Combined heat supply system based on PVT heat collector and double-source heat pump and control method

Abstract

The invention relates to the field of new energy heat supply, and discloses a combined heat supply system based on a PVT heat collector and a double-source heat pump and a control method.The combined heat supply system comprises a main pipeline, a branch pipeline, the PVT heat collector, a temperature sensor, a reversing valve, the double-source heat pump and a water pump; the main pipeline is closed and comprises a water return section, a heat exchange section, a water supply section and a heat consumption section which are sequentially distributed in the flowing direction of working fluid. The PVT heat collector is internally provided with a photoelectric conversion part and a photo-thermal conversion part which can exchange heat with the heat exchange section, and the heat exchange position of the heat exchange section and the photoelectric conversion part is located on the upstream of the heat exchange position of the heat exchange section and the photo-thermal conversion part. And the PVT heat collector and the double-source heat pump are combined, so that efficient comprehensive utilization of solar energy is improved, and the heat supply efficiency of the heat supply system under different weather environment conditions is improved.

Description

Technical Field

[0001] The present invention relates to the field of new energy heating, and specifically to a combined heating system and control method based on a PVT collector and a dual-source heat pump. Background Art

[0002] As a clean and renewable energy source, solar energy has great potential for development and utilization. In recent years, with the growth of energy demand and the emphasis on environmental protection, the utilization methods of solar energy have been continuously innovated. Among them, the Photovoltaic / Thermal Collector (PVT collector), which integrates the functions of solar photovoltaic conversion and solar thermal conversion, has received extensive attention. The PVT collector aims to achieve the efficient comprehensive utilization of solar energy. Through its photovoltaic conversion part, solar energy is converted into electrical energy, and at the same time, the solar thermal conversion part is used to convert solar energy into heat energy to meet different energy demands.

[0003] However, there are some problems in the existing PVT collectors that need to be solved urgently. Specifically, the photovoltaic conversion part and the solar thermal conversion part of the existing PVT collectors are independent in structure and function, lacking a collaborative working mechanism. This independence results in the inability to achieve effective energy complementarity and optimal configuration between the two parts, limiting the improvement of the overall system performance. For example, when the light intensity is high, the photovoltaic conversion part may reduce the conversion efficiency due to the increase in temperature, while the solar thermal conversion part cannot make full use of this part of the heat for energy reuse; conversely, when the light intensity is weak, the heat output of the solar thermal conversion part is insufficient, and the electrical output of the photovoltaic conversion part is also difficult to meet the demand, and the energy cannot be optimally allocated through cooperation.

[0004] In addition, the working efficiency of the existing PVT collectors is highly dependent on weather conditions. On sunny days, although high energy output can be obtained, on cloudy, rainy days or during periods of insufficient light, the photovoltaic conversion and solar thermal conversion efficiencies will both drop significantly, resulting in obvious intermittency of energy output. This intermittency makes it difficult for PVT collectors to provide a stable and continuous energy supply. Especially in the industrial production field, where high requirements are placed on the stability and continuity of energy, the poor stability of the energy output of the existing PVT collectors cannot meet the demand for uninterrupted energy supply in industrial production, limiting its wide application in the industrial field. Summary of the Invention

[0005] The object of the present invention is to overcome the problems that the photovoltaic component and the solar thermal component in the PVT collector cannot be synergistically utilized and the heating efficiency of the PVT collector is limited by weather conditions, and to provide a combined heating system based on a PVT collector and a dual-source heat pump. The combined heating system can synergistically utilize the photovoltaic component and the solar thermal component in the PVT collector, and combine the PVT collector and the dual-source heat pump to improve the efficient comprehensive utilization of solar energy and the heating efficiency of the heating system under different weather conditions.

[0006] To achieve the above object, in the first aspect of the present invention, a combined heating system based on a PVT collector and a dual-source heat pump is provided. The combined heating system includes a main pipeline, a branch pipeline, a PVT collector, a temperature sensor, a reversing valve, a dual-source heat pump, and a water pump, wherein: The main pipeline is closed and includes a return water section, a heat exchange section, a water supply section, and a heat utilization section distributed in sequence along the flow direction of the working fluid; The PVT collector has a photoelectric conversion part and a solar thermal conversion part that can exchange heat with the heat exchange section. The heat exchange position between the heat exchange section and the photoelectric conversion part is upstream of the heat exchange position between the heat exchange section and the solar thermal conversion part; The temperature sensor is used to monitor the temperature of the working fluid after heat exchange in the heat exchange section; The reversing valve is connected to the heat exchange section, the water supply section, and the branch pipeline. The reversing valve is electrically connected to the temperature sensor. If the temperature of the working fluid monitored by the temperature sensor is lower than the heating temperature set by the system, the reversing valve guides the working fluid from the heat exchange section to the branch pipeline. If the temperature of the working fluid monitored by the temperature sensor is not lower than the heating temperature set by the system, the reversing valve guides the working fluid from the heat exchange section to the water supply section; One end of the branch pipeline is connected to the reversing valve and the other end is connected to the water supply section; The dual-source heat pump is configured to heat the working fluid on the branch pipeline and make the temperature of the heated working fluid not lower than the system set temperature; The water pump is configured to drive the working fluid to flow in the main pipeline and the branch pipeline.

[0007] In some embodiments, the combined heating system further includes a flow regulating valve. The flow regulating valve is arranged on the return water section, and the opening degree of the flow regulating valve increases or remains stable as the working temperature of the PVT collector increases.

[0008] In some embodiments, water tanks are connected to both the main pipeline and the branch pipeline. The water tanks include a circulating water tank and a hot water storage tank, wherein: The circulating water tank is arranged on the branch pipeline and is upstream of the heating position of the dual-source heat pump; The hot water storage tank is arranged on the water supply section, and one end of the branch pipeline away from the reversing valve is communicated with the hot water storage tank.

[0009] In some embodiments, the water tank further includes a cooling water tank, which is disposed on the return water section of the main pipeline, and a water replenishment structure is provided on the cooling water tank.

[0010] In some embodiments, the water pump includes a cooling water pump, a circulating water pump and a supply water pump, wherein: The cooling water pump is arranged on the water return section and is located downstream of the cooling water tank; The circulating water pump is arranged on the branch pipeline and is located between the circulating water tank and the heating position of the dual-source heat pump; The supply water pump is arranged on the water supply section and is located downstream of the hot water storage tank.

