Distributed combined cooling heating and power system and control method thereof

Abstract

The invention relates to the technical field of energy utilization, in particular to a distributed combined cooling heating and power system and a control method thereof. The system comprises a power generation circulation loop, a heating loop, an absorption type refrigeration loop and path switching valves, all the loops are connected through the path switching valves, the power generation circulation loop utilizes a screw expander to replace a turbine for power generation, the technical bottleneck of miniaturization of the combined cooling heating and power system is solved, meanwhile, the control method of the system is further provided, and the energy utilization rate is improved based on energy cascade application. Three system use modes are designed, the comprehensive energy utilization efficiency and the economic performance of the combined cooling heating and power system are improved, and energy conservation and emission reduction are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of energy utilization, and in particular to a distributed cooling, heating and power trigeneration system and a control method thereof. Background Art

[0002] The combined heat, cooling and power (CHP) system is a system based on the concept of cascaded utilization of energy. The primary energy can be industrial waste heat, geothermal energy, biomass energy, solar energy, etc. It is a cogeneration system that produces heat, electricity and cooling. Through the cascaded utilization of energy, the waste heat generated in the power generation process is used for heating and cooling, so that energy is fully utilized. The comprehensive energy utilization efficiency can reach more than 90%, which improves energy utilization efficiency compared to traditional combined heat, cooling and power supply systems.

[0003] At present, most combined heating, cooling and power systems generate electricity through Rankine cycle, organic Rankine cycle, Stirling cycle or Brayton cycle. The main power devices that drive the generator include turbines, internal combustion engines, fuel cells and Stirling engines. The biggest disadvantage of turbine-based systems is that the larger the system scale, the more economical it is, and it is difficult to achieve small-scale distributed trigeneration. At the same time, the Rankine cycle inlet requires a very high superheat to avoid droplets from damaging the turbine blades during the expansion of water vapor, but high superheat has limited effect on improving the thermal efficiency of the Rankine cycle. Systems based on internal combustion engines have high requirements for fuel quality; systems based on fuel cells are expensive and the technology is immature; and systems based on Stirling engines are complex to control, expensive, and have a short service life. Summary of the invention

[0004] In view of this, an object of the present invention is to solve at least one aspect of the above-mentioned problems and defects in the prior art.

[0005] One of the purposes of the present invention is to provide a trigeneration system, which uses a screw expander instead of a turbine to generate electricity, thereby effectively solving the technical bottleneck of miniaturization faced by the trigeneration system.

[0006] Another object of the present invention is to provide a novel control method for a distributed trigeneration system, based on the energy cascade application, to improve the comprehensive energy utilization efficiency and economic performance of the system and achieve energy conservation and emission reduction.

[0007] According to one aspect of the present invention, a distributed combined cooling, heating and power system is provided, which includes: a power generation cycle, a heating cycle, an absorption refrigeration cycle and a switching valve, the heating cycle and the refrigeration cycle are connected to the power generation cycle through the switching valve, the switching valve includes a first valve input end, a second valve input end and a third valve input end, the power generation cycle includes a collector, a heat storage device, a screw expander, a generator and a Rankine cycle condenser connected by pipelines, the screw expander includes a first expander output port, a second expander output port and an expander input port, the first expander output port is connected to the generator, the second expander output port is connected to the Rankine cycle condenser, the heat collector is connected to the expander input port and the heat storage device; the heating cycle includes a heat exchanger, the input side of the heat exchanger is connected to the Rankine cycle condenser, and the output side of the heat exchanger is connected to the second input end of the valve; the absorption refrigeration circuit is provided with a generator, the Rankine cycle condenser is connected to the heat source input port of the generator, and the third valve input end is connected to the heat source return port of the generator; the first valve input end is connected to the Rankine cycle condenser.

