JP2006071229A - Heat pump device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the efficiency of a heat pump device having a constitution that a compressor and an expander are integrated. <P>SOLUTION: This heat pump device is provided with a refrigeration cycle formed by successively connecting the compressor 2, a radiator 12, the expander 3 integrated with the compressor 2 and mounted on a downstream side in the flowing direction of a refrigerant with respect to the radiator 12 to take out power by depressurizing and expanding the refrigerant, an electronic expansion valve 13 mounted further on a downstream side of the expander 3, and an evaporator 14, by piping, and further comprises a compressor discharge temperature detecting means TH1 mounted on discharge piping 11 for detecting a discharge temperature of the compressor 2, and a control means C1 controlling the electronic expansion valve 13 on the basis of the discharge temperature of the compressor 2 and increasing an outlet temperature of the expander 3, thus energy recovered as power by the expander 3 can be increased in maximum to improve cycle efficiency by optimally controlling temperature difference between the compressor 2 and the expander 3, that is, the quantity of heat moved from the compressor 2 to the expander 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a heat pump apparatus in which a compressor and an expander that achieve high efficiency by effectively recovering energy generated by expansion of a fluid are configured integrally.

In recent years, as a means for further improving the efficiency of the refrigeration cycle, an expander is provided in place of the expansion valve, and in the process of expansion of the refrigerant, the pressure energy is recovered in the form of electric power or power by the expander. Power recovery cycles have been proposed that only reduce compressor input. (For example, refer to Patent Document 1).
FIG. 6 is a configuration diagram of a conventional heat pump device described in Patent Document 1. In FIG. As shown in FIG. 6, the outdoor unit 1 includes a compressor 2 that is rotationally driven by a motor (not shown), an expander 3 that is connected to the compressor 2 on one axis, an outdoor heat exchanger 4, and a compression unit. The accumulator 5 provided in the suction side refrigerant pipe of the machine 2, the receiver 6 provided in the suction side refrigerant pipe of the expander 3, the first four-way switching valve 7, and the second four-way A switching valve 8 is provided. The indoor unit 9 is provided with an indoor heat exchanger 10.
During the cooling operation, the refrigerant gas discharged from the compressor 2 is cooled and condensed in the outdoor heat exchanger 4 through the first four-way switching valve 7 to be liquid refrigerant. This liquid refrigerant is introduced into the expander 3 through the receiver 6, is decompressed by isentropic expansion in the expander 3, and is then introduced into the indoor heat exchanger 10 through the second four-way switching valve 8. The liquid refrigerant introduced into the indoor heat exchanger 10 evaporates here to cool the room with the heat of evaporation, and the evaporated gas refrigerant passes through the first four-way switching valve 7 and the accumulator 5 and is compressed by the compressor. 2 is inhaled.
On the other hand, during the heating operation, the gas refrigerant discharged from the compressor 2 is introduced into the indoor heat exchanger 10 through the first four-way switching valve 7, where it condenses into a liquid refrigerant. The room is heated by the heat of condensation. The liquid refrigerant condensed in the indoor heat exchanger 10 is introduced into the expander 3 through the second four-way switching valve 8 and is decompressed by isentropic expansion in the expander 3, and then the second four-way switching valve 8. After being introduced into the outdoor heat exchanger 4 and evaporating into a gas refrigerant, the refrigerant is sucked into the compressor 2 through the first four-way switching valve 7 and the accumulator 5.
FIG. 7 is a Mollier diagram of a conventional heat pump device and shows the principle of high efficiency by the expander 3. As shown in FIG. 7, the refrigerant gas (point a) condensed and supercooled from the outlet of the compressor 2 (point d) is introduced into the expander 3, and is expanded by isentropic expansion in the expander 3. The evaporator (for example, indoor heat exchanger 10 at the time of cooling) at the inlet (point b) and the evaporator (for example, indoor heat exchange at the time of cooling) when the enthalpy expansion is performed from the point a by the expansion valve as in the prior art. The pressure energy at the time of refrigerant expansion is recovered to the refrigerant system side as motive power by the amount of enthalpy (ha) between the container 10) inlet (point e). As a result, only the value (hb-ha) obtained by subtracting the recovered power (ha) from the required input (hb) needs to be actually input to the compressor 2, and the cycle efficiency is increased by the reduction of the compressor 2 input. Is realized.
JP 2001-66006 A

