PV / T electricity storage direct drive heat pump drying system

Abstract

The invention discloses a PV / T power storage direct-drive heat pump drying system, which belongs to the field of solar heat pump combined drying and comprises a PV / T combined heat and power generation system, a multi-heat-source variable-frequency heat pump system and a drying room drying system. The PV / T combined heat and power generation system comprises a PV / T array assembly, an inverse control all-in-one machine, a storage battery pack, a heat collection pump and a water tank which are sequentially communicated end to end, and a water side evaporator is arranged in the water tank. The system takes solar energy, air energy and mains supply as input and hot air as output, the solar energy is converted into heat energy and electric energy through PV / T, the electric energy is utilized by the system through the inverse control all-in-one machine or stored by the storage battery pack, the heat energy is temporarily stored in the water tank, the storage battery pack can achieve peak load shifting of fluctuating solar energy, the electricity taking amount of the system from a power grid is reduced, and energy is saved. And the economical efficiency of the system is ensured. The three evaporators of the multi-heat-source variable-frequency heat pump system can extract heat from air, the water tank and moisture exhausted from the drying room, heat sources are flexibly configured according to actual operation conditions, the energy efficiency ratio of the system is increased, and the multi-heat-source variable-frequency heat pump system has high economic and social values.

Description

Technical Field

[0001] The present invention relates to the technical field of solar heat pump combined drying, and in particular to a PV / T electricity storage directly driven heat pump drying system. Background Art

[0002] As a ubiquitous and free renewable energy source, solar energy's efficient and low-cost utilization holds significant value and significance for global economic and social development and climate change mitigation. Among solar energy utilization devices, traditional solar thermal devices, such as all-glass vacuum tube solar collectors and flat-plate solar collectors, offer high photothermal conversion efficiencies but produce low-quality thermal energy. Trough, tower, and dish solar thermal power generation systems can convert solar energy into high-quality electricity, but their efficiency is generally low. Photovoltaic modules, such as monocrystalline silicon, polycrystalline silicon, and perovskite, can generate high-quality electricity, but their photoelectric conversion efficiency is generally low because they fail to utilize the majority of long-wavelength radiation, resulting in consistently low solar energy utilization efficiency. With the continuous advancement of solar energy utilization devices, integrated photovoltaic / thermal devices (PV / T) have attracted widespread attention worldwide due to their ability to convert solar energy into both photoelectric and photothermal energy, achieving photoelectric and photothermal efficiencies as high as 80%. Combining PV / T with heat pumps to create energy supply systems effectively mitigates the unreliable nature of solar energy and the high energy consumption of heat pumps, and has long been a research hotspot for many scholars in the renewable energy field.

[0003] To address the aforementioned technical issues, Chinese patent application number 202311269374.9 discloses a PV / T solar heat pump combined drying system, comprising a heat pump heating system, a solar photovoltaic thermal system, and a drying oven. The heat pump heating system also includes a compressor, copper pipes, a heat exchanger, a condenser, and a regenerator, forming a closed circuit. Although the heat exchanger recovers some of the waste heat from the exhaust gas, the high relative humidity and large specific heat capacity of the exhaust gas limit the amount of heat that can be recovered without a phase-conversion heat exchanger. Furthermore, the system lacks a heat storage device, which can affect the system's operating efficiency during periods of unstable solar energy. The overall energy efficiency of the entire system still has significant room for improvement. Chinese patent application number 202411544566.0 discloses a dual-source heat pump direct expansion drying system based on photovoltaic thermal energy and its operation method. The system includes a photovoltaic thermal module, a PV / T heat source side plate heat exchanger, a liquid reservoir, a four-way reversing valve, an evaporator, a condenser, a compressor, a first solenoid valve and a second solenoid valve. The photovoltaic thermal module is connected to the PV / T heat source side plate heat exchanger to provide a heat source to the PV / T heat source side plate heat exchanger. The liquid outlet of the liquid reservoir is connected to the liquid inlet of the PV / T heat source side plate heat exchanger through the first solenoid valve, and is connected to the liquid inlet of the evaporator through the second solenoid valve. The liquid outlet of the PV / T heat source side plate heat exchanger is connected in parallel with the liquid outlet of the evaporator through the four-way reversing valve, and is connected in series with the liquid inlet of the compressor. The liquid outlet of the compressor is connected to the condenser, and the condenser is connected to the liquid reservoir through the four-way reversing valve. While this dual-source heat pump effectively utilizes both photovoltaic and solar thermal energy from solar energy, the system's waste heat is directly discharged into the atmosphere. This high-temperature, relatively humid air contains a significant amount of valuable heat energy required for the drying room, which has significant recycling value and should not be wasted. Furthermore, the system lacks batteries, making it difficult to offset peak and valley fluctuations in solar energy, and its off-grid operation is unstable. Therefore, a PV / T energy storage, direct-driven heat pump drying system was proposed. Summary of the Invention

[0004] The present invention provides a PV / T electricity storage direct-drive heat pump drying system, which aims to overcome the shortcomings of the existing technology and solve the problems mentioned in the above background technology.

