JP2012247081A - Composite system cum power generation and heat pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the operational efficiency by circulating refrigerant of an adequate amount in both a Rankine cycle operation and a heat pump cycle operation.SOLUTION: A composite system cum power generation and a heat pump includes: a compressor cum expander 11 which recovers the work of the refrigerant flowing in a circulation path and generates the electric power in the state of the Rankine cycle operation, and compresses the refrigerant by using the electric power supplied from the outside in the state of the heat pump cycle operation; and a liquid storage tank 15 for adjusting the total amount of the refrigerant flowing in the circulation path. The liquid storage tank 15 adjusts total amount of the refrigerant flowing in the circulation path in such a manner that total amount of the refrigerant is smaller in a state in which the Rankine cycle operation is switched to the heat pump cycle operation than in the state of the Rankine cycle operation.

Description

  The present invention relates to a combined power generation and heat pump system.

  Japanese Patent Laid-Open No. 4-254168 (Patent Document 1) is a prior document disclosing the configuration of the combined power generation and heat pump system. In the combined power generation and heat pump system described in Japanese Patent Laid-Open No. 4-254168 (Patent Document 1), a screw type compressor to which an induction generator is coupled, and between the first entrance and the second entrance of the compressor. A first heat exchanger that exchanges heat with a low-temperature heat source that is sequentially connected to the pump, a pump that has a first switching valve, and a second heat exchanger that exchanges heat with the high-temperature heat source.

  Further, an expansion valve having a second switching valve is connected in parallel with a pump having the first switching valve. The power generation cycle and the heat pump cycle are switched by switching the first and second switching valves.

JP-A-4-254168

  FIG. 13 is a state diagram in the Rankine cycle and the heat pump cycle. In FIG. 13, the vertical axis represents pressure and the horizontal axis represents specific enthalpy. The Rankine cycle is indicated by a solid line, and the heat pump cycle is indicated by a dotted line.

  As shown in FIG. 13, in the heat pump cycle, the refrigerant that has been liquefied by the condenser and is in the state of point A in the figure is decompressed by the expansion valve to be in the state of point B in the figure, and is vaporized at the inlet of the evaporator. The liquid is mixed.

  In the Rankine cycle, the refrigerant that has been liquefied by the condenser and is in the state of point C in the figure is pressurized by the pump to be in the state of point D in the figure, and is in a supercooled liquid phase state at the evaporator inlet It has become.

  Thus, the Rankine cycle is a cycle with a large degree of supercooling compared to the heat pump cycle. Therefore, in the Rankine cycle operation state, a large amount of refrigerant is required to cause a sufficient amount of phase transformation in the condenser.

  On the other hand, when the total amount of the refrigerant is increased in accordance with the Rankine cycle operation state, the input to the compressor becomes excessive in the heat pump cycle operation state.

  The present invention has been made in view of the above problems, and provides a combined power generation and heat pump system capable of improving operation efficiency by circulating an appropriate amount of refrigerant in both Rankine cycle operation and heat pump cycle operation. For the purpose.

  The power generation / heat pump combined system according to the present invention is a power generation / heat pump combined system capable of selectively switching between Rankine cycle operation and heat pump cycle operation. In the Rankine cycle operation state, the combined power generation and heat pump system collects the work of the refrigerant flowing through the circulation path to generate power, and in the heat pump cycle operation state, the refrigerant is compressed using the electric power supplied from the outside. And a compressor / expander and total amount adjusting means for adjusting the total amount of refrigerant flowing through the circulation path. In a state where the Rankine cycle operation is switched to the heat pump cycle operation, the total amount adjusting means reduces the total amount of refrigerant flowing through the circulation path as compared with the Rankine cycle operation state.

  In one aspect of the present invention, the total amount adjusting means includes a liquid storage section that is connected to the circulation path and provided in a bypass path through which the refrigerant does not flow in the Rankine cycle operation state. In the state of the heat pump cycle operation, a part of the refrigerant is stored in the liquid storage part by flowing the refrigerant through the bypass path.

  In one aspect of the present invention, the total amount adjusting means is configured by a bypass path that is connected to the circulation path and through which the refrigerant does not flow in the Rankine cycle operation state. In the heat pump cycle operation state, the refrigerant flows through the bypass path and a part of the refrigerant is stored.

  In one aspect of the present invention, the total amount adjusting means increases the total amount of refrigerant flowing through the circulation path by discharging the stored refrigerant to the circulation path when switching from heat pump cycle operation to Rankine cycle operation.

  In one aspect of the present invention, the total amount adjusting means includes a liquid storage section that is connected to the circulation path and is provided in a bypass path through which the refrigerant does not flow in the state of heat pump cycle operation. In the Rankine cycle operation state, the refrigerant flows through the bypass path.

  In one embodiment of the present invention, the total amount adjusting means is configured by a bypass path that is connected to the circulation path and through which the refrigerant does not flow in the state of the heat pump cycle operation. In the Rankine cycle operation state, the refrigerant flows through the bypass path.