[0008] Compared with the existing technology, the technical effects achieved by adopting this technical solution are as follows: the screw expander is used as the power generation device. First, compared with the traditional trigeneration system based on large-scale turbine equipment, this system is easier to deploy and apply in small areas or specific places, reducing the dependence on centralized energy supply and improving the reliability and autonomy of energy supply; second, the screw expander inlet does not need to be overheated, and saturated steam, saturated water and working fluids in the two-phase zone can directly enter the expansion to do work, eliminating the superheater in the traditional trigeneration system, and further improving the miniaturization of the distributed trigeneration system; third, the primary energy is collected by the collector, and then the high-temperature medium is sent to the screw expander to expand and generate mechanical energy to drive the generator to generate electricity. At the same time, the low-temperature terminal heat generated is used in the heating circuit and the refrigeration circuit, and the refrigeration and heating functions are switched by the switching valve, realizing the cascade utilization of energy and improving the comprehensive energy utilization efficiency of the distributed trigeneration system. Fourth, the distributed trigeneration system is equipped with a heat storage device. When the system is idle, the heat energy is transferred to the heat storage device for storage. When the system power cannot meet user needs, the heat stored in the heat storage tank is used as a heat source to drive the system to operate, optimizing the system's operating conditions and energy utilization strategies.

[0009] In the technical solution of the present invention, the collector is a solar collector.

[0010] Compared with the existing technology, the technical effect achieved by adopting this technical solution is as follows: solar energy is used as the primary energy source of the distributed trigeneration system, the system uses a screw expander instead of a turbine to generate electricity, and the temperature of the output of the solar collector to the screw expander can reach 200°C, meeting the requirements of the screw expander inlet temperature and the trigeneration system. At the same time, solar energy, as a clean energy, has positive significance for environmental protection and helps alleviate energy crises and environmental pollution problems.

[0011] Furthermore, the Rankine cycle condenser includes: a first power generation input end and a first power generation output end, the first power generation input end is connected to the screw expander, the first power generation output end is connected to the collector, and a first working fluid pump is provided on the pipeline connecting the first power generation output end and the collector, which is used to control the working fluid circulation of the power generation cycle loop.

[0012] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: a first working fluid pump is arranged on the pipeline connected to the collector at the first output end of the power generation, which can provide sufficient power for the working fluid. During the entire power generation cycle, the first working fluid pump ensures the smooth progress of this cycle, maintains the energy conversion and transmission process of the distributed combined cooling, heating and power system, and enables the screw expander to continuously obtain stable working fluid input, thereby stably driving the generator to generate electricity. At the same time, by controlling the flow and pressure parameters of the working fluid pump, the circulation speed of the working fluid in the power generation cycle pipeline can be adjusted, thereby optimizing the working efficiency of the Rankine cycle and the overall performance of the system.

[0013] Furthermore, the distributed trigeneration system includes: a second working fluid pump, a Rankine cycle condenser is provided with a second power generation input end and a second power generation output end, the input side of the heat exchanger and the heat source input port of the generator are connected to the second power generation input end, the second power generation output end is connected to the first input end of the valve, and the second working fluid pump is arranged on one side of the second power generation input end.

[0014] Compared with the existing technology, the technical effect achieved by adopting this technical solution is as follows: the Rankine cycle condenser is used for heat exchange between the power generation cycle circuit and the heating circuit and the refrigeration circuit to ensure the heating and cooling functions of the trigeneration system; the second working fluid pump controls the working fluid flow distribution and pressure parameters of the absorption refrigeration circuit and the heating circuit, adjusts the circulation state of the working fluid, and improves the stability of the overall system.

[0015] Furthermore, the absorption refrigeration circuit also includes a refrigeration cycle condenser, a first throttle valve and a refrigeration cycle evaporator which are sequentially connected through pipelines, the generator is provided with a refrigerant output end, and the refrigeration cycle condenser is connected to the refrigerant output end; The generator outputs the refrigerant through the refrigerant output end.

[0016] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: by connecting the refrigeration cycle condenser, the first throttle valve and the refrigeration cycle evaporator in sequence, and connecting the refrigerant output end of the generator to the refrigeration cycle condenser, a complete refrigerant circulation loop is constructed to provide users with stable cold energy output.

