Heat pump efficient drying system based on condensation-runner cascade dehumidification

Abstract

The invention discloses a heat pump efficient drying system based on condensation-rotating wheel cascade dehumidification, and relates to the technical field of agricultural product heat pump coupling rotating wheel dehumidification. During drying, high-humidity return air of a drying bin is cooled through an evaporation section of a heat exchanger, then cooled and dehumidified through an evaporator I and then enters a drying area of a dehumidification rotating wheel to be dehumidified again; the obtained low-temperature and low-moisture-content air is heated through a condenser II and then enters a drying bin to dry the materials, drying circulation is completed, and the drying quality of the materials is guaranteed through primary cooling dehumidification of an evaporator I in the heat pump drying system and dehumidification of a dehumidification rotary wheel drying area. Meanwhile, the dehumidification rotating wheel conducts deep dehumidification on the air, the lower air moisture content can be obtained, the drying rate can be obviously increased, meanwhile, due to the fact that the drying rate is increased, the operation energy consumption of the system is lower, and the problem that an existing heat pump drying system is low in drying rate in order to guarantee the material drying quality is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of heat pump coupling rotary wheel dehumidification for agricultural products, and particularly to a high-efficiency heat pump drying system based on condensation-rotary wheel cascade dehumidification. Background Art

[0002] The drying and dehydration treatment of agricultural products is not only the core process for extending their shelf life for safe storage, but also the processing requirement for a series of dried products. Heat pump drying has the remarkable advantages of being environmentally friendly and having a high energy efficiency ratio, and its application range is very wide. In addition, the heat pump can achieve low-temperature drying, especially having significant advantages for the drying of some heat-sensitive crops or Chinese herbal medicine products with high economic value.

[0003] The following is the specific analysis idea of the applicant's research and design: The heat pump drying technology is widely used in the fields of wood, fruits, vegetables, medicinal materials and grain drying due to its characteristics of being green, environmentally friendly, energy-saving, efficient, easy to operate and having strong applicability. The heat pump system can be divided into a closed drying system and an open drying system. During the operation of the closed heat pump drying equipment, in the early stage of drying, the air discharged from the drying chamber has a high humidity, and the moisture can be fully condensed on the wall surface of the evaporator, thus making full use of the latent heat of vaporization of the moisture in the air, and the system energy efficiency is relatively high. In the later stage of drying, due to the reduction of the moisture content of the material, the heat obtained by the evaporator is less and less, which not only affects the system energy efficiency, but also because the heat discharged from the condenser is always greater than the heat absorbed by the evaporator, the temperature of the drying chamber gradually rises with the increase of the drying time, resulting in the heat pump triggering high-pressure protection and being prone to shutdown, thereby affecting the drying quality, and the drying quality of the material is relatively low. For the open drying system, the drying quality of the material is relatively high, but it has certain regional and seasonal limitations in use and is greatly affected by the environmental temperature and humidity. When the environmental temperature is relatively low, it is difficult to heat the circulating air to the required drying temperature, and the drying rate is low. Summary of the Invention

[0004] Aiming at the deficiencies in the above background art, the present invention proposes a high-efficiency heat pump drying system based on condensation-rotary wheel cascade dehumidification, which solves the technical problem that the existing heat pump drying system has a low drying rate in order to ensure the drying quality of the material.

[0005] The technical solution of the present invention is realized as follows: A high-efficiency heat pump drying system based on condensation-rotary wheel cascade dehumidification includes a condenser I, an evaporator I, a heat exchanger, the drying area of a dehumidification rotary wheel, an evaporator II, a condenser II, and a drying bin for drying materials. When the drying system is drying, the return air of the drying bin sequentially flows through the evaporation section of the heat exchanger, the evaporator I, the drying area of the dehumidification rotary wheel, and the condenser II and then returns to the air inlet of the drying chamber. At the same time, fresh air sequentially flows through the condensation section of the heat exchanger, the condenser I, the regeneration area of the dehumidification rotary wheel, and the evaporator II and then is discharged into the atmosphere. When the heat pump drying system of the present application is drying, the high-humidity return air of the drying bin is cooled by the evaporation section of the heat exchanger, then cooled and dehumidified by the evaporator I, and then enters the drying area of the dehumidification rotary wheel to be dehumidified again. The obtained low-temperature and low-moisture-content air is heated by the condenser II and then enters the drying bin to dry the materials, completing a drying cycle. Through the preliminary cooling and dehumidification of the evaporator I in the heat pump drying system and the dehumidification of the drying area of the dehumidification rotary wheel, the drying quality of the materials is ensured. At the same time, the dehumidification rotary wheel deeply dehumidifies the air, and a lower air moisture content can be obtained, which can significantly improve the drying rate, overcome the defect of slow drying rate. At the same time, due to the increase in the drying rate, the operating energy consumption of the system is lower, solving the technical problem of the low drying rate of the existing heat pump drying system in order to ensure the drying quality of the materials.

