JP2008180423A - Heat pump system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat pump system capable of lowering a high pressure side coolant pressure without complicated control. <P>SOLUTION: The heat pump system is provided with a compressor 4 compressing a coolant, a radiator 5 radiating heat of the coolant from the compressor 4, an expansion valve 6 expanding the coolant from the radiator 5, an evaporator 7 evaporating the coolant from the expansion valve 6, a heater 9 heating the coolant from the evaporator 7 and supplying it to the compressor 4, and a coolant piping 10 circulating the coolant in an order of the compressor 4, the radiator 5, the expansion valve 6, the evaporator 7, and the heater 9. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a heat pump system.

  Conventionally, chlorofluorocarbon refrigerants have been widely used as refrigerants for heat pumps. However, chlorofluorocarbon refrigerants have problems such as ozone layer destruction and global warming. Attention has been focused on natural refrigerants widely present in Japan. In particular, since carbon dioxide is not toxic or flammable, it has been investigated as an alternative to fluorocarbon refrigerants. However, when carbon dioxide is used as a heat pump refrigerant, the pressure on the high-pressure side of the refrigeration cycle increases. There is.

For this reason, the heat pump system described in Patent Document 1 includes a refrigeration cycle in which a compressor, a radiator, a first expansion valve, an auxiliary heat exchanger, a second expansion valve, and an evaporator are sequentially connected in an annular shape. The opening of the first expansion valve is controlled to reduce the high-pressure side refrigerant pressure. That is, when the refrigerant state is supercritical, the density of the refrigerant increases with an increase in pressure, so increasing the opening of the first expansion valve reduces the amount of refrigerant present in the radiator. Thus, the density is reduced and the refrigerant pressure on the high pressure side is reduced.
JP 2005-315558 A

  However, in the heat pump system described in Patent Document 1, control for lowering the high-pressure side refrigerant pressure is complicated, and other approaches have been desired.

  Then, this invention makes it a subject to provide the heat pump system which can reduce a high pressure side refrigerant | coolant pressure, without requiring complicated control.

  The heat pump system according to the present invention is made to solve the above-described problems, and includes a compressor that compresses the refrigerant, a radiator that dissipates the refrigerant from the compressor, and expands the refrigerant from the radiator. An expansion valve for evaporating, an evaporator for evaporating the refrigerant from the expansion valve, a heater for heating the refrigerant from the evaporator and supplying the refrigerant to the compressor, the compressor, a radiator, an expansion valve, and an evaporator And a refrigerant pipe for circulating the refrigerant in the order of the heater.

  Thus, in the heat pump system according to the present invention, the heater is installed between the evaporator and the compressor, and the refrigerant from the evaporator is heated by this heater. Therefore, since the temperature of the refrigerant supplied to the compressor becomes high and the enthalpy increases, when the refrigerant is compressed by the compressor and raised to a predetermined temperature, compared to the case where no heater is provided. Even at a low pressure, the refrigerant can be raised to a predetermined temperature. As a result, the high-pressure side refrigerant pressure can be reduced, and high-temperature heat exchange can be performed even at a low pressure.

  Although various things can be utilized as a heat source of the heater of the said heat pump system, the heat source of a heater can be ensured by comprising a heat pump system as follows, for example. That is, a tank for storing the load-side medium, a heat receiving pipe for circulating the load-side medium in the tank so as to exchange heat with the refrigerant in the radiator and return it to the tank, and a heater for the load-side medium in the tank And a heat radiating pipe for circulating the refrigerant so as to be returned to the tank. As described above, the load-side medium stored in the tank is heated through heat exchange with the refrigerant in the radiator by circulating through the heat receiving pipe. The load-side medium heated and stored in the tank is used as a heat source for the heater by circulating through the heat radiation pipe. For this reason, it is possible to provide a simpler and more efficient heat pump system without requiring a separate heat source.