[0011] In some embodiments, the power output end of the photoelectric conversion unit is connected to an inverter, the power output end of the inverter is connected to an internal power grid, and the power in the internal power grid is configured to at least provide power required by the combined heating system.

[0012] A second aspect of the present invention provides a method for controlling heating of the above-mentioned combined heating system based on a PVT collector and a dual-source heat pump, the control method comprising a main control method, the main control method comprising the following steps: S100: Acquiring the working fluid temperature T monitored by a temperature sensor; S200: If T <T0,换向阀将换热段与支管路导通,支管路上的工作液经双源热泵加热后重新流回主管路的供水段中; If T≥T0, the reversing valve connects the heat exchange section with the water supply section; Among them, T0 is the heating temperature set by the system.

[0013] In some embodiments, when the combined heating system is further equipped with a flow regulating valve, the flow regulating valve is kept in a normally open state, and the control method includes a first sub-control method, which includes the following steps: S10: obtaining the operating temperature T' of the PVT collector and the opening L of the flow control valve, the allowable operating temperature range of the operating temperature T' of the PVT collector is T1~T2, and the opening L range of the flow control valve is 0%~100%; S11: If T' <T1,则获取距离上一次T’<T1时的时间间隔t; If t ≥ t0, keep the PVT collector off, where t0 is the judgment time set by the system; Otherwise, keep the PVT collector open and reduce the opening L of the flow control valve; If T'>T2, determine whether the opening L of the flow control valve is 100%; If yes, keep the current flow control valve opening L; Otherwise, increase the opening L of the flow control valve; If T1≤T'≤T2, maintain the current opening L of the flow control valve.

[0014] In some embodiments, when the combined heating system is further configured with a cooling water tank, a circulating water tank and a hot water storage tank, and the water pump is configured with a cooling water pump, a circulating water pump and a supply water pump, the cooling water pump and the supply water pump are kept normally open, and the circulating water pump and the dual-source heat pump are kept normally closed, the control method further includes a second sub-control method, and the second sub-control method includes the following steps: S20: Obtaining the liquid level H of the hot water storage tank; S21: If H>H1, keep the circulating water pump and the dual-source heat pump turned off; If H <H2,则保持循环水泵和双源热泵处于打开; If H2≤H≤H1, the circulating water pump and dual-source heat pump maintain the current state; Among them, H1 is the upper limit liquid level set for the hot water storage tank, H2 is the lower limit liquid level set for the hot water storage tank, and H1>H2.

[0015] In some embodiments, the control method further includes a third sub-control method, and the third sub-control method includes the following steps: S30: Obtaining the liquid level H' of the circulating water tank; S31: If H'>H3, keep the cooling water pump closed; If H' <H4,则保持冷却水泵处于打开; If H4≤H'≤H3, the cooling water pump maintains the current state; Among them, H3 is the upper limit liquid level set for the circulating water tank, H4 is the lower limit liquid level set for the circulating water tank, H3>H4; Preferably, before S30, it also includes: obtaining the use status of the PVT collector (3), if the PVT collector is in use, then S20 is performed, otherwise S30 is performed.

[0016] The combined heating system based on the PVT collector and the dual-source heat pump using the above technical solution of the present invention has the following effects: Heat exchange is carried out between the heat exchange section in the main pipeline and the photoelectric conversion section and the photothermal conversion section in the PVT collector. Moreover, the heat exchange position between the heat exchange section and the photoelectric conversion section is upstream of the heat exchange position between the heat exchange section and the photothermal conversion section, so that the heat exchange section first exchanges heat with the photoelectric conversion section to reduce the temperature of the photoelectric conversion section, avoid too high temperature at the photoelectric conversion section from affecting the photovoltaic power generation efficiency, and then the working fluid after heat exchange and cooling of the photoelectric conversion section exchanges heat with the photothermal conversion section to absorb the solar heat and improve the synergy between the photovoltaic and photoelectric parts in the PVT collector.

[0017] When the temperature of the working fluid cannot meet the heating demand after heat exchange in the PVT collector, the working fluid is heated by a dual-source heat pump to make the temperature of the working fluid meet the heating demand. Combining the PVT collector and the dual-source heat pump not only ensures the heating efficiency of the heating system in cloudy days or at night when the solar energy is weak, but also can reduce the electric energy input of the dual-source heat pump.

[0018] Other features and advantages of the present invention will be described in detail in the subsequent specific implementation part. Brief Description of the Drawings

[0019] Figure 1 is a schematic structural diagram of a combined heating system based on a PVT collector and a dual-source heat pump according to the first embodiment of the present invention; Figure 2 is a schematic structural diagram of a combined heating system based on a PVT collector and a dual-source heat pump according to the second embodiment of the present invention; Figure 3 is a schematic structural diagram of a combined heating system based on a PVT collector and a dual-source heat pump according to the third embodiment of the present invention; Figure 4 is a schematic structural diagram of a combined heating system based on a PVT collector and a dual-source heat pump according to the fourth embodiment of the present invention; Figure 5 is a logic block diagram of the main control method in the control method for heating a combined heating system based on a PVT collector and a dual-source heat pump of the present invention; Figure 6 is a logic block diagram of the first sub-control method in the control method for heating a combined heating system based on a PVT collector and a dual-source heat pump of the present invention; Figure 7 is a logic block diagram of the second sub-control method in the control method for heating a combined heating system based on a PVT collector and a dual-source heat pump of the present invention; Figure 8 is a logic block diagram of the third sub-control method in the control method for heating a combined heating system based on a PVT collector and a dual-source heat pump of the present invention; Figure 9It is a logic block diagram of a control method for heating a combined heating system based on a PVT collector and a dual-source heat pump in the first embodiment of the present invention; Figure 10 It is a logic block diagram of a control method for heating a combined heating system based on a PVT collector and a dual-source heat pump in the second embodiment of the present invention.