[0017] Furthermore, the absorption refrigeration circuit also includes an absorber, a solution heat exchanger and a second throttle valve, the generator is provided with a solution inlet end and a solution outlet end, the absorber is provided with a first absorption side, a second absorption side and a third absorption side, the solution heat exchanger is provided with a first exchanger port, a second exchanger port, a third exchanger port and a fourth exchanger port, which are used for solution circulation of the absorption refrigeration circuit; wherein the solution outlet end is connected to the third exchanger port, the first exchanger port is connected to one end of the second throttle valve, the other end of the second throttle valve is connected to the first absorption side, the second absorption side is connected to the second exchanger port, the fourth exchanger port is connected to the solution inlet end, and the third absorption side is connected to the refrigeration cycle condenser.

[0018] Compared with the existing technology, the technical effect achieved by adopting this technical solution is as follows: during the refrigeration process, the heated and concentrated solution in the generator flows to the absorber, absorbs the refrigerant vapor generated by the evaporator to form a dilute solution, and then returns to the generator through the solution heat exchanger and pipelines, ensuring the continuous circulation of the lithium bromide solution in the absorption refrigeration circuit, maintaining the stable operation of the refrigeration cycle, and ensuring that the system can continue to refrigerate.

[0019] Furthermore, the absorption refrigeration circuit is also provided with a third working fluid pump, which is arranged on a pipeline connecting the fourth port of the exchanger and the solution inlet end, and is used to control the absorbent circulation of the absorption refrigeration circuit.

[0020] Compared with the existing technology, the technical effect achieved by adopting this technical solution is: the setting of the third working fluid pump accurately controls the absorbent circulation in the absorption refrigeration circuit, while maintaining the pressure balance and solution distribution uniformity in the absorption refrigeration circuit, reducing the risk of system failure caused by solution circulation problems.

[0021] Furthermore, the refrigerant of the absorption refrigeration circuit is water; and / or the absorbent is lithium bromide.

[0022] Compared with the existing technology, the technical effects achieved by adopting this technical solution are as follows: using water-lithium bromide as the working fluid pair of the absorption refrigeration circuit, firstly, matching solar energy as the primary energy source of the system, secondly, reducing the pollution to the environment and the atmospheric ozone layer, and saving energy, and thirdly, when the evaporation temperature and pressure of the absorption refrigeration circuit are reduced, the absorption capacity is only reduced to a limited extent, and the overall operation of the distributed cooling, heating and power trigeneration system is stable.

[0023] Furthermore, the distributed CCHP system includes a detection module, which includes a temperature detector, and the temperature detector is arranged on the Rankine cycle condenser and the collector.

[0024] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: by setting temperature detectors on the Rankine cycle condenser and the collector, the system real-time allocates the system heat source according to the condensation temperature of the Rankine cycle condenser. When the system power is insufficient, the heat source stored in the heat storage device is used to supply the normal operation of the entire system.

[0025] The present invention also provides a novel control method for a distributed trigeneration system, which is applied to the distributed trigeneration system in any of the above technical solutions. The control method includes: The distributed CCHP system has independent power generation mode, CCHP mode and CCHP mode; Obtain the condensing temperature of the Rankine cycle condenser and the ambient temperature; The operating mode of the distributed trigeneration system is switched based on the condensing temperature and the ambient temperature; in the single power generation mode, the distributed trigeneration system only runs the power generation cycle, the generator generates electricity, and the switching valve is closed; in the combined heat and power mode, the first port of the valve and the second port of the valve are opened, the distributed trigeneration system can generate electricity and heat, and the heat exchanger is used to provide heat energy to users; in the combined cooling and power mode, the first port of the valve and the third port of the valve are opened, the distributed trigeneration system can generate electricity and cool, and the refrigeration cycle evaporator is used to provide cold energy to users.

