A phase change heat storage type high-efficiency clean energy heating system, control and design method

Abstract

The present invention discloses a phase-change heat storage type high-efficiency clean energy heating system, control and design method, including a first-cycle air source heat pump cycle heating and heat storage cycle, a second-cycle water ring heat pump warming cycle and a third-cycle heating cycle. The present invention determines the high-temperature operation period based on the typical day outdoor temperature change curve, the typical day building heat consumption change curve and the total building consumption. According to the daily temperature forecast, the high-temperature operation time of the air source heat pump is calculated in advance to ensure the efficient operation of the air source heat pump during the high-temperature operation period. During the low-temperature period, only the low-temperature second-cycle warming cycle is operated to extract heat from the phase-change heat storage tank to ensure the efficient operation of the entire system. The present invention reduces the outlet water temperature of the air source heat pump, improves the energy efficiency ratio of the air source heat pump and the energy efficiency ratio of the heating system, expands the application range of the air source heat pump, and has stable operation and significant energy-saving effects.

Description

Technical Field

[0001] The present invention belongs to the technical field of clean energy utilization, and specifically relates to a phase-change heat storage type high-efficiency clean energy heating system, and a control and design method. Background Art

[0002] During winter heating, biomass energy sources such as coal, oil, and natural gas are increasingly restricted, and renewable clean energy heating is gaining widespread attention and support. Air source heat pumps and water source heat pumps, as a type of renewable energy, have been vigorously promoted and applied. However, the outdoor temperature varies sinusoidally throughout the day. In severely cold and cold regions of my country where outdoor temperatures are relatively low, the outdoor temperature is higher during the day and lower at night. Air source heat pumps utilize a reverse Carnot cycle to extract heat from the outdoor air and produce hot air or hot water. Their heating capacity and energy efficiency ratio decrease significantly as the outdoor temperature decreases and as the outlet water temperature increases.

[0003] When the rated heating capacity of the unit is constant, when the outdoor temperature is high, the air source heat pump has a large heating capacity and a high unit energy efficiency ratio (COP), but the required heat load of the building is small at this time; when the outdoor temperature is low, the air source heat pump has a small heating capacity and a low unit energy efficiency ratio (COP), but the required heat load is large at this time. Therefore, the working principle of the traditional air source heat pump system causes a scissors difference between the heating capacity of the air source heat pump and the building heat load when the air source heat pump is used for heating, resulting in problems such as mismatch. In addition, air source heating also has the problem that when the outdoor temperature drops, its suction pressure decreases and the exhaust pressure increases, causing its compression ratio to increase, making it prone to shutdown phenomena such as high-pressure protection, and poor stability; when the outdoor humidity is high, it is easy to fail to provide heat during defrosting, and the heating is unstable.

[0004] Therefore, traditional air-source heat pump heating suffers from poor climate adaptability, significant influence of outdoor temperature on heating supply, poor stability, and significant decrease in energy efficiency and high energy consumption as outdoor temperature decreases and water supply temperature increases. This results in a low COP for the entire system when using air-source heat pump heating, preventing it from fully leveraging its advantages as a clean energy source for heating. Traditional water-source heat pumps also face numerous geological constraints, such as high well drilling costs, difficulty in recharging well water, and the potential for groundwater contamination, limiting their regional adaptability. Summary of the Invention

[0005] In order to make up for the shortcomings of the existing technology, the present invention provides a phase change thermal storage type high-efficiency clean energy heating system, control and design method, which can fully utilize the high temperature outdoor period in winter to improve the COP of the air source heat pump, and reduce the outlet water temperature of the air source heat pump, further improving the COP of the air source heat pump; it realizes heating and heat storage during the high temperature outdoor period and heat use during the low temperature outdoor period, solving a series of problems such as the mismatch between the heating supply of a single air source heat pump and the building heat load, unstable heating, and low system energy efficiency.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A phase change heat storage type high efficiency clean energy heating system, characterized by comprising three circulation loops:

[0008] The first circulation loop is an air source heat pump heating and heat storage cycle, including a first compressor, a first evaporator, a first throttling expansion valve, a first condenser and a first circulating water pump;

[0009] The second circulation loop is a water ring heat pump warming cycle, including a second compressor, a second evaporator, a second throttling expansion valve, a second condenser, a second circulating water pump and a low-temperature phase change heat storage tank; the third circulation loop is a heating cycle, including a third circulating water pump and a user-end heat dissipation device.