  Moreover, in order to ensure the heat source of a heater, a heat pump system can also be set as the following structures. That is, a tank for storing the load-side medium, and a pipe for circulating the heat-exchanged medium in the tank so that the load-side medium in the tank is heat-exchanged with the refrigerant in the heater and then returned to the tank. , May be provided. With this configuration, not only a separate heat source is not required as described above, but also the following effects can be obtained. That is, since the load-side medium is cooled by once exchanging heat with the refrigerant in the heater, the refrigerant in the radiator exchanges heat with the cooled load-side medium. Therefore, since the refrigerant that has passed through the radiator has a lower temperature, that is, the amount of heat given to the load-side medium becomes larger, a good coefficient of performance can be obtained. Moreover, since only one pipe for circulating the load side medium is sufficient, the cost can be reduced.

  As the refrigerant, it is preferable to use carbon dioxide which is not toxic or flammable and can be obtained at low cost.

  ADVANTAGE OF THE INVENTION According to this invention, the heat pump system which can reduce a high voltage | pressure side refrigerant pressure can be provided, without requiring complicated control.

(First embodiment)
Hereinafter, a first embodiment of a heat pump system according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a circuit diagram of a heat pump system 1 according to the first embodiment.

  As shown in FIG. 1, the heat pump system 1 includes a refrigerant circuit 2 and a hot water supply circuit 3. The refrigerant circuit 2 includes an annular refrigerant pipe 10 through which the refrigerant passes, and a compressor 4, a radiator 5, an expansion valve 6, an evaporator 7, and a heater 9 are connected to the refrigerant pipe 10 in this order. Has been. The compressor 4 is for compressing the refrigerant. The refrigerant discharged from the compressor 4 is radiated by the radiator 5 and the refrigerant sent from the radiator 5 is decompressed by the expansion valve 6. . The refrigerant decompressed by the expansion valve 6 evaporates by the evaporator 7, and the refrigerant evaporated by the evaporator 7 to become saturated vapor is further heated by the heater 9. Carbon dioxide is used as the refrigerant in the refrigerant circuit 2.

  The hot water supply circuit 3 provides a load-side medium heated by the refrigerant circuit 2 for hot water supply in a bath or kitchen, and is configured as a circuit independent of the refrigerant circuit 2. A tank 11 storing the side medium, a heat receiving pipe 12 for exchanging heat between the load side medium in the tank 11 and the refrigerant in the radiator 5, and exchanging heat between the load side medium in the tank 11 and the refrigerant in the heater 9. And a heat dissipating pipe 13. In addition, the load side medium of the hot water supply circuit 3 is hot water (water).

  Next, the components of the refrigerant circuit 2 will be described in order. The compressor 4 is driven by a driving device (not shown), and is configured to compress the sucked refrigerant to a high temperature and discharge the refrigerant to the radiator 5 side.

  The radiator 5 is for radiating heat of the refrigerant that has been compressed by the compressor 4 and has reached a high temperature, and the high-temperature refrigerant that flows inside the radiator 5 flows through the heat receiving pipe 12 of the hot water supply circuit 3. Heat exchange. The refrigerant flowing in the radiator 5 and the load-side medium flowing in the heat receiving pipe 12 can exchange heat by various methods. For example, the inside of the heat receiving pipe 12 located at a position corresponding to the radiator 5 By constituting a double-pipe heat exchanger in which the radiator 5 extends, heat can be exchanged between the refrigerant and the load-side medium. Note that the refrigerant in the radiator 5 and the load-side medium in the heat receiving pipe 12 flow in opposite directions.

  The expansion valve 6 is configured to reduce the refrigerant to a low pressure and a low temperature by throttle expansion, and includes various expansion valves such as a manual expansion valve, a constant pressure expansion valve, a temperature automatic expansion valve, a capillary tube, a float expansion valve, and an electronic expansion valve. Can be used.

  The evaporator 7 heats and evaporates the refrigerant by exchanging heat between the refrigerant and the outside air. Note that a fan 8 is provided close to the evaporator 7 and receives air from the fan 8 to efficiently exchange heat between the outside air and the refrigerant.

  The heater 9 uses a load-side medium flowing in the heat radiation pipe 13 as a heat source, and heats the refrigerant by exchanging heat between the refrigerant in the heater 9 and the load-side medium in the heat radiation pipe 13. The temperature is rising.