[0006] The dehumidification rotary wheel is the dehumidification rotary wheel on a rotary dehumidifier. The dehumidification rotary wheel includes a treatment area and a regeneration area. The regeneration temperature of the dehumidification rotary wheel involved in this patent is generally in the range of 45°C - 70°C, and the condensation heat of the condenser I in the heat pump drying system is used as the driving energy for the regeneration of the dehumidification rotary wheel, making the system more flexible in application.

[0007] Preferably, the heat exchanger is a heat pipe heat exchanger. The heat exchanger is a heat pipe heat exchanger because the heat pipe heat exchanger has the following advantages: 1. Ultra-high thermal conductivity: The heat pipe transfers heat through the phase change (evaporation and condensation) of the working fluid, and its equivalent thermal conductivity can reach hundreds to thousands of times that of ordinary metals (such as copper), and it can achieve rapid heat transfer with a very small temperature difference. 2. Complete separation of hot and cold fluids: Through the middle partition design, the hot and cold media do not mix with each other, reducing the risk of leakage, especially suitable for occasions with flammable, explosive or corrosive fluids. 3. Compact design: Using external-tube flow heat transfer (fin tubes expand the heat transfer area), the volume is only 1 / 3 of that of an ordinary heat exchanger, saving space.

[0008] Preferably, a second fan is provided at the air inlet of the drying chamber, and the second fan is located between the drying chamber and the second condenser; a first fan is connected to the fresh air inlet. A fan converts mechanical energy into gas kinetic energy and pressure energy by rotating the impeller to do work on the gas, forming a directional air flow. The second fan is provided to introduce high-temperature gas pressurized by the second fan into the air inlet of the drying chamber and improve the rate of input of the high-temperature gas into the drying chamber. The first fan is provided to facilitate the entry of fresh air and improve the rate of fresh air entry.

[0009] Preferably, a damper for controlling the flow direction is provided on the drying system. The damper is provided to adjust the flow direction of the air flow in the return circuit of the drying system, thereby controlling whether the drying system is in the preheating stage or the material drying stage and realizing the adjustment of the two-stage circuit.

[0010] Among them, the drying system of the present application is provided with a first damper, a second damper, a third damper and a fourth damper. The preheating process is as follows: the return air from the drying bin enters the second condenser through the fourth damper for heating and temperature rise, and then is sent to the drying bin under the action of the second fan, and this cycle continues until the ambient temperature of the drying bin reaches the set value. At the same time, the fresh air enters the second evaporator through the third damper under the action of the first fan, and the air is cooled and then discharged into the atmosphere. During this operation stage, the first damper and the second damper are closed. After the ventilation preheating stage ends, it enters the ventilation drying stage. The high-humidity return air from the drying bin passes through the second damper, is cooled by the evaporation section of the heat exchanger, then is cooled and dehumidified by the first evaporator, and then enters the drying area of the rotary wheel for further dehumidification. The obtained low-temperature and low-moisture-content air is heated by the second condenser and then enters the drying bin through the second fan to dry the material, completing one cycle. At the same time, the fresh air enters the condensation section of the heat exchange tube through the first damper under the action of the first fan, is heated, and then is heated by the first condenser. The obtained high-temperature air enters the rotary wheel to regenerate the ineffective dehumidification material, and then is cooled and dehumidified by the second evaporator and discharged into the atmosphere.

[0011] Preferably, a first circulation loop is connected to the first condenser. The first circulation loop is provided to realize the circulation of the refrigerant on the first condenser.

[0012] Preferably, the first circulation loop includes a compressor I. The outlet of the compressor I is connected to a condenser I. The liquid outlet of the condenser I is communicated with the liquid inlet of an evaporator I. A first control member for regulating the refrigerant flow rate is provided on the connecting pipe between the condenser I and the evaporator I. The first control member is mainly used to regulate the refrigerant flow rate, thereby ensuring the stability of the first circulation loop. After the low-pressure refrigerant gas is compressed by the compressor I, the obtained high-pressure refrigerant gas enters the condenser I to exchange heat with air and is cooled into a high-pressure refrigerant liquid. Then, after throttling and pressure reduction by the first control member, the obtained low-temperature and low-pressure refrigerant wet steam enters the evaporator I and exchanges heat with the air flowing through the evaporator I. Among them, the low-pressure refrigerant liquid is completely vaporized and then enters the compressor I to be compressed again, thus completing a cycle.