  In one aspect of the present invention, the total amount adjusting means reduces the total amount of refrigerant flowing through the circulation path by causing the refrigerant to flow into the bypass path and storing part of the refrigerant when switching from Rankine cycle operation to heat pump cycle operation. To do.

  According to the present invention, it is possible to improve operation efficiency by circulating an appropriate amount of refrigerant in both Rankine cycle operation and heat pump cycle operation.

It is a systematic diagram which shows the structure of the electric power generation and heat pump composite system which concerns on Embodiment 1 of this invention. It is a figure which shows the flow of the refrigerant | coolant in the state of a heat pump cycle driving | operation in the combined electric power generation and heat pump system which concerns on the same embodiment. It is a figure which shows the flow of a refrigerant | coolant at the time of switching from heat pump cycle operation to Rankine cycle operation in the electric power generation and heat pump combined system which concerns on the same embodiment. It is a figure which shows the flow of the refrigerant | coolant in the state of Rankine cycle driving | operation in the electric power generation and heat pump combined system which concerns on the same embodiment. It is a systematic diagram which shows the structure of the electric power generation and heat pump composite system which concerns on Embodiment 2 of this invention. It is a figure which shows the flow of the refrigerant | coolant in the state of a heat pump cycle driving | operation in the combined electric power generation and heat pump system which concerns on the same embodiment. It is a figure which shows the flow of a refrigerant | coolant at the time of switching from heat pump cycle operation to Rankine cycle operation in the electric power generation and heat pump combined system which concerns on the same embodiment. It is a figure which shows the flow of the refrigerant | coolant in the state of Rankine cycle driving | operation in the electric power generation and heat pump combined system which concerns on the same embodiment. It is a systematic diagram which shows the structure of the electric power generation and heat pump composite system which concerns on Embodiment 3 of this invention. It is a figure which shows the flow of the refrigerant | coolant in the state of Rankine cycle driving | operation in the electric power generation and heat pump combined system which concerns on the same embodiment. It is a figure which shows the flow of the refrigerant | coolant at the time of switching from Rankine cycle operation to heat pump cycle operation in the electric power generation and heat pump combined system which concerns on the same embodiment. It is a figure which shows the flow of the refrigerant | coolant in the state of a heat pump cycle driving | operation in the combined electric power generation and heat pump system which concerns on the same embodiment. It is a state figure in a Rankine cycle and a heat pump cycle.

  Hereinafter, the combined power generation and heat pump system according to Embodiment 1 of the present invention will be described. In the following description of the embodiments, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated.

(Embodiment 1)
FIG. 1 is a system diagram showing a configuration of a combined power generation / heat pump system according to Embodiment 1 of the present invention. FIG. 2 is a diagram showing the refrigerant flow in the heat pump cycle operation state in the combined power generation and heat pump system according to the present embodiment. FIG. 3 is a diagram showing a refrigerant flow when switching from the heat pump cycle operation to the Rankine cycle operation in the combined power generation and heat pump system according to the present embodiment. FIG. 4 is a diagram showing the refrigerant flow in the Rankine cycle operation state in the combined power generation and heat pump system according to the present embodiment.

  As shown in FIG. 1, in the combined power generation and heat pump system 1 according to Embodiment 1 of the present invention, the first heat exchanger connected to the pump 14, the first on-off valve 31, and a part of the high-temperature heat source 60. 21, the compressor / expander 11, and the second heat exchanger 22 connected to a part of the low-temperature heat source 70 are connected by piping to form a circulation path.

  A generator / motor 12 is connected to the compressor / expander 11. The second heat exchanger 22 is provided with first temperature detection means 51 in the middle and second temperature detection means 52 in the vicinity of the end on the pump 14 side.

  In the combined power generation / heat pump system 1, a bypass path 41 is provided that connects between the first on-off valve 31 and the first heat exchanger 21 and between the pump 14 and the second heat exchanger 22. In the bypass path 41, the second on-off valve 32, the liquid storage tank 15, which is a liquid storage unit, the expansion valve 13, and the third on-off valve 33 are connected by piping. In the present embodiment, the liquid storage tank 15 functions as a total amount adjusting unit that adjusts the total amount of refrigerant flowing through the circulation path.

  In the first heat exchanger 21, heat exchange is performed between the refrigerant (working medium) circulating in the power generation / heat pump combined system 1 and the high-temperature heat source 60. In the second heat exchanger 22, heat exchange is performed between the refrigerant circulating in the power generation / heat pump combined system 1 and the low-temperature heat source 70.

  As the refrigerant, for example, so-called Freon gas such as R134a can be used. The pump 14 has a function of causing the refrigerant to flow under pressure. The expansion valve 13 has a function of depressurizing the refrigerant.

  The compressor / expander 11 selectively compresses or expands the refrigerant. As will be described later, in the Rankine cycle operation state, the compressor / expander 11 is driven as an expander, the generator / motor 12 is rotated by the pressure of the refrigerant, and the generator / motor 12 is used as a generator. Function. In the state of the heat pump cycle operation, electric power is supplied from the outside and the generator / motor 12 is driven as the motor, and the compressor / expander 11 functions as a compressor.

