A cascaded heat pump drying system with phase change energy storage coupled with solar energy

Abstract

The present invention relates to the technical field of drying systems, and in particular to a phase-change energy storage cascade heat pump drying system coupled with solar energy, comprising a primary heat pump unit, a secondary heat pump unit and a solar heating unit; the primary heat pump unit comprises a primary heat pump compressor, a heat exchanger, an evaporator and a first condensing fan, the primary heat pump compressor is connected to the evaporator and the heat exchanger respectively, the evaporator and the heat exchanger are connected, and the first condensing fan is installed on the evaporator; the secondary heat pump unit comprises a secondary heat pump compressor, a condenser, a heat exchanger, a second condensing fan and a drying chamber; the solar heating unit comprises a first water pump, a second water pump, a heat storage tank and a solar collector, so that the heat in the water system is used as a low-grade heat source for the secondary heat pump during the day, without starting the primary heat pump system, only the water pump is turned on to utilize the low-grade heat source to make the heating temperature reach 85°C, thereby reducing the operating cost of the equipment.

Description

Technical Field

[0001] The invention relates to the technical field of drying systems, and in particular to a phase-change energy storage cascade heat pump drying system coupled with solar energy. Background Art

[0002] As a free and clean energy source, solar energy can supplement heat at the user end and reduce the power load at the user end. However, the intensity of solar radiation is easily affected by the weather, and phase change energy storage technology must be used for peak regulation and stabilization.

[0003] Traditional drying uses the method of indirectly heating the air by burning fossil fuels, supplying high-temperature air above 100°C to the terminal drying chamber. This method is difficult to ensure the quality of the dried product, and the burning of fossil fuels will emit a large amount of carbon dioxide, polluting the surrounding environment.

[0004] The operation of heat pumps requires electricity. Conventional cascade high-temperature heat pumps consume a lot of electricity, and the maximum heating temperature on the high-temperature heat source side is 90°C, which fails to meet the requirement of 100°C for drying indoor air. Summary of the invention

[0005] The technical problem to be solved by the present invention is: in order to overcome the problem that the conventional cascade high-temperature heat pump in the prior art has a large power consumption and the maximum heating temperature on the high-temperature heat source side is 90°C, which fails to meet the requirement of 100°C for the drying temperature of the indoor air, a phase change energy storage cascade heat pump drying system coupled with solar energy is provided.

[0006] The technical solution adopted by the present invention to solve the technical problem is: a phase change energy storage cascade heat pump drying system coupled with solar energy, comprising a primary heat pump unit, a secondary heat pump unit and a solar heating unit;

[0007] The primary heat pump unit includes a primary heat pump compressor, a heat exchanger, an evaporator and a first condensing fan, the primary heat pump compressor is connected to the evaporator and the heat exchanger respectively, the evaporator and the heat exchanger are connected, and the first condensing fan is installed on the evaporator;

[0008] The secondary heat pump unit includes a secondary heat pump compressor, a condenser, a heat exchanger, a second condensing fan and a drying chamber. The secondary heat pump compressor is connected to the heat exchanger and the condenser respectively. The condenser is installed in the drying chamber, and the second condensing fan is installed on the condenser.

[0009] The solar heating unit includes a first water pump, a second water pump, a heat storage tank and a solar thermal collecting plate. The heat storage tank is connected to the solar thermal collecting plate, the first water pump and the second water pump respectively. The first water pump is connected to the heat exchanger, and the solar thermal collecting plate and the second water pump are both connected to the heat exchanger.

[0010] It further includes a first-stage heat pump unit including a first one-way expansion valve, a second one-way expansion valve, a third electromagnetic on-off valve and a fourth electromagnetic on-off valve. The first one-way expansion valve and the second one-way expansion valve are located on the head end pipeline of the evaporator. The first one-way expansion valve and the second one-way expansion valve are installed between the heat exchanger and the evaporator, and the first one-way expansion valve and the second one-way expansion valve are arranged in parallel. The first one-way expansion valve is connected in series with the third electromagnetic on-off valve, and the second one-way expansion valve is connected in series with the fourth electromagnetic on-off valve.

[0011] It further includes that the end of the evaporator is connected to the first-stage heat pump compressor through a four-way valve, and the first-stage heat pump compressor is connected to the heat exchanger through the four-way valve.