[0013] Preferably, a preheating unit is provided on the drying system; the preheating unit includes a condenser II. When the drying system is preheated, the return air of the drying chamber sequentially passes through the condenser II and a fan II and then returns to the air inlet of the drying chamber. At the same time, the fresh air sequentially passes through a fan I and an evaporator II and then is discharged into the atmosphere. The setting of the preheating unit enables the drying system of the present application to have the function of rapid preheating and a short system stabilization time. The preheating unit mainly rapidly raises the temperature of the environment in the drying bin to reach the set temperature. When the drying system is preheated, the return air of the drying bin enters the condenser II through a valve IV for heating and temperature raising, and then is sent to the drying bin under the action of the fan, and so on in a cycle until the environmental temperature of the drying bin reaches the set value. At the same time, the fresh air enters the evaporator II through a valve III under the action of the fan I, and the air is cooled and then discharged into the atmosphere. In this operating stage, the valve I and the valve II are closed.

[0014] Preferably, a second circulation loop is connected to the condenser II. The setting of the second circulation loop is to realize the circulation and flow of the refrigerant on the condenser II.

[0015] Preferably, the second circulation loop includes a compressor II. The outlet of the compressor II is connected to the condenser II. The liquid outlet of the condenser II is communicated with the liquid inlet of the evaporator II. A second control member for regulating the refrigerant flow rate is provided on the connecting pipe between the evaporator II and the condenser II. The second control member is mainly used to regulate the refrigerant flow rate, thereby ensuring the stability of the second circulation loop. After the low-pressure refrigerant gas is compressed by the compressor II, the obtained high-pressure refrigerant gas enters the condenser II to exchange heat with air and is cooled into a high-pressure liquid. Then, after throttling and pressure reduction by the second control member, the obtained low-temperature and low-pressure refrigerant wet steam enters the evaporator I and exchanges heat with the air flowing through the evaporator I. Among them, the low-pressure refrigerant liquid is completely vaporized and then enters the compressor I to be compressed again, thus completing a cycle.

[0016] Preferably, both the first control member and the second control member are electromagnetic expansion valves. The functions of the electromagnetic expansion valve mainly include throttling and pressure reduction, controlling superheat, and regulating the refrigerant flow rate. As a throttle valve, the electronic expansion valve can reduce the high-pressure refrigerant liquid from the condenser to a low-pressure liquid and send it into the evaporator. In this application, both the first control member and the second control member are electromagnetic expansion valves to adjust the refrigerant flow rate, and then by adjusting the opening degree of the electromagnetic expansion valve and the compression ratio of the compressor, different drying mode requirements such as high-temperature drying, low-temperature drying, and high-temperature and low-temperature cascade drying of materials can be achieved. That is, by adjusting the opening degree of the second control member on the second circulation loop and the compression ratio of the compressor II, different drying mode requirements such as high-temperature drying, low-temperature drying, and high-temperature and low-temperature cascade drying of materials can be achieved.

[0017] Advantages of the present invention: 1. Through the preliminary cooling and dehumidification of the evaporator I in the heat pump drying system and the deep dehumidification in the dehumidifying rotary wheel drying area, a lower moisture content in the air can be obtained, which can significantly improve the drying rate. Due to the increase in the drying rate, the operating energy consumption of the system is lower.

[0018] 2. The system first uses the evaporator for condensation dehumidification and then the rotary wheel for deep dehumidification, which not only gives full play to the advantages of condensation dehumidification and rotary wheel dehumidification, greatly reduces the dehumidification load of the rotary wheel, but also has the characteristics of an integrated heat pump opening and closing drying system, making the system more efficient and energy-saving.

[0019] 3. In this application, by adjusting the opening degree of the electromagnetic expansion valve in the second circulation loop and the compression ratio of the compressor II, different drying mode requirements such as high-temperature drying, low-temperature drying, and high-temperature and low-temperature cascade drying of materials can be achieved, which is suitable for the drying of more agricultural products. The system has a wide application range, especially for some high-value heat-sensitive agricultural products. In addition, the switching and control between various operating modes are simple.