  The combined power generation / heat pump system 1 according to the present embodiment can selectively switch between the Rankine cycle operation state and the heat pump cycle operation state.

  The Rankine cycle operation state means that the first heat exchanger 21 absorbs heat from the high-temperature heat source 60 when the refrigerant can absorb more heat than the amount of heat necessary for power generation by the generator / engine 12. This is an operating state for converting heat into electric power. For example, hot water stored in a high-temperature heat storage tank using nighttime electric power is used as a high-temperature heat source 60 to generate Rankine cycle operation during the daytime.

  The state of the heat pump cycle operation is an operation state for storing the amount of heat absorbed by the refrigerant from the low temperature heat source 70 in the second heat exchanger 22 in the high temperature heat source 60 in the first heat exchanger 21. For example, the heat pump cycle operation is performed using nighttime electric power, the water stored in the low temperature heat storage tank as the low temperature heat source 70 is cooled, and the hot water stored in the high temperature heat storage tank as the high temperature heat source 60 is heated.

  Hereinafter, in the power generation and heat pump combined system 1 according to the present embodiment, the refrigerant flow path and the refrigerant flow state in the Rankine cycle operation state and the heat pump cycle operation state will be described.

  As shown in FIG. 2, in the state of heat pump cycle operation, the first on-off valve 31 is closed, the second on-off valve 32 is opened, and the third on-off valve 33 is open. By driving the generator / motor 12 as an engine with electric power supplied from outside, the refrigerant circulates in the direction indicated by the arrow in the figure.

  First, the refrigerant is compressed by the compressor / expander 11 to a high pressure. The compressed refrigerant in the high-pressure gas phase is heated by the first heat exchanger 21 to be condensed and liquefied by applying heat to the high-temperature heat source 60. The liquefied liquid refrigerant flows through the bypass passage 41 and a part thereof is stored in the liquid storage tank 15.

  The liquid refrigerant that has passed through the liquid storage tank 15 is depressurized by the expansion valve 13, then takes heat from the low-temperature heat source 70 by the second heat exchanger 22, evaporates and vaporizes. The vaporized refrigerant is compressed again by the compressor / expander 11 and becomes high pressure. As the refrigerant circulates in this way, the high temperature heat source 60 is heated and the low temperature heat source 70 is cooled.

  As shown in FIG. 3, when switching from heat pump cycle operation to Rankine cycle operation, the second on-off valve 32 is closed. Thereafter, the opening degree of the expansion valve 13 is increased. By doing in this way, the pressure in the liquid storage tank 15 falls. As a result, as the refrigerant in the liquid storage tank 15 evaporates, the liquid refrigerant 10 is pushed out of the liquid storage tank 15 and flows into the second heat exchange unit 22.

  In this state, the third on-off valve 33 is closed after a predetermined time has elapsed. Thereafter, the driving of the generator / motor 12 is stopped. By doing in this way, the liquid refrigerant 10 stored in the liquid storage tank 15 in the state of the heat pump cycle operation can be discharged to the circulation path. As a result, the total amount of refrigerant flowing through the circulation path can be increased.

  As shown in FIG. 4, in the Rankine cycle operation state, the first on-off valve 31 is open, the second on-off valve 32 is closed, and the third on-off valve 33 is closed. The refrigerant is circulated in the direction indicated by the arrow in the figure by being pressurized by the pump 14 and fed.

  First, the liquid refrigerant pressurized by the pump 14 takes heat from the high-temperature heat source 60 in the first heat exchanger 21 and evaporates to vaporize. When the high-pressure gas-phase refrigerant expands in the compressor / expander 11, power is generated by driving the generator / motor 12 as a generator.

  The low-pressure gas-phase refrigerant that has passed through the compressor / expander 11 is condensed and liquefied by applying heat to the low-temperature heat source 70 in the second heat exchanger 22. The liquid refrigerant in the low-pressure liquid phase is pressurized again by the pump 14 and fed. In this way, the refrigerant circulates, whereby the high-temperature heat source 60 is cooled, the low-temperature heat source 70 is heated, and power generation is performed.

  In the bypass passage 41, the second on-off valve 32 and the third on-off valve 33 are closed, so that the refrigerant confined in the bypass passage 41 does not flow. In other words, the refrigerant does not flow through the liquid storage tank 15 in the Rankine cycle operation state.

  By providing the bypass path 41 including the liquid storage tank 15, the total amount of refrigerant flowing through the circulation path can be reduced in the heat pump cycle operation state compared to the Rankine cycle operation state.

  In the present embodiment, the first temperature detection means 51 measures the refrigerant condensation temperature, and the second temperature detection means 52 measures the outflow temperature when the liquid refrigerant flows out of the second heat exchanger 22. The difference between the measured condensation temperature and the outflow temperature is defined as the degree of refrigerant supercooling.

  In the Rankine cycle operation state, if the degree of supercooling of the refrigerant is larger than a preset value, the pressure difference between the refrigerants before and after the compressor / expander 11 becomes small, and the power generation efficiency decreases.