  However, since the compressor 2 and the expander 3 are connected by a single shaft in the above-described conventional configuration, the compressor 2 that has a high temperature in a cycle such as during cooling operation in summer, and the cycle Under the condition that the temperature difference with the expander 3 that is low in temperature increases, the heat transfer from the compressor 2 to the expander 3 through the internal parts such as the shaft and the outer wall becomes remarkable. As a result, the refrigerant is affected by heat when it expands in the expander 3, so that the isentropic expansion (point a → b) as shown in FIG. 7 does not occur, but the ratio of the evaporator inlet (point b). Enthalpy increased, the amount of energy (ha) recovered as power decreased, and there was a problem that the efficiency of the actual cycle was significantly reduced compared to the theoretical efficiency.

  Therefore, this invention solves the said conventional subject, and it aims at providing the heat pump apparatus which can suppress the calorie | heat amount which moves from a compressor to an expander, and can improve cycle efficiency.

The heat pump device according to the first aspect of the present invention includes a compressor, a radiator, an expander that extracts power by decompressing and expanding a refrigerant, a decompression unit, and an evaporator connected by a pipe, and the expander Is provided on the downstream side of the radiator, the pressure reducing means is provided on the downstream side of the expander to constitute a refrigeration cycle, and the expander and the compressor are integrated into a heat pump device, Compressor discharge temperature detection means for detecting the discharge temperature of the compressor, and control means for controlling the decompression means according to the discharge temperature of the compressor.
According to a second aspect of the present invention, in the heat pump apparatus according to the first aspect, the heat pump device further includes an expander outlet temperature detecting unit that detects an outlet temperature of the expander, and the control unit includes a discharge temperature of the compressor and the discharge temperature of the compressor. The pressure reducing means is controlled by a temperature difference from an outlet temperature of the expander.
According to a third aspect of the present invention, there is provided a heat pump device comprising: a compressor; a radiator; an expander that extracts power by decompressing and expanding a refrigerant; a decompression unit; Is provided on the downstream side of the radiator, the pressure reducing means is provided on the downstream side of the expander to constitute a refrigeration cycle, and the expander and the compressor are integrated into a heat pump device, A capillary tube is used as the decompression means.
According to a fourth aspect of the present invention, in the heat pump device according to the third aspect, the capillary tube and a suction pipe connected from the evaporator outlet to the compressor are configured to exchange heat.
According to a fifth aspect of the present invention, in the heat pump apparatus according to any one of the first to fourth aspects, the operation is performed with the pressure on the high-pressure side of the refrigeration cycle being in a supercritical state.

  The heat pump device of the present invention can maximize the energy recovered as power in the expander by optimally controlling the amount of heat transferred from the compressor to the expander, thereby improving the efficiency of the heat pump device.

