Solar-driven composite heat pump heat supply system and method

Abstract

According to the solar-driven composite heat pump heat supply system and method, the molten salt serves as a medium to absorb solar energy, the high-low temperature heat storage tank is matched to balance the supply and demand relation between solar energy intermittency and user heat load fluctuation, heat energy of the high-temperature molten salt is utilized stage by stage, and the heat supply efficiency is improved. Waste heat existing after high-temperature molten salt heats heat supply network circulating water is used for sequentially providing a driving heat source for an organic Rankine cycle and an absorption type heat pump, finally, low-temperature waste heat of outlet molten salt serves as a low-temperature heat source of a compression type heat pump, heat of different grades in the molten salt is sufficiently utilized at the same temperature, and the heat supply efficiency is improved. Organic Rankine cycle power drives a two-stage compression heat pump compressor and a solution pump of an absorption type heat pump which are coaxial to provide energy input for main power units of the two heat pumps, heat supply network return water sequentially passes through the absorption type heat pump, a fused salt heater and the compression type heat pump to be heated step by step, the temperature difference of the supply water and the return water is increased, and the heat supply network circulating water flow and the power consumption of the water pump are reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy heating, and in particular relates to a solar-driven composite heat pump heating system and method. Background Art

[0002] In recent years, with the increasing global awareness of environmental protection and the urgent need for sustainable energy development, the development and utilization of new energy has been raised to an unprecedented level. Against this background, building a new power system with new energy as the main body has become a key link in promoting energy transformation. Solar energy, as an almost endless, widely distributed and cost-reducing renewable energy source, plays a vital role in the optimization and upgrading of the energy structure.

[0003] Solar heating technology, as an important branch of solar energy utilization, focuses on the efficient conversion of solar energy into thermal energy to meet the heating needs of residential and commercial buildings. At present, this technology mainly relies on solar collectors. Solar collectors directly absorb sunlight, convert light energy into thermal energy, heat the circulating medium (such as water) to a suitable temperature, and then provide hot water heating to the user end through a heat exchange system. The advantage of this technical route is that it is flexible and diverse in form. It can exist as an independent heating system or be integrated with the existing heating system to achieve complementary heating, greatly improving the flexibility and efficiency of energy use.

[0004] However, a major challenge facing solar heating technology in practical applications is the uneven temporal distribution of solar energy resources. The availability of solar energy is strictly limited by the duration of sunshine, that is, it is mainly available during the day and cannot be directly used at night. In addition, the intensity of solar radiation varies significantly throughout the day, usually reaching a peak during the noon period. Although the sunlight is the strongest during this period, the collector should theoretically be able to produce the most heat energy, but the actual situation is that due to the high ambient temperature, the actual heat load demand of users is often relatively low. This "supply and demand mismatch" phenomenon, that is, the maximum output of solar collectors happens to be the time when users have the lowest heat demand, resulting in a large amount of precious solar energy resources not being effectively utilized, and the overall energy efficiency of the system is not high.

[0005] The water supply temperature of conventional solar heating systems is low, and the indoor temperature of users' heating is difficult to reach the standard value, resulting in poor heating effect. In addition, the low water supply temperature leads to a small temperature difference between the supply and return water, resulting in a large circulating water flow in the heating network, high power consumption of the circulating water pump in the heating network, and high heat transmission cost. The above factors have limited the application and development of solar heating systems to a certain extent. How to break through the current limitations and improve the utilization rate of solar energy and heating effect is the main direction of the current development of new energy applications. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides a solar-driven composite heat pump heating system and method. By efficiently coupling a solar-molten salt heat storage loop with a two-stage compression heat pump, an absorption heat pump, and an organic Rankine cycle power loop, a novel solar-driven composite heat pump heating system is constructed. By cascading utilization of solar energy to produce high-grade thermal energy, the purpose of energy saving and consumption reduction in the heating network is achieved. At the same time, the efficiency of solar energy utilization is improved, the heating cost and pollutant emissions are reduced, and a technical route of economical, energy-saving, efficient and low-carbon heating is realized.