[0026] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: the overall heat source of the system is distributed according to the condensation temperature of the Rankine cycle condenser and the ambient temperature. As the seasons change, the user's demand for heat and cooling also changes accordingly. The present invention meets the different needs of users by setting three modes. At the same time, in order to cope with the instability of solar energy resources, a heat storage device is provided for heat storage. When the sun is sufficient, the system uses the heat brought by solar radiation to directly evaporate water in the collector to drive the generator to generate electricity, and at the same time stores excess steam in the heat storage tank. At night or in rainy weather, the solar radiation is insufficient, and the heat stored in the heat storage tank is used as a heat source to drive the system to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A transmission circuit diagram of a distributed cooling, heating and power trigeneration system according to an embodiment of the present invention; Figure 2 A schematic diagram of a separate power generation mode of a distributed cooling, heating and power trigeneration system according to an embodiment of the present invention; Figure 3 A schematic diagram of a cogeneration mode of a distributed cooling, heating and power trigeneration system according to an embodiment of the present invention; Figure 4 This is a combined cooling and power mode of a distributed combined cooling, heating and power system in an embodiment of the present invention.

[0028] Description of reference numerals: 1. Heat collector; 2. Heat storage device; 3. Screw expander; 4. Generator; 5. Rankine cycle condenser; 6a. First working fluid pump; 6b. Second working fluid pump; 6c. Third working fluid pump; 7. Heat exchanger; 8. Switching valve; 9. Generator; 10. Solution heat exchanger; 11. First throttle valve; 12. Second throttle valve; 13. Absorber; 14. Refrigeration cycle evaporator; 15. Refrigeration cycle condenser; 3a, expander input port; 3b, expander first output port; 3c, expander second output port; 5a, power generation first input port; 5b, power generation first output port; 5c, power generation second output port; 5d, power generation second input port; 8a, valve first input port; 8b, valve second input port; 8c, valve third input port; 9a, refrigerant output port; 9b, solution inlet port; 9c, heat source reflux port; 9d, heat source input port; 9e, solution outlet port; 10a, exchanger first port; 10b, exchanger second port; 10c, exchanger third port; 10d, exchanger fourth port; 13a, absorption first side; 13b, absorption second side; 13c, absorption third side. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0030] See also Figure 1-Figure 4The present embodiment provides a distributed combined cooling, heating and power system, which includes: a power generation cycle, a heating cycle, an absorption refrigeration cycle and a switching valve 8. The heating cycle and the refrigeration cycle are connected to the power generation cycle through the switching valve 8. The switching valve 8 includes a first valve input end 8a, a second valve input end 8b and a third valve input end 8c. The power generation cycle includes a collector 1, a heat storage device 2, a screw expander 3, a generator 4 and a Rankine cycle condenser 5 connected by pipelines. The screw expander 3 includes a first expander output port 3b, a second expander output port 3c and an expander input port 3a, the first output port 3b of the expander is connected to the generator 4, the second output port 3c of the expander is connected to the Rankine cycle condenser 5, the collector 1 is connected to the expander input port 3a and the heat storage device 2; the heating circuit includes a heat exchanger 7, the input side of the heat exchanger 7 is connected to the Rankine cycle condenser 5, and the output side of the heat exchanger 7 is connected to the second input end 8b of the valve; the absorption refrigeration circuit is provided with a generator 9, the Rankine cycle condenser 5 is connected to the heat source input port 9d of the generator 9, and the third input end 8c of the valve is connected to the heat source reflux port 9c of the generator 9; the first input end 8a of the valve is connected to the Rankine cycle condenser 5.

[0031] For example, the switching valve 8 is a three-way valve; the heat exchanger 7 is also provided with a user side, which is connected to other devices of the user; The screw expander 3 is used as the power generation device. First, compared with the traditional trigeneration system based on large-scale turbine equipment, this system is easier to deploy and apply in small areas or specific places, reducing the dependence on centralized energy supply and improving the reliability and autonomy of energy supply; second, the inlet of the screw expander 3 does not need to be overheated, and saturated steam, saturated water and working fluids in the two-phase zone can directly enter the expansion to do work, eliminating the superheater in the traditional trigeneration system, and further improving the miniaturization of the distributed trigeneration system; third, the primary energy is collected by the collector 1, and then the high-temperature medium is sent to the screw expander 3, so that it expands to generate mechanical energy to drive the generator 4 to generate electricity. At the same time, the low-temperature terminal heat generated is used in the heating circuit and the refrigeration circuit, and the refrigeration and heating functions are switched by the switching valve 8, realizing the cascade utilization of energy and improving the comprehensive energy utilization efficiency of the distributed cooling, heating and power trigeneration system. Fourth, the distributed trigeneration system is equipped with a heat storage device 2. When the system is idle, the heat energy is transferred to the heat storage device 2 for storage. When the system power cannot meet the user's demand, the heat stored in the heat storage tank is used as a heat source to drive the system to operate, thereby optimizing the system's operating conditions and energy utilization strategies.