[0012] The secondary heat pump unit further comprises a third one-way expansion valve, and the third one-way expansion valve is installed at the tail end of the heat exchanger.

[0013] The solar heating unit further includes a first electromagnetic on-off valve, a second electromagnetic on-off valve, a fifth electromagnetic on-off valve, a sixth electromagnetic on-off valve, a seventh electromagnetic on-off valve, an eighth electromagnetic on-off valve and a first electromagnetic three-way valve. The first electromagnetic on-off valve is installed between the first water pump and the heat exchanger, the second electromagnetic on-off valve is installed at the tail end of the heat exchanger, the fifth electromagnetic on-off valve is installed at the tail end of the solar collector, the seventh electromagnetic on-off valve is installed at the tail end of the second water pump, the second electromagnetic on-off valve is connected to the fifth electromagnetic on-off valve and the seventh electromagnetic on-off valve respectively, the sixth electromagnetic on-off valve is connected to the eighth electromagnetic on-off valve and the solar collector, the first electromagnetic three-way valve is connected in parallel to the eighth electromagnetic on-off valve, and the first electromagnetic three-way valve is connected to the heat storage tank, and the eighth electromagnetic on-off valve is connected to the first water pump.

[0014] It further includes water, a primary refrigerant and a secondary refrigerant in the internal pipe of the heat exchanger.

[0015] The beneficial effects of the present invention are as follows: the present invention provides a phase change energy storage cascade heat pump drying system coupled with solar energy, which couples a primary heat pump unit, a secondary heat pump unit, and a solar heating unit through a three-channel heat exchanger, and adjusts the operation mode of the heat pump through a controller so that the heating temperature in the drying room can reach a maximum of over 100°C.

[0016] 1. Conventional cascade high-temperature heat pumps achieve a heating temperature of 85°C through low-temperature cycles and high-temperature cycles. The present invention uses valley electricity heat storage at night and solar energy heat collection during the day to allow the heat in the water system to be used as a low-grade heat source for the secondary heat pump during the day. There is no need to start the primary heat pump system. Only the water pump is turned on to use the low-grade heat source to achieve a heating temperature of 85°C, thereby reducing the operating cost of the equipment.

[0017] 2. Conventional cascade high-temperature heat pumps can only provide one low-grade heat source, so that the secondary heat pump can achieve a maximum heating temperature of 90°C. In the extreme mode, the present invention obtains 2-3 low-grade heat sources through the control methods of heat storage tank + primary heat pump, solar collector panel + primary heat pump, heat storage tank + solar collector panel + primary heat pump, so that the heating temperature of the secondary heat pump reaches above 100°C, and has good stability, and heat supplement can be achieved between low-temperature heat sources.

[0018] 3. The secondary heat pump unit needs to be turned on in the defrosting state of the primary heat pump. In the defrosting state of the present invention, the secondary heat pump unit does not need to be turned on. Only the water pump needs to be turned on. The heat storage tank is used to supply hot water to the primary heat pump unit in the three-channel heat exchanger, thereby reducing the operating cost of the equipment.

[0019] 4. The three-channel heat exchanger couples the primary heat pump unit, the secondary heat pump unit, and the solar heating unit. The controller is used to realize the heat source supplement between different units, ensure the stability of the low-temperature heat source, and make the secondary heat pump run stably. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0021] Figure 1 The schematic diagram of the phase change energy storage cascade heat pump drying system coupled with solar energy;

[0022] Figure 2 It is a schematic diagram of the heat exchange process of a three-channel heat exchanger;

[0023] Figure 3 Schematic diagram of the heat exchange structure of a three-channel heat exchanger.

[0024] In the figure: 101, a first-stage heat pump compressor, 102, a second-stage heat pump compressor, 2, a four-way valve, 3, a heat exchanger, 401, a first one-way expansion valve, 402, a second one-way expansion valve, 403, a third one-way expansion valve, 5, an evaporator, 601, a first condensing fan, 602, a second condensing fan, 8, a condenser, 9, a drying chamber, 1001, a first water pump, 1002, a second water pump, 11, a heat storage tank, 12, a solar collector, 1301, a first electromagnetic on-off valve, 1302, a second electromagnetic on-off valve, 1303, a third electromagnetic on-off valve, 1304, a fourth electromagnetic on-off valve , 1305, the fifth electromagnetic on-off valve, 1306, the sixth electromagnetic on-off valve, 1307, the seventh electromagnetic on-off valve, 1308, the eighth electromagnetic on-off valve, 1401, the first electromagnetic three-way valve, 15, the control unit, 1605, the first-level heat pump refrigerant pipeline inlet, 1606, the first-level heat pump refrigerant pipeline outlet, 1603, the second-level heat pump refrigerant pipeline inlet, 1604, the second-level heat pump refrigerant pipeline outlet, 1601, the water pipeline inlet, 1602, the water pipeline outlet, 1607, the water channel, 1608, the first-level heat pump refrigerant channel, 1609, the second-level heat pump refrigerant channel. DETAILED DESCRIPTION