[0005] To achieve its purpose, the present invention adopts the following technical solutions: A PV / T electricity storage direct-drive heat pump drying system, comprising a PV / T cogeneration system, a multi-heat source variable frequency heat pump system and a drying room drying system; The PV / T cogeneration system includes a PV / T array assembly, an inverter-controlled integrated unit, a battery pack, a heat pump, and a water tank connected end to end. A water-side evaporator is provided in the water tank, and a refrigerant is introduced into the water-side evaporator as a circulating medium. The multi-heat source variable frequency heat pump system includes a compressor, a throttle valve, a condenser, a solenoid valve and an evaporator, and the compressor, throttle valve, condenser, solenoid valve and evaporator form a closed loop; the evaporator includes a water side evaporator, an air side evaporator and an outlet moisture evaporator arranged in parallel; The drying room drying system includes a drying room, which is equipped with an induced draft fan, a turbulent fan and a storage rack. A condenser is provided on the side wall of the drying room; the induced draft fan outlet is connected to the outlet moisture evaporator inlet, the outlet moisture evaporator outlet is connected to the condenser inlet, and the condenser outlet is connected to the turbulent fan inlet.

[0006] Preferably, the photovoltaic cell material of the PV / T array assembly is one or more combinations of monocrystalline silicon, polycrystalline silicon or perovskite.

[0007] Preferably, the structure of the PV / T array assembly is one or more combinations of air cooling, water cooling, heat pipe or pulsating cooling.

[0008] Preferably, the multi-heat source variable frequency heat pump system is one or more combinations of a vapor compression dual-heat source heat pump, an absorption dual-heat source heat pump or an adsorption dual-heat source heat pump.

[0009] Preferably, the drying room is a combination of one or more of a box-type drying room, a tunnel-type drying room, a room-type drying room or a belt-type drying room.

[0010] Preferably, the outlet moisture evaporator is always enabled, and the water side evaporator or the air side evaporator is started only when and only when the heat absorbed by the multi-heat source variable frequency heat pump system from the outlet moisture evaporator cannot maintain the required temperature of the drying room, and the activation priority of the water side evaporator is higher than that of the air side evaporator.

[0011] Preferably, the electricity usage priority of the PV / T power storage direct-drive heat pump drying system is PV / T array component instantaneous power income > battery pack > grid power.

[0012] Preferably, the heat pump startup condition is that the inlet and outlet temperatures of the PV / T array components are ≥5°C, and the shutdown condition is that the inlet and outlet temperatures are ≤2°C.

[0013] Preferably, the PV / T array assembly adopts forced circulation heat collection.

[0014] Preferably, the refrigerant is R141b, acetone, R134a or R22.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The PV / T energy storage, direct-drive heat pump drying system provided by this invention uses solar energy, air energy, and mains electricity as inputs, and outputs hot air. By configuring a battery pack, a water tank, and a PV / T array assembly, the PV / T array converts solar energy into heat and electricity. The electricity is utilized by the system or stored by the battery pack via an integrated inverter controller, while the heat is temporarily stored in the water tank. This system efficiently utilizes and stores both long- and short-wave solar radiation, overcoming the poor stability and low energy flow density of solar energy due to environmental factors. The battery pack reduces peak and valley fluctuations in solar energy, reducing the system's grid power requirements and ensuring system efficiency.

[0016] 2. The PV / T electricity storage direct-drive heat pump drying system provided by the present invention can extract heat from the air, water tank, and moisture discharged from the drying room through the water-side evaporator, air-side evaporator, and outlet moisture evaporator included in the multi-heat source variable frequency heat pump system. The scientific and flexible control strategy adopted when configuring the heat source can ensure high energy efficiency of the system, and effectively utilize the beneficial heat in the moisture to reduce the heat loss of the system exhaust gas.