  Therefore, when the degree of supercooling of the refrigerant is larger than a preset value, the second on-off valve 32 is opened. When the second on-off valve 32 is opened, the refrigerant flows from the circulation path into the bypass path 41. The refrigerant flowing into the liquid storage tank 15 is condensed and liquefied. As a result, a part of the liquid refrigerant can be stored in the liquid storage tank 15 and the total amount of refrigerant flowing through the circulation path can be reduced.

  In this way, since the amount of refrigerant that is vaporized in the first heat exchanger 21 and expanded in the generator / motor 12 can be increased, the pressure difference between the refrigerant before and after the compressor / expander 11 increases, Power generation efficiency is improved.

  On the other hand, when the degree of supercooling of the refrigerant is smaller than a preset set value in the Rankine cycle operation state, the amount of refrigerant liquefied in the second heat exchanger 22 decreases. As a result, a part of the liquid refrigerant is vaporized and the refrigerant flows into the pump 14 in a gas-liquid mixed state. In this case, the ability of the pump 14 to send the refrigerant decreases.

  Therefore, when the degree of supercooling of the refrigerant is smaller than a preset value, the third on-off valve 33 is opened. When the third on-off valve 33 is opened, the liquid refrigerant 10 in the liquid storage tank 15 evaporates, whereby the liquid refrigerant 10 is pushed out of the liquid storage tank 15 and flows into the second heat exchange unit 22. As a result, it is possible to increase the total amount of refrigerant flowing through the circulation path by discharging a part of the liquid refrigerant 10 stored in the liquid storage tank 15 to the circulation path.

  In this way, since the amount of refrigerant liquefied in the second heat exchanger 22 can be increased, the refrigerant can be prevented from flowing into the pump 14 in a gas-liquid mixed state.

  With the above configuration, an appropriate amount of refrigerant can be circulated in both Rankine cycle operation and heat pump cycle operation, and power generation efficiency and operation efficiency can be improved.

  Compared with the case where the total amount of the refrigerant is adjusted by providing an independent path through which the refrigerant does not flow in both the Rankine cycle operation and the heat pump cycle operation, the power generation / heat pump combined system 1 of the present embodiment has a simple configuration. Therefore, the apparatus cost can be reduced.

  In the present embodiment, the liquid storage tank 15 is provided as the total amount adjusting means, but when a sufficient amount of refrigerant can be stored in the bypass passage 41 by increasing the pipe diameter of the bypass passage 41. Alternatively, the bypass path 41 in which the liquid storage tank 15 is not provided may be used as the total amount adjusting means.

  Hereinafter, the combined power generation and heat pump system 2 according to Embodiment 2 of the present invention will be described.

(Embodiment 2)
FIG. 5 is a system diagram showing the configuration of the combined power generation and heat pump system according to Embodiment 2 of the present invention. FIG. 6 is a diagram illustrating the flow of the refrigerant in the heat pump cycle operation state in the combined power generation and heat pump system according to the present embodiment. FIG. 7 is a diagram illustrating a refrigerant flow when switching from the heat pump cycle operation to the Rankine cycle operation in the combined power generation and heat pump system according to the present embodiment. FIG. 8 is a diagram illustrating the refrigerant flow in the Rankine cycle operation state in the combined power generation and heat pump system according to the present embodiment.

  As shown in FIG. 5, in the combined power generation and heat pump system 2 according to the second embodiment of the present invention, the pump 14, the first on-off valve 31, and a part of the high-temperature heat source 60 that uses exhaust heat of the engine as a heat source. The first heat exchanger 21, the compressor / expander 11, the three-way switching valve 36, and the second heat exchanger 22 connected to each other by pipes constitute a circulation path.

  A generator / motor 12 is connected to the compressor / expander 11. The second heat exchanger 22 is provided with first temperature detection means 51 in the middle and second temperature detection means 52 in the vicinity of the end on the pump 14 side. A first blower 24 is provided in the vicinity of the second heat exchanger 22.

  A bypass path 41 that connects between the second heat exchanger 22 and the pump 14 and between the compressor / expander 11 and the three-way switching valve 36 is provided. In the bypass path 41, the second on-off valve 32, the expansion valve 13, the third heat exchanger 23, and the third on-off valve 33 are connected by piping. A second blower 25 is provided in the vicinity of the third heat exchanger 23.

  In the combined power generation / heat pump system 2, a bypass path 43 that connects the first on-off valve 31 and the first heat exchanger 21 and the three-way switching valve 36 is provided.

  In the first heat exchanger 21, heat exchange is performed between the refrigerant (working medium) circulating in the power generation / heat pump combined system 2 and the high-temperature heat source 60. In the second heat exchanger 22, heat exchange is performed between the refrigerant circulating in the power generation / heat pump combined system 2 and the outdoor air. In the third heat exchanger 23, heat is exchanged between the refrigerant circulating in the power generation / heat pump combined system 2 and the room air.

  Hereinafter, in the combined power generation and heat pump system 2 according to the present embodiment, the refrigerant flow path and the refrigerant flow state in the Rankine cycle operation state and the heat pump cycle operation state will be described.