[0007] The present invention is achieved through the following technical solutions: Solar-driven compound heat pump heating system, including: A solar molten salt heat collection and heating unit, an organic Rankine cycle power unit, a first solar collector, an absorption heat pump unit, and a two-stage compression heat pump unit; The two-stage compression heat pump unit includes a low-temperature evaporator, a low-pressure compressor, a high-pressure compressor, a condensing heater and an economic heat exchanger; The molten salt side outlet of the solar molten salt heat collection and heating unit is connected to the organic Rankine cycle power unit, the high temperature side of the absorption heat pump unit and the molten salt side inlet of the low temperature evaporator in sequence; the molten salt side outlet of the low temperature evaporator is connected to the molten salt side inlet of the solar molten salt heat collection and heating unit; The working fluid side outlet of the low-temperature evaporator is connected to the inlet of the low-pressure compressor, the high-pressure compressor, the condensing heater and the economic heat exchanger in sequence; One outlet of the economic heat exchanger is connected to the inlet of the first solar thermal collector, and the outlet of the first solar thermal collector is connected to the low-pressure compressor; another outlet of the economic heat exchanger is connected to the working fluid side inlet of the low-temperature evaporator; The water side outlet of the condensing heater is connected to the water supply pipeline of the heating network, and the water side inlet of the condensing heater is connected to the return water pipeline of the heating network through the solar molten salt heat collection and heating unit and the absorption heat pump unit.

[0008] Preferably, the absorption heat pump unit comprises a generator, a first expansion valve, a heat exchanger, an absorber, a solution pump, a second condenser, a second expansion valve and a first evaporator; Connect the working fluid side of the generator, the first expansion valve, the high-temperature solution side of the heat exchanger, the working fluid side of the absorber, the low-temperature solution side of the heat exchanger, and the inlet and outlet of the solution pump in sequence through the working fluid solution pipeline; The inlets and outlets of the water vapor side of the generator, the condensed water side of the second condenser, the second expansion valve, the water vapor side of the first evaporator and the water vapor side of the absorber are connected in sequence through a water pipeline.

[0009] Preferably, the circulating water side inlet of the second condenser is connected to the circulating water side outlet of the absorber, and the circulating water side inlet of the absorber is connected to the heat network return water pipeline.

[0010] Preferably, the organic Rankine cycle power unit comprises a molten salt evaporator, a turbine, a first condenser and a first compressor which are sequentially connected via an organic working fluid pipeline.

[0011] Preferably, the cooling water side of the first evaporator is connected to the water side of the first condenser; A cooling water pump is provided on the pipeline between the cooling water side outlet of the first evaporator and the water side inlet of the first condenser.

[0012] Preferably, the low-pressure compressor, the high-pressure compressor, the turbine and the first compressor are coaxially connected.

[0013] Preferably, the solar molten salt heat collection and heating unit comprises a low-temperature molten salt heat storage tank, a low-temperature molten salt circulation pump, a trough solar collector, a high-temperature molten salt heat storage tank, a high-temperature molten salt circulation pump and a molten salt heater which are sequentially connected through a molten salt pipeline; The molten salt side outlet of the molten salt heater is connected to the molten salt side of the molten salt evaporator, the generator and the molten salt side inlet of the low-temperature evaporator in sequence, and the molten salt side outlet of the low-temperature evaporator is connected to the inlet of the low-temperature molten salt heat storage tank.

[0014] Preferably, the water side outlet of the molten salt heater is connected to the water side inlet of the condensation heater; The water side outlet of the molten salt heater is connected to the circulating water side outlet of the second condenser; Preferably, the working fluid outlet pipeline of the condensing heater is divided into two routes, one of which is an intermediate heat supplement branch connected to the inlet of the first solar collector through the third expansion valve and the economic heat exchanger, and the other is connected to the working fluid side of the low-temperature evaporator through the economic heat exchanger and the third expansion valve.