[0020] 4. This system uses the high-temperature exhaust gas for the regeneration of the dehumidifying rotary wheel as the heat source of the evaporator. Under the condition of ensuring a reasonable compression ratio, the compressor has higher energy efficiency and a higher drying temperature can be obtained. Since the waste heat of the rotary wheel regeneration exhaust gas is fully utilized, the system has significant energy savings.

[0021] 5. A heat pipe heat exchanger is arranged between the low-temperature fresh air and the high-temperature return air in the drying chamber, which increases the fresh air temperature, reduces the heat load of the condenser for the rotary wheel regeneration, and at the same time reduces the air temperature entering the rotary wheel dehumidification, improving the dehumidification performance of the air in the rotary wheel and further improving the energy efficiency of the system. Description of the Drawings

[0022] To more clearly illustrate the embodiments of the present invention, the accompanying drawings required for the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0023] Figure 1 It is a schematic diagram of the present invention.

[0024] In the figure: 1 is compressor I, 2 is condenser I, 3 is evaporator I, 4 is the first control member, 5 is the heat exchanger, 6 is air valve I, 7 is fan I, 8 is the dehumidification wheel, 9 is compressor II, 10 is evaporator II, 11 is condenser II, 12 is the second control member, 13 is fan II, 14 is the drying bin, 15 is air valve II, 16 is air valve III, 17 is air valve IV. Specific embodiments

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0026] Embodiment 1, a heat pump efficient drying system based on condensation - wheel cascade dehumidification, as Figure 1As shown, it includes a condenser I 2, an evaporator I 3, a heat exchanger 5, the drying area of a dehumidifying rotor 8, an evaporator II 10, a condenser II 11, and a drying bin 14 for drying materials. When the drying system is drying, the return air of the drying bin 14 sequentially flows through the evaporation section of the heat exchanger 5, the evaporator I 3, the drying area of the dehumidifying rotor 8, and the condenser II 11 and then returns to the air inlet of the drying chamber 14. At the same time, the fresh air sequentially flows through the condensation section of the heat exchanger 5, the condenser I 2, the regeneration area of the dehumidifying rotor 8, and the evaporator II 10 and then is discharged into the atmosphere. When the heat pump drying system of the present application is drying, the high-humidity return air of the drying bin 14 is cooled by the evaporation section of the heat exchanger 5, then cooled and dehumidified by the evaporator I 3, then enters the drying area of the dehumidifying rotor 8 and is dehumidified again. The obtained low-temperature and low-moisture-content air is heated by the condenser II 11 and then enters the drying bin 14 to dry the materials, completing a drying cycle. Through the preliminary cooling and dehumidification of the evaporator I 3 in the heat pump drying system and the dehumidification in the drying area of the dehumidifying rotor 8, the drying quality of the materials is guaranteed. At the same time, the dehumidifying rotor 8 deeply dehumidifies the air, and a lower air moisture content can be obtained, which can significantly improve the drying rate, overcome the defect of slow drying rate. At the same time, due to the increase in the drying rate, the operating energy consumption of the system is lower, solving the technical problem that the existing heat pump drying system has a low drying rate in order to ensure the drying quality of the materials.

[0027] The dehumidifying rotor 8 is the dehumidifying rotor on a rotary dehumidifier. The dehumidifying rotor includes a treatment area and a regeneration area. The regeneration temperature of the dehumidifying rotor 8 involved in this patent is generally in the range of 45°C - 70°C, and the condensation heat of the condenser I 2 in the heat pump drying system is used as the driving energy for the regeneration of the dehumidifying rotor 8, making the system application more flexible.

[0028] Example 2, on the basis of Example 1, a heat pump high-efficiency drying system based on condensation-rotor cascade dehumidification, as Figure 1 shown, the heat exchanger 5 is a heat pipe heat exchanger. The heat exchanger 5 is a heat pipe heat exchanger because the heat pipe heat exchanger has the following advantages: 1. Ultra-high heat conduction performance: The heat pipe transfers heat through the phase change of the working medium (evaporation and condensation), and its equivalent heat conduction coefficient can reach hundreds to thousands of times that of ordinary metals (such as copper), and it can achieve rapid heat transfer with a very small temperature difference. 2. Complete separation of hot and cold fluids: Through the middle partition design, the hot and cold media do not mix with each other, overcoming the air leakage defect.