[0032] In this embodiment, the collector 1 is a solar collector 1. For example, the collector 1 is any one of a parabolic trough collector 1, a compound parabolic collector 1, a linear Fresnel collector 1, a heat pipe vacuum tube collector 1, and a flat plate vacuum collector 1.

[0033] Solar energy is used as the primary energy source of the distributed trigeneration system. The system uses a screw expander 3 to replace turbine power generation. The temperature of the output of the solar collector 1 to the screw expander 3 can reach 200°C, which meets the requirements of the inlet temperature of the screw expander 3 and the trigeneration system. At the same time, solar energy, as a clean energy, has positive significance for environmental protection and helps to alleviate energy crisis and environmental pollution problems.

[0034] Specifically, participating Figure 1 The Rankine cycle condenser 5 includes: a first power generation input end 5a and a first power generation output end 5b. The first power generation input end 5a is connected to the screw expander 3, and the first power generation output end 5b is connected to the collector 1. A first working fluid pump 6a is provided on the pipeline connecting the first power generation output end 5b and the collector 1 for controlling the working fluid circulation of the power generation cycle loop.

[0035] A first working fluid pump 6a is provided on the pipeline connecting the first power generation output end 5b and the collector 1, which can provide sufficient power for the working fluid. During the entire power generation cycle, the first working fluid pump 6a ensures the smooth progress of this cycle, maintains the energy conversion and transmission process of the distributed combined cooling, heating and power system, and enables the screw expander 3 to continuously obtain a stable working fluid input, thereby stably driving the generator 4 to generate electricity. At the same time, by controlling the flow and pressure parameters of the working fluid pump, the circulation speed of the working fluid in the power generation cycle pipeline can be adjusted, thereby optimizing the working efficiency of the Rankine cycle and the overall performance of the system.

[0036] Specifically, see Figure 1 and Figure 3 The distributed cooling, heating and power trigeneration system includes: a second working fluid pump 6b, a Rankine cycle condenser 5 is provided with a second power generation input terminal 5d and a second power generation output terminal 5c, the input side of the heat exchanger 7 and the heat source input port 9d of the generator 9 are connected to the second power generation input terminal 5d, the second power generation output terminal 5c is connected to the first valve input terminal 8a, and the second working fluid pump 6b is arranged on one side of the second power generation input terminal 5d.

[0037] The Rankine cycle condenser 5 is used for heat exchange between the power generation cycle and the heating and refrigeration cycles to ensure the heating and cooling functions of the trigeneration system. The second working fluid pump 6b controls the working fluid flow distribution and pressure parameters of the absorption refrigeration cycle and the heating cycle, adjusts the circulation state of the working fluid, and improves the stability of the overall system.

[0038] Specifically, see Figure 1 and Figure 4 The absorption refrigeration circuit further includes a refrigeration cycle condenser 15, a first throttle valve 11 and a refrigeration cycle evaporator 14 which are sequentially connected through pipelines, the generator 9 is provided with a refrigerant output end 9a, and the refrigeration cycle condenser 15 is connected to the refrigerant output end 9a; The generator 9 outputs the refrigerant through the refrigerant output terminal 9a.

[0039] By connecting the refrigeration cycle condenser 15, the first throttle valve 11 and the refrigeration cycle evaporator 14 in sequence, and connecting the refrigerant output end 9a of the generator 9 to the refrigeration cycle condenser 15, a complete refrigerant circulation loop is constructed to provide users with stable cold energy output.