  As shown in FIG. 6, in the state of heat pump cycle operation, the first on-off valve 31 is closed, the second on-off valve 32 is opened, and the third on-off valve 33 is open. The three-way switching valve 36 constitutes a path so that the refrigerant flows from the first heat exchanger 21 to the second heat exchanger 22. By driving the generator / motor 12 as an engine with electric power supplied from outside, the refrigerant circulates in the direction indicated by the arrow in the figure.

  First, the refrigerant is compressed by the compressor / expander 11 to a high pressure. The compressed refrigerant in the high-pressure gas phase passes through the first heat exchanger 21 without exchanging heat, and then condenses and liquefies by applying heat to the outdoor air in the second heat exchanger 22.

  The liquefied liquid refrigerant is decompressed by the expansion valve 13 and flows into the third heat exchanger 23 in a gas-liquid mixed state. The refrigerant flowing into the third heat exchanger 23 takes heat from the indoor air and evaporates. The vaporized refrigerant is compressed again by the compressor / expander 11 and becomes high pressure. As the refrigerant circulates in this way, the indoor air can be cooled.

  As shown in FIG. 7, when switching from heat pump cycle operation to Rankine cycle operation, the second on-off valve 32 is closed. Thereafter, the opening degree of the expansion valve 13 is increased. By doing in this way, the pressure in the 3rd heat exchanger 23 falls. As a result, the refrigerant in the third heat exchanger 23 evaporates and flows into the compressor / expander 11.

  In this state, the third on-off valve 33 is closed after a predetermined time has elapsed. Thereafter, the driving of the generator / motor 12 is stopped. By doing in this way, the refrigerant stored in the 3rd heat exchanger 23 in the state of heat pump cycle operation can be discharged to a circulation way. As a result, the total amount of refrigerant flowing through the circulation path can be increased. In this embodiment, the 3rd heat exchanger 23 becomes a liquid storage part.

  As shown in FIG. 8, in the Rankine cycle operation state, the first on-off valve 31 is open, the second on-off valve 32 is closed, and the third on-off valve 33 is closed. The three-way switching valve 36 forms a path so that the refrigerant flows from the compressor / expander 11 to the second heat exchanger 22. The refrigerant is circulated in the direction indicated by the arrow in the figure by being pressurized by the pump 14 and fed.

  First, the liquid refrigerant pressurized by the pump 14 takes heat from the high-temperature heat source 60 in the first heat exchanger 21 and evaporates to vaporize. When the high-pressure gas-phase refrigerant expands in the compressor / expander 11, power is generated by driving the generator / motor 12 as a generator.

  The refrigerant in the low-pressure gas-phase state that has passed through the compressor / expander 11 gives heat to the outdoor air in the second heat exchanger 22 and condenses and liquefies. The liquid refrigerant in the low-pressure liquid phase is pressurized again by the pump 14 and fed. In this manner, power generation using the heat of the high-temperature heat source 60 is performed by circulating the refrigerant.

  In the bypass passage 41, the second on-off valve 32 and the third on-off valve 33 are closed, so that the refrigerant confined in the bypass passage 41 does not flow. In other words, the refrigerant does not flow through the bypass path 41 in the Rankine cycle operation state.

  Moreover, in the bypass path 43, since the one end is closed by the three-way switching valve 36, the refrigerant in the bypass path 43 does not flow. In other words, the refrigerant does not flow through the bypass path 43 in the Rankine cycle operation state.

  By providing the bypass path 41 including the third heat exchanger 23, the total amount of refrigerant flowing through the circulation path can be reduced in the heat pump cycle operation state compared to the Rankine cycle operation state.

  In the present embodiment, the first temperature detection means 51 measures the refrigerant condensation temperature, and the second temperature detection means 52 measures the outflow temperature when the liquid refrigerant flows out of the second heat exchanger 22. The difference between the measured condensation temperature and the outflow temperature is defined as the degree of refrigerant supercooling.

  In the Rankine cycle operation state, if the degree of supercooling of the refrigerant is larger than a preset value, the pressure difference between the refrigerants before and after the compressor / expander 11 becomes small, and the power generation efficiency decreases.

  Therefore, when the degree of supercooling of the refrigerant is larger than a preset value, the third on-off valve 33 is opened. When the third on-off valve 33 is opened, the refrigerant flows from the circulation path into the bypass path 41. The refrigerant that has flowed into the third heat exchanger 23 is condensed and liquefied. As a result, a part of the liquid refrigerant can be stored in the third heat exchanger 23 to reduce the total amount of refrigerant flowing through the circulation path.

  In this way, since the amount of refrigerant that is vaporized in the first heat exchanger 21 and expanded in the generator / motor 12 can be increased, the pressure difference between the refrigerant before and after the compressor / expander 11 increases, Power generation efficiency is improved.

  On the other hand, when the degree of supercooling of the refrigerant is smaller than a preset set value in the Rankine cycle operation state, the amount of refrigerant liquefied in the second heat exchanger 22 decreases. As a result, a part of the liquid refrigerant is vaporized and the refrigerant flows into the pump 14 in a gas-liquid mixed state. In this case, the ability of the pump 14 to send the refrigerant decreases.

