain pan 7 is preferably located below not only the evaporator 1 , but also the heat exchanger 2 .
  • the drain pan 7 is preferably disposed below the first heat exchanging portion 21 because the process air is mainly precooled in the first heat exchanging portion 21 and some moisture may possibly be condensed in the first heat exchanging portion 21 .
  • a refrigerant vapor pressurized by the compressor 4 is introduced into the condenser 5 via the refrigerant pipe 41 connected to the discharge port of the compressor 4 .
  • the refrigerant vapor compressed by the compressor 4 is cooled and condensed by the outside air OA as cooling air.
  • the refrigerant liquid flowing out of the condenser 5 is branched into the branched refrigerant paths 42 , 43 , 44 .
  • the refrigerants similarly flow through the respective refrigerant paths 42 , 43 , 44 . Therefore, the refrigerant flowing through the refrigerant path 42 will mainly be described below, and the refrigerants flowing through the other refrigerant paths 43 , 44 will not be described in detail below.
  • the refrigerant flowing through the refrigerant path 42 is depressurized by the restriction 11 and expanded so as to be partly evaporated (flashed).
  • the refrigerant which is a mixture of the liquid and the vapor reaches the evaporating section 61 a , where the refrigerant liquid flows so as to wet the inner wall surface of the tube in the evaporating section 61 a .
  • the refrigerant flows into the evaporating section 61 a in the liquid phase.
  • the refrigerant may be a refrigerant liquid which has been partly evaporated to slightly contain a vapor phase. While the refrigerant liquid is flowing through the evaporating section 61 a , it is evaporated to cool (precool) the process air before flowing into the evaporator 1 .
  • the refrigerant itself is heated while increasing the vapor phase thereof.
  • the evaporating section 61 a and the condensing section 62 a are constructed as a continuous tube. Specifically, since the evaporating section 61 a and the condensing section 62 a are provided as an integral passage, the refrigerant vapor evaporated in the evaporating section 61 a (and the refrigerant liquid which has not been evaporated) flows into the condensing section 62 a , and heats (reheats) the process air, which has been cooled and dehumidified in the evaporator 1 and has a temperature lower than the process air in the evaporating section 61 a .
  • the condensed refrigerant liquid flows into the next evaporating section 61 b and the subsequent evaporating section 61 c to cool (precool) the process air before flowing into the evaporator 1 in the same manner as described above. Thereafter, the refrigerant vapor flows into the condensing section 62 c to heat (reheat) the process air. In this manner, the refrigerant flows through the branched refrigerant path while changing in phase between the vapor phase and the liquid phase. Thus, heat is exchanged between the process air before being cooled by the evaporator 1 and the process air which has been cooled by the evaporator 1 to lower its absolute humidity.
  • the refrigerant liquid condensed in the condensing section 62 c is depressurized and expanded by the restriction 14 provided at the downstream side of the second heat exchanging portion 22 , for thereby lowering its pressure. Then, the refrigerant liquid is joined to the refrigerants which have flowed through the other branched refrigerant liquid paths 43 , 44 . The joined refrigerant liquid enters the evaporator 1 to be evaporated to cool the process air with heat of evaporation. The refrigerant which has been evaporated into a vapor in the evaporator 1 is introduced into the suction side of the compressor 4 through the path 40 , and thus the above cycle is repeated.
  • FIG. 5 is a Mollier diagram of the heat pump HP 1 included in the dehumidifying air-conditioning apparatus shown in FIG. 2.
  • the diagram shown in FIG. 5 is a Mollier diagram in the case where HFC134a is used as the refrigerant.
  • the horizontal axis represents the enthalpy
  • the vertical axis represents the pressure.
  • HFC407C and HFC410A are suitable refrigerants for the heat pump and the dehumidifying air-conditioning apparatus according to the present invention. These refrigerants have an operating pressure region shifted toward a higher pressure side than HFC134a.
  • a point a represents a state of the refrigerant which has been evaporated by the evaporator 1 shown in FIG. 2, and the refrigerant is in the form of a saturated vapor.