  Next, components of the hot water supply circuit 3 will be described. First, the tank 11 is configured to store the load-side medium, and is preferably configured from a heat insulating material.

  The heat receiving pipe 12 includes a load-side medium forward path portion 12 a extending from the tank 11 to the radiator 5, and a load extending from the radiator 5 to the tank 11 so that the load-side medium exchanging heat with the refrigerant of the radiator 5 returns to the tank 11. And a return path 12b of the side medium. A pump 14 for circulating the load-side medium is installed in the forward path portion 12 a of the heat receiving pipe 12. Further, the heat radiation pipe 13 includes a load medium forward path 13 a extending from the tank 11 to the heater 9, and a load medium that exchanges heat with the refrigerant by the heater 9 from the heater 9 to the tank 11. It is composed of a return path medium b 13b that extends. Similarly to the heat receiving pipe 12, a pump 15 for circulating the load side medium is installed in the forward path portion 13 a of the heat radiating pipe 13.

  Next, the operation of the heat pump system configured as described above will be described with reference to FIGS. 1 and 2. FIG. 2 is a Mollier diagram of the refrigerant circulating in the refrigerant circuit.

  First, the refrigerant circuit 2 will be mainly described. As shown in FIG. 1, the refrigerant is compressed by the compressor 4 to a high pressure, thereby increasing the temperature of the refrigerant. The refrigerant heated to a high temperature by the compressor 4 is radiated by the radiator 5 to exchange heat with the load side medium circulating in the heat receiving pipe 12 to heat the load side medium, and the temperature of the refrigerant itself decreases.

  The refrigerant radiated by the radiator 5 is further reduced in temperature due to a sudden pressure drop by the expansion valve 6 and becomes wet steam. The refrigerant that has become wet steam exchanges heat with the atmosphere sent from the fan 8 by the evaporator 7 to receive heat from the atmosphere and become saturated steam. Subsequently, the refrigerant exchanges heat with the load-side medium circulating in the heat radiation pipe 13 in the heater 9 and receives heat from the load-side medium to be heated, so that the temperature rises as superheated steam. . And the refrigerant | coolant which temperature rose with the heater 9 is sent to the compressor 4, and circulates through the refrigerant circuit 2 so that the said process may be repeated again.

  The hot water supply circuit 3 will be mainly described. First, the pump 14 is operated to circulate the load-side medium in the tank 11 in the heat receiving pipe 12. The load side medium circulating in the heat receiving pipe 12 exchanges heat with the refrigerant in the radiator 5 at a position corresponding to the radiator 5. Since the refrigerant in the radiator 5 is heated by being compressed by the compressor 4, the load-side medium is heated by the refrigerant and the temperature rises. Thus, the high temperature load side medium returns into the tank 11, and the temperature of the load side medium in the tank 11 rises. And the hot water whose temperature rose in the tank 11 is utilized for hot water supply of a bath or a kitchen.

  In addition, by operating the pump 15 simultaneously with the pump 14, the load side medium in the tank 11 is circulated in the heat radiation pipe 13. The load-side medium circulating in the heat radiation pipe 13 exchanges heat with the refrigerant in the heater 9 at a position corresponding to the heater 9. Here, since the temperature of the load-side medium circulating in the heat radiation pipe 13 is higher than that of the refrigerant in the heater 9, the load-side medium heats the refrigerant and raises the temperature of the refrigerant. Thus, the load side medium circulating in the heat radiation pipe 13 is used as a heat source for the heater 9.

  In the process in the hot water supply circuit 3 described above, the temperature of the load side medium circulating through the heat receiving pipe 12 rises and the temperature of the load side medium circulating through the heat radiating pipe 13 falls, but circulates through the heat receiving pipe 12. Since the amount of heat received by the load-side medium is larger than the amount of heat released by the load-side medium circulating through the heat radiation pipe 13, the temperature of the load-side medium in the tank 11 gradually increases by repeating the above steps.