[0010] Furthermore, in the first circulation loop, the first throttling expansion valve is provided on the path from the first condenser to the first evaporator; the first compressor is provided on the path from the first evaporator to the first condenser; and the first circulating water pump is provided on the path between the first condenser and the low-temperature phase-change thermal storage tank.

[0011] Furthermore, a second circulating water pump is provided on a loop formed by the low-temperature phase-change heat storage tank and the second evaporator; a second throttling expansion valve is provided on a path from the second condenser to the second evaporator; and a second compressor is provided on a path from the second evaporator to the second condenser.

[0012] Furthermore, a circulation loop is formed between the user's heat dissipation terminal and the second condenser through a third circulating water pump.

[0013] Furthermore, the low-temperature phase change thermal storage tank stores low-temperature phase change materials such as sodium sulfate decahydrate or calcium chloride hexahydrate, and the melting point of the phase change thermal storage material is lower than 35°C.

[0014] A control method for a phase-change thermal storage type high-efficiency clean energy heating system, characterized in that: according to the outdoor temperature on a typical meteorological day, the outdoor temperature is divided into a "high temperature period (T1-T2)" and a "low temperature period (T2-T1)";

[0015] Operation method during high temperature period (T1-T2): Calculate the operation time of the air source heat pump during high temperature period in advance according to the daily temperature forecast. Start the first circulation loop air source heat pump heating and heat storage cycle during high temperature period (T1-T2). Use the reverse Carnot cycle to extract the heat from the outdoor temperature. The low-temperature phase change heat storage material in the low-temperature phase change heat storage tank stores heat to 35°C. At the same time, start the second circulation loop water loop heat pump warming cycle. Use the reverse Carnot cycle to extract the heat from the low-temperature phase change heat storage material. Heat the return water in the third circulation loop heating cycle. After the return water at 35-40°C is heated to 45-50°C, it is pumped to the user's heat dissipation terminal using the third circulation water pump to meet the user's heating needs.

[0016] Operation method during low temperature period (T2~T1): In this stage, only the second circulation loop water ring heat pump warming cycle and the third circulation loop heating cycle are operated; the second circulation loop water ring heat pump warming cycle is turned on, and the reverse Carnot cycle is used to extract the heat stored in the low-temperature phase change thermal storage material in advance during the high temperature period (T1~T2), and heat the return water in the third circulation loop heating cycle. After the return water at 35~40℃ is heated to 45~50℃, the third circulation water pump (3-1) is used to send it to the user's heat dissipation terminal to meet the user's heating needs.

[0017] A design method for a phase-change thermal storage type high-efficiency clean energy heating system is characterized by:

[0018] 1) Design method of the first loop air source heat pump heating and thermal storage cycle:

[0019] According to local climatic conditions, determine the typical day outdoor temperature change curve L1, and use it to calculate the typical day building heat consumption curve L2 and the total building heat consumption M0. Comprehensively determine the typical day outdoor temperature change curve L1 and the typical day building heat consumption curve L2. According to the performance of the selected first cycle air source heat pump, determine the high temperature operation period (T1~T2), calculate the theoretical heating capacity Q0 required per unit time during the high temperature period, further calculate the nominal heating capacity Q of the selected air source heat pump, and use this to calculate the first cycle water pump flow G1;

[0020] The theoretical heating capacity Q0 is:

[0021]

[0022] The nominal heating capacity Q of the air source heat pump is:

[0023]

[0024] Where K1 is the defrost correction coefficient during the high temperature period, and K2 is the temperature correction coefficient during the high temperature period;

[0025] The flow rate G1 of the first circulating water pump is:

[0026] Where, t2 is the outlet water temperature of the first condenser, and t1 is the inlet water temperature of the first condenser;

[0027] 2) Design method for the second circulation loop water ring heat pump heating cycle and the third circulation loop heating cycle:

[0028] According to local climate conditions and the local winter heating design temperature, calculate the building's winter heating heat load Q1, and combine the performance of the selected water ring heat pump to calculate the nominal heating capacity Qs of the selected second circulation water ring heat pump, and use this to calculate the second circulation water pump flow G2 and the third circulation water pump flow G3;