  • the refrigerant has a pressure of 0.234 MPa, a temperature of 5° C., and an enthalpy of 395.1 kJ/kg.
  • a point b represents a state of the vapor drawn and compressed by the compressor 4 , i.e., a state at the outlet port of the compressor 4 .
  • the refrigerant has a pressure of 0.706 MPa and is in the form of a superheated vapor.
  • the refrigerant vapor at the point b is cooled in the condenser 5 and reaches a state represented by a point c in the Mollier diagram.
  • the refrigerant is in the form of a saturated vapor and has a pressure of 0.706 MPa and a temperature of 38° C. Under this pressure, the refrigerant is cooled and condensed to reach a state represented by a point d.
  • the refrigerant is in the form of a saturated liquid and has the same pressure and temperature as those in the point c.
  • the saturated liquid has an enthalpy of 237.4 kJ/kg.
  • the refrigerant liquid is branched into the branched refrigerant liquid paths 42 , 43 , 44 , and the branched refrigerant liquids flow into the heat exchanger 2 .
  • the refrigerant flowing through the refrigerant path 43 will be described below.
  • the refrigerant liquid is depressurized by the restriction 12 and flows into the evaporating section 63 a in the first heat exchanging portion 21 . This state is indicated at a point e on the Mollier diagram.
  • the refrigerant liquid is a mixture of the liquid and the vapor because a part of the liquid is evaporated.
  • the pressure of the refrigerant liquid is an intermediate pressure between the condensing pressure in the condenser 5 and the evaporating pressure in the evaporator 1 , i.e., is of an intermediate value between 0.234 MPa and 0.706 MPa in the present embodiment.
  • the refrigerant liquid is evaporated under the intermediate pressure, and reaches a state represented by a point f1, which is located intermediately between the saturated liquid curve and the saturated vapor curve, under the intermediate pressure.
  • a point f1 which is located intermediately between the saturated liquid curve and the saturated vapor curve, under the intermediate pressure.
  • the refrigerant liquid remains in a considerable amount.
  • the refrigerant in the state represented by the point f1 flows into the condensing sections 64 a , 64 b .
  • the refrigerant in the state represented by the point g1 flows into the evaporating sections 63 b , 63 c , where heat is removed from the refrigerant.
  • the refrigerant increases its liquid phase and reaches a state represented by a point f2.
  • the refrigerant flows into the condensing section 64 c , where the refrigerant increases its liquid phase and reaches a state represented by a point g2.
  • the point g2 is on the saturated liquid curve. In this point, the refrigerant has a temperature of 18° C. and an enthalpy of 209.5 kJ/kg.
  • the refrigerant liquid at the point g2 is depressurized to 0.234 MPa, which is a saturated pressure at a temperature of 5° C., by the restriction 15 , and reaches a state represented by a point h.
  • the refrigerant at the point h flows as a mixture of the refrigerant liquid and the vapor at a temperature of 5° C. into the evaporator 1 , where the refrigerant removes heat from the process air to thus be evaporated into a saturated vapor at the state indicated by the point a on the Mollier diagram.
  • the evaporated vapor is drawn again by the compressor 4 , and thus the above cycle is repeated.
  • the refrigerant flowing into the refrigerant path 42 passes through the restriction 11 , the evaporating sections, the condensing sections, and the restriction 14 .
  • the refrigerant goes through states represented by points j, i1, k1, i2, and k2 and reaches the a state represented by a point l.
  • the refrigerant flowing into the refrigerant path 44 passes through the restriction 13 , the evaporating sections, the condensing sections, and the restriction 16 .
  • the refrigerant goes through states represented by points m, n1, o1, n2, and o2 and reaches a state represented by a point P.
  • the refrigerant goes through changes of the evaporated state from the point e to the point f1 or from the point g1 to the point f2 in the evaporating section 51 , and goes through changes of the condensed state from the point f1 to the point g1 or from the point f2 to the point g2 in the condensing section 52 . Since the refrigerant transfers heat by way of evaporation and condensation, the rate of heat transfer is very high and the efficiency of heat exchanger is high.