[0020] Description of the reference numerals 1a, return water section; 1b, heat exchange section; 1c, water supply section; 1d, heat utilization section; 2, branch pipeline; 3, PVT collector; 3a, photovoltaic conversion part; 3b, solar-thermal conversion part; 4, temperature sensor; 5, reversing valve; 6, dual-source heat pump; 7a, circulation water pump; 7b, supply water pump; 7c, cooling water pump; 8, flow regulating valve; 9a, circulation water tank; 9b, hot water storage tank; 9c, cooling water tank; 10, inverter; 11, water replenishing structure; 12, heat utilization equipment; Ⅰ, logic block diagram of the main control method; Ⅱ, logic block diagram of the first sub-control method; Ⅲ, logic block diagram of the second sub-control method; Ⅳ, logic block diagram of the third sub-control method. Detailed implementation manners

[0021] The following provides a detailed description of the specific implementation manners of the present invention. It should be understood that the specific implementation manners described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0022] In the first aspect of the present invention, a combined heating system based on a PVT collector 3 and a dual-source heat pump 6 (hereinafter referred to as the combined heating system) is provided, which synergistically utilizes the photovoltaic component and the solar-thermal component in the PVT collector 3, and combines the PVT collector 3 and the dual-source heat pump 6 to improve the efficient comprehensive utilization of solar energy and enhance the heating efficiency of the heating system under different weather and environmental conditions. As shown in the attached Figure 1 figure, the combined heating system includes a main pipeline, a branch pipeline 2, a PVT collector 3, a temperature sensor 4, a reversing valve 5, a dual-source heat pump 6, and a water pump. A further description of the combined heating system is as follows.

[0023] For the main pipeline: The main pipeline is closed and includes a return water section 1a, a heat exchange section 1b, a water supply section 1c, and a heat utilization section 1d arranged in sequence along the flow direction of the working fluid. The main pipeline serves as the main flow pipeline of the working fluid in the combined heating system, and the flow path of the working fluid in the main pipeline is: return water section 1a → heat exchange section 1b → water supply section 1c → heat utilization section 1d → return water section 1a. Combining the attached Figure 1, when the working fluid flows in the main pipeline, the working fluid in the return water section 1a first flows into the heat exchange section 1b. The working fluid in the heat exchange section 1b is used to exchange heat with the PVT collector 3. The working fluid that meets the heating temperature set by the system then flows into the water supply section 1c. The working fluid in the water supply section 1c then flows into the heat utilization section 1d. After the working fluid provides heat energy to the heat utilization equipment 12 at the heat utilization section 1d, it flows into the return water section 1a. The working fluid in the return water section 1a then reflows into the heat exchange section 1b to realize the flow cycle of the working fluid.

[0024] For the PVT collector 3: The PVT collector 3 has a photoelectric conversion part 3a and a photothermal conversion part 3b. Both the photoelectric conversion part 3a and the photothermal conversion part 3b can exchange heat with the heat exchange section 1b. The heat exchange position between the heat exchange section 1b and the photoelectric conversion part 3a is upstream of the heat exchange position between the heat exchange section 1b and the photothermal conversion part 3b. Specifically, both the photoelectric conversion part 3a and the photothermal conversion part 3b can exchange heat with the heat exchange section 1b. Substantially, it is the photoelectric conversion part 3a and the photothermal conversion part 3b that exchange heat with the working fluid in the heat exchange section 1b. Among them, the photoelectric conversion part 3a is based on the photovoltaic effect and performs photoelectric conversion through a solar panel, converting the light energy in solar energy into electrical energy. During the photoelectric conversion process, the solar panel in the photoelectric conversion part 3a will generate heat. The heat exchange between the photoelectric conversion part 3a and the heat exchange section 1b is to transfer the heat generated by the solar panel into the working fluid in the heat exchange section 1b. Designed in this way, it can not only utilize the heat generated by photovoltaic power generation in the photoelectric conversion part 3a, but also avoid the problem of the decrease in photovoltaic power generation efficiency caused by the too high temperature of the solar panel. In addition, the photothermal conversion part 3b transfers the heat energy in solar energy to the working fluid in the heat exchange section 1b through heat exchange. And the heat exchange position between the heat exchange section 1b and the photoelectric conversion part 3a being upstream of the heat exchange position between the heat exchange section 1b and the photothermal conversion part 3b is to ensure the heat exchange effect of the photoelectric conversion part 3a. In the heat exchange process, the greater the temperature difference between the two groups of media undergoing heat exchange, the more obvious the heat exchange effect. The working fluid in the heat exchange section 1b first exchanges heat with the photoelectric conversion part 3a, enabling the photoelectric conversion part 3a to exchange heat with the working fluid at a lower temperature first, so as to ensure the heat exchange effect of the photoelectric conversion part 3a, thereby ensuring the power generation efficiency of the solar panel and improving the comprehensive utilization efficiency of solar energy.

[0025] For the temperature sensor 4: The temperature sensor 4 is used to monitor the temperature of the working fluid after heat exchange in the heat exchange section 1b. To ensure the stability of heat supply, the working fluid temperature monitored by the temperature sensor 4 is the average temperature of the working fluid within a certain time period. Generally, the time period can be selected as 5 minutes, 10 minutes, and usually the time period needs to be less than 30 minutes.

[0026] For the reversing valve 5: The reversing valve 5 is connected to the heat exchange section 1b, the water supply section 1c, and the branch pipeline 2, and the reversing valve 5 is electrically connected to the temperature sensor 4. If the temperature of the working fluid monitored by the temperature sensor 4 is lower than the heating temperature set by the system, the reversing valve 5 will conduct the heat exchange section 1b and the branch pipeline 2, and direct the working fluid from the heat exchange section 1b to the branch pipeline 2. If the temperature of the working fluid monitored by the temperature sensor 4 is not lower than the heating temperature set by the system, the reversing valve 5 will conduct the heat exchange section 1b and the water supply section 1c, and direct the working fluid from the heat exchange section 1b to the water supply section 1c. Specifically, the reversing valve 5 uses an electric three-way control valve, which has one inlet and two outlets. The inlet is connected to the heat exchange section 1b, and the two outlets are respectively connected to the water supply section 1c and the branch pipeline 2. The electric three-way control valve and the temperature sensor 4 can be electrically connected through a PLC control program to realize the switching of the flow direction of the working fluid based on the temperature of the working fluid monitored by the temperature sensor 4.