The heat pump device according to the first embodiment of the present invention includes a compressor discharge temperature detecting means for detecting the discharge temperature of the compressor, and a control means for controlling the pressure reducing means by the discharge temperature of the compressor. . According to this embodiment, the outlet temperature of the expander under the condition that the temperature difference between the compressor that becomes high in the cycle and the expander that becomes low in the cycle becomes large, such as during cooling operation in summer. By optimizing the temperature, the temperature difference between the compressor and the expander, that is, the amount of heat transferred from the compressor to the expander is optimally controlled to maximize the energy recovered as power in the expander and improve the cycle efficiency. be able to. In addition, since the density of the refrigerant at the inlet / outlet of the expander can be controlled by controlling the pressure reducing means, there is also an effect that excess refrigerant in the cycle that occurs when the outside air temperature decreases extremely can be retained in the expander. .
The second embodiment of the present invention includes an expander outlet temperature detecting means for detecting an outlet temperature of the expander in the heat pump apparatus according to the first embodiment, and the control means includes a discharge temperature and an expansion of the compressor. The pressure reducing means is controlled by the temperature difference from the outlet temperature of the machine. According to the present embodiment, the amount of heat transferred from the compressor to the expander is proportional to the temperature difference between the discharge temperature of the compressor and the outlet temperature of the expander, so that the amount of heat can be controlled more precisely. It becomes possible, and the energy recovered as power by the expander can be raised to the maximum with higher accuracy.
The heat pump apparatus according to the third embodiment of the present invention uses a capillary tube as the decompression means. According to the present embodiment, by raising the outlet temperature of the expander using a capillary tube as a decompression means, the energy recovered as power by the expander can be raised, and the cycle efficiency can be improved. In addition, there is an effect that the cost can be reduced.
In the heat pump device according to the third embodiment, the fourth embodiment of the present invention is configured to exchange heat between the capillary tube and the suction pipe connected to the compressor from the evaporator outlet. According to the present embodiment, the energy that has been wasted to the surroundings from the suction pipe can be recovered as the refrigerating capacity of the evaporator, so that the cycle efficiency can be further improved.
In the heat pump apparatus according to the first to fourth embodiments, the fifth embodiment of the present invention operates with the pressure on the high-pressure side of the refrigeration cycle set to a supercritical state. According to the present embodiment, the high-low pressure difference in the cycle becomes large, so that the function of the expander that converts the energy of the pressure difference into power can be maximized, and the cycle efficiency can be further improved. it can.

FIG. 1 is a configuration diagram of a heat pump device according to a first embodiment of the present invention. In addition, the same code | symbol is attached | subjected about the same structure as background art.
In FIG. 1, the heat pump device of the first embodiment includes a compressor 2, a discharge pipe 11, a radiator 12, an expander 3, an electronic expansion valve 13 driven by a pulse motor, for example, a decompression unit, and evaporation. The refrigeration cycle is configured by connecting the vessel 14 and the suction pipe 15 sequentially by pipes. The expander 3 is provided on the downstream side of the radiator 12 with respect to the refrigerant flow direction, and the decompression means 13 is provided on the further downstream side of the expander 3. Here, the expander 3 takes out power by decompressing and expanding the refrigerant. The expander 3 is configured as an integral unit with the compressor 2. Here, the integral type is configured such that at least the drive shafts of the expander 3 and the compressor 2 are connected, and one heat is transmitted to the other through the drive shaft.
The discharge pipe 11 is provided with compressor discharge temperature detection means TH1 which is, for example, a thermistor for detecting the discharge temperature of the compressor 2, and an electronic expansion valve is detected by a signal from the compressor discharge temperature detection means TH1. The control means C1 which controls the opening degree of 13 is provided.

A change in the energy state of the refrigerant of the heat pump apparatus configured as described above will be described with reference to a Mollier diagram of the heat pump apparatus in this embodiment shown in FIG.
The low-temperature and low-pressure refrigerant sucked into the compressor 2 is compressed by the operation of the compressor 2 to be discharged as a high-temperature and high-pressure refrigerant (A → B in the figure). The discharged refrigerant exchanges heat with tap water (not shown) in the radiator 12 through the discharge pipe 11 and dissipates heat while heating the tap water to a high temperature of about 80 ° C. (B → C). Then, the expander 3 performs expansion close to isentropic expansion, is decompressed while generating mechanical energy, and reaches an electronic expansion valve 13 driven by, for example, a pulse motor serving as decompression means (C → D).
Thereafter, the electronic expansion valve 13 is depressurized while performing equal enthalpy expansion by the action of the electronic expansion valve 13 to become a low-temperature and low-pressure refrigerant and reach the evaporator 14 (D → E). In the evaporator 14, the refrigerant that has exchanged heat with outdoor air becomes gaseous, and is then sucked into the compressor 2 through the suction pipe 15. (E → A)

  By the way, C → G represented by a dotted line in the figure is a theoretical isentropic expansion process, and C → F represented by a one-dot chain line recovers power only by an expander 3 having no conventional expansion valve. This is the expansion process. Comparing the specific enthalpy at the inlet of the evaporator 14 of the conventional expansion process C → F and the isentropic expansion process C → G, the specific enthalpy iF is very large in the conventional expansion process C → F. This is under the condition that the temperature difference between the compressor 2 that becomes high temperature in the cycle and the expander 3 that becomes low temperature in the cycle becomes large (for example, compressor 2 discharge temperature = 80 ° C., expander 3 outlet temperature (F point). ) = 0 ° C.), since the heat transfer from the compressor 2 to the expander 3 through the internal parts such as the shaft and the outer wall becomes remarkable, when the refrigerant expands in the expander 3, the heat is received and the specific enthalpy This is because of the increase.