  • FIG. 6 is a psychrometric chart showing an air-conditioning cycle in the dehumidifying air-conditioning apparatus shown in FIG. 2.
  • the alphabetical letters K, X, L, M correspond to the encircled letters in FIG. 2.
  • the process air (in a state K) from the air-conditioned space 100 flows through the path 30 into the first heat exchanging portion 21 in the heat exchanger 2 , where the process air is cooled to a certain extent by the refrigerant that is evaporated in the evaporating section 51 .
  • This process can be referred to as precooling because the process air is preliminarily cooled before being cooled to a temperature lower than its dew point by the evaporator 1 .
  • the process air is being precooled in the evaporating section 51 , a certain amount of moisture is removed from the air to lower the absolute humidity of the air, and then air reaches a point X on the saturation curve.
  • the air may be precooled to an intermediate point between the point K and the point X. Further, the air may be precooled to a point that is shifted beyond the point X slightly toward a lower humidity on the saturation curve.
  • the process air precooled by the first heat exchanging portion 21 is introduced through the path 31 into the evaporator 1 , where the air is cooled to a temperature lower than its dew point by the refrigerant which has been depressurized by the restrictions 14 - 16 and is evaporated at a low temperature. Moisture is removed from the air to lower the absolute humidity and the dry bulb temperature of the air, and the air reaches a point L. Although the thick line representing a change from the point X to the point L is plotted as being remote from the saturation curve for illustrative purpose in FIG. 6, it is actually aligned with the saturation curve.
  • the process air in the state represented by the point L flows through the path 32 into the second heat exchanging portion 22 in the heat exchanger 2 , where the process air is heated, with the constant absolute humidity, by the refrigerant condensed in the condensing section 52 , and reaches a point M.
  • the process air in the point M has a sufficiently lower absolute humidity than the process air in the point K, a dry bulb temperature which is not excessively lower than the process air in the point K, and a suitable relative humidity.
  • the process air in the point M is then drawn by the air blower 3 and returned to the air-conditioned space 100 through the path 34 .
  • the amount of heat which has precooled the process air in the first heat exchanging portion 21 i.e., the amount AH of heat which has reheated the process air in the second heat exchanging portion 22
  • the amount of heat which has cooled the process air in the evaporator 1 is represented by ⁇ Q.
  • the cooling effect for cooling the air-conditioned space 100 is represented by ⁇ i.
  • the process air is precooled by evaporation of the refrigerant in the evaporating section 51 , and the process air is reheated by condensation of the refrigerant in the condensing section 52 .
  • the refrigerant evaporated in the evaporating section 51 is condensed in the condensing section 52 .
  • the same refrigerant is thus evaporated and condensed to perform a heat exchange indirectly between the process air before being cooled in the evaporator 1 and the process air after being cooled in the evaporator 1 .
  • the same refrigerant is used as a heat transfer medium in the evaporator for cooling the process air to a temperature lower than its dew point, the precooler for precooling the process air, and the reheater for reheating the process air. Therefore, the refrigerant system is simplified.
  • the refrigerant is positively circulated because the pressure difference between the evaporator and the condenser can be utilized. Since a boiling phenomenon with a phase change is applied to heat exchanges for precooling and reheating the process air, a high heat transfer efficiency can be achieved.
  • the refrigerant path is branched into the three branched refrigerant paths.
  • the refrigerant path may be branched into any number of branched refrigerant paths.
  • FIG. 7 is a graph showing the relationship between the number of branched refrigerant paths and the temperature efficiency in a dehumidifying air-conditioning apparatus according to the present invention. It is inferred from FIG. 7 that the temperature efficiency can be improved when the number of branched refrigerant paths is larger. Thus, when a plurality of branched refrigerant paths are provided, the operative temperature of the refrigerant can gradually be changed to achieve a high efficiency of heat exchange.