  Therefore, when the degree of supercooling of the refrigerant is smaller than a preset value, the second on-off valve 32 and the third on-off valve 33 are opened. When the third on-off valve 33 is opened, the gas-phase refrigerant flows into the third heat exchanger 23. Since the second on-off valve 32 is open, the liquid refrigerant 10 pushed out of the third heat exchanger 23 by the gas-phase refrigerant flowing into the third heat exchanger 23 flows out toward the pump 14.

  As a result, by discharging a part of the liquid refrigerant 10 stored in the third heat exchanger 23 to the circulation path, the total amount of refrigerant flowing through the circulation path can be increased. In this way, since the amount of refrigerant liquefied in the second heat exchanger 22 can be increased, the refrigerant can be prevented from flowing into the pump 14 in a gas-liquid mixed state.

  With the above configuration, an appropriate amount of refrigerant can be circulated in both Rankine cycle operation and heat pump cycle operation, and power generation efficiency and operation efficiency can be improved.

  Hereinafter, the combined power generation and heat pump system 3 according to Embodiment 3 of the present invention will be described.

(Embodiment 3)
FIG. 9 is a system diagram showing a configuration of a combined power generation / heat pump system according to Embodiment 3 of the present invention. FIG. 10 is a diagram showing the refrigerant flow in the Rankine cycle operation state in the combined power generation and heat pump system according to the present embodiment. FIG. 11 is a diagram illustrating a refrigerant flow when switching from Rankine cycle operation to heat pump cycle operation in the combined power generation and heat pump system according to the present embodiment. FIG. 12 is a diagram showing the refrigerant flow in the heat pump cycle operation state in the combined power generation and heat pump system according to the present embodiment.

  As shown in FIG. 9, in the combined power generation / heat pump system 3 according to Embodiment 3 of the present invention, the compressor / expander 11, the second heat exchanger 22, the fourth on-off valve 34, and the expansion valve 13. And the 3rd heat exchanger 23 and the 3rd on-off valve 33 are connected with piping, and the circulation path 42 is comprised.

  A generator / motor 12 is connected to the compressor / expander 11. The second heat exchanger 22 is provided with first temperature detection means 51 in the middle and second temperature detection means 52 in the vicinity of the end on the pump 14 side. A first blower 24 is provided in the vicinity of the second heat exchanger 22. A third temperature detection means 53 is provided in the middle part of the third heat exchanger 23. A second blower 25 is provided in the vicinity of the third heat exchanger 23. The 4th temperature detection means 54 is provided in the opposite side to the 3rd heat exchanger 23 side of the 2nd air blower 25. As shown in FIG.

  A bypass path 41 that connects between the second heat exchanger 22 and the fourth on-off valve 34 and between the compressor / expander 11 and the third on-off valve 33 is provided. In the bypass path 41, the first on-off valve 32, the pump 14, the first heat exchanger 21 connected to a part of the high-temperature heat source 60 that uses exhaust heat of the engine as a heat source, the first on-off valve 31, Are connected by piping.

  In the combined power generation and heat pump system 3, a bypass path 43 is provided that connects between the pump 14 and the first heat exchanger 21 and between the second on-off valve 32 and the second heat exchanger 22. Yes. A fifth on-off valve 35 is provided in the bypass path 43.

  In the first heat exchanger 21, heat exchange is performed between the refrigerant (working medium) circulating in the power generation / heat pump combined system 3 and the high-temperature heat source 60. In the second heat exchanger 22, heat exchange is performed between the refrigerant circulating in the power generation / heat pump combined system 3 and the room air. In the third heat exchanger 23, heat exchange is performed between the refrigerant circulating in the power generation / heat pump combined system 3 and the outdoor air. In this embodiment, the 1st heat exchanger 21 is a liquid storage part.

  Hereinafter, in the power generation / heat pump combined system 3 according to the present embodiment, the refrigerant flow path and the refrigerant flow state in the Rankine cycle operation state and the heat pump cycle operation state will be described.

  As shown in FIG. 10, in the Rankine cycle operation state, the first on-off valve 31 is opened, the second on-off valve 32 is opened, the third on-off valve 33 is closed, the fourth on-off valve 34 is closed, and the fifth on-off valve is closed. The valve 35 is closed. The refrigerant is circulated in the direction indicated by the arrow in the figure by being pressurized by the pump 14 and fed. That is, the refrigerant flows through the bypass path 41 in the Rankine cycle operation state.

  First, the liquid refrigerant pressurized by the pump 14 takes heat from the high-temperature heat source 60 in the first heat exchanger 21 and evaporates to vaporize. When the high-pressure gas-phase refrigerant expands in the compressor / expander 11, power is generated by driving the generator / motor 12 as a generator.

  The low-pressure gas-phase refrigerant that has passed through the compressor / expander 11 heats the indoor air in the second heat exchanger 22 and condenses and liquefies. The liquid refrigerant in the low-pressure liquid phase is pressurized again by the pump 14 and fed. Thus, by circulating the refrigerant, it is possible to generate electricity while heating the room using the heat of the high-temperature heat source 60.