[0015] The operating method of the solar-driven composite heat pump heating system comprises: When the light conditions are sufficient, the low-temperature molten salt absorbs light through the solar molten salt heat collection and heating unit and is heated to high-temperature molten salt, which heats the hot water at the outlet of the absorption heat pump unit. The high-temperature molten salt heats the organic working fluid of the organic Rankine cycle power unit as a driving heat source, driving the absorption heat pump unit to do work, and then enters the low-temperature evaporator as a low-temperature heat source for the two-stage compression heat pump unit. The outlet molten salt of the low-temperature evaporator flows back to the solar molten salt heat collection and heating unit. The main loop working fluid of the two-stage compression heat pump unit is heated and evaporated by low-temperature molten salt in the low-temperature evaporator, then enters the low-pressure compressor to be compressed, and is mixed with the working fluid at the outlet of the first solar collector of the branch to enter the high-pressure compressor to be compressed, and then condenses in the condensing heater to heat the circulating water of the heat network. The condensed working fluid at the outlet of the condensing heater transfers heat to the branch working fluid of the two-stage compression heat pump unit through the economic heat exchanger, and then enters the low-temperature evaporator after being reduced in pressure. After the branch working fluid is reduced in pressure, it absorbs the heat of the main loop working fluid in the economic heat exchanger, enters the first solar collector to absorb light heat, and then mixes with the main loop working fluid at the outlet of the low-pressure compressor and enters the high-pressure compressor together, transfers heat to the condensing heater, and performs secondary heating on the return water of the heat network. The return water of the heat network is heated to the water supply temperature in the condensing heater and supplied to the heat users.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention provides a solar-driven composite heat pump heating system and method. Molten salt is used as a medium to absorb solar energy. High and low temperature heat storage tanks are used to balance the supply and demand relationship between the intermittent solar energy and the fluctuation of user heat load. A heat energy cascade utilization heating system with efficient coupling of organic Rankine cycle, two-stage compression heat pump and absorption heat pump is established. The thermal energy grade of high-temperature molten salt is utilized step by step. The waste heat after the high-temperature molten salt is used to heat the circulating water of the heat network is used to provide driving heat sources for the organic Rankine cycle and the absorption heat pump in turn. Finally, the low-temperature waste heat of the molten salt is exported as the low-temperature heat source of the compression heat pump. The temperature matching makes full use of the heat of different grades in the molten salt. The Rankine cycle power drives the coaxial two-stage compression heat pump compressor and the solution pump of the absorption heat pump to provide energy input for the main power units of the two heat pumps. The return water of the heat network is heated step by step through the absorption heat pump, the molten salt heater and the compression heat pump in turn, thereby widening the temperature difference between the supply and return water and reducing the circulating water flow rate of the heat network and the power consumption of the water pump. By efficiently coupling the solar-molten salt heat storage loop with the two-stage compression heat pump, absorption heat pump, and organic Rankine cycle power loop, a new solar-driven composite heat pump heating system is constructed. By using solar energy in a cascaded manner to produce high-quality thermal energy, the goal of energy saving and consumption reduction in the heating network is achieved. At the same time, the efficiency of solar energy utilization is improved, heating costs and pollutant emissions are reduced, and a technical route for economical, energy-saving, efficient and low-carbon heating is realized.