[0029] The nominal heating capacity Qs of the second circulating water ring heat pump is:

[0030]

[0031] Where K3 is the water inlet temperature modification coefficient of the water ring heat pump;

[0032] The flow rate G2 of the second circulating water pump is:

[0033]

[0034] Where, t3 is the inlet water temperature of the second evaporator, t4 is the outlet water temperature of the second evaporator, and COPs is the COP value of the water ring heat pump in this working state;

[0035] The flow rate G3 of the third circulating water pump is:

[0036]

[0037] Where, t6 is the water supply temperature at the heat dissipation end, and t5 is the return water temperature at the heat dissipation end;

[0038] 3) Design method of low-temperature phase change thermal storage tank:

[0039] Based on the total building heat consumption M0 calculated above, combined with the melting point, specific heat capacity in liquid state and latent heat of fusion of the selected low-temperature phase change thermal storage material, the theoretical mass m of the required low-temperature phase change thermal storage material is calculated as follows:

[0040]

[0041] Where Cs is the specific heat capacity of the low-temperature phase change thermal storage material in liquid form, Kj / (kg.℃);

[0042] ts is the melting point of the low-temperature phase change thermal storage material;

[0043] rs is the latent heat of fusion of low-temperature phase change thermal storage material (KJ / kg).

[0044] Beneficial effects of the present invention:

[0045] 1) The present invention utilizes the daily sinusoidal variation of outdoor temperature. The first cycle of heating and heat storage cycle only operates during high temperature periods, thereby improving the energy efficiency ratio (COP) of the air source heat pump and greatly improving the environmental adaptability of the air source heat pump.

[0046] 2) The present invention reduces the outlet water temperature of the air source heat pump to only 35°C, which greatly improves the COP of the air source heat pump and reduces the capacity configuration of the air source heat pump;

[0047] 3) The first cycle of the present invention, an air-source heating and heat storage cycle, operates only during high-temperature periods, resolving issues such as poor stability, high attenuation, and non-heating during defrosting, often associated with air-source heat pumps operating at low temperatures. The second cycle, a water-loop heat pump, stabilizes the water temperature at the inlet of the second evaporator after heat exchange in the low-temperature phase-change heat storage tank, maintaining a temperature far above its rated inlet water temperature. This significantly improves the heating stability of the water-loop heat pump, significantly increasing its energy efficiency ratio (COP), and resulting in significant energy savings.

[0048] 4) The present invention can effectively reduce the outlet water temperature of the air source heat pump, significantly improve the energy efficiency ratio of the air source heat pump and the energy efficiency ratio of the entire heating system, expand the scope of application of the air source heat pump, ensure reliable operation stability, and adopt phase change heat storage, which greatly reduces the floor space of the machine room and reduces the primary investment. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a structural diagram of the phase-change thermal storage type high-efficiency clean energy heating system of the present invention;

[0050] Figure 2 A flow chart of the design method of the present invention;

[0051] Figure 3 It is a curve diagram of outdoor temperature change and building heat consumption;

[0052] In the figure, 1-1, the first compressor, 1-2, the first evaporator, 1-3, the first throttling expansion valve, 1-4, the first condenser, 1-5, the first circulating water pump, 2-1, the second compressor, 2-2, the second evaporator, 2-3, the second throttling expansion valve, 2-4, the second condenser, 2-5, the second circulating water pump, 2-6, the low-temperature phase change heat storage tank, 3-1, the third circulating water pump, 3-2, the user's heat dissipation terminal. DETAILED DESCRIPTION

[0053] The present invention will be described in detail below with reference to specific embodiments.

[0054] 1) Phase change thermal storage type efficient clean energy heating system

[0055] like Figure 1 As shown, the phase change thermal storage type high-efficiency clean energy heating system of the present invention includes three circulation loops:

[0056] a) The first circulation loop is an air source heat pump heating and thermal storage cycle, including a first compressor 1-1, a first evaporator 1-2, a first throttling expansion valve 1-3, a first condenser 1-4, and a first circulating water pump 1-5. In the first circulation loop, the first throttling expansion valve 1-3 is arranged on the path from the first condenser 1-4 to the first evaporator 1-2; the first compressor 1-1 is arranged on the path from the first evaporator 1-2 to the first condenser 1-4; and the first circulating water pump 1-5 is arranged on the path from the first condenser 1-4 to the low-temperature phase change thermal storage tank 2-6.