[0029] Example 3, on the basis of Example 2, a heat pump high-efficiency drying system based on condensation-rotor cascade dehumidification, as Figure 1As shown in the figure, a blower II 13 is provided at the air inlet of the drying chamber 14, and the blower II 13 is located between the drying chamber 14 and the condenser II 11; a blower I 7 is connected to the fresh air inlet. A blower works by rotating an impeller to do work on the gas, converting mechanical energy into gas kinetic energy and pressure energy to form a directional air flow. The blower II 13 is provided to introduce high-temperature gas pressurized by the blower II 13 into the air inlet of the drying chamber 14 and improve the rate of input of the high-temperature gas into the drying chamber 14. The blower I 7 is provided to allow fresh air to enter and improve the rate of fresh air entry.

[0030] Example 4. On the basis of Example 3, a heat pump high-efficiency drying system based on condensation-rotary cascade dehumidification, as Figure 1 shown, a damper for controlling the flow direction is provided on the drying system. The damper is provided to adjust the flow direction of the air flow in the return circuit of the drying system, thereby controlling the drying system to be in the preheating stage or the material drying stage and realizing the adjustment of the two-stage circuit.

[0031] Among them, the drying system of the present application is provided with a damper I 6, a damper II 15, a damper III 16 and a damper IV 17. The preheating working process is as follows: the return air of the drying bin 14 enters the condenser II 11 through the damper IV 17 for heating and temperature rise, and then is sent to the drying bin 14 under the action of the blower II 13, and this cycle continues until the ambient temperature of the drying bin 14 reaches the set value. At the same time, the fresh air enters the evaporator II 10 through the damper III 16 under the action of the blower I 7, and the air is cooled and then discharged into the atmosphere. In this operating stage, the damper I 6 and the damper II 15 are closed. After the ventilation preheating stage ends, it enters the ventilation drying stage. The high-humidity return air of the drying bin 14 passes through the damper II 15, is cooled by the evaporation section of the heat exchanger 5, then is cooled and dehumidified by the evaporator I 3, and then enters the drying area of the dehumidification rotor 8 to be dehumidified again. The obtained low-temperature and low-moisture-content air is heated by the condenser II 11 and then enters the drying bin 14 through the blower II 13 to dry the material, completing one cycle. At the same time, the fresh air enters the condensation section of the heat exchange tube 5 through the damper I 6 under the action of the blower I 7 and is heated, and then is heated by the condenser I 2. The obtained high-temperature air enters the dehumidification rotor 8 to regenerate the ineffective dehumidification material, and then is cooled and dehumidified by the evaporator II 10 and discharged into the atmosphere.

[0032] Example 5. On the basis of Example 4, a heat pump high-efficiency drying system based on condensation-rotary cascade dehumidification, as Figure 1 shown, a first circulation circuit is connected to the condenser I 2. The first circulation circuit is provided to realize the circulation and flow of the refrigerant on the condenser I 2.

[0033] Example 6. On the basis of Example 5, a heat pump high-efficiency drying system based on condensation-rotary cascade dehumidification, as Figure 1As shown, the first circulation loop includes a compressor I 1. The outlet of the compressor I 1 is connected to a condenser I 2. The liquid outlet of the condenser I 2 is communicated with the liquid inlet of an evaporator I 3. A first control member 4 for adjusting the refrigerant flow rate is provided on the connecting pipe between the condenser I 2 and the evaporator I 3. The first control member 4 is mainly used for adjusting the refrigerant flow rate, thereby ensuring the stability of the first circulation loop. After the low-pressure refrigerant gas is compressed by the compressor I 1, the obtained high-pressure refrigerant gas enters the condenser I 2 to exchange heat with air and is cooled into a high-pressure refrigerant liquid. Then, after throttling and pressure reduction by the first control member 4, the obtained low-temperature and low-pressure refrigerant wet steam enters the evaporator I 3 and exchanges heat with the air flowing through the evaporator I 3, where the low-pressure refrigerant liquid is completely vaporized and then enters the compressor I 1 for re-compression, thus completing a cycle.

[0034] Embodiment 7. Based on any one of Embodiments 3 to 6, a heat pump high-efficiency drying system based on condensation-rotary cascade dehumidification, as Figure 1 shown, a preheating unit is provided on the drying system; the preheating unit includes a condenser II 11. When the drying system is preheating, the return air of the drying chamber 14 sequentially passes through the condenser II 11 and the fan II 13 and then returns to the air inlet of the drying chamber 14. At the same time, the fresh air sequentially passes through the fan I 7 and the evaporator II 10 and then is discharged into the atmosphere. The setting of the preheating unit enables the drying system of the present application to have the function of rapid preheating, and the system has a short stable time. The preheating unit mainly rapidly raises the temperature of the environment in the drying bin 14 to reach the set temperature. When the drying system is preheating, the return air of the drying bin 14 enters the condenser II 11 through the air valve IV 17 for heating and temperature raising, and then under the action of the fan II 13, it is sent to the drying bin 14, and so on in a cycle until the environmental temperature of the drying bin 14 reaches the set value. At the same time, under the action of the fan I 7, the fresh air enters the evaporator II 10 through the air valve III 16, and the air is cooled and then discharged into the atmosphere. In this operating stage, the air valve I 6 and the air valve II 15 are closed.