[0017] Furthermore, trough solar collectors are used with high and low temperature molten salt heat storage tanks and circulation pumps to balance the quantitative relationship between intermittent solar energy and fluctuating user heating heat loads, provide a continuous and stable heat source, ensure user water supply temperature, improve the utilization rate of high temperature solar energy, and reduce heating costs; Furthermore, the waste heat after the high-temperature molten salt is used to heat the circulating water of the heat network drives the organic Rankine cycle to provide operating power for the heat pump. The molten salt waste heat is used in a coaxial manner for the turbine, solution pump, Rankine cycle compressor, and heat pump two-stage compressor to directly supply energy to the system power equipment. The direct transmission between mechanical energy and mechanical energy avoids energy waste caused by the conversion of energy forms, and further improves the efficiency of solar energy utilization under the premise of increasing the temperature difference between the supply and return water of the heat network. Furthermore, the low-temperature molten salt waste heat at the outlet of the absorption heat pump is used as the low-temperature heat source of the two-stage compression heat pump, and the solar collector is used as the medium-temperature heat source of the heat pump. The two compression processes are divided into two stages, and the intermediate air supplement and enthalpy increase method is adopted to reduce the overall power consumption of the compressor, reduce the working temperature difference of the heat pump, increase the COP, improve the heating efficiency, realize the cascade utilization of high-temperature solar energy, and once again improve the utilization efficiency of solar energy; Furthermore, the waste heat from the cold end of the organic Rankine cycle is used as the heat source for the absorption heat pump, which can fully recover the cold source loss during the work process, while reducing the working temperature difference of the absorption heat pump, increasing COP, improving heating efficiency, and improving the comprehensive energy utilization efficiency of the system; Furthermore, by using solar energy to drive compound heat pumps, we can achieve the cascade utilization of high-grade solar thermal energy with matching temperatures, realize large temperature difference heating, reduce heating costs and transportation costs, reduce heating costs and carbon emissions, comply with the national dual carbon and clean heating policies, and achieve multiple economic, energy-saving, and environmental protection benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of a solar-coupled absorption heat pump steam supply system; In the figure: 1- low-temperature molten salt heat storage tank; 2- low-temperature molten salt circulation pump; 3- trough type solar collector; 4- high-temperature molten salt heat storage tank; 5- high-temperature molten salt circulation pump; 6- molten salt heater; 7- molten salt evaporator; 8- turbine; 9- first condenser; 10- first compressor; 11- generator; 12- first expansion valve; 13- heat exchanger; 14- absorber; 15- solution pump; 16- second condenser; 17- second expansion valve; 18- first evaporator; 19- cooling water pump; 20- low-temperature evaporator; 21- low-pressure compressor; 22- high-pressure compressor; 23- condensation heater; 24- third expansion valve; 25- solar collector; 26- economic heat exchanger; 27- fourth expansion valve. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0020] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0021] The present invention provides a solar-driven composite heat pump heating system and method. Molten salt is used as a medium to absorb solar energy. High and low temperature heat storage tanks are used to balance the supply and demand relationship between the intermittent solar energy and the fluctuation of user heat load. A heat energy cascade utilization heating system with efficient coupling of organic Rankine cycle, two-stage compression heat pump and absorption heat pump is established. The thermal energy grade of high-temperature molten salt is utilized step by step. The waste heat after the high-temperature molten salt is used to heat the circulating water of the heat network is used to provide driving heat sources for the organic Rankine cycle and the absorption heat pump in turn. Finally, the low-temperature waste heat of the molten salt is exported as the low-temperature heat source of the compression heat pump. The temperature matching makes full use of the heat of different grades in the molten salt. The Rankine cycle power drives the coaxial two-stage compression heat pump compressor and the solution pump of the absorption heat pump to provide energy input for the main power units of the two heat pumps. The return water of the heat network is heated step by step through the absorption heat pump, the molten salt heater and the compression heat pump in turn, thereby widening the temperature difference between the supply and return water and reducing the circulating water flow rate of the heat network and the power consumption of the water pump. By efficiently coupling the solar-molten salt heat storage loop with the two-stage compression heat pump, absorption heat pump, and organic Rankine cycle power loop, a new solar-driven composite heat pump heating system is constructed. By using solar energy in a cascaded manner to produce high-quality thermal energy, the goal of energy saving and consumption reduction in the heating network is achieved. At the same time, the efficiency of solar energy utilization is improved, heating costs and pollutant emissions are reduced, and a technical route for economical, energy-saving, efficient and low-carbon heating is realized.

[0022] Solar-driven compound heat pump heating system, such as Figure 1 As shown, including A solar molten salt heat collection and heating unit, an organic Rankine cycle power unit, a first solar collector 25, an absorption heat pump unit, and a two-stage compression heat pump unit; The system mainly consists of 4 parts. The first part is a solar molten salt heat collection and heating unit, which is composed of a molten salt pipeline connecting the inlets and outlets of a low-temperature molten salt heat storage tank 1, a low-temperature molten salt circulation pump 2, a trough solar collector 3, a high-temperature molten salt heat storage tank 4, a high-temperature molten salt circulation pump 5, a molten salt heater 6, a molten salt evaporator 7, a generator 11, and a low-temperature evaporator 20 in sequence; the second part is an organic Rankine cycle power unit, which is composed of an organic working fluid pipeline connecting a molten salt evaporator 7, a turbine 8, a first condenser 9, and a first compressor 10 in sequence, wherein a cooling water pipeline connects the water side inlets and outlets of the first condenser 9, the first evaporator 18, and the cooling water pump 19 in sequence; the third part is an absorption heat pump unit, which is composed of a working fluid solution pipeline connecting the inlets and outlets of a generator 11, a first expansion valve 12, a high-temperature solution side of a heat exchanger 13, an absorber 14, a low-temperature solution side of a heat exchanger 13, and a solution pump 15 in sequence, and a water vapor and water pipeline connect the generator 11 , the second condenser 16, the second expansion valve 17, the first evaporator 18, and the inlet and outlet of the absorber 14 are connected in sequence; the fourth part is a two-stage compression heat pump unit, and the inlet and outlet of the low-temperature evaporator 20, the low-pressure compressor 21, the high-pressure compressor 22, the condensing heater 23, the economic heat exchanger 26, and the fourth expansion valve 27 are connected in sequence by the organic working fluid pipeline inside the heat pump, wherein the working fluid outlet pipeline of the condensing heater 23 is divided into two branches, and the other branch is the intermediate heat supplement branch, which is connected at the outlet tee of the condensing heater 23, and is connected in sequence by the branch side of the third expansion valve 24, the economic heat exchanger 26, and the inlet and outlet of the first solar collector 25, and the outlet pipeline of the first solar collector 25 is connected to the outlet tee of the low-pressure compressor 21; the heat network circulating water pipeline is composed of the absorber 14, the second condenser 16, the molten salt collector 6, and the condensing heater 23, whose inlet and outlet on the water side of the heat network are connected in sequence, and the outlet of the condensing heater 23 supplies water to the heat users.