[0027] For the branch pipeline 2: One end of the branch pipeline 2 is connected to the reversing valve 5 and the other end is connected to the water supply section 1c. As a branch of the main pipeline, the working fluid flowing through the branch pipeline 2 will eventually flow back into the water supply section 1c of the main pipeline.

[0028] For the dual-source heat pump 6: The dual-source heat pump 6 is configured to heat the working fluid on the branch pipeline 2 and make the temperature of the heated working fluid not lower than the system-set temperature. The working fluid whose temperature still does not meet the heating temperature set by the system after heat exchange with the PVT collector 3 will flow to the branch pipeline 2, and then after the dual-source heat pump 6 heats the working fluid in the branch pipeline 2 and meets the heating temperature set by the system, the working fluid will flow back into the water supply section 1c in the main pipeline and can be used for heating. The combined heating of the PVT collector 3 and the dual-source heat pump 6 is realized to ensure the heating efficiency of the heating system under different weather conditions.

[0029] For the water pump: The water pump is configured to drive the working fluid to flow in the main pipeline and the branch pipeline 2. To ensure the flow stability and heating stability of the working fluid, the water pump generally uses a variable-frequency constant-pressure water pump.

[0030] In some embodiments, in combination with the attached Figure 1 、attached Figure 2 and attached Figure 4As shown, the combined heating system further includes a flow regulating valve 8. The flow regulating valve 8 is provided on the return water section 1a, and the opening degree of the flow regulating valve 8 increases or remains stable as the operating temperature of the PVT collector 3 increases. Specifically, the operating temperature of the PVT collector 3 refers to the temperature of the solar panel in the photoelectric conversion section 3a. Therefore, the opening degree of the flow regulating valve 8 increases or remains stable as the temperature of the solar panel in the PVT collector 3 increases. When the operating temperature of the PVT collector 3 increases, the opening degree of the flow regulating valve 8 generally also increases, thereby increasing the flow rate of the working fluid flowing into the PVT collector 3 and enhancing the heat exchange effect between the photoelectric conversion section 3a and the working fluid. Similarly, when the operating temperature of the PVT collector 3 decreases, the opening degree of the flow regulating valve 8 generally also decreases, thereby reducing the flow rate of the working fluid flowing into the PVT collector 3 and reducing the heat exchange effect between the photoelectric conversion section 3a and the working fluid. The purpose of adjusting the opening degree of the flow regulating valve 8 is to keep the operating temperature of the PVT collector 3 at a suitable temperature. Too high or too low operating temperature of the PVT collector 3 will affect the photoelectric conversion efficiency. Generally, the suitable or allowable operating temperature of the PVT collector 3 is 30°C to 50°C.

[0031] In addition, the opening degree range of the flow regulating valve 8 is 0% to 100%. When the opening degree of the flow regulating valve 8 is 0%, the flow regulating valve 8 is in a closed state, and at this time, the flow rate passing through the flow regulating valve 8 is zero. When the opening degree of the flow regulating valve 8 is 100%, the flow regulating valve 8 is in a fully open state, and at this time, the flow rate passing through the flow regulating valve 8 is the maximum value allowed to flow through the flow regulating valve 8. At this time, even if the operating temperature of the PVT collector 3 continues to rise, the opening degree of the flow regulating valve 8 can only be stable at 100%. At this time, to avoid the suitable or allowable temperature from continuing to rise, an external cooling device can be used to cool the photoelectric conversion section 3a.

[0032] To ensure that the working fluid in the main pipeline can circulate, the opening degree of the flow regulating valve 8 generally will not be reduced to 0%. When the operating temperature of the PVT collector 3 is lower than 30°C, it indicates that the solar intensity is low. If the operating temperature of the PVT collector 3 is lower than 30°C and remains for a certain period of time, the utilization efficiency of the PVT collector 3 for solar energy is low. At this time, the PVT collector 3 can be turned off, and the heating demand of the heating system is provided by the dual-source heat pump 6 to meet the heating function of the heating system in weather conditions such as cloudy days and nights.

[0033] In some embodiments, in combination with the attached Figure 1 attachment Figure 3 and attachment Figure 4As shown in the figure, water tanks are connected to both the main pipeline and the branch pipeline 2. The water tank includes a circulating water tank 9a and a hot water storage tank 9b. Among them, the circulating water tank 9a is arranged on the branch pipeline 2 and upstream of the heating position of the dual-source heat pump 6, and the hot water storage tank 9b is arranged on the water supply section 1c. One end of the branch pipeline 2 away from the reversing valve 5 is connected to the hot water storage tank 9b. The setting of the water tank can improve the water storage capacity in the combined heating system, thereby ensuring the heating capacity of the combined heating system.

[0034] Specifically, when the heat demand increases, the flow demand of the working fluid in the heat-using section 1d increases. At this time, the working fluid in the hot water storage tank 9b that meets the heating temperature set by the system will flow to the heat-using section 1d preferentially, and the liquid level in the hot water storage tank 9b will drop, thereby reducing the flow pressure of the working fluid in the heat exchange section 1b. If the flow pressure of the working fluid in the heat exchange section 1b is large, it will cause the working fluid in the heat exchange section 1b to fail to exchange heat with the PVT collector 3 in time, resulting in a reduction in the heat utilization rate of the PVT collector 3.

[0035] The setting of the circulating water tank 9a is to meet the situation where the working fluid capacity in the hot water storage tank 9b cannot meet the heating demand. When the working fluid capacity in the hot water storage tank 9b cannot meet the heating demand, the working fluid in the circulating water tank 9a will be heated by the dual-source heat pump 6 to reach the heating temperature set by the system. After meeting the temperature condition, the working fluid flows into the heating section and the heat-using section 1d, and is used for heating in the heat-using section 1d.

[0036] In some embodiments, in combination with the attached Figure 1 attachment Figure 3 and the attached Figure 4 As shown, the water tank further includes a cooling water tank 9c. The cooling water tank 9c is arranged on the return water section 1a of the main pipeline, and a water replenishment structure 11 is arranged on the cooling water tank 9c. On the one hand, the cooling water tank 9c can also improve the water storage capacity in the combined heating system. On the other hand, during the operation of the combined heating system, the working fluid will inevitably leak and be consumed. At this time, the water replenishment structure 11 arranged on the cooling water tank 9c can be used to replenish the working fluid into the combined heating system. Generally, the replenished working fluid has a lower temperature, and in the entire combined heating system, the working fluid in the return water section 1a has the lowest temperature. Therefore, the cooling water tank 9c is suitable as the water replenishment point for the replenished working fluid. Among them, generally, a water replenishment port and a water replenishment pipe are reserved on the water tank as the water replenishment structure 11. The water replenishment port is normally closed and opened during water replenishment.