[0057] The first cycle is composed of an air source heat pump circulation heating and heat storage system based on the reverse Carnot cycle principle. The condenser of this air source heat pump system, the first condenser 1-4, is connected to the low-temperature phase-change thermal storage tank 2-6. During the operation of the first cycle, low-temperature hot water of about 35°C is prepared and heat is exchanged with the low-temperature phase-change thermal storage tank 2-6, melting the low-temperature phase-change thermal storage material from a solid state to a liquid working fluid for heat storage. In extremely cold areas, the working fluid of the first cycle air source heat pump heating cycle can be R744; in cold areas, the internal working fluid of the first cycle can be R134a. The circulating working fluid of the first cycle connecting the first condenser 1-4 and the low-temperature phase-change thermal storage tank 2-6 can be water in cold areas and antifreeze in extremely cold areas.

[0058] For traditional air source heat pump heating, the hot water temperature needs to be above 50℃. As the outdoor temperature drops, the outlet water temperature increases, the energy efficiency ratio (COP) decreases, and the heating capacity decreases. In order to meet the heating needs, the capacity configuration needs to be increased. However, the outlet water temperature of the air source heat pump in this system is only 35℃, which greatly improves the COP of the air source heat pump and reduces the capacity configuration of the air source heat pump.

[0059] b) The second circulation loop is a water-ring heat pump heating loop, comprising a second compressor 2-1, a second evaporator 2-2, a second throttling expansion valve 2-3, a second condenser 2-4, a second circulating water pump 2-5, and a low-temperature phase-change thermal storage tank 2-6; the second circulating water pump 2-5 is disposed in the loop formed by the low-temperature phase-change thermal storage tank 2-6 and the second evaporator 2-2; the second throttling expansion valve 2-3 is disposed on the path from the second condenser 2-4 to the second evaporator 2-2; the second compressor 2-1 is disposed on the path from the second evaporator 2-2 to the second condenser 2-4; the low-temperature phase-change thermal storage tank 2-6 stores a low-temperature phase-change material such as sodium sulfate decahydrate or calcium chloride hexahydrate, the melting point of the phase-change thermal storage material being lower than 35°C;

[0060] The second cycle heating circulation system is a water ring heat pump. After the water temperature at the inlet of the second evaporator passes through the low-temperature phase change heat storage tank, the water temperature is stable and far higher than its rated inlet water temperature. This greatly improves the heating stability of the water ring heat pump and the energy efficiency ratio (COP), resulting in significant energy saving effects.

[0061] The second evaporator 2-2 of this water ring heat pump heat exchange system is connected to the low-temperature phase change thermal storage tank 2-6 for heat exchange, extracting the heat stored in the low-temperature phase change thermal storage tank 2-6, and after being heated by the second condenser 2-4, it is transported to the user's heat exchange end; the refrigerant in the second cycle can be R134a, etc.

[0062] c) The third circulation loop is a heating circulation loop, including a third circulation water pump 3-1 and a user-end heat dissipation device 3-2; a circulation loop is formed between the user heat dissipation terminal 3-2 and the second condenser 2-4 through the third circulation water pump 3-1; the third circulation is a heating circulation system, and the circulating medium is water. A user-end hot water circulation water pump 3-1 is provided on the path from the second condenser 2-4 to the heat dissipation terminal 3-2; after the condenser 2-4 generates 45-50°C, it is sent to the user heat dissipation terminal 3-2 by the third circulation water pump 3-1, and after heat dissipation at the hot user heat dissipation terminal 3-2, it is reduced to 35-40°C return water, and then heated to 45-50°C by the warm condenser 2-4 before being sent out, and the cycle repeats.

[0063] The above equipment includes two evaporators, two compressors, two condensers, two throttling expansion valves, three water pumps, low-temperature phase-change thermal storage materials and heat dissipation terminals, all of which can be commonly used equipment in this field.