  The change of the refrigerant described above will be described based on the Mollier diagram of FIG. 2. First, the refrigerant is compressed by the compressor 4 to become high temperature and high pressure, and isentropic changes from the state of point E to the state of point A. Next, the heat is dissipated by the radiator 5 to lower the temperature, and the pressure is changed from the state of the point A to the state of the point B. Subsequently, the refrigerant becomes low-pressure and low-temperature by the expansion valve 6 to become wet steam, and the enthalpy changes from the state of the point B to the state of the point C. Then, the refrigerant that has become wet steam exchanges heat with the atmosphere in the evaporator 7 to become saturated steam, and the pressure changes from the state of the point C to the state of the point D. Subsequently, the refrigerant that has become saturated vapor is heated by the heater 9 to become superheated vapor, and the temperature rises, and the pressure changes from the state of the point D to the state of the point E. The refrigerant repeats the above changes to heat the load side medium.

As described above, according to the first embodiment, the heater 9 is installed between the evaporator 7 and the compressor 4, and the temperature of the refrigerant is increased by the heater 9 before being sent to the compressor 4. It is configured. For this reason, as shown in FIG. 2, for example, the temperature of the load-side medium in the tank 11 is 60 ° C., and the temperature of the refrigerant sent to the radiator 5 is 120 ° C. in order to heat the load-side medium at 60 ° C. When the heat pump system 1 according to the first embodiment is compared with the heat pump system not provided with the heater 9, the following effects can be obtained. That is, the change of the refrigerant in the heat pump system not provided with the heater 9 draws a locus D → A ′ → B ′ → C ′ → D indicated by a broken line in FIG. This refrigerant is in the state of point D. In order to increase the temperature of the refrigerant from the state of this point D to 120 ° C., for example, the compressor 4 needs to compress the refrigerant until the refrigerant pressure reaches P ₁ . On the other hand, in the heat pump system 1 according to the first embodiment, the refrigerant is further heated from the state of the point D by the heater 9 to increase the temperature and increase the enthalpy to change to the state of the point E. Yes. For this reason, the refrigerant temperature can be increased to 120 ° C. only by compressing the refrigerant 9 until the refrigerant pressure becomes P ₂ (<P ₁ ). Thus, by providing the heater 9 and raising the temperature of the refrigerant before being sent to the compressor 4, the high-pressure side refrigerant pressure can be lowered. Further, even at such a low pressure, the temperature of the refrigerant can be set to 120 ° C. The high temperature load medium at 60 ° C. is heated by the 120 ° C. refrigerant to further increase the temperature. It becomes possible to do.

(Second Embodiment)
Next, a second embodiment of the heat pump system according to the present invention will be described with reference to FIGS. FIG. 3 is a circuit diagram of the heat pump system according to the second embodiment, and FIG. 4 is a Mollier diagram of the refrigerant in the refrigerant circuit of the heat pump system according to the second embodiment. The heat pump system 1 ′ according to the second embodiment is greatly different from the heat pump system 1 according to the first embodiment in that the number of pipes of the hot water supply circuit 3 is one, and the other configuration is the same as that in the first embodiment. Therefore, below, the same code | symbol is attached | subjected to the structure same as 1st Embodiment, and description is abbreviate | omitted.

  First, as shown in FIG. 3, a heat pump system 1 ′ according to the second embodiment includes a refrigerant circuit 2 and a hot water supply circuit 3 ′. The refrigerant circuit 2 has the same configuration as that of the first embodiment, and the compressor 4, the radiator 5, the expansion valve 6, the evaporator 7, and the heater 9 are annularly connected in this order by the refrigerant pipe 10. is doing. Carbon dioxide, which is a refrigerant, circulates in the refrigerant circuit 2.

  The hot water supply circuit 3 ′ has a tank 11 for storing the load-side medium, and a pipe 16 for exchanging heat with the refrigerant in the radiator 5 while exchanging heat with the refrigerant in the heater 9. And.

  Thus, unlike the said 1st Embodiment, the piping 16 which circulates a load side medium is not divided into heat receiving piping and heat radiating piping. That is, the pipe 16 includes an outward path portion 16 a extending from the tank 11 to the heater 9, an intermediate portion 16 b extending from the heater 9 to the radiator 2, and from the radiator 2 to the tank 11 so as to return from the radiator 2 to the tank 11. The return path part 16c extends. A pump 17 for circulating the load side medium in the pipe 16 is installed in the forward path portion 16 a of the pipe 16.