[0025] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0026] like Figure 1 It is a structural schematic diagram of the present invention, a phase change energy storage cascade heat pump drying system coupled with solar energy, comprising a primary heat pump unit, a secondary heat pump unit and a solar heating unit;

[0027] like Figure 1 As shown, the primary heat pump unit includes a primary heat pump compressor 101, a heat exchanger 3, an evaporator 5 and a first condensing fan 601, the primary heat pump compressor 101 is connected to the evaporator 5 and the heat exchanger 3 respectively, the evaporator 5 is connected to the heat exchanger 3, and the first condensing fan 601 is installed on the evaporator 5;

[0028] like Figure 1 As shown, the first-stage heat pump unit includes a first one-way expansion valve 401, a second one-way expansion valve 402, a third electromagnetic on-off valve 1303 and a fourth electromagnetic on-off valve 1304. The first one-way expansion valve 401 and the second one-way expansion valve 402 are located on the head end pipeline of the evaporator 5, the first one-way expansion valve 401 and the second one-way expansion valve 402 are installed between the heat exchanger 3 and the evaporator 5, and the first one-way expansion valve 401 and the second one-way expansion valve 402 are arranged in parallel, the first one-way expansion valve 401 is connected in series with the third electromagnetic on-off valve 1303, and the second one-way expansion valve 402 is connected in series with the fourth electromagnetic on-off valve 1304.

[0029] The end of the evaporator 5 is connected to the primary heat pump compressor 101 through the four-way valve 2 , and the primary heat pump compressor 101 is connected to the heat exchanger 3 through the four-way valve 2 .

[0030] like Figure 1 As shown, the two-stage heat pump unit includes a two-stage heat pump compressor 102, a condenser 8, a heat exchanger 3, a second condensing fan 602 and a drying chamber 9. The two-stage heat pump compressor 102 is connected to the heat exchanger 3 and the condenser 8 respectively. The condenser 8 is installed in the drying chamber 9. The second condensing fan 602 is installed on the condenser 8.

[0031] The secondary heat pump unit includes a third one-way expansion valve 403 , which is installed at the tail end of the heat exchanger 3 .

[0032] like Figure 1 As shown, the solar heating unit includes a first water pump 1001, a second water pump 1002, a heat storage tank 11 and a solar thermal collecting panel 12. The heat storage tank 11 is connected to the solar thermal collecting panel 12, the first water pump 1001 and the second water pump 1002 respectively. The first water pump 1001 is connected to the heat exchanger 3, and the solar thermal collecting panel 12 and the second water pump 1002 are both connected to the heat exchanger 3.

[0033] like Figure 1 As shown, the solar heating unit includes a first electromagnetic on-off valve 1301, a second electromagnetic on-off valve 1302, a fifth electromagnetic on-off valve 1305, a sixth electromagnetic on-off valve 1306, a seventh electromagnetic on-off valve 1307, an eighth electromagnetic on-off valve 1308 and a first electromagnetic three-way valve 1401, the first electromagnetic on-off valve 1301 is installed between the first water pump 1001 and the heat exchanger 3, the second electromagnetic on-off valve 1302 is installed at the tail end of the heat exchanger 3, and the fifth electromagnetic on-off valve 1305 is installed at the solar collector 1 2 tail end, the seventh electromagnetic on-off valve 1307 is installed at the tail end of the second water pump 1002, the second electromagnetic on-off valve 1302 is connected to the fifth electromagnetic on-off valve 1305 and the seventh electromagnetic on-off valve 1307 respectively, the sixth electromagnetic on-off valve 1306 is connected to the eighth electromagnetic on-off valve 1308 and the solar collector 12, the eighth electromagnetic on-off valve 1308 is connected in parallel with the first electromagnetic three-way valve 1401, and the first electromagnetic three-way valve 1401 is connected to the heat storage tank 11, and the eighth electromagnetic on-off valve 1308 is connected to the first water pump 1001.