[0023] The molten salt side outlet of the solar molten salt heat collection and heating unit is connected to the organic Rankine cycle power unit, the high temperature side of the absorption heat pump unit and the molten salt side inlet of the low temperature evaporator 20 in sequence; the molten salt side outlet of the low temperature evaporator 20 is connected to the molten salt side inlet of the solar molten salt heat collection and heating unit; The outlet of the low-temperature evaporator 20 on the working medium side is connected to the inlet of the low-pressure compressor 21, the high-pressure compressor 22, the condensing heater 23 and the economic heat exchanger 26 in sequence; One outlet of the economic heat exchanger 26 is connected to the inlet of the first solar collector 25, and the outlet of the first solar collector 25 is connected to the low-pressure compressor 21; another outlet of the economic heat exchanger 26 is connected to the working fluid side inlet of the low-temperature evaporator 20; The water side outlet of the condensing heater 23 is connected to the water supply pipeline of the heating network, and the water side inlet of the condensing heater 23 is connected to the return water pipeline of the heating network through the solar molten salt heat collection and heating unit and the absorption heat pump unit.

[0024] The absorption heat pump unit includes a generator 11, a first expansion valve 12, a heat exchanger 13, an absorber 14, a solution pump 15, a second condenser 16, a second expansion valve 17 and a first evaporator 18; The working fluid side of the generator 11, the first expansion valve 12, the high temperature solution side of the heat exchanger 13, the working fluid side of the absorber 14, the low temperature solution side of the heat exchanger 13 and the inlet and outlet of the solution pump 15 are connected in sequence through the working fluid solution pipeline; The inlets and outlets of the water vapor side of the generator 11, the condensed water side of the second condenser 16, the second expansion valve 17, the water vapor side of the first evaporator 18, and the water vapor side of the absorber 14 are connected in sequence through a water pipeline.

[0025] The organic Rankine cycle power unit comprises a molten salt evaporator 7, a turbine 8, a first condenser 9 and a first compressor 10 which are sequentially connected through an organic working fluid pipeline; The cooling water side of the first evaporator 18 is connected to the water side of the first condenser 9; A cooling water pump 19 is provided on the pipeline between the cooling water side outlet of the first evaporator 18 and the water side inlet of the first condenser 9; The solar molten salt heat collection and heating unit comprises a low-temperature molten salt heat storage tank 1, a low-temperature molten salt circulation pump 2, a trough solar collector 3, a high-temperature molten salt heat storage tank 4, a high-temperature molten salt circulation pump 5 and a molten salt heater 6 which are sequentially connected through a molten salt pipeline; The molten salt side outlet of the molten salt heater 6 is connected to the molten salt side of the molten salt evaporator 7, the generator 11 and the molten salt side inlet of the low-temperature evaporator 20 in sequence, and the molten salt side outlet of the low-temperature evaporator 20 is connected to the inlet of the low-temperature molten salt heat storage tank 1.

[0026] The water side outlet of the molten salt heater 6 is connected to the water side inlet of the condensation heater 23; The water side outlet of the molten salt heater 6 is connected to the circulating water side outlet of the second condenser 16; The circulating water side inlet of the second condenser 16 is connected to the circulating water side outlet of the absorber 14 , and the circulating water side inlet of the absorber 14 is connected to the return water pipeline of the heat network.

[0027] The low-pressure compressor 21, the high-pressure compressor 22, the turbine 8 and the first compressor 10 are coaxially connected and connected by a coupling; The working medium outlet pipeline of the condensing heater 23 is divided into two routes, one of which is an intermediate heat supplement branch, which is connected to the inlet of the first solar collector 25 through the third expansion valve 24 and the economic heat exchanger 26, and the other is connected to the working medium side of the low-temperature evaporator 20 through the economic heat exchanger 26 and the third expansion valve 24.