[0037] In addition, as shown in the attached Figure 3 attachment Figure 4As shown, a water replenishing structure 11 can also be provided on the circulating water tank 9a. Since the temperature of the working fluid flowing in the branch pipeline 2 does not meet the heating temperature set by the system, the working fluid in the circulating water tank 9a provided on the branch pipeline 2 also belongs to the low-temperature working fluid with a temperature lower than the heating temperature set by the system. Therefore, the circulating water tank 9a can also be used as a water replenishing point for supplementing the working fluid.

[0038] In some embodiments, in combination with the attached Figure 3 and the attached Figure 4 As shown, the water pumps include a cooling water pump 7c, a circulating water pump 7a, and a supply water pump 7b. The cooling water pump 7c is provided on the return water section 1a and is located downstream of the cooling water tank 9c. The circulating water pump 7a is provided on the branch pipeline 2 and is located between the circulating water tank 9a and the heating position of the dual-source heat pump 6. The supply water pump 7b is provided on the water supply section 1c and is located downstream of the hot water storage tank 9b. Through the setting of multiple water pumps, the stable flow of the working fluid in the entire combined heating system is ensured. In addition, the setting of multiple water pumps can independently cut off the flow of the working fluid on the return water section 1a, the heating section, and the branch pipeline 2 to meet different heating requirements.

[0039] In some embodiments, in combination with the attached Figure 1 and the attached Figure 2 and the attached Figure 3 and in combination with the attached Figure 4 As shown, the power output terminal of the photovoltaic conversion unit 3a is connected to an inverter 10. The power output terminal of the inverter 10 is linked to the internal power grid, and the electric energy in the internal power grid is configured to at least supply the electric energy required by the combined heating system. The electric energy output by the photovoltaic converter in the PVT collector 3 is direct current. The inverter 10 is provided to convert the direct current into industrial frequency alternating current and store it in the internal power grid for production and living use. During the operation of the combined heating system, the system itself also has a demand for electric energy. The electric energy stored in the internal power grid is preferentially used for the electric energy demand of the combined heating system, and the excess electric energy in the internal power grid can be provided externally. If the electric energy stored in the internal power grid cannot meet the electric energy demand of the combined heating system, electric energy needs to be introduced from the outside to supply sufficient electric energy to the combined heating system to ensure the normal operation of the combined heating system.

[0040] The second aspect of the present invention provides a control method for heating the combined heating system based on the PVT collector 3 and the dual-source heat pump 6 in any of the above embodiments. The control method includes a main control method. In combination with the attached Figure 5 , the main control method includes the following steps: S100: Obtain the temperature T of the working fluid monitored by the temperature sensor 4; S200: If T < T0, the reversing valve 5 conducts the heat exchange section 1b and the branch pipeline 2, and the working fluid on the branch pipeline 2 is heated by the dual-source heat pump 6 and then flows back into the water supply section 1c of the main pipeline; If T≥T0, the reversing valve 5 connects the heat exchange section 1b with the water supply section 1c; Among them, T0 is the heating temperature set by the system.

[0041] During the circulation of the working fluid in the main pipeline, the working fluid with a lower temperature in the return water section 1a flows into the heat exchange section 1b, and the working fluid in the heat exchange section 1b is heat exchanged through the PVT collector 3. The temperature sensor 4 monitors the temperature of the working fluid after the heat exchange, and controls the reversing valve 5 based on the comparison result between the working fluid temperature T after the heat exchange and the heating temperature T0 set by the system, so that the working fluids of different temperatures can flow along different paths to achieve the heating function. Generally, the heating temperature set by the system is determined based on the heating temperature required by the heat-using device 12. For example, if the heat demand of the heat-using device 12 is 50°C, the heating temperature set by the system should be greater than or equal to 50°C.

[0042] If the working fluid temperature T after heat exchange is lower than the heating temperature T0 set by the system, the reversing valve 5 connects the heat exchange section 1b with the branch pipeline 2, so that the working fluid whose temperature does not meet the heating conditions flows into the branch pipeline 2, and the working fluid in the branch pipeline 2 is heated by the dual-source heat pump 6. The temperature of the heated working fluid meets the heating conditions and flows back to the heating section in the main pipeline, and then flows to the heat-using section 1d through the heating section to supply heat to the heat-using equipment 12.

[0043] If the working fluid temperature T after heat exchange is not less than the heating temperature T0 set by the system, the heat exchange valve connects the heat exchange section 1b with the heating section, so that the working fluid whose temperature meets the heating conditions flows directly to the heating section, and then flows to the heat-using section 1d through the heating section to provide heat to the heat-using equipment 12.

[0044] In some embodiments, the combination Figure 6 When the combined heating system is also equipped with a flow regulating valve 8, the flow regulating valve 8 remains in a normally open state. The control method includes a first sub-control method, and the first sub-control method includes the following steps: S10: obtaining the operating temperature T' of the PVT collector 3 and the opening L of the flow regulating valve 8, the allowable operating temperature range of the operating temperature T' of the PVT collector 3 is T1-T2, and the opening L range of the flow regulating valve 8 is 0%-100%; S11: If T' <T1,则获取距离上一次T’<T1时的时间间隔t; If t≥t0, keep the PVT collector 3 turned off, where t0 is the judgment time set by the system; Otherwise, keep the PVT collector 3 open and reduce the opening L of the flow regulating valve 8; If T'>T2, then determine whether the opening L of the flow control valve 8 is 100%; If yes, keep the current opening L of the flow control valve 8; Otherwise, increase the opening L of the flow control valve 8; If T1≤T'≤T2, the current opening L of the flow control valve 8 is maintained.

[0045] In this embodiment, the allowable operating temperature range of the PVT collector 3 is 30° C. to 50° C., and the judgment time set by the system is 30 minutes.