[0034] The internal pipes of the heat exchanger 3 contain water, primary refrigerant and secondary refrigerant.

[0035] The directions of the four-way valve 2 are named counterclockwise from the right port, namely the first port, the second port, the third port, and the fourth port.

[0036] like Figure 2 , Figure 3As shown, the heat exchanger 3 is a three-channel heat exchanger 3, and the heat exchanger 3 has a primary heat pump refrigerant pipeline inlet 1605, a primary heat pump refrigerant pipeline outlet 1606, a secondary heat pump refrigerant pipeline inlet 1603, a secondary heat pump refrigerant pipeline outlet 1604, a water pipeline inlet 1601, a water pipeline outlet 1602, a water channel 1607, a primary heat pump refrigerant channel 1608 and a secondary heat pump refrigerant channel 1609. The primary heat pump refrigerant pipeline inlet 1605 of the three-channel heat exchanger 3 is connected to the first port of the four-way valve 2, and the outlet end of the primary heat pump refrigerant channel 1608 of the three-channel heat exchanger 3 is respectively connected to the third electromagnetic on-off valve 1303 and the second one-way expansion valve 402, the second one-way expansion valve 402 is connected to the fourth electromagnetic on-off valve 1304, and the first one-way expansion valve 401 is connected to the third electromagnetic on-off valve 1303. The head end of the evaporator 5 is respectively connected to the outlet end of the first one-way expansion valve 401 and the fourth electromagnetic on-off valve 1304. The end of the evaporator 5 is connected to the third inlet end of the four-way valve 2, and the fourth port of the four-way valve 2 is connected to the end of the compressor 101. The three-channel heat exchanger 3, the third one-way expansion valve 403, the second condenser 8, and the two-stage heat pump compressor 102 in the two-stage heat pump unit are connected in sequence to form a closed loop. The first electromagnetic on-off valve 1301 is connected to the end of the first water pump 1001, and the first water pump 1001 is connected to the solar collector 12 through the eighth electromagnetic on-off valve 1308 and the sixth electromagnetic on-off valve 1306. The end of the branch of the first water pump 1001 is connected to the first electromagnetic three-way valve 1401, and the first electromagnetic three-way valve 1401 is connected to the second water pump 1002 through the heat storage tank 11. The outlet end of the solar collector 12 intersects with the end of the seventh electromagnetic on-off valve 1307 through the fifth electromagnetic on-off valve 1305, and the head end of the first electromagnetic on-off valve 1301 and the end of the second electromagnetic on-off valve 1302 are respectively connected to the inlet end and the outlet end of the water pipeline of the three-channel heat exchanger 3.

[0037] The three-channel heat exchanger has a total of 12 heat exchange plates. Starting from the refrigerant inlet end of the first-stage heat pump unit, the 1st-2nd heat exchange plates are double-channel heat exchange plates, that is, the through holes are water pipeline channels and the first-stage heat pump unit refrigerant channels. The 3rd-7th heat exchange plates are three-channel heat exchange plates, that is, the through holes are water pipeline channels, first-stage heat pump unit refrigerant channels and second-stage heat pump unit refrigerant channels. The water pipeline channels are located at the two ends of the left side of the heat exchange plate, the first-stage heat pump unit refrigerant channels are located at the two ends in the middle of the heat exchange plate, and the second-stage heat pump unit refrigerant channels are located at the two ends on the right side of the heat exchange plate. The 8th-9th heat exchange plates are double-channel heat exchange plates, that is, the through holes are the first-stage heat pump unit refrigerant channels and the second-stage heat pump unit refrigerant pipelines. The 10th-12th heat exchange plates are single-channel heat exchange plates, that is, the through-hole first-stage heat pump unit refrigerant channels are located at the two ends in the middle of the heat exchange plate. A heat exchange channel is formed between the heat exchange plates and the pipelines inside the three-channel heat exchanger. Starting from the refrigerant inlet end of the primary heat pump unit, the heat exchange channel is water, primary refrigerant, secondary refrigerant, water, primary refrigerant, secondary refrigerant, water, primary refrigerant, secondary refrigerant, primary refrigerant, and primary refrigerant in sequence.