[0064] 2) Control method of phase change thermal storage type high-efficiency clean energy heating system

[0065] According to the outdoor temperature on a typical meteorological day, the outdoor temperature is divided into "high temperature period (T1-T2)" and "low temperature period (T2-T1)";

[0066] Operation method during high temperature period (T1-T2): Based on the daily temperature forecast, the operation time of the air source heat pump during the high temperature period is calculated in advance. During the high temperature period (T1-T2), the first circulation loop air source heat pump heating and heat storage cycle is started, and the reverse Carnot cycle is used to extract heat from the "high temperature" outdoor temperature. The low-temperature phase change heat storage material in the low-temperature phase change heat storage tank 2-6 stores heat to 35°C; at the same time, the second circulation loop water ring heat pump warming cycle is started, and the reverse Carnot cycle is used to extract heat from the low-temperature phase change heat storage material to heat the return water in the third circulation loop heating cycle. After the return water at 35-40°C is heated to 45-50°C, the return water is sent to the user's heat dissipation terminal 3-2 by the third circulation water pump 3-1 to meet the user's heating needs;

[0067] Traditional air source heat pump heating systems operate 24 hours a day, and during high temperature periods, their efficiency cannot be fully utilized due to the low building heat load. During low temperature periods, the heating efficiency is low. To effectively solve this problem, the first cycle heating and heat storage cycle of the present invention only operates during high temperature periods, which can improve the energy efficiency ratio (COP) of the air source heat pump and greatly improve the environmental adaptability of the air source heat pump.

[0068] Operation method during the low-temperature period (T2-T1): During this stage, only the second circulation loop water-loop heat pump warming cycle and the third circulation loop heating cycle are operated; the second circulation loop water-loop heat pump warming cycle is turned on, and the reverse Carnot cycle is used to extract the heat stored in the low-temperature phase change thermal storage material in advance during the high-temperature period (T1-T2), and heat the return water in the third circulation loop heating cycle. After the return water at 35-40°C is heated to 45-50°C, the third circulation water pump 3-1 is used to deliver it to the user's heat dissipation terminal 3-2 to meet the user's heating needs.

[0069] 3) Design method of phase change thermal storage type high-efficiency clean energy heating system

[0070] a) Design method for the first loop air source heat pump heating and thermal storage cycle:

[0071] According to local climate conditions, determine the typical day outdoor temperature change curve L1, and use it to calculate the typical day building heat consumption curve L2 and the total building heat consumption M0 (kJ), such as Figure 3 As shown; comprehensively determine the typical day outdoor temperature change curve L1 and the typical day building heat consumption curve L2, determine the high temperature operation period (T1~T2) according to the performance of the selected first cycle air source heat pump, calculate the theoretical heating capacity Q0 (kW) required per unit time during the high temperature period, further calculate the nominal heating capacity Q (kW) of the selected air source heat pump, and use this to calculate the first cycle water pump flow G1 (m3 / h);

[0072] The theoretical heating capacity Q0 is:

[0073]

[0074] The nominal heating capacity Q of the air source heat pump is:

[0075]

[0076] Where K1 is the defrost correction coefficient during the high temperature period, and K2 is the temperature correction coefficient during the high temperature period;

[0077] The flow rate G1 of the first circulating water pump is:

[0078] Where, t2 is the outlet water temperature of the first condenser, and t1 is the inlet water temperature of the first condenser;

[0079] b) Design method for the second circulation loop water ring heat pump heating cycle and the third circulation loop heating cycle:

[0080] According to local climate conditions and the local winter heating design temperature, calculate the building's winter heating heat load Q1 (kW), and combine the performance of the selected water-ring heat pump to calculate the nominal heating capacity Qs (kW) of the selected second-circulation water-ring heat pump. Based on this, calculate the second-circulation water pump flow rate G2 (m3 / h) and the third-circulation water pump flow rate G3 (m3 / h);

[0081] The nominal heating capacity Qs of the circulating water heat pump is:

[0082]

[0083] Where K3 is the water inlet temperature modification coefficient of the water ring heat pump;

[0084] The flow rate G2 of the second circulating water pump is:

[0085]

[0086] Where, t3 is the inlet water temperature of the second evaporator, t4 is the outlet water temperature of the second evaporator, and COPs is the COP value of the water ring heat pump in this working state;