Therefore, in this embodiment, the outlet pressure (point D) of the expander 3 is increased by restricting the flow path of the electronic expansion valve 13 disposed on the downstream side of the expander 3. As a result, the outlet temperature (point D) of the expander 3 increases as the outlet pressure of the expander 3 increases, and the temperature difference between the discharge temperature of the compressor 2 and the expander 3 outlet temperature becomes small. It is possible to suppress the amount of heat transferred from the to the expander 3.
As a result, the expansion (C → D) of the refrigerant in the expander 3 becomes closer to the isentropic expansion (C → G), and the expansion (D → E) in the electronic expansion valve 13 performs the isenthalpy expansion. Therefore, although energy recovery cannot be performed, the specific enthalpy iE at the inlet of the evaporator 14 can be made smaller than the conventional specific enthalpy iF.

Thereby, when using the heat pump apparatus using the heat radiator 12 of this cycle in a water heater, a heater, a vending machine, etc., the coefficient of performance COP = (iB−iC) / ((iB−iA) − (iC -IE)), and the required power of the compressor can be reduced compared to the conventional case, so that the efficiency of the cycle is improved.
On the other hand, when the refrigeration cycle apparatus using the evaporator 14 of this cycle is used in a domestic refrigerator, commercial refrigerator, air conditioner, ice making machine, vending machine, etc., the coefficient of performance COP = ((iA−iF) + (IF-iE)) / ((iB-iA)-(iC-iE)). Compared with the prior art, the required power of the compressor is reduced and the refrigeration effect is increased. improves.

Next, a method for controlling the electronic expansion valve 13 will be described.
FIG. 3 is an energy loss diagram of the heat pump apparatus in the present embodiment, and is a graph showing the relationship between the discharge temperature of the compressor 3 and the energy loss. The solid line in the figure indicates the case where the opening degree of the electronic expansion valve 13 on the downstream side of the expander 3 is controlled, and the dotted line indicates the case where the refrigerant is expanded only by the conventional expander 3.
When the discharge temperature of the compressor 3 is higher than a predetermined temperature T1, as described above, the cycle efficiency is improved by controlling the electronic expansion valve 13 to increase the outlet temperature of the expander 3. Loss is small. However, when the temperature is lower than a predetermined temperature T1, the cycle efficiency is reduced when the electronic expansion valve 13 is controlled to increase the outlet temperature of the expander 3, and the energy loss is increased.
For example, when the discharge temperature of the compressor 2 is relatively low in a heating operation in which air heated by the radiator 12 in winter is introduced into the room, the temperature difference between the compressor 2 side and the expander 3 side is small. Therefore, the movement of heat through the internal parts such as the shaft and the outer wall is reduced, and as a result, the amount of heat received when the refrigerant expands in the expander 3 is reduced, so that the increase in specific enthalpy is suppressed.
Under such conditions, when the opening temperature of the expander 3 is increased by controlling the opening degree of the electronic expansion valve 13, the expansion (D → E) in the electronic expansion valve 13 is equal enthalpy as described above. Since the energy cannot be recovered for expansion, the inlet of the evaporator 14 when the opening degree of the electronic expansion valve 13 is controlled rather than the specific enthalpy iF of the inlet of the evaporator 14 in the conventional expansion without the electronic expansion valve 13. The specific enthalpy iE becomes larger and the cycle efficiency is lowered.