[0046] When the operating temperature of the PVT collector 3 is less than 30° C. and is maintained for 30 minutes, the PVT collector 3 is closed. At this time, when the working fluid flows through the PVT collector 3 , no heat exchange occurs in the PVT collector 3 .

[0047] When the PVT collector 3 is in operation, the opening of the flow regulating valve 8 is positively adjusted along with the operating temperature of the PVT collector 3. The working fluid flowing through the PVT collector 3 is not only used for heat exchange, but also used to reduce the temperature of the solar panels of the PVT collector 3 to keep the operating temperature of the PVT collector 3 at 30°C to 50°C. The flow regulating valve 8 adopts an electrically controlled regulating valve to improve the degree of adaptive regulation.

[0048] When the operating temperature of the PVT collector 3 is greater than 30°C and the opening of the flow regulating valve 8 is 100%, the working fluid can no longer meet the cooling effect of the operating temperature of the PVT collector 3. At this time, the solar panels of the PVT collector 3 can be cooled by an external cooling device to keep the operating temperature of the PVT collector 3 at 30°C~50°C.

[0049] In some embodiments, the combination Figure 7 When the combined heating system is also equipped with a cooling water tank 9c, a circulating water tank 9a and a hot water storage tank 9b, and the water pump is equipped with a cooling water pump 7c, a circulating water pump 7a and a supply water pump 7b, the cooling water pump 7c and the supply water pump 7b are kept open, and the circulating water pump 7a and the dual-source heat pump 6 are kept closed. The control method also includes a second sub-control method, which includes the following steps: S20: Obtaining the liquid level H of the hot water storage tank 9b; S21: If H>H1, keep the circulating water pump 7a and the dual-source heat pump 6 turned off; If H <H2,则保持循环水泵7a和双源热泵6处于打开; If H2≤H≤H1, the circulating water pump 7a and the dual-source heat pump 6 maintain the current state; Among them, H1 is the upper limit liquid level set for the hot water storage tank 9b, H2 is the lower limit liquid level set for the hot water storage tank 9b, and H1>H2.

[0050] In this embodiment, when the liquid level H in the hot water storage tank 9b is greater than the set upper limit liquid level H1 of the hot water storage tank 9b, the circulation water pump 7a and the dual-source heat pump 6 are turned off. At this time, the working fluid in the branch pipeline 2 will not flow to the heating section, and all the working fluid used in the heat-using section 1d comes from the working fluid in the hot water storage tank 9b. It should be noted that during this process, the working fluid heated by the PVT collector 3 in the heat exchange section 1b will still flow to the heating section or the branch pipeline 2 through the reversing valve 5. In addition, during this process, the liquid level H in the hot water storage tank 9b will be in the liquid level stage of H2≤H≤H1. At this time, the circulation water pump 7a and the dual-source heat pump 6 maintain their current states, that is, the circulation water pump 7a and the dual-source heat pump 6 remain off. At this time, all the working fluid used in the heat-using section 1d still comes from the working fluid in the hot water storage tank 9b.

[0051] When the liquid level H in the hot water storage tank 9b is less than the set lower limit liquid level H2 of the hot water storage tank 9b, the circulation water pump 7a and the dual-source heat pump 6 are kept on. At this time, the working fluid in the branch pipeline 2 is heated by the dual-source heat pump 6 until it meets the heating condition and then flows to the heating section. The working fluid used in the heat-using section 1d comes from the working fluid in the hot water storage tank 9b and the working fluid in the branch pipeline 2. During this stage, the working fluid in the hot water storage tank 9b is consumed less, and the liquid level in the hot water storage tank 9b will rise. In addition, during this process, the liquid level H in the hot water storage tank 9b will also be in the liquid level stage of H2≤H≤H1. At this time, the circulation water pump 7a and the dual-source heat pump 6 maintain their current states, that is, the circulation water pump 7a and the dual-source heat pump 6 remain on until the liquid level H in the hot water storage tank 9b is greater than the set upper limit liquid level H1 of the hot water storage tank 9b.

[0052] In some embodiments, in combination with the attached Figure 8 , the control method further includes a third sub-control method, and the third sub-control method includes the following steps: S30: Obtain the liquid level H' of the circulation water tank 9a; S31: If H'>H3, keep the cooling water pump 7c off; If H'<H4, keep the cooling water pump 7c on; If H4≤H'≤H3, the cooling water pump 7c maintains its current state; wherein, H3 is the set upper limit liquid level of the circulation water tank 9a, H4 is the set lower limit liquid level of the circulation water tank 9a, and H3>H4.

[0053] In this embodiment, when the liquid level H' in the circulating water tank 9a is greater than the set upper limit liquid level H3 of the circulating water tank 9a, the cooling water pump 7c is turned off. At this time, the working fluid in the return water section 1a will not flow to the heat exchange section 1b, and all the working fluid used in the heat utilization section 1d comes from the hot water storage tank 9b or the working fluid in both the hot water storage tank 9b and the circulating water tank 9a. When all the working fluid in the heat utilization section 1d comes from the hot water storage tank 9b and the liquid level H' in the circulating water tank 9a is greater than the set upper limit liquid level H3 of the circulating water tank 9a, the working fluid in the circulating water tank 9a will not flow to the heat supply section either. Therefore, when the liquid level H' in the circulating water tank 9a is greater than the set upper limit liquid level H3 of the circulating water tank 9a, there is a risk of overflow in the circulating water tank 9a.

[0054] It should be noted that through the settings of the cooling water pump 7c, the circulating water pump 7a, and the supply water pump 7b, the flow rate of the working fluid in the entire main pipeline remains stable, that is: the total amount of the working fluid flowing into the heat supply section and the branch pipeline 2 through the reversing valve 5 is equal to the total amount of the working fluid flowing from the heat supply section into the heat utilization section 1d. Therefore, the working fluid capacity in the heat supply section and the branch pipeline 2 maintains a dynamic balance. Without considering the working fluid capacity in the pipeline, the total amount of the working fluid in the heat supply section and the branch pipeline 2 is equal to the sum of the working fluid capacities in the hot water storage tank 9b and the circulating water tank 9a.