  • FIG. 8 is a flow diagram of a dehumidifying air-conditioning apparatus according to the second embodiment of the present invention
  • FIG. 9 is a Mollier diagram of a heat pump HP 2 included in the dehumidifying air-conditioning apparatus shown in FIG. 8.
  • FIGS. 8 and 9 like parts and components are denoted by the same reference numerals and characters as those of the first embodiment and will not be described below.
  • a refrigerant path is branched into a plurality of refrigerant paths at the downstream side of the condenser 5 to form branched refrigerant paths 142 , 143 , 144 .
  • the present embodiment differs from the first embodiment in that these branched refrigerant paths 142 , 143 , 144 extend to the interior of an evaporator 101 , respectively, and joined to each other at the downstream side of the evaporator 101 .
  • the refrigerant path for the refrigerant which exchanges heat with the process air having a high temperature i.e., the branched refrigerant path 142
  • the ejector 8 provided thereon for pressurizing the refrigerant which exchanges heat with the process air having a low temperature, i.e., the refrigerant that has passed through the refrigerant path 144 .
  • a point a represents a state of the refrigerant which has been evaporated by the evaporator 101 shown in FIG. 8, and the refrigerant is in the form of a saturated vapor.
  • the refrigerant has a pressure of 0.262 MPa, a temperature of 8° C., and an enthalpy of 396.8 kJ/kg.
  • a point b represents a state of the vapor drawn and compressed by the compressor 4 , i.e., a state at the outlet port of the compressor 4 .
  • the refrigerant has a pressure of 0.706 MPa and is in the form of a superheated vapor.
  • the refrigerant vapor is cooled in the condenser 5 and reaches a state represented by a point c in the Mollier diagram.
  • the refrigerant is in the form of a saturated vapor and has a pressure of 0.706 MPa and a temperature of 38° C. Under this pressure, the refrigerant is cooled and condensed to reach a state represented by a point d.
  • the refrigerant is in the form of a saturated liquid and has the same pressure and temperature as those in the point c.
  • the saturated liquid has an enthalpy of 237.4 kJ/kg.
  • the refrigerant liquid is depressurized by the restriction 12 and reaches a state represented by a point e on the Mollier diagram.
  • the pressure of the refrigerant liquid is an intermediate pressure between the condensing pressure in the condenser 5 and the evaporating pressure in the evaporator 101 , i.e., is of an intermediate value between 0.262 MPa and 0.706 MPa in the present embodiment.
  • the refrigerant flows alternately through the evaporating sections in the first heat exchanging portion 21 and the condensing sections in the second heat exchanging portion 22 and goes through states represented by points f1, g1, f2, and g2.
  • the refrigerant is depressurized by the restriction 15 to a saturation pressure of 0.262 MPa at a temperature of 8° C. and reaches a state represented by the point h.
  • the refrigerant at the point h is delivered as a mixture of the refrigerant liquid and the vapor at a temperature of 8° C. to the evaporator 101 , in which the mixture removes heat from the process air and is evaporated to reach a state of the saturated vapor, which is represented by the point a in the Mollier diagram.
  • the saturated vapor is drawn into the compressor 4 again, and the above cycle is repeated.
  • the refrigerant flowing into the refrigerant path 142 passes through the restriction 11 , the evaporating sections, the condensing sections, and the restriction 14 .
  • the refrigerant goes through states represented by points j, i1, k1, i2, and k2 and reaches the a state represented by a point 1 .
  • the refrigerant in the state represented by the point 1 flows into the evaporator 101 , where the refrigerant removes heat from the process air to be evaporated and reaches a state indicated by the point q on the Mollier diagram.
  • the refrigerant flowing into the refrigerant path 144 passes through the restriction 13 , the evaporating sections, the condensing sections, and the restriction 16 .
  • the refrigerant goes through states represented by points m, n1, o1, n2, and o2 and reaches a state represented by a point P.
  • the refrigerant in the state represented by the point p flows into the evaporator 101 , where the refrigerant removes heat from the process air to be evaporated and reaches a state indicated by the point r on the Mollier diagram.