[0087] The flow rate G3 of the third circulating water pump is:

[0088]

[0089] Where, t6 is the water supply temperature at the heat dissipation end, and t5 is the return water temperature at the heat dissipation end;

[0090] c) Design method of low-temperature phase change thermal storage tank:

[0091] Based on the total building heat consumption M0 (kJ) calculated above, combined with the melting point, specific heat capacity in liquid state and latent heat of fusion of the selected low-temperature phase change thermal storage material, the theoretical mass m (kg) of the required low-temperature phase change thermal storage material is calculated as follows:

[0092]

[0093] Where Cs is the specific heat capacity of the low-temperature phase change thermal storage material in liquid form, Kj / (kg.℃);

[0094] ts is the melting point of the low-temperature phase change thermal storage material;

[0095] rs is the latent heat of fusion of low-temperature phase change thermal storage material, (kJ / kg)

[0096] The present invention works as follows:

[0097] 1) Operation process during high temperature period (T1~T2)

[0098] During the high-temperature period (T1-T2), the first cycle heating and heat storage cycle is started, and the reverse Carnot cycle is used to extract heat from the "high-temperature" outdoor air to heat the low-temperature phase-change heat storage material in the phase-change heat storage tank 2-6 to its melting point. At the same time, the second cycle warming cycle is started, and the reverse Carnot cycle is used to extract heat from the phase-change heat storage tank 2-6 to heat the return water in the heating cycle. After the return water at 35-40°C is heated to 45-50°C, it is delivered to the user's heat dissipation terminal 3-2 by the third circulating water pump 3-1 to meet the user's heating needs.

[0099] The specific working process is as follows:

[0100] The low-pressure refrigerant vapor from the first evaporator 1-2 is converted into high-pressure and high-temperature refrigerant vapor through the work of the first compressor 1-1, and then passes through the first condenser 1-4 to heat the circulating water from the low-temperature phase-change thermal storage tank 2-6, heating the circulating water from t1 to t2; after the temperature of the refrigerant vapor is reduced, it passes through the first throttle valve 1-3 to become a low-temperature and low-pressure liquid refrigerant, passes through the first evaporator 1-2 to exchange heat with the external "high-temperature" air, absorbs the heat of the outdoor air, becomes a low-temperature and low-pressure gas, and then enters the first compressor 1-1; this cycle is repeated, and the heat of the outdoor high-temperature air is stored in the low-temperature phase-change thermal storage tank 2-6; the low-temperature hot water in the low-temperature phase-change thermal storage tank 2-6 is provided with circulation power by the first circulating pump 1-5, completing its circulation with the first condenser 1-4;

[0101] The low-pressure refrigerant vapor from the second evaporator 2-2 is converted into high-pressure and high-temperature refrigerant vapor through the work of the second compressor 2-1. The refrigerant vapor then passes through the second condenser 2-4 to heat the return water from the heat user 3-4, raising the return water temperature from t5 to t6. After the refrigerant vapor temperature drops, it passes through the second throttle valve 2-3 and becomes a low-temperature and low-pressure liquid refrigerant. The refrigerant vapor then exchanges heat with the low-temperature phase-change thermal storage material in the low-temperature phase-change thermal storage tank 2-6 through the second evaporator 2-2. After absorbing the heat of the low-temperature phase-change thermal storage material, the refrigerant vapor becomes a low-temperature and low-pressure gas and enters the second compressor 2-1. This cycle repeats to meet the heating needs of the end user.

[0102] The second circulation pump 2-5 provides circulation power for the low-temperature hot water flowing through the low-temperature phase change storage tank 2-6, completing its circulation with the second evaporator 2-2; the high-temperature hot water t6 generated by the second condenser 2-4 is provided with circulation power by the third circulation pump 3-1 and sent to the user heat dissipation terminal 3-2 for heat dissipation, and the temperature is reduced to t5 to the second condenser 2-4.