[0038] The heat storage tank 11 is filled with heat storage balls with a phase change temperature of 50°C. The mass percentages of the components of the heat storage material inside the phase change heat storage balls are as follows: 10-15% potassium nitrate, 10-20% sodium hydroxide, 1-5% graphite powder, 30-40% sodium sulfate, and 10-20% water.

[0039] A phase-change energy storage type two-stage heat pump drying system coupled with solar energy, wherein both the first-stage heat pump unit and the second-stage heat pump unit adopt R245FA refrigerant.

[0040] A phase change energy storage type two-stage heat pump drying system coupled with solar energy is specifically implemented as follows: a controller unit 16 is connected to a first-stage heat pump compressor 101, a second-stage heat pump compressor 102, a four-way valve 2, a first condensing fan 601, a second condensing fan 602, a first water pump 1001, a second water pump 1002, a first electromagnetic on-off valve 1301, a second electromagnetic on-off valve 1302, a third electromagnetic on-off valve 1303, a fourth electromagnetic on-off valve 1304, a fifth electromagnetic on-off valve 1305, a sixth electromagnetic on-off valve 1306, a seventh electromagnetic on-off valve 1307, an eighth electromagnetic on-off valve 1308, a first electromagnetic three-way valve 1401, a first temperature probe T1, a second temperature probe T2, a third temperature probe T3, a fourth temperature probe T4, a fifth temperature probe T5, a sixth temperature probe T6 and a control wire through a control wire.

[0041] The first temperature probe T1 is connected to the surface of the evaporator 5, the second temperature probe T2 is connected to the end of the water pipeline of the solar collector 12, the third temperature probe T3 is connected to the surface of the condenser 8, the fourth temperature probe T4 is connected to the inside of the heat storage tank 11, the fifth temperature probe T5 is connected to the output end of the second water pump 1002, and the sixth temperature probe T6 is connected to the input end of the first electromagnetic on-off valve 1301.

[0042] System principle: A phase change energy storage cascade heat pump drying system coupled with solar energy is composed of three independent cycles, including a low temperature cycle, a high temperature cycle, a water pipeline cycle, a low temperature cycle, a high temperature cycle, and the water pipeline cycle is connected together through a three-channel heat exchanger 3, and the inner cavity channels of the three-channel heat exchanger 3 are water, a primary refrigerant, and a secondary refrigerant. The heating cycle of the primary heat pump condenses and releases heat in the primary heat pump refrigerant channel in the three-channel heat exchanger 3, enters the evaporator for gasification and heat absorption after throttling by the expansion valve, and circulates continuously. The primary heat pump provides heat for the water channel 1607 and the secondary heat pump refrigerant channel 1609 in the three-channel heat exchanger. At night, heat is exchanged through the primary heat pump refrigerant channel 1608 and the water channel 1607, and the heat is stored in the heat storage tank 11. The high-temperature heat pump absorbs the heat released by the primary refrigerant and hot water in the secondary heat pump refrigerant channel 1609 in the three-channel heat exchanger 3 and evaporates into gas, which is compressed into high-temperature and high-pressure gas in the secondary compressor 102 and condensed and released in the condenser 8.

[0043] The control method includes the following operation modes: valley electricity heat storage mode, solar energy heat storage mode, limit mode, high temperature mode, and defrost mode.

[0044] 1. Valley Power Thermal Storage Mode

[0045] This mode mainly occurs at night when the fourth temperature probe T 4 Detected temperature <T tp (Where T tp When the temperature is the phase change point of the heat storage ball), the four-way valve reversing valve 2 is turned, the first compressor 1001 and the first condensing fan 601 are turned on, the third electromagnetic on-off valve 1303 is opened, and the fourth electromagnetic on-off valve 1304 is closed. The refrigerant in the primary heat pump pipeline flows in a clockwise direction. At the same time, the first water pump 1001 and the second water pump 1002 are started, the first electromagnetic on-off valve 1301, the second electromagnetic on-off valve 1302, and the seventh electromagnetic on-off valve 1307 are opened, the eighth electromagnetic on-off valve 1308 and the fifth electromagnetic on-off valve 1305 are closed, and the first electromagnetic three-way valve 1401 is turned. The return water flows through the heat storage tank 11 and finally enters the three-way heat exchanger until the fifth temperature probe T 5 Detected temperature - sixth temperature probe T 6 Detected temperature<ΔT 1 , the fifth temperature probe T 5 Detected temperature>T tp(where ΔT 1 The heat pump stops supplying heat when the compressor is turned off and the fan is turned off after a delay.