[0040] Specifically, see Figure 1 and Figure 4 The absorption refrigeration circuit also includes an absorber 13, a solution heat exchanger 10 and a second throttle valve 12. The generator 9 is provided with a solution inlet end 9b and a solution outlet end 9e. The absorber 13 is provided with an absorption first side 13a, an absorption second side 13b and an absorption third side 13c. The solution heat exchanger 10 is provided with an exchanger first port 10a, an exchanger second port 10b, an exchanger third port 10c and an exchanger fourth port 10d, which are used for solution circulation of the absorption refrigeration circuit; wherein the solution outlet end 9e is connected to the exchanger third port 10c, the exchanger first port 10a is connected to one end of the second throttle valve 12, the other end of the second throttle valve 12 is connected to the absorption first side 13a, the absorption second side 13b is connected to the exchanger second port 10b, the exchanger fourth port 10d is connected to the solution inlet end 9b, and the absorption third side 13c is connected to the refrigeration cycle condenser 15.

[0041] During the refrigeration process, the heated and concentrated solution in the generator 9 flows to the absorber 13, absorbs the refrigerant vapor produced by the evaporator to form a dilute solution, and then returns to the generator 9 through the solution heat exchanger 10 and the pipeline, ensuring the continuous circulation of the lithium bromide solution in the absorption refrigeration circuit, maintaining the stable operation of the refrigeration cycle, and ensuring that the system can continue to refrigerate.

[0042] Specifically, see Figure 1 and Figure 4 The absorption refrigeration circuit is further provided with a third working fluid pump 6c, which is arranged on a pipeline connecting the fourth port 10d of the exchanger and the solution inlet port 9b, and is used to control the absorbent circulation of the absorption refrigeration circuit.

[0043] The third working fluid pump 6c is provided to precisely control the absorbent circulation in the absorption refrigeration circuit, while maintaining the pressure balance and solution distribution uniformity in the absorption refrigeration circuit, thereby reducing the risk of system failure caused by solution circulation problems.

[0044] Specifically, the refrigerant of the absorption refrigeration circuit is water; and / or the absorbent is lithium bromide. For example, the heating circuit and the power generation circulation circuit of the distributed cooling, heating and power trigeneration system also use water as the working fluid.

[0045] Using water-lithium bromide as the working fluid pair of the absorption refrigeration circuit, firstly, it matches solar energy as the primary energy source of the system, secondly, it reduces the pollution to the environment and the atmospheric ozone layer, and saves energy, and thirdly, when the evaporation temperature and pressure of the absorption refrigeration circuit decrease, the absorption capacity is only reduced to a limited extent, and the overall operation of the distributed cooling, heating and power trigeneration system is stable.

[0046] Specifically, the distributed cooling, heating and power trigeneration system includes a detection module, which includes a temperature detector. The temperature detector is arranged on the Rankine cycle condenser 5 and the collector 1.

[0047] By setting temperature detectors on the Rankine cycle condenser 5 and the collector 1, the system real-time allocates the system heat source according to the condensation temperature of the Rankine cycle condenser 5. When the system power is insufficient, the heat source stored in the heat storage device 2 is used to supply the normal operation of the entire system.

[0048] This embodiment also provides a novel control method for a distributed cooling, heating and power trigeneration system, which is applied to the distributed cooling, heating and power trigeneration system in any of the above technical solutions. The control method includes: The distributed CCHP system has independent power generation mode, CCHP mode and CCHP mode; Obtaining the condensation temperature of the Rankine cycle condenser 5 and the ambient temperature; The operating mode of the distributed combined cooling, heating and power trigeneration system is switched based on the condensing temperature and the ambient temperature; wherein, in the single power generation mode, the distributed combined cooling, heating and power trigeneration system only runs the power generation cycle, the generator 4 generates electricity, and the switching valve 8 is closed; in the combined heat and power mode, the first valve port and the second valve port are opened, the distributed combined cooling, heating and power trigeneration system can generate electricity and heat, and the heat exchanger 7 is used to provide heat energy to the user; in the combined cooling and power mode, the first valve port and the third valve port are opened, the distributed combined cooling, heating and power trigeneration system can generate electricity and cool, and the refrigeration cycle evaporator 14 is used to provide cold energy to the user.