[0103] 2) Operation process during low temperature period (T2~T1)

[0104] During this stage, only the second circulation loop water ring heat pump warming cycle and the third circulation loop heating cycle are operated; the second circulation loop water ring heat pump warming cycle is turned on, and the reverse Carnot cycle is used to extract the heat stored in the low-temperature phase change thermal storage material in advance during the high-temperature period (T1~T2). During the process, the low-temperature phase change material undergoes phase change to release heat, heating the return water in the third circulation loop heating cycle. After the return water at 35~40℃ is heated to 45~50℃, it is sent to the user's heat dissipation terminal 3-2 by the third circulation water pump 3-1 to meet the user's heating needs.

[0105] The content of the present invention is not limited to the embodiments listed. Any equivalent transformation of the technical solution of the present invention made by ordinary technicians in this field after reading the description of the present invention is covered by the claims of the present invention.

Claims

1. A control method for a phase change thermal storage type high-efficiency clean energy heating system, characterized by: The phase change thermal storage type efficient clean energy heating system includes three circulation loops: The first circulation loop is an air source heat pump heating and heat storage cycle, comprising a first compressor (1-1), a first evaporator (1-2), a first throttling expansion valve (1-3), a first condenser (1-4), and a first circulating water pump (1-5); The second circulation loop is a water ring heat pump warming cycle, comprising a second compressor (2-1), a second evaporator (2-2), a second throttling expansion valve (2-3), a second condenser (2-4), a second circulating water pump (2-5) and a low-temperature phase change heat storage tank (2-6); The third circulation loop is a heating circulation, including a third circulation water pump (3-1) and a user heat dissipation terminal (3-2); In the first circulation loop, the first throttling expansion valve (1-3) is arranged on a path from the first condenser (1-4) to the first evaporator (1-2); the first compressor (1-1) is arranged on a path from the first evaporator (1-2) to the first condenser (1-4); and the first circulating water pump (1-5) is arranged on a path between the first condenser (1-4) and the low-temperature phase-change heat storage tank (2-6). The second circulating water pump (2-5) is arranged on a loop formed by the low-temperature phase-change heat storage tank (2-6) and the second evaporator (2-2); the second throttling expansion valve (2-3) is arranged on a path from the second condenser (2-4) to the second evaporator (2-2); and the second compressor (2-1) is arranged on a path from the second evaporator (2-2) to the second condenser (2-4). A circulation loop is formed between the user heat dissipation terminal (3-2) and the second condenser (2-4) via a third circulating water pump (3-1); The control method is specifically as follows: According to the outdoor temperature on a typical meteorological day, the outdoor temperature is divided into high temperature period and low temperature period; Operation method during high temperature period: Based on the daily temperature forecast, calculate the operation time of the air source heat pump during the high temperature period in advance, start the first circulation loop air source heat pump heating and heat storage cycle during the high temperature period, use the reverse Carnot cycle to extract the heat of the outdoor temperature, and store the low-temperature phase change heat storage material in the low-temperature phase change heat storage tank (2-6) to 35°C; at the same time, start the second circulation loop water ring heat pump warming cycle, use the reverse Carnot cycle to extract the heat of the low-temperature phase change heat storage material, heat the return water in the third circulation loop heating cycle, and increase the temperature of the return water at 35~40°C to 45~50°C. Then, use the third circulation water pump (3-1) to send it to the user's heat dissipation terminal (3-2) to meet the user's heating needs; Operation method during low temperature period: In this stage, only the second circulation loop water ring heat pump warming cycle and the third circulation loop heating cycle are operated; the second circulation loop water ring heat pump warming cycle is turned on, and the reverse Carnot cycle is used to extract the heat stored in the low-temperature phase change thermal storage material in advance during the high temperature period, and the return water in the third circulation loop heating cycle is heated. After the return water at 35~40℃ is heated to 45~50℃, the third circulation water pump (3-1) is used to send it to the user's heat dissipation terminal (3-2) to meet the user's heating needs.

2. The control method of a phase change thermal storage type high-efficiency clean energy heating system according to claim 1, characterized in that: The low-temperature phase-change thermal storage tank (2-6) stores a low-temperature phase-change material of sodium sulfate 10 hydrate or calcium chloride 6 hydrate, and the melting point of the phase-change thermal storage material is lower than 35°C.