  • the refrigerant in the state represented by the point r is pressurized by the ejector 8 provided on the refrigerant path 142 .
  • the refrigerant at a low pressure in the state represented by the point r is pressurized by the refrigerant at a high pressure in the state represented by the point q.
  • the refrigerant in the state represented by the point r and the refrigerant in the state represented by the point q reach a state of the saturated vapor, which is represented by the point a in the Mollier diagram.
  • the ejector 8 since the operative temperature of the evaporator is increased to improve the theoretical cooling effect, the theoretical work of compression is reduced to achieve a high efficiency.
  • the specific volume of the refrigerant is reduced to increase the flow rate of the refrigerant drawn by the compressor. Therefore, an amount of moisture removal is increased according to the improved cooling effect, and hence a high efficiency can be achieved.
  • the number of the evaporating sections on the respective branched refrigerant paths in the first heat exchanging portion and the number of the condensing sections on the respective branched refrigerant paths in the second heat exchanging portion are not limited to the illustrated examples.
  • the refrigerant may be introduced into the heat exchanger from the second heat exchanging portion in place of the first heat exchanging portion.
  • the dehumidifying air-conditioning apparatus has been described as the dehumidifying air-conditioning apparatus for air-conditioning a space.
  • the dehumidifying air-conditioning apparatus according to the present invention is applicable not only to the air-conditioned space, but also to other spaces that need to be dehumidified.
  • the present invention is suitable for use in a heat pump with a high coefficient of performance (COP) and a dehumidifying air-conditioning apparatus which has such a heat pump and a high moisture removal per energy consumption.
  • COP coefficient of performance

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Central Air Conditioning (AREA)
  • Compression-Type Refrigeration Machines With Reversible Cycles (AREA)
US10/468,832 2001-03-02 2002-03-01 Heat pump and dehumidifying air-conditioning apparatus Pending US20040118133A1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP2001059330A JP3253021B1 (ja) 2001-03-02 2001-03-02 ヒートポンプ及び除湿空調装置
IL142051 2001-03-16
IL147812 2002-01-24
PCT/JP2002/001897 WO2002070958A1 (en) 2001-03-02 2002-03-01 Heat pump and dehumidifying air-conditioning apparatus

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EP (1) EP1370809A4 (ja)
JP (1) JP3253021B1 (ja)
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US20060123841A1 (en) * 2004-12-10 2006-06-15 Lg Electronics Inc. Air conditioner
US20080078842A1 (en) * 2006-10-02 2008-04-03 Lennox Manufacturing Inc. Dehumidification enhancement via blower control
US20110276185A1 (en) * 2009-02-20 2011-11-10 Yoshiyuki Watanabe Use-side unit and air conditioner
US20140338883A1 (en) * 2012-08-05 2014-11-20 Yokohama Heat Use Technology Dehumidifying Device for Vehicle, Flexible Dehumidifying Member, and HVAC Device for Vehicle

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EP1915580A4 (en) * 2005-07-28 2010-12-22 Carrier Corp CLOSED LOOP DEHUMIDIFICATION CIRCUIT FOR A REFRIGERATED SYSTEM
CN107120746B (zh) * 2016-02-25 2020-06-02 维谛技术有限公司 一种复合型制冷除湿方法与制冷除湿复合***

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US7555915B2 (en) * 2004-12-10 2009-07-07 Lg Electronics Inc. Air conditioner
US20080078842A1 (en) * 2006-10-02 2008-04-03 Lennox Manufacturing Inc. Dehumidification enhancement via blower control
US8544288B2 (en) * 2006-10-02 2013-10-01 Lennox Manufacturing Inc. Dehumidification enhancement via blower control
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EP1370809A4 (en) 2006-10-04
JP2002257375A (ja) 2002-09-11
WO2002070958A1 (en) 2002-09-12
JP3253021B1 (ja) 2002-02-04
CN1223804C (zh) 2005-10-19
EP1370809A1 (en) 2003-12-17

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