[0049] The overall heat source of the system is distributed according to the condensation temperature of the Rankine cycle condenser 5 and the ambient temperature. As the seasons change, the user's demand for heat and cooling also changes. The present invention meets the different needs of users by setting three modes. At the same time, in order to cope with the instability of solar energy resources, a heat storage device 2 is provided for heat storage. When the sun is sufficient, the system uses the heat brought by solar radiation to directly evaporate water in the collector 1 to drive the generator 4 to generate electricity, and at the same time, the excess steam is stored in the heat storage tank. At night or in rainy weather, the solar radiation is insufficient, and the heat stored in the heat storage tank is used as a heat source to drive the system to operate.

[0050] For example, Figure 2As shown, when the user only needs the system to provide electricity, the system is in the independent power generation mode. In the independent power generation mode, all the heat absorbed by the collector 1 is only used for power generation. When the distributed trigeneration system operates in the independent power generation mode, the condensation temperature of the Rankine cycle condenser 5 is affected by the ambient temperature. When the Rankine cycle condensation temperature is equal to the ambient temperature, the system is in the rated independent power generation mode.

[0051] like Figure 3 As shown, for example, when the user has a heating demand, the system is in the cogeneration mode. When the system is running in the cogeneration mode, the condensation temperature of the Rankine cycle condenser 5 is determined by the user's demand for heating and bathing. Preferably, when the condensation temperature of the Rankine cycle condenser 5 is 80°C, the system is in the rated cogeneration mode.

[0052] like Figure 3 As shown, for example, when the user has a cooling demand, the system is in the CCHP mode, and the condensing temperature of the Rankine cycle condenser 5 is determined by the user's cooling demand. Preferably, when the condensing temperature of the Rankine cycle condenser 5 is 120°C, the system is in the rated CCHP mode.

[0053] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A distributed cooling, heating and power trigeneration system, characterized in that: The distributed cooling, heating and power trigeneration system comprises: A power generation cycle, a heating cycle, an absorption refrigeration cycle and a switching valve (8), wherein the heating cycle and the absorption refrigeration cycle are connected to the power generation cycle via the switching valve (8), the switching valve (8) comprising a first valve input end (8a), a second valve input end (8b) and a third valve input end (8c), the power generation cycle comprising a heat collector (1), a heat storage device (2), a screw expander (3), a generator (4) and a Rankine cycle condenser (5) connected via a pipeline, the screw expander (3) comprising a first expander output port (3b), a second expander output port (3c) and an expander input port (3a), the first expander output port (3b) being connected to the generator (4), the second expander output port (3c) being connected to the Rankine cycle condenser (5), the heat collector (1) being connected to the expander input port (3a) and the heat storage device (2); The heating circuit comprises a heat exchanger (7), the input side of the heat exchanger (7) being connected to the Rankine cycle condenser (5), and the output side of the heat exchanger (7) being connected to the second input end (8b) of the valve; The absorption refrigeration circuit comprises a generator (9), the Rankine cycle condenser (5) is connected to a heat source input port (9d) of the generator (9), and the third input port (8c) of the valve is connected to a heat source return port (9c) of the generator (9); The first valve input end (8a) is connected to the Rankine cycle condenser (5).

2. The distributed cooling, heating and power trigeneration system according to claim 1 is characterized in that: The heat collector (1) is a solar heat collector (1).

3. A distributed cooling, heating and power trigeneration system according to claim 1, characterized in that: The Rankine cycle condenser (5) comprises: a first input end of the Rankine cycle condenser (5) and a first output end of the Rankine cycle condenser (5), wherein the first input end of the Rankine cycle condenser (5) is connected to the screw expander (3), and the first output end of the Rankine cycle condenser (5) is connected to the collector (1), and a first working fluid pump (6a) is provided on a pipeline connecting the first output end of the Rankine cycle condenser (5) and the collector (1) for controlling the working fluid circulation of the power generation cycle loop.