[0028] The operation method of the operation system of the solar-driven composite heat pump heating system comprises: When the light conditions are sufficient, the low-temperature molten salt absorbs light through the solar molten salt heat collection and heating unit and is heated to high-temperature molten salt, which heats the hot water in the outlet of the absorption heat pump unit. The high-temperature molten salt heats the organic working fluid of the organic Rankine cycle power unit as a driving heat source, driving the absorption heat pump unit to do work, and then enters the low-temperature evaporator 20 as a low-temperature heat source for the two-stage compression heat pump unit. The outlet molten salt of the low-temperature evaporator 20 flows back to the solar molten salt heat collection and heating unit; The main loop working fluid of the two-stage compression heat pump unit is heated and evaporated by the low-temperature molten salt on the other side in the low-temperature evaporator 20, and then enters the low-pressure compressor 21 to be compressed, and then enters the high-pressure compressor 22 to be compressed after mixing with the working fluid at the outlet of the first solar collector 25 of the branch, and then condenses in the condensation heater 23 to heat the circulating water of the heat network on the other side. The condensed working fluid at the outlet of the condensation heater 23 is divided into two paths. One path is the main loop, which transfers heat to the branch working fluid through the economic heat exchanger 26, and then enters the low-temperature evaporator 20 after being reduced in pressure. After the branch working fluid is reduced in pressure, it absorbs the heat of the main loop working fluid in the economic heat exchanger 26, and then enters the first solar collector 25 to absorb the heat of light, and then mixes with the main working fluid at the outlet of the low-pressure compressor 21 and enters the high-pressure compressor 22 together, and transfers the heat to the condensation heater 23. The water vapor generated by the work of the absorption heat pump unit performs secondary heating on the return water of the heat network. The return water of the heat network is heated to the water supply temperature in the condensation heater 23 and supplied to the heat users. The specific operation process is: When the system is running, the light conditions are sufficient, and the low-temperature molten salt circulation pump 2 extracts the low-temperature molten salt in the low-temperature molten salt heat storage tank 1 and sends it to the trough solar collector 3 to absorb light and be heated to high-temperature molten salt, and then sent to the high-temperature molten salt heat storage tank 4. The frequency of the high-temperature molten salt circulation pump 5 is adjusted according to the user's heat load demand, and the high-temperature molten salt of the corresponding flow rate is sent to the molten salt heater 6 to heat the absorption heat pump outlet hot network water. The molten salt at the outlet of the molten salt heater 6 enters the molten salt evaporator 7 to heat the organic working fluid as the driving heat source of the organic Rankine power cycle. The molten salt at the outlet of the molten salt evaporator 7 enters the generator 11 to drive the absorption heat pump. The molten salt at the outlet of the generator 11 enters the low-temperature evaporator 20 as a low-temperature heat source for the two-stage compression heat pump. The molten salt at the outlet of the low-temperature evaporator 20 flows back to the low-temperature In the molten salt heat storage tank 1; the organic working fluid in the molten salt evaporator 7 is evaporated by the molten salt and enters the turbine 8 to expand and do work, driving the coaxial first compressor 10, solution pump 15, low-pressure compressor 21, and high-pressure compressor 22 to operate and input power for them. The exhaust steam of the organic working fluid at the outlet of the turbine 8 enters the first condenser 9 to condense and transfer the heat to the cooling water on the other side. The organic working fluid at the outlet of the first condenser 9 enters the first compressor 10 to be compressed and then enters the molten salt evaporator 7 to complete the power cycle; the heated cooling water at the outlet of the first condenser 9 enters the water side of the first evaporator 18 and is heated by the absorption heat pump. The cooling water at the outlet of the first evaporator 18 is sent back to the water side inlet of the first condenser 9 through the cooling water pump 19; the dilute working fluid solution in the generator 11 is heated and evaporated by the molten salt on the other side The concentrated solution is decomposed into water vapor and concentrated solution. After the pressure is reduced by the first expansion valve 12, the concentrated solution transfers heat to the dilute solution on the other side in the heat exchanger 13, and then enters the absorber 14 to mix with the water vapor from the first evaporator 18 to release heat. The released heat performs primary heating on the return water of the hot network on the other side. The dilute solution formed after mixing is pumped back to the generator 11 by the solution pump 15. During the period, it absorbs the heat of the concentrated solution on the other side when passing through the heat exchanger 13. The water vapor at the outlet of the generator 11 performs secondary heating on the return water of the hot network in the second condenser 16. The outlet condensed water enters the first evaporator 18 after the pressure is reduced by the second expansion valve 17. The condensed water absorbs the heat of the cooling water on the other side in 18 and evaporates, and then enters the absorber 14 to complete the internal circulation of the absorption heat pump; two-stage compression heat The organic working fluid in the main loop of the pump is heated and evaporated by the low-temperature molten salt on the other side in the low-temperature evaporator 20, and then enters the low-pressure compressor 21 to be compressed, and then enters the high-pressure compressor 22 to be compressed after mixing with the organic working fluid at the outlet of the first solar collector 25 of the branch, and then condenses in the condensation heater 23 to heat the circulating water of the heat network on the other side. The condensed working fluid at the outlet of the condensation heater 23 is divided into two paths, one is the main path, which transfers heat to the branch working fluid through the economic heat exchanger 26, and then enters the low-temperature evaporator 20 after being reduced in pressure by the fourth expansion valve 27. After the branch working fluid is reduced in pressure by the third expansion valve 24, it absorbs the heat of the main working fluid in the economic heat exchanger 26, and then enters the first solar collector 25 to absorb the heat from light, and then mixes with the main working fluid at the outlet of 21 and enters 22 together;The return water from the heat network is now heated in the absorber 14, and then in the second condenser 16. It is further heated by the molten salt in the molten salt collector 6, and finally heated to the water supply temperature in the condensation heater 23 and supplied to the heat users. ;