  In the present embodiment, the first temperature detection means 51 measures the refrigerant condensation temperature, and the second temperature detection means 52 measures the outflow temperature when the liquid refrigerant flows out of the second heat exchanger 22. The difference between the measured condensation temperature and the outflow temperature is defined as the degree of refrigerant supercooling.

  In the Rankine cycle operation state, if the degree of supercooling of the refrigerant is larger than a preset value, the pressure difference between the refrigerants before and after the compressor / expander 11 becomes small, and the power generation efficiency decreases.

  Therefore, when the degree of supercooling of the refrigerant is larger than a preset value, the third on-off valve 33 is opened. When the third on-off valve 33 is opened, the refrigerant flows from the bypass path 41 into the circulation path 42. The refrigerant that has flowed into the third heat exchanger 23 is condensed and liquefied. As a result, a part of the liquid refrigerant can be stored in the third heat exchanger 23 and the total amount of refrigerant flowing through the bypass path 41 can be reduced.

  In this way, since the amount of refrigerant that is vaporized in the first heat exchanger 21 and expanded in the generator / motor 12 can be increased, the pressure difference between the refrigerant before and after the compressor / expander 11 increases, Power generation efficiency is improved.

  On the other hand, when the degree of supercooling of the refrigerant is smaller than a preset set value in the Rankine cycle operation state, the amount of refrigerant liquefied in the second heat exchanger 22 decreases. As a result, the refrigerant flows into the pump 14 in a gas-liquid mixed state. In this case, the ability of the pump 14 to send the refrigerant decreases.

  Therefore, when the degree of supercooling of the refrigerant is smaller than a preset value, the fourth on-off valve 34 is opened. When the fourth on-off valve 34 is opened, the liquid refrigerant 10 in the third heat exchanger 23 evaporates, whereby the liquid refrigerant 10 is pushed out from the third heat exchanger 23 and flows into the second heat exchange unit 22. . As a result, by discharging a part of the liquid refrigerant 10 stored in the third heat exchanger 23 to the bypass path 41, the total amount of refrigerant flowing through the bypass path 41 can be increased.

  In this way, since the amount of refrigerant liquefied in the second heat exchanger 22 can be increased, the refrigerant can be prevented from flowing into the pump 14 in a gas-liquid mixed state.

  As shown in FIG. 11, when switching from Rankine cycle operation to heat pump cycle operation, the supply of heat from the high-temperature heat source 60 is stopped, the pump 14 is also stopped, and the second on-off valve 32 is closed. By driving the generator / motor 12 as an engine with electric power supplied from the outside, the refrigerant flows in the direction indicated by the arrow in the figure.

  The refrigerant is compressed by the compressor / expander 11 and becomes high pressure. The compressed refrigerant in the high-pressure gas phase is condensed and liquefied in the first heat exchanger 21. The liquefied liquid refrigerant is stored in the first heat exchanger 21 in the bypass passage 41.

  In this state, the first on-off valve 31 is closed after a predetermined time has elapsed. By doing so, the refrigerant flows into the bypass path 41 and a part of the refrigerant is stored in the first heat exchanger 21, thereby reducing the total amount of refrigerant flowing through the circulation path 42 in the heat pump cycle operation state. can do.

  As shown in FIG. 12, in the heat pump cycle operation state, the first on-off valve 31 is closed, the second on-off valve 32 is closed, the third on-off valve 33 is opened, the fourth on-off valve 34 is opened, and the fifth on-off valve is opened. The valve 35 is closed. By driving the generator / motor 12 as an engine with electric power supplied from outside, the refrigerant circulates in the direction indicated by the arrow in the figure.

  First, the refrigerant is compressed by the compressor / expander 11 to a high pressure. The compressed refrigerant in the high-pressure gas phase state is condensed and liquefied by applying heat to the outdoor air in the third heat exchanger 23.

  The liquefied liquid refrigerant is decompressed by the expansion valve 13 and flows into the second heat exchanger 22 in a gas-liquid mixed state. The refrigerant that has flowed into the second heat exchanger 22 takes heat from the room air and evaporates. The vaporized refrigerant is compressed again by the compressor / expander 11 and becomes high pressure. As the refrigerant circulates in this way, the indoor air can be cooled.

  In the bypass passage 41, the first on-off valve 31, the second on-off valve 32, and the fifth on-off valve 35 are closed, so that the refrigerant confined in the bypass passage 41 does not flow. In other words, the refrigerant does not flow through the bypass path 41 in the heat pump cycle operation state.

  In the present embodiment, the third temperature detection means 53 measures the refrigerant condensation temperature in the third heat exchanger 23, and the fourth temperature detection means 54 measures the outside air temperature.

  In the state of the heat pump cycle operation, when the difference between the condensation temperature and the outside air temperature is smaller than the preset value from the outside air temperature, the condensation pressure is insufficient and the refrigerant is not completely liquefied in the third heat exchanger 23. As a result, the amount of liquid refrigerant that evaporates in the second heat exchanger 22 is reduced, so that the indoor air cannot be sufficiently cooled.