[0017] 3. The PV / T energy storage, direct-drive heat pump drying system provided by this invention utilizes a heat pump condenser to flexibly select the gas to be heated, depending on the operating conditions. The heat pump condenser heats the gas to maintain the set temperature in the drying chamber, while the evaporator cools and dehumidifies the gas. This invention can be widely used for drying a variety of foods, agricultural products, and traditional Chinese medicines, offering high economic and social value, further improving system energy efficiency, and reducing operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic structural diagram of the PV / T power storage direct-drive heat pump drying system of the present invention; In the figure: 1-PV / T array assembly; 2-water tank; 3-inverter control integrated machine; 4-battery pack; 5-heat pump; 6-throttle valve; 7-induced draft fan; 8-turbulent fan; 9-storage rack; 10-drying room; 11-condenser; 12-compressor; 13-outlet moisture evaporator; 14-air side evaporator; 15-water side evaporator. DETAILED DESCRIPTION

[0019] In order to facilitate intuitive understanding of the technical means, innovative features, and practical effects achieved by the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0020] like Figure 1 As shown, the present invention discloses a PV / T electricity storage direct-drive heat pump drying system, including a PV / T cogeneration system, a multi-heat source variable frequency heat pump system and a drying room drying system; The PV / T cogeneration system comprises a PV / T array assembly 1, an integrated inverter 3, a battery pack 4, a heat pump 5, and a water tank 2, connected end-to-end. The water tank 2 houses a water-side evaporator 15, which circulates a refrigerant to absorb heat through evaporation. The PV / T array assembly 1 is a common integrated photovoltaic and thermal device. Its photovoltaic cells are made of one or a combination of single-crystal silicon, polycrystalline silicon, or perovskite, with single-crystal silicon being used in this case. The PV / T array assembly 1 features a configuration that can be air-cooled, water-cooled, heat pipe-cooled, or pulse-cooled, with a heat pipe configuration being used in this case. The refrigerant can be R141b, acetone, R134a, or R22, with R141b being used in this case. The PV / T array assembly 1 converts solar energy into both electrical and thermal energy. The electrical energy is converted to AC power by the integrated inverter 3 to drive the heat pump or stored in the battery pack 4. The thermal energy is transferred to the water tank 2 for storage via the heat pump 5.

[0021] The multi-heat-source variable-frequency heat pump system includes a compressor 12, a throttle valve 6, a condenser 11, a solenoid valve, and an evaporator, forming a closed circuit. The evaporator includes a water-side evaporator 15, an air-side evaporator 14, and an outlet moisture evaporator 13, arranged in parallel. The multi-heat-source variable-frequency heat pump system is a combination of one or more vapor compression dual-heat-source heat pumps, absorption dual-heat-source heat pumps, or adsorption dual-heat-source heat pumps, specifically a vapor compression dual-heat-source heat pump. This system allows for flexible configuration of heat sources (air energy, solar energy, outlet moisture waste heat) based on specific operating conditions, selecting appropriate electricity usage priorities, and achieving higher energy efficiency for the system while reducing operating expenses.

[0022] The drying room drying system includes a drying room 10, which is equipped with an induced draft fan 7, a turbulent fan 8, and a storage rack 9. A condenser 11 is installed on the side wall of the drying room 10. The outlet of the induced draft fan 7 is connected to the inlet of an outlet moisture evaporator 13 via a ventilation duct, which in turn is connected to the inlet of the condenser 11 via a ventilation duct. The outlet of the condenser 11 is also connected to the inlet of the turbulent fan 8 via a ventilation duct. The drying room 10 can be a combination of a box-type drying room, a tunnel-type drying room, a room-type drying room, or a belt-type drying room, with the box-type drying room being used in this case. Heat released by the condenser 11 is transferred to the drying room 10 via the turbulent fan 8. This solves the problems of high energy consumption and low drying efficiency in existing drying technologies and reduces electrical energy consumption during the drying process.

[0023] Specifically, the PV / T array assembly 1 uses forced circulation heat collection. The heat pump 5 is activated when the inlet and outlet temperatures of the PV / T array assembly 1 are ≥ 5°C, and is deactivated when the inlet and outlet temperatures are ≤ 2°C. This configuration prevents the heat pump 5 from continuously operating and wasting energy. In particular, the activation and deactivation thresholds for the heat pump 5 can be adjusted based on actual conditions.