4. The distributed cooling, heating and power trigeneration system according to claim 1, characterized in that: The distributed cooling, heating and power trigeneration system comprises: a second working fluid pump (6b); the Rankine cycle condenser (5) is provided with a second input end of the Rankine cycle condenser (5) and a second output end of the Rankine cycle condenser (5); the input side of the heat exchanger (7) and the heat source input port (9d) of the generator (9) are connected to the second input end of the Rankine cycle condenser (5); the second output end of the Rankine cycle condenser (5) is connected to the first input end (8a) of the valve; and the second working fluid pump (6b) is arranged on one side of the second input end of the Rankine cycle condenser (5).

5. The distributed cooling, heating and power trigeneration system according to claim 1, characterized in that: The absorption refrigeration circuit further comprises a refrigeration cycle condenser (15), a first throttle valve (11), and a refrigeration cycle evaporator (14) which are sequentially connected via pipelines; the generator (9) is provided with a refrigerant output end (9a), and the refrigeration cycle condenser (15) is connected to the refrigerant output end (9a); The generator (9) outputs the refrigerant through the refrigerant output end (9a).

6. The distributed cooling, heating and power trigeneration system according to claim 5, characterized in that: The absorption refrigeration circuit further comprises an absorber (13), a solution heat exchanger (10) and a second throttle valve (12); the generator (9) is provided with a solution inlet end (9b) and a solution outlet end (9e); the absorber (13) is provided with an absorption first side (13a), an absorption second side (13b) and an absorption third side (13c); the solution heat exchanger (10) is provided with an exchanger first port (10a), an exchanger second port (10b), an exchanger third port (10c) and an exchanger fourth port (10d), which are used for solution circulation of the absorption refrigeration circuit; The solution outlet port (9e) is connected to the third port (10c) of the exchanger, the first port (10a) of the exchanger is connected to one end of the second throttle valve (12), the other end of the second throttle valve (12) is connected to the first absorption side (13a), the second absorption side (13b) is connected to the second port (10b) of the exchanger, the fourth port (10d) of the exchanger is connected to the solution inlet port (9b), and the third absorption side (13c) is connected to the refrigeration cycle condenser (15).

7. The distributed cooling, heating and power trigeneration system according to claim 6, characterized in that: The absorption refrigeration circuit is also provided with a third working fluid pump (6c), which is arranged on a pipeline connecting the fourth port (10d) of the exchanger and the solution inlet end (9b) and is used to control the absorbent circulation of the absorption refrigeration circuit.

8. The distributed cooling, heating and power trigeneration system according to claim 7 is characterized in that: The refrigerant of the absorption refrigeration circuit is water; And / or, the absorbent is lithium bromide.

9. The distributed cooling, heating and power trigeneration system according to any one of claims 1 to 8, characterized in that: The distributed combined cooling, heating and power system comprises a detection module, wherein the detection module comprises a temperature detector, and the temperature detector is arranged on the Rankine cycle condenser (5) and the collector (1).

10. A control method for a distributed combined cooling, heating and power trigeneration system, implemented by the distributed combined cooling, heating and power trigeneration system according to any one of claims 1 to 9, characterized in that: The control method comprises: The distributed combined cooling, heating and power system has a single power generation mode, a combined heat and power mode and a combined cooling and power mode; Obtaining the condensation temperature of the Rankine cycle condenser (5) and the ambient temperature; Switching the distributed cooling, heating and power trigeneration system operation mode based on the condensing temperature and the ambient temperature; Wherein, in the single power generation mode, the distributed combined cooling, heating and power trigeneration system only operates the power generation cycle loop, the generator (4) generates electricity, and the switching valve (8) is closed; In the cogeneration mode, the first valve port and the second valve port are open, the distributed cogeneration system can generate electricity and heat, and the heat exchanger (7) is used to provide heat energy to users; In the combined cooling and power mode, the first valve port and the third valve port are open, the distributed combined cooling, heating and power system can generate electricity and perform cooling, and the refrigeration cycle evaporator (14) is used to provide cold energy to users.

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