Therefore, in this embodiment, when the detected temperature from the compressor discharge temperature detecting means TH1 that is disposed in the discharge pipe 11 and detects the discharge temperature is equal to or higher than a predetermined temperature T1, the electronic expansion valve 13 is If the opening temperature is controlled to increase the outlet temperature of the expander 3 and is equal to or less than T1, the opening of the electronic expansion valve 13 is fully opened to minimize the resistance on the downstream side of the expander 3, and the expander The refrigerant is expanded only by 3. Thus, the electronic expansion valve 13 is optimally controlled by the discharge temperature.
As a result, in the heat pump apparatus of this embodiment, the energy loss in FIG. 3 is a solid line when the discharge temperature of the compressor 3 is T1 or higher, and a dotted line when the discharge temperature is T1 or lower. In this case, the cycle efficiency can always be maximized.

Further, since the amount of heat transferred from the compressor 2 to the expander 3 is proportional to the temperature difference between the discharge temperature of the compressor 2 and the outlet temperature of the expander 3, the outlet temperature of the expander 3 is detected as shown in FIG. When the expander outlet temperature detection means TH2 is provided and the temperature difference between the compressor 2 discharge temperature TB and the outlet temperature TD of the expander 3 when the opening degree of the electronic expansion valve 13 is fully opened is greater than or equal to a predetermined temperature ΔT1. Then, the opening degree of the expander 3 is increased by controlling the opening degree of the electronic expansion valve 13, and if the temperature is equal to or lower than the predetermined temperature ΔT1, the opening degree of the electronic expansion valve 13 is not fully controlled and is fully opened. The configuration may be such that the refrigerant is expanded only by the expander 3 while minimizing the resistance of the downstream piping.
In this way, the amount of heat transferred from the compressor 2 to the expander 3 can be more precisely controlled by optimally controlling the electronic expansion valve 13 of the decompression means by the temperature difference between the discharge temperature of the compressor 2 and the outlet temperature of the expander 3. It becomes possible to control, and the efficiency of the cycle of the heat pump apparatus can be further improved with maximum accuracy.

FIG. 4 is a configuration diagram of the heat pump apparatus in the second embodiment of the present invention. In addition, the same code | symbol is attached | subjected about the same structure as 1st Example.
In FIG. 4, the heat pump device of the second embodiment is disposed downstream of the compressor 2, the discharge pipe 11, the radiator 12, and the refrigerant flow direction with respect to the refrigerant flow direction to decompress the refrigerant. An expander 3 that is integrated with the compressor 2 that extracts power by expansion, a capillary tube 16 that is a decompression means provided further downstream of the expander 3, an evaporator 14, and a suction pipe 15. The refrigeration cycle is formed by sequentially connecting the pipes.
Further, the capillary tube 16 and the suction pipe 15 connected from the outlet of the evaporator 14 to the compressor 2 are configured to exchange heat, for example, the capillary tube 16 and the suction pipe 15 are in contact with each other by solder or the like.

A change in the energy state of the refrigerant of the heat pump apparatus configured as described above will be described with reference to a Mollier diagram of the heat pump apparatus in the present embodiment shown in FIG.
The low-temperature and low-pressure refrigerant sucked into the compressor 2 is compressed by the operation of the compressor 2 to be discharged as a high-temperature and high-pressure refrigerant (A → B in the figure). The discharged refrigerant exchanges heat with tap water (not shown) in the radiator 12 through the discharge pipe 11 and dissipates heat while heating the tap water to a high temperature of about 80 ° C. (B → C). Then, the expander 3 performs expansion close to isentropic expansion, is decompressed while generating mechanical energy, and reaches the capillary tube 16 serving as decompression means (C → D).
Since heat is exchanged with the refrigerant passing through the suction pipe 15 in the capillary tube 16, the pressure is reduced while reducing the specific enthalpy, and the refrigerant becomes a low-temperature and low-pressure refrigerant and reaches the evaporator 14 (D → H). In the evaporator 14, the refrigerant that has exchanged heat with outdoor air becomes gaseous and is discharged from the outlet of the evaporator 14 (H → I). Thereafter, the refrigerant flowing into the suction pipe 15 increases the specific enthalpy while exchanging heat with the capillary tube 16 and is sucked into the compressor 2 (I → A).
Further, by exchanging heat with the suction pipe 15 using the capillary tube 16, it is possible to recover the amount of heat that has been wasted from the suction pipe 15 to the surroundings. As a result, the specific enthalpy iH at the inlet of the evaporator 14 becomes smaller than the specific enthalpy iE at the inlet of the evaporator 14 corresponding to the case where the electronic expansion valve 13 is used.