  For this reason, the fifth on-off valve 35 is opened when the condensation temperature and the outside air temperature are smaller than the preset set values. When the fifth on-off valve 35 is opened, the liquid refrigerant 10 stored in the first heat exchanger 21 evaporates, so that the liquid refrigerant 10 is pushed out from the first heat exchanger 21 and the second heat exchange unit 22. Flows in. As a result, by discharging a part of the liquid refrigerant 10 stored in the first heat exchanger 21 to the circulation path 42, the total amount of refrigerant flowing through the circulation path 42 can be increased, and the condensation pressure is increased. be able to.

  Thus, since the amount of refrigerant liquefied in the third heat exchanger 23 can be increased, the indoor air can be sufficiently cooled by the second heat exchanger 22.

  On the other hand, when the difference between the condensation temperature and the outside air temperature is larger than a preset value in the heat pump cycle operation state, the condensation pressure in the third heat exchanger 23 is too high and is consumed by the compressor / expander 11. The power to do becomes excessive.

  Therefore, when the difference between the condensation temperature and the outside air temperature is larger than a preset value, the first on-off valve 31 is opened. When the first on-off valve 31 is opened, the refrigerant flows from the circulation path 42 into the bypass path 41. The refrigerant flowing into the first heat exchanger 21 is condensed and liquefied. As a result, a part of the liquid refrigerant can be stored in the first heat exchanger 21 to reduce the total amount of refrigerant flowing through the circulation path 42, and the condensation pressure can be lowered.

  Thus, since the refrigerant | coolant amount vaporized in the 2nd heat exchanger 22 can be reduced, it can suppress that excessive electric energy is consumed with the compressor and expander 11. FIG. When switching from the heat pump cycle operation to the Rankine cycle operation, a part of the refrigerant stored in the first heat exchanger 21 is discharged to the circulation path 42.

  With the above configuration, an appropriate amount of refrigerant can be circulated in both Rankine cycle operation and heat pump cycle operation, and power generation efficiency and operation efficiency can be improved.

  It should be thought that embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1,2,3 Power generation / heat pump combined system, 10 liquid refrigerant, 11 compressor / expander, 12 generator / motor, 13 expansion valve, 14 pump, 15 liquid storage tank, 21 first heat exchanger, 22 2 heat exchanger, 23 3rd heat exchanger, 24 1st blower, 25 2nd blower, 31 1st on-off valve, 32 2nd on-off valve, 33 3rd on-off valve, 34 4th on-off valve, 35 5th on-off Valve, 36 three-way switching valve, 41, 43 bypass path, 42 circulation path, 51 first temperature detection means, 52 second temperature detection means, 53 third temperature detection means, 54 fourth temperature detection means, 60 high temperature heat source, 70 Low temperature heat source.

Claims (7)

A combined power generation and heat pump system capable of selectively switching between Rankine cycle operation and heat pump cycle operation,
In the Rankine cycle operation state, the work of the refrigerant flowing through the circulation path is collected to generate electric power, and in the heat pump cycle operation state, the refrigerant is compressed using electric power supplied from the outside. Machine,
A total amount adjusting means for adjusting the total amount of refrigerant flowing through the circulation path,
In the state where the Rankine cycle operation is switched to the heat pump cycle operation, the total amount adjusting means reduces the total amount of refrigerant flowing through the circulation path as compared with the Rankine cycle operation state. The total amount adjusting means includes a liquid storage section provided in a bypass path that is connected to the circulation path and in which the refrigerant does not flow in the Rankine cycle operation state,
2. The combined power generation and heat pump system according to claim 1, wherein a part of the refrigerant is stored in the liquid storage part by allowing the refrigerant to flow through the bypass path in the state of the heat pump cycle operation. The total amount adjusting means is configured by a bypass path that is connected to the circulation path and through which refrigerant does not flow in the Rankine cycle operation state.
2. The combined power generation and heat pump system according to claim 1, wherein a refrigerant flows through the bypass path and a part of the refrigerant is stored in the heat pump cycle operation state.   The total amount adjusting means increases the total amount of refrigerant flowing through the circulation path by discharging the stored refrigerant to the circulation path when switching from the heat pump cycle operation to the Rankine cycle operation. The combined power generation and heat pump system described in 1. The total amount adjusting means includes a liquid storage section provided in a bypass path that is connected to the circulation path and in which the refrigerant does not flow in the state of the heat pump cycle operation.
The combined power generation and heat pump system according to claim 1, wherein a refrigerant flows through the bypass path in the Rankine cycle operation state. The total amount adjusting means is configured by a bypass path that is connected to the circulation path and through which the refrigerant does not flow in the state of the heat pump cycle operation,
The combined power generation and heat pump system according to claim 1, wherein a refrigerant flows through the bypass path in the Rankine cycle operation state.   The total amount adjusting means reduces the total amount of refrigerant flowing through the circulation path by causing the refrigerant to flow into the bypass path and storing part of the refrigerant when switching from the Rankine cycle operation to the heat pump cycle operation. Item 7. The combined power generation and heat pump system according to Item 5 or 6.

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