[0029] It should be noted that the terms "first", "second", "low temperature", "high temperature", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0030] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may be a central component. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may be a central component at the same time. When a component is considered to be "set on" another component, it may be directly set on the other component or there may be a central component at the same time.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0032] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in the industry can smoothly implement the present invention as shown in the drawings and described above. However, any equivalent changes, modifications and evolutions made by technicians familiar with the profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the technical solution of the present invention.

Claims

1. A solar-driven composite heat pump heating system, characterized in that: include, A solar molten salt heat collection and heating unit, an organic Rankine cycle power unit, a first solar collector (25), an absorption heat pump unit, and a two-stage compression heat pump unit; The two-stage compression heat pump unit comprises a low-temperature evaporator (20), a low-pressure compressor (21), a high-pressure compressor (22), a condensing heater (23), and an economic heat exchanger (26); The molten salt side outlet of the solar molten salt heat collection and heating unit is connected to the organic Rankine cycle power unit, the high temperature side of the absorption heat pump unit and the molten salt side inlet of the low temperature evaporator (20) in sequence; the molten salt side outlet of the low temperature evaporator (20) is connected to the molten salt side inlet of the solar molten salt heat collection and heating unit; The working fluid side outlet of the low-temperature evaporator (20) is connected in sequence to the inlet of the low-pressure compressor (21), the high-pressure compressor (22), the condensing heater (23) and the economic heat exchanger (26); One outlet of the economic heat exchanger (26) is connected to the inlet of the first solar thermal collector (25), and the outlet of the first solar thermal collector (25) is connected to the low-pressure compressor (21); another outlet of the economic heat exchanger (26) is connected to the working fluid side inlet of the low-temperature evaporator (20); The water side outlet of the condensing heater (23) is connected to the water supply pipeline of the heating network, and the water side inlet of the condensing heater (23) is connected to the water return pipeline of the heating network through the solar molten salt heat collection and heating unit and the absorption heat pump unit.

2. The solar-driven composite heat pump heating system according to claim 1, characterized in that: The absorption heat pump unit comprises a generator (11), a first expansion valve (12), a heat exchanger (13), an absorber (14), a solution pump (15), a second condenser (16), a second expansion valve (17) and a first evaporator (18); The working fluid side of the generator (11), the first expansion valve (12), the high-temperature solution side of the heat exchanger (13), the working fluid side of the absorber (14), the low-temperature solution side of the heat exchanger (13), and the inlet and outlet of the solution pump (15) are connected in sequence through a working fluid solution pipeline; The inlet and outlet of the water vapor side of the generator (11), the condensed water side of the second condenser (16), the second expansion valve (17), the water vapor side of the first evaporator (18) and the water vapor side of the absorber (14) are connected in sequence through a water pipeline.