[0046] 2. Solar thermal storage mode

[0047] This mode mainly occurs when there is sufficient solar light and the secondary heat pump unit is not working. If the second temperature probe T 2 Detected temperature>T tp (where Ttp is the phase change temperature of the heat storage ball), start the second water pump 1002, open the fifth electromagnetic on-off valve 1305, the sixth electromagnetic on-off valve 1306, and the seventh electromagnetic on-off valve 1307, close the second electromagnetic on-off valve 1302, the eighth electromagnetic on-off valve 1308, the first electromagnetic on-off valve 1301, and the second electromagnetic on-off valve 1302, and turn the first electromagnetic three-way valve 1401 until the second temperature probe T 2 Detected temperature - fifth temperature probe T 5 Detected temperature<ΔT 2 (where ΔT 2 The water is circulated between the solar collector 12 and the heat storage tank 11 to achieve heat storage.

[0048] 3. Extreme Mode

[0049] This mode is mainly used when the air supply temperature in the drying room is greater than 100°C. At this time, the third temperature probe T 3 The detected temperature is greater than 100°C, the fourth temperature probe T 4 Detected temperature>T tp , the second temperature probe T 2 Detected temperature>T tp , the secondary heat pump unit is in the working state, the first electromagnetic three-way valve 1401 is turned, the sixth electromagnetic on-off valve 1306 and the eighth electromagnetic on-off valve 1308 are opened, and the return water passes through the heat storage tank 11 and the solar collector 12 through the G3 and G4 pipelines and merges into the junction of the fifth electromagnetic on-off valve 1305 and the sixth electromagnetic on-off valve 1306, the first water pump 1001 and the second water pump 1002 are started, the first electromagnetic on-off valve 1031 and the second electromagnetic on-off valve 1302 are opened, and the hot water flows through the three-way heat exchanger 3. The four-way reversing valve 2 is turned, the compressor 1001 and the first condensing fan 601 are started, the third electromagnetic on-off valve 1303 is opened, and the fourth electromagnetic on-off valve 1304 is closed. The refrigerant of the primary heat pump unit flows counterclockwise, and the refrigerant pipeline and the water pipeline are used as the low-temperature heat source of the secondary heat pump. If the second temperature probe T is in the process of heating in the water pipeline 2 Detected temperature <T tpAt this time, the fifth electromagnetic on-off valve 1305, the sixth electromagnetic on-off valve 1306, and the eighth electromagnetic on-off valve 1308 are closed, and the return water only passes through the heat storage tank 11, and finally enters the three-way heat exchanger 3 through the first water pump 1002.

[0050] 4. High temperature mode

[0051] This mode is mainly used when the air supply temperature in the drying room is lower than 100℃. 3 The detected temperature is less than 100°C, the fourth temperature probe T 4 Detected temperature>T tp , the second temperature probe T 2 Detected temperature>T tp , the secondary heat pump unit is in working state, turn the first electromagnetic three-way valve 1401, open the fifth electromagnetic on-off valve 1305, the sixth electromagnetic on-off valve 1306, the seventh electromagnetic on-off valve 1307, and the eighth electromagnetic on-off valve 1308, and the return water passes through the heat storage tank 11 and the solar collector 12 through the G3 and G4 pipelines and merges into the junction of the fifth electromagnetic on-off valve 1305 and the sixth electromagnetic on-off valve 1306, start the first water pump 1002 and the second water pump 1001, open the first electromagnetic on-off valve 1301 and the second electromagnetic on-off valve 1302, and the hot water flows through the three-way heat exchanger 3. The hot water in the heat storage tank 11 and the hot water generated by the solar collector 12 are supplemented as low-temperature heat sources. If the second temperature probe T 2 Detected temperature < fourth temperature probe T 4 The detected temperature closes the sixth electromagnetic on-off valve 1306, the fifth electromagnetic on-off valve 1305, and the eighth electromagnetic on-off valve 1308, and the hot water in the heat storage tank 11 is used as a low-temperature heat source. If the fourth temperature probe T 4 Detected temperature <T tp -2℃, close the first electromagnetic on-off valve 1301 and the second electromagnetic on-off valve 1302, close the first water pump 1001 and the second water pump 1002, turn on the four-way reversing valve 2, and start the first-level heat pump unit to supplement the heat for the low-temperature heat source.