[0024] Specifically, during seasons with high ambient temperatures, since the temperature of the gas exiting the outlet moisture evaporator 13 is low, much lower than that of the atmospheric air, the heat pump condenser 11 is used to heat the atmospheric air. Specifically, manual valve W6 is opened and manual valve W7 is closed. The gas flowing through the outlet moisture evaporator 13 is directly discarded and discharged into the atmosphere. The heated air is then drawn into the drying room 10 by the induced draft fan 7 to dry the various materials. The temperature in the drying room 10 is between 45°C and 70°C, and the appropriate drying temperature can be selected based on the specific material being dried.

[0025] Specifically, during periods of low ambient temperature, typically those consistently below 5°C or lower, the circulating gas is the dry / wet gas continuously circulating within the drying room 10 to dry various materials. Specifically, manual valve W7 is opened and manual valve W6 is closed. This allows the heat from the outlet moisture evaporator 13 to be absorbed, significantly lowering the moisture temperature and forcing the moisture in the moisture to condense and precipitate. This increases the dryness of the gas while maintaining a higher temperature than the ambient air. Directly heating the dried gas with the heat pump condenser 11 is more economical, and the hot gas is then fed into the drying room 10 to dry various materials.

[0026] The outlet moisture evaporator 13 is always enabled. The water side evaporator 15 or the air side evaporator 14 is started only when and only when the heat absorbed by the multi-heat source variable frequency heat pump system from the outlet moisture evaporator 13 is unable to maintain the required temperature of the drying room 10. Only one of the two will be enabled, and since the water side evaporator 15 has a higher energy efficiency ratio, its activation priority is higher than that of the air side evaporator 14.

[0027] Specifically, when the drying room 10 requires a high amount of heat, the heat pump's heat absorption from the outlet moisture evaporator 13 alone is insufficient to maintain the desired temperature. A new heat source is required. Specifically, when the temperature of the water tank 2 exceeds 10°C, solenoid valves M2 and M4 are opened, and solenoid valve M3 is closed. This activates the water-side evaporator 15 and the outlet moisture evaporator 13, allowing them to absorb heat together. This heat is then heated by the condenser 11 and fed into the drying room 10 to maintain the desired temperature. Manual valves W3, W4, and W5 within the heat pump are always open and closed only when necessary.

[0028] Specifically, when the drying room 10 requires a large amount of heat and the water tank 2 temperature is below 10°C, the economic efficiency of a heat pump using water as a heat source is also low, and a new heat source needs to be configured. Specifically, when the water tank 2 temperature is below 10°C, solenoid valves M3 and M4 are opened, and solenoid valve M2 is closed. This activates the air-side evaporator 14 and the outlet moisture evaporator 13 to absorb heat, and heats the air through the condenser 11 and sends it into the drying room 10 to maintain the required temperature. The above temperature parameters, such as the water tank temperature below 10°C and the ambient temperature below 5°C, can be reasonably adjusted according to specific implementation conditions to achieve a higher system energy efficiency ratio.

[0029] Specifically, the power usage priority of the PV / T energy storage direct-drive heat pump drying system is: PV / T array assembly 1 instantaneous power gain > battery pack 4 > grid power. When the photovoltaic power of PV / T array assembly 1 meets the system's power requirements, this power can directly drive heat pumps and other electrical equipment. When the power generated by PV / T array assembly 1 is lower than the system's power requirements, PV / T array assembly 1 and battery pack 4 are used to compensate for powering heat pumps and other electrical equipment. When battery pack 4's SOC is unsuitable for external discharge, PV / T array assembly 1 and mains power are used to compensate for powering heat pumps and other electrical equipment. When both battery pack 4 and PV / T array assembly 1 are unsuitable for external discharge, the grid is used to drive heat pumps and other electrical equipment. This power usage priority ensures that the system can promptly absorb the power generated by PV / T, reducing losses incurred during the storage and release of system power.

[0030] The specific system comprehensive energy efficiency ratio of the PV / T power storage direct-drive heat pump drying system of this application depends not only on the control strategy, but also on the performance of the compressor, the comprehensive performance of the PV / T array component 1, etc. In particular, the electrical efficiency of the PV / T device depends on the material of the photovoltaic cells used. According to existing industry standards, its electrical efficiency is generally not less than 21%. Due to the large number of research results on PV / T devices, the thermal efficiency of most PV / T devices can be maintained at 35%-50%. Taking the solar energy resources in Lanzhou as an example, the area is 2.5m 2 The PV / T system generates 797.53 kW·h of electricity annually, based on a 21% electrical efficiency, and 1519.1 kW·h of heat annually, based on a 40% overall thermal efficiency. This provides a significant amount of heat and valuable electricity for the drying system in the drying room. Furthermore, the electricity and heat generated by the PV / T system are pollution-free, continuous, and clean. The multi-source variable-frequency heat pump system allows for flexible heat source configuration based on control strategies, ensuring overall system energy efficiency. The PV / T direct-drive heat pump drying system offers significant energy-saving, economic, and environmental benefits.