[0055] Therefore, it is only necessary to ensure that the sum of the working fluid capacities in the hot water storage tank 9b and the circulating water tank 9a satisfies: when the circulating water tank 9a is critically full, the liquid level H in the hot water storage tank 9b is less than the set lower limit liquid level H2 of the hot water storage tank 9b. At this time, the circulating water pump 7a and the dual-source heat pump 6 are turned on and the working fluid in the circulating water tank 9a is heated and discharged, thereby eliminating the risk of overflow in the circulating water tank 9a. In actual application, the working fluid flow rate fluctuates frequently. Therefore, when the liquid level H' in the circulating water tank 9a is greater than the set upper limit liquid level H3 of the circulating water tank 9a, the cooling water pump 7c is turned off, which can improve the reliability of the combined heat supply system.

[0056] When the working fluid in the circulating water tank 9a flows to the heat supply section after being heated, the liquid level H' in the circulating water tank 9a will be in the liquid level stage where H4 ≤ H' ≤ H3. At this time, the cooling water pump 7c maintains its current off state.

[0057] When the liquid level H' in the circulating water tank 9a is less than the set lower limit liquid level H4 of the circulating water tank 9a, the cooling water pump 7c is turned on, and the working fluid in the return water section 1a is replenished to the hot water storage tank 9b and the circulating water tank 9a after heat exchange through the heat exchange section 1b. Similarly, in this stage, the liquid level in the circulating water tank 9a will rise, and the liquid level H' in the circulating water tank 9a will also be in the liquid level stage where H4 ≤ H' ≤ H3. At this time, the cooling water pump 7c maintains its current on state until the liquid level H' in the circulating water tank 9a is greater than the set upper limit liquid level H3 of the circulating water tank 9a.

[0058] In some preferred embodiments, between S30, it further includes: obtaining the usage status of the PVT collector 3. If the PVT collector 3 is in the usage state, then S20 is performed; otherwise, S30 is performed. When the PVT collector 3 is in the usage state and the cooling water pump 7c is in the closed state, there is no working fluid flowing in the heat exchange section 1b at this time, which will reduce the utilization efficiency of the PVT collector 3 for solar energy. Therefore, when the PVT collector 3 is in the usage state, the cooling water pump 7c is always in the open state to ensure the utilization efficiency of the PVT collector 3 for solar energy. When the PVT collector 3 is in the closed state, the switch of the cooling water pump 7c is controlled based on the liquid level of the circulation water tank 9a. Among them, when the PVT collector 3 is in the closed state and the cooling transfer pump is in the open state, all the working fluid flowing through the heat exchange section 1b flows into the circulation water tank 9a.

[0059] Combined with the attached Figure 9 , when the combined heating system is configured with a flow regulating valve 8, a cooling water tank 9c, a circulation water tank 9a, a hot water storage tank 9b, a cooling water pump 7c, a circulation water pump 7a, and a hot water storage pump, and the control method includes a main control method, a first sub-control method, a second sub-control method, and a third sub-control method, the present invention provides the following embodiments of the control method.

[0060] When the PVT collector 3 is in the open state, the main control method, the first sub-control method, and the second sub-control method are performed to control and adjust the reversing valve 5, the flow regulating valve 8, the circulation water pump 7a, and the dual-source heat pump 6.

[0061] When the PVT collector 3 is in the closed state, first the third sub-control method is performed to first control and adjust the switch of the cooling water pump 7c, and then the main control method and the second sub-control method are performed to control the reversing valve 5, the circulation water pump 7a, and the dual-source heat pump 6. At this time, since the PVT collector 3 is in the closed state, the flow regulating valve 8 does not need to be adjusted.

[0062] It should be noted that when the cooling water pump 7c is in the open state, there is working fluid flowing in the heat exchange section 1b, and the temperature sensor 4 needs to monitor the temperature of the working fluid to control the reversing valve 5 to determine the flow direction of the working fluid. When the cooling water pump 7c is in the closed state, there is no working fluid flowing in the heat exchange section 1b, and at this time the temperature sensor 4 is actually in an idle state. At this time, after performing the third sub-control method and keeping the cooling water pump 7c closed, the main control method can still be performed, simplifying the control method.

[0063] Combined with the attached Figure 10, the present invention also provides another embodiment of the following control method, which is different in that: when the PVT collector 3 is in the closed state, the third sub-control method is first performed. First, the switch of the cooling water pump 7c is controlled and adjusted, and then whether to run the main control method is determined based on the switch state of the cooling water pump 7c. Specifically, when the cooling water pump 7c is in the open state, the main control method and the second sub-control method are run after the third sub-control method is run. When the cooling water pump 7c is in the closed state, the second sub-control method is directly run after the third sub-control method is run.

[0064] It should be noted in this embodiment that in S31 of the third sub-control method, if H4 ≤ H' ≤ H3, the cooling water pump 7c maintains its current state. And when H4 ≤ H' ≤ H3, the cooling water pump 7c may maintain the open state or the closed state. Therefore, when H4 ≤ H' ≤ H3 and the cooling water pump 7c maintains the open state, the main control method and the second sub-control method are run; when H4 ≤ H' ≤ H3 and the cooling water pump 7c maintains the closed state, the second sub-control method is run.

[0065] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0066] In addition, it should be noted that, in the case of no contradiction, the various specific technical features described in the above specific embodiments can be combined in any suitable way. To avoid unnecessary repetition, the present invention will not describe various possible combination methods separately.

[0067] In addition, any combination can be made between various different embodiments of the present invention as long as it does not violate the idea of the present invention, and it should also be regarded as the content disclosed by the present invention.

Claims

1. A combined heating system based on a PVT collector and a dual-source heat pump, characterized in that The combined heating system includes a main pipeline, branch pipelines (2), PVT collectors (3), temperature sensors (4), reversing valves (5), dual-source heat pumps (6), and water pumps, where: The main pipeline is closed and includes a return water section (1a), a heat exchange section (1b), a water supply section (1c), and a heat utilization section (1d) distributed in sequence along the flow direction of the working fluid; The PVT collector (3) has a photoelectric conversion part (3a) and a photothermal conversion part (3b) capable of exchanging heat with the heat exchange section (1b), and the heat exchange position between the heat exchange section (1b) and the photoelectric conversion part (3a) is upstream of the heat exchange position between the heat exchange section (1b) and the photothermal conversion part (3b); The temperature sensor (4) is used to monitor the temperature of the working fluid after heat exchange in the heat exchange section (1b); The reversing valve (5) is connected to the heat exchange section (1b), the water supply section (1c), and the branch pipeline (2), and the reversing valve (5) is electrically connected to the temperature sensor (4). If the temperature of the working fluid monitored by the temperature sensor (4) is lower than the heating temperature set by the system, the reversing valve (5) guides the working fluid from the heat exchange section (1b) to the branch pipeline (2). If the temperature of the working fluid monitored by the temperature sensor (4) is not lower than the heating temperature set by the system, the reversing valve (5) guides the working fluid from the heat exchange section (1b) to the water supply section (1c); One end of the branch pipeline (2) is connected to the reversing valve (5) and the other end is connected to the water supply section (1c); The dual-source heat pump (6) is configured to heat the working fluid on the branch pipeline (2) and make the temperature of the heated working fluid not lower than the system set temperature; The water pump is configured to drive the working fluid to flow in the main pipeline and the branch pipeline (2).