[0052] Five: Defrost mode

[0053] This mode mainly occurs when the evaporator surface is frosted, that is, the first temperature probe T 1 The detected temperature is less than 0°C, the four-way reversing valve 2 is turned, the control unit starts the first compressor 1001 and the first condensing fan 601 through the control wire, opens the fourth electromagnetic on-off valve 1304, closes the third electromagnetic on-off valve 1303, and the refrigerant in the primary heat pump unit flows counterclockwise. If the fourth temperature probe T 4 Detected temperature +10℃>Second temperature probe T 2 Detected temperature>T tp, the fourth temperature probe T 4 Detected temperature>T tp , start the first water pump 1001 and the second water pump 1002, open the first electromagnetic on-off valve 1301, the eighth electromagnetic on-off valve 1308, the sixth electromagnetic on-off valve 1306, the fifth electromagnetic on-off valve 1305, the second electromagnetic on-off valve 1302, and the seventh electromagnetic on-off valve 1307, turn the first electromagnetic three-way valve 1401, and the return water flows through the solar collector 12 and the heat storage tank 11 through the branch, and then enters the three-channel heat exchanger 3 through the G2 pipeline, and completes the heat exchange between the refrigerant pipeline of the first-level heat pump unit and the water pipeline in the three-channel heat exchanger 3 to achieve evaporator defrosting. If the second temperature probe T 2 Detected temperature < fourth temperature probe T 4 When the temperature detected is reached, the fifth, sixth, and eighth electromagnetic on-off valves are closed, and the return water only flows through the heat storage tank 11 into the three-channel heat exchanger 3 to complete the defrosting of the evaporator 5. 2 Detected temperature > fourth temperature probe T 4 The detected temperature is +10°C, the sixth electromagnetic on-off valve 1306 and the fifth electromagnetic on-off valve 1305 are opened, the eighth electromagnetic on-off valve 1308, the seventh electromagnetic on-off valve 1307 and the second water pump 1002 are closed, and the first electromagnetic three-way valve 1401 is turned, and the return water only flows through the solar collector 12 into the three-channel heat exchanger 3, completing the defrosting of the evaporator side. The first temperature probe T 1 The detected temperature is greater than 5° C., and the defrosting is completed. The first water pump 1001 and the second water pump 1002 are turned off, and the first electromagnetic on-off valve 1301 and the second electromagnetic on-off valve 1302 are closed.