Thereby, when using the heat pump apparatus using the heat radiator 12 of this cycle in a water heater, a heater, a vending machine, etc., the coefficient of performance COP = (iB−iC) / ((iB−iA) − (iC -IH)), compared with the case where the electronic expansion valve 13 is used, since the required power of the compressor can be reduced, the efficiency of the cycle is improved.
On the other hand, when the refrigeration cycle apparatus using the evaporator 14 of this cycle is used in a home refrigerator, commercial refrigerator, air conditioner, ice making machine, vending machine, etc., the coefficient of performance COP = ((iI−iE) + (IE-iH)) / ((iB-iA)-(iC-iH)), and the required power of the compressor is reduced and the refrigeration effect is increased as compared with the conventional case. improves.

As described above, in the heat pump apparatus of the present embodiment, the outlet temperature of the expander is raised using a capillary tube as a pressure reducing means, so that the influence of heat moving from the compressor to the expander can be suppressed, and the cycle efficiency can be reduced. Can be improved.
Further, since the capillary tube is used instead of the electronic expansion valve 13, the cycle efficiency can be improved at the lowest cost.
Further, since the energy that was wasted to the surroundings from the suction pipe by the capillary tube can be recovered as the refrigerating capacity of the evaporator, the efficiency of the cycle can be further improved.

  In the heat pump devices of the first and second embodiments, the difference between high and low pressures in the cycle is increased by using, for example, carbon dioxide as a refrigerant that operates in a supercritical state on the high pressure side of the refrigeration cycle. Therefore, the function of the expander 3 that converts the energy of the pressure difference into motive power can be maximized, and the cycle efficiency can be further improved.

  As described above, the heat pump device according to the present invention can maximize the energy recovered as power in the expander by optimally controlling the amount of heat transferred from the compressor to the expander. It can also be applied to a wide range of equipment such as air conditioning and air conditioning equipment, vending machines, household refrigerators, commercial refrigerators, and ice makers.

The block diagram of the heat pump apparatus in 1st Example of this invention Mollier diagram of the heat pump apparatus in this embodiment Energy loss diagram of heat pump device in this embodiment The block diagram of the heat pump apparatus in 2nd Example of this invention Mollier diagram of the heat pump apparatus in this embodiment Configuration diagram of a conventional heat pump device Mollier diagram of a conventional heat pump device

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 Compressor 3 Expander 11 Discharge piping 12 Radiator 13 Electronic expansion valve 14 Evaporator 15 Suction piping 16 Capillary tube C1 Control means TH1 Compressor discharge temperature detection means TH2 Expander outlet temperature detection means

Claims (5)

  A compressor, a radiator, an expander that takes out power by expanding the refrigerant under reduced pressure, a decompression unit, and an evaporator are connected by piping, and the expander is provided downstream of the radiator, A heat pump device in which a decompression means is provided downstream of the expander to constitute a refrigeration cycle, and the expander and the compressor are integrated, and the compressor discharge temperature detects the discharge temperature of the compressor A heat pump apparatus comprising: a detection unit; and a control unit that controls the decompression unit according to a discharge temperature of the compressor.   An expander outlet temperature detecting means for detecting an outlet temperature of the expander is provided, and the control means controls the pressure reducing means by a temperature difference between a discharge temperature of the compressor and an outlet temperature of the expander. The heat pump device according to claim 1.   A compressor, a radiator, an expander that takes out power by expanding the refrigerant under reduced pressure, a decompression unit, and an evaporator are connected by piping, and the expander is provided downstream of the radiator, A heat pump device in which a decompression means is provided downstream of the expander to constitute a refrigeration cycle, and the expander and the compressor are integrally configured, wherein a capillary tube is used as the decompression means, Heat pump device.   The heat pump device according to claim 3, wherein heat exchange is performed between the capillary tube and a suction pipe connected to the compressor from an outlet of the evaporator. The heat pump device according to any one of claims 1 to 4, wherein the operation is performed with a pressure on a high-pressure side of the refrigeration cycle being in a supercritical state.

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