3. The solar-driven composite heat pump heating system according to claim 2, characterized in that: The circulating water side inlet of the second condenser (16) is connected to the circulating water side outlet of the absorber (14), and the circulating water side inlet of the absorber (14) is connected to the heat network return water pipeline.

4. The solar-driven composite heat pump heating system according to claim 2, characterized in that: The organic Rankine cycle power unit comprises a molten salt evaporator (7), a turbine (8), a first condenser (9), and a first compressor (10) which are connected in sequence via an organic working fluid pipeline.

5. The solar-driven composite heat pump heating system according to claim 4, characterized in that: The cooling water side of the first evaporator (18) is connected to the water side of the first condenser (9); A cooling water pump (19) is provided on the pipeline between the cooling water side outlet of the first evaporator (18) and the water side inlet of the first condenser (9).

6. The solar-driven composite heat pump heating system according to claim 4, characterized in that: The low-pressure compressor (21), the high-pressure compressor (22), the turbine (8) and the first compressor (10) are coaxially connected.

7. The solar-driven composite heat pump heating system according to claim 4, characterized in that: The solar molten salt heat collection and heating unit comprises a low-temperature molten salt heat storage tank (1), a low-temperature molten salt circulation pump (2), a trough-type solar collector (3), a high-temperature molten salt heat storage tank (4), a high-temperature molten salt circulation pump (5) and a molten salt heater (6) which are sequentially connected via a molten salt pipeline; The molten salt side outlet of the molten salt heater (6) is connected in sequence to the molten salt side of the molten salt evaporator (7), the generator (11) and the molten salt side inlet of the low-temperature evaporator (20), and the molten salt side outlet of the low-temperature evaporator (20) is connected to the inlet of the low-temperature molten salt heat storage tank (1).

8. The solar-driven composite heat pump heating system according to claim 4, characterized in that: The water side outlet of the molten salt heater (6) is connected to the water side inlet of the condensation heater (23); The water side outlet of the molten salt heater (6) is connected to the circulating water side outlet of the second condenser (16).

9. The solar-driven composite heat pump heating system according to claim 1, characterized in that: The working fluid outlet pipeline of the condensing heater (23) is divided into two paths, one of which is an intermediate heat supplement branch, connected to the inlet of the first solar collector (25) through the third expansion valve (24) and the economic heat exchanger (26), and the other is connected to the working fluid side of the low-temperature evaporator (20) through the economic heat exchanger (26) and the third expansion valve (24).

10. The operating method of the solar-driven composite heat pump heating system according to any one of claims 1 to 9, characterized in that: include, When the light conditions are sufficient, the low-temperature molten salt absorbs light through the solar molten salt heat collection and heating unit and is heated to high-temperature molten salt, which heats the hot water in the heat network at the outlet of the absorption heat pump unit. The cooled high-temperature molten salt heats the organic working fluid of the organic Rankine cycle power unit as a driving heat source, drives the absorption heat pump unit and the two-stage compression heat pump unit, and then enters the low-temperature evaporator (20) as a low-temperature heat source for the two-stage compression heat pump unit. The outlet molten salt of the low-temperature evaporator (20) flows back to the solar molten salt heat collection and heating unit; The main loop working fluid of the two-stage compression heat pump unit is heated and evaporated by low-temperature molten salt in the low-temperature evaporator (20), enters the low-pressure compressor (21) to be compressed, is mixed with the working fluid at the outlet of the first branch solar collector (25), enters the high-pressure compressor (22) to be compressed, and then condenses in the condensing heater (23) to heat the heat network circulating water. The condensed working fluid at the outlet of the condensing heater (23) transfers heat to the branch working fluid of the two-stage compression heat pump unit through the economic heat exchanger (26), and then is reduced. After being compressed, the branch working fluid enters the low-temperature evaporator (20), and after being reduced in pressure, it absorbs the heat of the main loop working fluid in the economic heat exchanger (26), enters the first solar collector (25) to absorb the heat of sunlight, and then mixes with the main loop working fluid at the outlet of the low-pressure compressor (21) and enters the high-pressure compressor (22) to transfer the heat to the condensing heater (23) to perform secondary heating on the return water of the heating network. The return water of the heating network is heated to the water supply temperature in the condensing heater (23) and supplied to the heat users.

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