  The operation of the heat pump system 1 ′ configured as described above will be described with reference to FIGS. 3 and 4.

  First, the refrigerant circuit 2 will be mainly described. As shown in FIG. 3, as in the first embodiment, the compressor 4 compresses the refrigerant to a high pressure to raise the temperature of the refrigerant. The refrigerant heated to a high temperature by the compressor 4 dissipates heat by the radiator 5 to heat exchange with the load side medium circulating in the pipe 16 to heat the load side medium, and the temperature of the refrigerant itself decreases.

  The refrigerant radiated by the radiator 5 is further reduced in temperature by the pressure suddenly dropping by the expansion valve 6 and becomes wet steam. The refrigerant that has become wet steam exchanges heat with the atmosphere sent from the fan 8 by the evaporator 7 to receive heat from the atmosphere and become saturated steam. Subsequently, the refrigerant exchanges heat with the load-side medium circulating in the pipe 16 in the heater 9 and receives heat from the load-side medium to be heated, so that the temperature rises as superheated steam. And the refrigerant | coolant which temperature rose with the heater 9 is sent to the compressor 4, and circulates through the inside of the refrigerant circuit 2 so that the said process may be repeated again.

  Further, the hot water supply circuit 3 ′ will be mainly described. First, the pump 17 is operated to circulate the load side medium in the tank 11 in the pipe 16. The load side medium circulating in the pipe 16 exchanges heat with the refrigerant in the heater 9 at a position corresponding to the heater 9. Here, since the temperature of the refrigerant in the heater 9 is lower than that of the load-side medium, the load-side medium heats the refrigerant in the heater 9 by heating, and the load-side medium itself is deprived of the heat and the temperature is increased. descend. Thus, the load side medium which became low temperature by heating a refrigerant | coolant further advances the inside of the piping 16, and heat-exchanges with the refrigerant | coolant in the radiator 5 in the position corresponding to the radiator 5. FIG. Since the refrigerant in the heater 5 is compressed by the compressor 4 and has a high temperature and is higher than the load-side medium, the load-side medium generates heat from the refrigerant in the radiator 5 at a position corresponding to the radiator 5. Receives and heats up and the temperature rises. Thus, the load-side refrigerant that has received heat from the refrigerant in the radiator 5 and has reached a high temperature finally returns into the tank 11 and raises the temperature of the load-side medium in the tank 11. By repeating this process, the temperature of the load side medium in the tank 11 gradually increases.

  The change of the refrigerant described above will be described based on the Mollier diagram of FIG. 4. First, the refrigerant is compressed by the compressor 4 to become high temperature and high pressure, and isentropic changes from the state of point J to the state of point F. Next, the refrigerant is dissipated by the radiator 5 and the temperature decreases, and the pressure changes from the state of the point F to the state of the point G. Subsequently, the refrigerant becomes low pressure and low temperature in the expansion valve 6 to become wet steam, and the enthalpy changes from the point G state to the point H state. Then, the refrigerant that has become wet steam exchanges heat with the atmosphere in the evaporator 7 to become saturated steam, and changes from the point H state to the point I state at an equal pressure. The refrigerant that has become saturated steam is heated by the heater 9 to become superheated steam, and the temperature rises, and the pressure changes from the state at point I to the state at point J. The refrigerant repeats the above changes to heat the load side medium.