[0054] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A cascaded heat pump drying system with phase change energy storage coupled with solar energy, characterized in that, it includes a first-stage heat pump unit, a second-stage heat pump unit, and a solar heating unit; The first-stage heat pump unit includes a first-stage heat pump compressor (101), a heat exchanger (3), an evaporator (5), and a first condensation fan (601). The first-stage heat pump compressor (101) is respectively connected to the evaporator (5) and the heat exchanger (3). The evaporator (5) and the heat exchanger (3) are connected. The first condensation fan (601) is installed on the evaporator (5); The second-stage heat pump unit includes a second-stage heat pump compressor (102), a condenser (8), a heat exchanger (3), a second condensation fan (602), and a drying chamber (9). The second-stage heat pump compressor (102) is respectively connected to the heat exchanger (3) and the condenser (8). The condenser (8) is installed in the drying chamber (9). The second condensation fan (602) is installed on the condenser (8); The heat exchanger (3) is a three-channel heat exchanger. The heat exchanger (3) has a first-stage heat pump refrigerant pipeline inlet (1605), a first-stage heat pump refrigerant pipeline outlet (1606), a second-stage heat pump refrigerant pipeline inlet (1603), a second-stage heat pump refrigerant pipeline outlet (1604), a water pipeline inlet (1601), a water pipeline outlet (1602), a water channel (1607), a first-stage heat pump refrigerant channel (1608), and a second-stage heat pump refrigerant channel (1609). The first-stage heat pump refrigerant pipeline inlet (1605) of the three-channel heat exchanger is connected to the first port of the four-way valve (2). The outlet end of the first-stage heat pump refrigerant channel (1608) of the three-channel heat exchanger is respectively connected to the third electromagnetic on-off valve (1303) and the second one-way expansion valve (402). The second one-way expansion valve (402) is connected to the fourth electromagnetic on-off valve (1304). The first one-way expansion valve (401) is connected to the third electromagnetic on-off valve (1303). The two end ports of the water channel (1607) are respectively the water pipeline inlet (1601) and the water pipeline outlet (1602). The water pipeline inlet (1601) and the water pipeline outlet (1602) of the water channel (1607) are respectively connected to the first end of the first electromagnetic on-off valve (1301) and the second electromagnetic on-off valve (1302), The two end ports of the first-stage heat pump refrigerant channel (1608) are respectively the first-stage heat pump refrigerant pipeline inlet (1605) and the first-stage heat pump refrigerant pipeline outlet (1606). The two end ports of the first-stage heat pump refrigerant channel (1608) are connected to the first-stage heat pump unit, The two end ports of the secondary heat pump refrigerant channel (1609) are respectively the secondary heat pump refrigerant pipeline inlet (1603) and the secondary heat pump refrigerant pipeline outlet (1604). The two end ports of the secondary heat pump refrigerant channel (1609) are connected to the secondary heat pump unit. The secondary heat pump refrigerant pipeline inlet (1603) and the secondary heat pump refrigerant pipeline outlet (1604) of the secondary heat pump refrigerant channel (1609) are respectively connected to the secondary heat pump compressor (102) and the third one-way expansion valve (403); The solar heating unit includes a first water pump (1001), a second water pump (1002), a heat storage tank (11), and a solar collector (12). The heat storage tank (11) is respectively communicated with the solar collector (12), the first water pump (1001), and the second water pump (1002). The first water pump (1001) is communicated with the heat exchanger (3), and both the solar collector (12) and the second water pump (1002) are communicated with the heat exchanger (3); The primary heat pump unit includes a first one-way expansion valve (401), a second one-way expansion valve (402), a third electromagnetic on-off valve (1303), and a fourth electromagnetic on-off valve (1304). The first one-way expansion valve (401) and the second one-way expansion valve (402) are located on the first pipeline of the evaporator (5). The first one-way expansion valve (401) and the second one-way expansion valve (402) are installed between the heat exchanger (3) and the evaporator (5), and the first one-way expansion valve (401) and the second one-way expansion valve (402) are arranged in parallel. The first one-way expansion valve (401) is connected in series with the third electromagnetic on-off valve (1303), and the second one-way expansion valve (402) is connected in series with the fourth electromagnetic on-off valve (1304); The end of the evaporator (5) is communicated with the primary heat pump compressor (101) through a four-way valve (2), and the primary heat pump compressor (101) is communicated with the heat exchanger (3) through a four-way valve (2); The secondary heat pump unit includes a third one-way expansion valve (403), and the third one-way expansion valve (403) is installed at the end of the heat exchanger (3); The solar heating unit includes a first electromagnetic on-off valve (1301), a second electromagnetic on-off valve (1302), a fifth electromagnetic on-off valve (1305), a sixth electromagnetic on-off valve (1306), a seventh electromagnetic on-off valve (1307), an eighth electromagnetic on-off valve (1308), and a first electromagnetic three-way valve (1401). The first electromagnetic on-off valve (1301) is installed between the first water pump (1001) and the heat exchanger (3). The second electromagnetic on-off valve (1302) is installed at the end of the heat exchanger (3). The fifth electromagnetic on-off valve (1305) is installed at the end of the solar collector panel (12). The seventh electromagnetic on-off valve (1307) is installed at the end of the second water pump (1002). The second electromagnetic on-off valve (1302) is respectively connected to the fifth electromagnetic on-off valve (1305) and the seventh electromagnetic on-off valve (1307). The sixth electromagnetic on-off valve (1306) is connected to the eighth electromagnetic on-off valve (1308) and the solar collector panel (12). A first electromagnetic three-way valve (1401) is connected in parallel to the eighth electromagnetic on-off valve (1308), and the first electromagnetic three-way valve (1401) is connected to the heat storage tank (11). The eighth electromagnetic on-off valve (1308) is connected to the first water pump (1001).

2. The cascade heat pump drying system coupled with solar energy according to claim 1, characterized in that: The internal pipes of the heat exchanger (3) contain water, a primary refrigerant, and a secondary refrigerant.

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