2. The combined heating system based on a PVT collector and a dual-source heat pump according to claim 1, wherein The combined heating system further includes a flow regulating valve (8), the flow regulating valve (8) is arranged on the return water section (1a), and the opening degree of the flow regulating valve (8) increases or remains stable as the working temperature of the PVT collector (3) increases.

3. The combined heating system based on a PVT collector and a dual-source heat pump according to claim 1, wherein Water tanks are connected to both the main pipeline and the branch pipeline (2), and the water tanks include a circulation water tank (9a) and a hot water storage tank (9b), where: The circulation water tank (9a) is arranged on the branch pipeline (2) and upstream of the heating position of the dual-source heat pump (6); The hot water storage tank (9b) is arranged on the water supply section (1c), and one end of the branch pipeline (2) far from the reversing valve (5) is connected to the hot water storage tank (9b).

4. The combined heating system based on a PVT collector and a dual-source heat pump according to claim 3, wherein, The water tank further includes a cooling water tank (9c), the cooling water tank (9c) is arranged on the return water section (1a) of the main pipeline, and a water replenishing structure (11) is arranged on the cooling water tank (9c).

5. The combined heating system based on a PVT collector and a dual-source heat pump according to claim 4, wherein The water pump includes a cooling water pump (7c), a circulation water pump (7a), and a supply water pump (7b), where: The cooling water pump (7c) is arranged on the return water section (1a) and downstream of the cooling water tank (9c); The circulation water pump (7a) is arranged on the branch pipeline (2) and between the circulation water tank (9a) and the heating position of the dual-source heat pump (6); The supply water pump (7b) is arranged on the water supply section (1c) and is located downstream of the hot water storage tank (9b).

6. The combined heating system based on a PVT collector and a dual-source heat pump according to any one of claims 1 to 5, characterized in that, The power output end of the photoelectric conversion unit (3a) is connected to an inverter (10), and the power output end of the inverter (10) is connected to an internal power grid, and the power in the internal power grid is configured to be used at least to provide power required by the combined heating system.

7. A control method for heating a combined heating system based on a PVT collector and a dual-source heat pump as described in any one of claims 1 to 6, characterized in that, The control method includes a main control method, and the main control method includes the following steps: S100: obtaining the working fluid temperature T monitored by the temperature sensor (4); S200: If T <T0,换向阀(5)将换热段(1b)与支管路(2)导通,支管路(2)上的工作液经双源热泵(6)加热后重新流回主管路的供水段(1c)中; If T ≥ T0, the reversing valve (5) connects the heat exchange section (1b) and the water supply section (1c); Among them, T0 is the heating temperature set by the system.

8. The control method according to claim 7, wherein When the combined heating system is further equipped with a flow regulating valve (8), the flow regulating valve (8) remains in a normally open state, and the control method comprises a first sub-control method, wherein the first sub-control method comprises the following steps: S10: obtaining the operating temperature T' of the PVT collector (3) and the opening L of the flow control valve (8); the allowable operating temperature range of the operating temperature T' of the PVT collector (3) is T1-T2, and the opening L range of the flow control valve (8) is 0%-100%; S11: If T' <T1,则获取距离上一次T’<T1时的时间间隔t; If t ≥ t0, keep the PVT collector (3) turned off, where t0 is the judgment time set by the system; Otherwise, keep the PVT collector (3) open and reduce the opening L of the flow control valve (8); If T'>T2, then determine whether the opening L of the flow control valve (8) is 100%; If yes, the current opening L of the flow control valve (8) is maintained; Otherwise, increase the opening L of the flow control valve (8); If T1≤T'≤T2, the current opening L of the flow control valve (8) is maintained.

9. The control method according to claim 7 or 8, characterized in that, When the combined heating system is further configured with a cooling water tank (9c), a circulating water tank (9a) and a hot water storage tank (9b), and the water pump is configured with a cooling water pump (7c), a circulating water pump (7a) and a supply water pump (7b), the cooling water pump (7c) and the supply water pump (7b) are kept normally open, and the circulating water pump (7a) and the dual-source heat pump (6) are kept normally closed, the control method further includes a second sub-control method, and the second sub-control method includes the following steps: S20: Obtaining the liquid level H of the hot water storage tank (9b); S21: If H>H1, keep the circulating water pump (7a) and the dual-source heat pump (6) turned off; If H <H2,则保持循环水泵(7a)和双源热泵(6)处于打开; If H2≤H≤H1, the circulating water pump (7a) and the dual-source heat pump (6) maintain the current state; Wherein, H1 is an upper limit liquid level set for the hot water storage tank (9b), H2 is a lower limit liquid level set for the hot water storage tank (9b), and H1>H2.

10. The control method according to claim 9, characterized in that, The control method further includes a third sub-control method, and the third sub-control method includes the following steps: S30: Obtain the liquid level H' of the circulation water tank (9a); S31: If H' > H3, keep the cooling water pump (7c) closed; If H' < H4, keep the cooling water pump (7c) open; If H4 ≤ H' ≤ H3, the cooling water pump (7c) maintains its current state; Wherein, H3 is the set upper liquid level of the circulation water tank (9a), H4 is the set lower liquid level of the circulation water tank (9a), and H3 > H4; Preferably, between S30, it further includes: obtaining the usage status of the PVT collector (3), if the PVT collector (3) is in the usage state, then perform S20, otherwise perform S30.

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