  As described above, according to the second embodiment, the following effects can be obtained in addition to the same effects as those of the first embodiment. For example, a case will be described in which the temperature of the load-side medium in the tank 11 is 60 ° C., and the load-side medium at 60 ° C. is heated by the refrigerant at 120 ° C. in the radiator 5. First, in the case where the heater 9 is not provided, the temperature of the refrigerant that has exchanged heat with the load-side medium at 60 ° C. in the radiator 5 decreases from 120 ° C. to 60 ° C., and the state of the refrigerant is as shown in FIG. The pressure changes from point F ′ to point G ′. In addition, the change of the refrigerant | coolant in the heat pump system which does not provide the heater 9 draws the locus | trajectory of the point I-> F '-> G'-> H '-> I shown by the dotted line of FIG. In contrast, in the heat pump system 1 ′ according to the second embodiment, the load-side medium exchanges heat with the refrigerant in the heater 9 before being heated by the radiator 5, and the temperature is, for example, from 60 ° C. The temperature has dropped to 20 ° C. For this reason, the temperature of the refrigerant heat-exchanged with the load-side medium by the radiator 5 decreases from 120 ° C. to 20 ° C., and the state of the refrigerant changes at a constant pressure from point F to point G as shown in FIG. Thus, compared with the work difference of the compressor 4, the difference of the calorie | heat amount which a refrigerant | coolant gives to a load side medium is large, and the heat amount which concerns on 2nd Embodiment shown by the continuous line so that FIG. Since 1 ′ is larger, the coefficient of performance of the heat pump system is better in the heat pump system 1 ′ according to the second embodiment.

  Further, in the heat pump system 1 ′ according to the second embodiment, since only one pipe or pump for circulating the load side medium is required, the structure can be simplified and the cost can be reduced. is there.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to these, A various change is possible unless it deviates from the meaning of this invention. For example, in the above embodiment, hot water is heated as the load-side medium, but is not limited thereto, and may be various liquids and gases, and the refrigerant is carbon dioxide. However, other natural refrigerants can also be used.

  Moreover, in the said embodiment, although the method of heat exchange with the refrigerant | coolant which flows through the heat radiator 5, and the load side medium which flows through the heat receiving piping 12 was mentioned, although configuring the double pipe | tube type heat exchanger was mentioned especially, The heat exchanger is not limited, and various heat exchangers such as a multi-tubular heat exchanger and a plate heat exchanger can be used.

  Moreover, in the said embodiment, although the load side medium in the hot water supply circuit 3 is used as a heat source of the heater 9, it is not limited to this, A refrigerant | coolant can also be heated with the well-known heat source provided separately. it can.

  In addition, in order to operate the heat pump system more efficiently, pressure sensors and temperature sensors can be installed before and after each component to control each component. For example, between the heater 9 and the compressor 4 The refrigerant temperature sensor 10 can be installed in the center. By installing the refrigerant temperature sensor 10 in this manner, the work amount of the compressor 4 is adjusted based on the refrigerant temperature measured by the refrigerant temperature sensor 10 or the flow rate of the load-side medium flowing to the heater 9 is adjusted. It may be adjusted.

1 is a circuit diagram showing a first embodiment of a heat pump system according to the present invention. It is a Mollier diagram which shows the state of the refrigerant | coolant of the heat pump system which concerns on 1st Embodiment. It is a circuit diagram which shows 2nd Embodiment of the heat pump system which concerns on this invention. It is a Mollier diagram which shows the state of the refrigerant | coolant of the heat pump system which concerns on 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat pump system 4 Compressor 5 Radiator 6 Expansion valve 7 Evaporator 9 Heater 11 Tank 12 Heat receiving piping 13 Radiating piping 16 Piping

Claims (4)

A compressor for compressing the refrigerant;
A radiator that dissipates heat from the compressor;
An expansion valve for expanding the refrigerant from the radiator;
An evaporator for evaporating the refrigerant from the expansion valve;
A heater for heating the refrigerant from the evaporator and supplying the refrigerant to the compressor;
A refrigerant pipe for circulating the refrigerant in the order of the compressor, radiator, expansion valve, evaporator and heater;
With heat pump system. A tank for storing the load side medium;
A heat-receiving pipe for circulating the load-side medium in the tank so as to exchange heat with the refrigerant in the radiator and return it to the tank;
A heat dissipating pipe for circulating the load side medium in the tank so as to exchange heat with the refrigerant in the heater and return it to the tank;
The heat pump system according to claim 1, further comprising: A tank for storing the load side medium;
After the heat exchange of the load side medium in the tank with the refrigerant in the heater, the piping for circulating the heat exchange with the refrigerant in the radiator to return to the tank;
The heat pump system according to claim 1, further comprising:   The heat pump system according to any one of claims 1 to 3, wherein carbon dioxide is used as a refrigerant.

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