[0031] The PV / T energy storage direct-drive heat pump drying system of this application can be used not only for drying agricultural products such as grains, fruits and vegetables, which require careful temperature and humidity control (such as the drying of wolfberries and mushrooms). It can also be used for drying and processing foods such as meat, seafood, and noodles, provided that it meets hygiene standards. In particular, when used for drying Chinese medicinal materials (such as ginseng and astragalus), low-temperature slow drying is required to maximize the retention of the medicinal ingredients.

[0032] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A PV / T electricity storage direct-drive heat pump drying system, characterized by: Including PV / T cogeneration system, multi-heat source variable frequency heat pump system and drying room drying system; The PV / T cogeneration system comprises a PV / T array assembly (1), an inverter-controlled integrated machine (3), a battery pack (4), a heat pump (5), and a water tank (2) connected end to end in sequence; a water-side evaporator (15) is provided in the water tank (2), and a refrigerant is introduced into the water-side evaporator (15) as a circulating working medium; The multi-heat source variable frequency heat pump system comprises a compressor (12), a throttle valve (6), a condenser (11), a solenoid valve and an evaporator, and the compressor (12), the throttle valve (6), the condenser (11), the solenoid valve and the evaporator form a closed loop; the evaporator comprises a water side evaporator (15), an air side evaporator (14) and an outlet moisture evaporator (13) arranged in parallel; The drying room drying system comprises a drying room (10), wherein an induced draft fan (7), a turbulent flow fan (8) and a storage rack (9) are provided in the drying room (10), and a condenser (11) is provided on the side wall of the drying room (10); the outlet of the induced draft fan (7) is communicated with the inlet of the outlet moisture evaporator (13), the outlet of the outlet moisture evaporator (13) is communicated with the inlet of the condenser (11), and the outlet of the condenser (11) is communicated with the inlet of the turbulent flow fan (8).

2. The PV / T electricity storage direct-drive heat pump drying system according to claim 1, characterized in that: The photovoltaic cell material of the PV / T array assembly (1) is one or more combinations of single crystal silicon, polycrystalline silicon or perovskite.

3. The PV / T electricity storage direct-drive heat pump drying system according to claim 2, characterized in that: The structure of the PV / T array assembly (1) is one or more combinations of air cooling type, water cooling type, heat pipe type or pulsation type.

4. The PV / T electricity storage direct-drive heat pump drying system according to claim 3, characterized in that: The multi-heat source variable frequency heat pump system is one or more combinations of a vapor compression dual-heat source heat pump, an absorption dual-heat source heat pump or an adsorption dual-heat source heat pump.

5. The PV / T electricity storage direct-drive heat pump drying system according to claim 4, characterized in that: The drying room (10) is one or more combinations of a box-type drying room, a tunnel-type drying room, a room-type drying room or a belt-type drying room.

6. The PV / T electricity storage direct-drive heat pump drying system according to claim 5, characterized in that: The outlet moisture evaporator (13) is always enabled, and the water side evaporator (15) or the air side evaporator (14) is enabled only when the heat absorbed by the multi-heat source variable frequency heat pump system from the outlet moisture evaporator (13) is unable to maintain the required temperature of the drying room (10), and the activation priority of the water side evaporator (15) is higher than that of the air side evaporator (14).

7. The PV / T electricity storage direct-drive heat pump drying system according to claim 6, characterized in that: The electricity consumption priority of the PV / T power storage direct drive heat pump drying system is: PV / T array component (1) instantaneous power income > battery pack (4) > grid power.

8. The PV / T electricity storage direct-drive heat pump drying system according to claim 7, characterized in that: The starting condition of the heat collecting pump (5) is that the inlet and outlet temperatures of the PV / T array assembly (1) are ≥5°C, and the shut-down condition is that the inlet and outlet temperatures are ≤2°C.

9. A PV / T electricity storage direct-drive heat pump drying system according to any one of claims 1 to 8, characterized in that: The PV / T array assembly (1) adopts forced circulation heat collection.

10. A PV / T electricity storage direct-drive heat pump drying system according to any one of claims 1 to 8, characterized in that: The refrigerant is R141b, acetone, R134a or R22.

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