3. A design method for a phase-change thermal storage type high-efficiency clean energy heating system, characterized by: The phase change thermal storage type efficient clean energy heating system includes three circulation loops: The first circulation loop is an air source heat pump heating and heat storage cycle, comprising a first compressor (1-1), a first evaporator (1-2), a first throttling expansion valve (1-3), a first condenser (1-4), and a first circulating water pump (1-5); The second circulation loop is a water ring heat pump warming cycle, comprising a second compressor (2-1), a second evaporator (2-2), a second throttling expansion valve (2-3), a second condenser (2-4), a second circulating water pump (2-5) and a low-temperature phase change heat storage tank (2-6); The third circulation loop is a heating circulation loop, including a third circulation water pump (3-1) and a user heat dissipation terminal (3-2); In the first circulation loop, the first throttling expansion valve (1-3) is arranged on a path from the first condenser (1-4) to the first evaporator (1-2); the first compressor (1-1) is arranged on a path from the first evaporator (1-2) to the first condenser (1-4); and the first circulating water pump (1-5) is arranged on a path between the first condenser (1-4) and the low-temperature phase-change heat storage tank (2-6). The second circulating water pump (2-5) is arranged on a loop formed by the low-temperature phase-change heat storage tank (2-6) and the second evaporator (2-2); the second throttling expansion valve (2-3) is arranged on a path from the second condenser (2-4) to the second evaporator (2-2); and the second compressor (2-1) is arranged on a path from the second evaporator (2-2) to the second condenser (2-4). A circulation loop is formed between the user heat dissipation terminal (3-2) and the second condenser (2-4) via a third circulating water pump (3-1); The design method is as follows: 1) Design method of the first loop air source heat pump heating and thermal storage cycle: According to local climatic conditions, determine the typical day outdoor temperature change curve L1, and use it to calculate the typical day building heat consumption curve L2 and the total building heat consumption M0. Comprehensively determine the typical day outdoor temperature change curve L1 and the typical day building heat consumption curve L2. According to the performance of the selected first-cycle air source heat pump, determine the high-temperature operation period, calculate the theoretical heating capacity Q0 required per unit time during the high-temperature period, calculate the nominal heating capacity Q of the selected air source heat pump, and use this to calculate the first-cycle water pump flow G1; The theoretical heating capacity Q0 is: The nominal heating capacity Q of the air source heat pump is: Where K1 is the defrost correction coefficient during the high temperature period, and K2 is the temperature correction coefficient during the high temperature period; The flow rate G1 of the first circulating water pump is: Where, t2 is the outlet water temperature of the first condenser, and t1 is the inlet water temperature of the first condenser; 2) Design method for the second circulation loop water ring heat pump heating cycle and the third circulation loop heating cycle: According to local climate conditions and the local winter heating design temperature, calculate the building's winter heating heat load Q1, and combine the performance of the selected water ring heat pump to calculate the nominal heating capacity Qs of the selected second circulation water ring heat pump, and use this to calculate the second circulation water pump flow G2 and the third circulation water pump flow G3; The nominal heating capacity Qs of the second circulating water ring heat pump is: Where K3 is the water inlet temperature modification coefficient of the water ring heat pump; The flow rate G2 of the second circulating water pump is: Where, t3 is the inlet water temperature of the second evaporator, t4 is the outlet water temperature of the second evaporator, and COPs is the COP value of the water ring heat pump in this working state; The flow rate G3 of the third circulating water pump is: Where, t6 is the water supply temperature at the heat dissipation end, and t5 is the return water temperature at the heat dissipation end; 3) Design method of low-temperature phase change thermal storage tank: Based on the total building heat consumption M0 calculated above, combined with the melting point, specific heat capacity in liquid state and latent heat of fusion of the selected low-temperature phase change thermal storage material, the theoretical mass m of the required low-temperature phase change thermal storage material is calculated as follows: Where Cs is the specific heat capacity of the low-temperature phase change thermal storage material in liquid form, kJ / (kg.℃); ts is the melting point of the low-temperature phase change thermal storage material; rs is the latent heat of fusion of low-temperature phase change thermal storage material, kJ / kg.

4. The design method of a phase change thermal storage type high-efficiency clean energy heating system according to claim 3 is characterized by: The low-temperature phase-change thermal storage tank (2-6) stores a low-temperature phase-change material of sodium sulfate 10 hydrate or calcium chloride 6 hydrate, and the melting point of the phase-change thermal storage material is lower than 35°C.

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