[0035] Embodiment 8. Based on Embodiment 7, a heat pump high-efficiency drying system based on condensation-rotary cascade dehumidification, as Figure 1 shown, a second circulation loop is connected to the condenser II 11. The setting of the second circulation loop is to realize the circulation and flow of the refrigerant on the condenser II 11.

[0036] Embodiment 9. Based on Embodiment 8, a heat pump high-efficiency drying system based on condensation-rotary cascade dehumidification, as Figure 1As shown in the figure, the second circulation loop includes a compressor II 9. The outlet of the compressor II 9 is connected to a condenser II 11. The liquid outlet of the condenser II 11 is communicated with the liquid inlet of the evaporator II 10. A second control member 12 for regulating the refrigerant flow rate is provided on the connecting pipe between the evaporator II 10 and the condenser II 11. The second control member 12 is mainly used to regulate the refrigerant flow rate, thereby ensuring the stability of the second circulation loop. After the low-pressure refrigerant gas is compressed by the compressor II 9, the obtained high-pressure refrigerant gas enters the condenser II 11 to exchange heat with air and is cooled into a high-pressure liquid. Then, after throttling and pressure reduction by the second control member 12, the obtained low-temperature and low-pressure refrigerant wet steam enters the evaporator I 3 and exchanges heat with the air flowing through the evaporator I 3. Among them, the low-pressure refrigerant liquid is completely vaporized and then enters the compressor I 1 to be compressed again, thus completing a cycle.

[0037] Embodiment 10. On the basis of Embodiment 9, a heat pump high-efficiency drying system based on condensation-rotary cascade dehumidification is as Figure 1 shown in the figure. The first control member 4 and the second control member 12 are both electromagnetic expansion valves. The functions of the electromagnetic expansion valve mainly include throttling and pressure reduction, controlling superheat, and regulating the refrigerant flow rate. As a throttle valve, the electronic expansion valve can reduce the high-pressure refrigerant liquid from the condenser to a low-pressure liquid and send it into the evaporator. In this application, the first control member 4 and the second control member 12 are both electromagnetic expansion valves in order to regulate the refrigerant flow rate by using the electromagnetic expansion valve. Furthermore, by adjusting the opening degree of the electromagnetic expansion valve and the compression ratio of the compressor, different drying mode requirements such as high-temperature drying, low-temperature drying, and high-temperature and low-temperature cascade drying of materials can be realized. That is, by adjusting the opening degree of the second control member 12 on the second circulation loop and the compression ratio of the compressor II 9, different drying mode requirements such as high-temperature drying, low-temperature drying, and high-temperature and low-temperature cascade drying of materials can be realized.

[0038] When Embodiment 10 is implemented, the operation of the drying system of this application includes ventilation drying and heat pump circulation. The ventilation drying can be divided into two stages. The first stage is the ventilation preheating stage, and the second stage is the material drying stage.

[0039] In the first stage, the rapid preheating stage of the system, the return air of the drying bin 14 enters the condenser II 11 through the air valve IV 17 to be heated and raised in temperature, and then under the action of the fan II 13, it is sent to the drying bin 14. Such a cycle is carried out until the ambient temperature of the drying bin 14 reaches the set value. At the same time, the fresh air enters the evaporator II 10 under the action of the fan I 7 through the air valve III 16, and the air is cooled and then discharged into the atmosphere. In this operation stage, the air valve I 6 and the air valve II 15 are closed.

[0040] In the second stage, the material drying stage, after the ventilation and preheating stage ends, it turns into the ventilation and drying stage. The high-humidity return air in the drying bin 14 passes through the air valve II 15, is cooled by the evaporation section of the heat exchanger 5, then is cooled and dehumidified by the evaporator I 3, and then enters the drying area of the dehumidification rotor 8 to be dehumidified again. The obtained low-temperature and low-moisture-content air is heated by the condenser II 11, and then enters the drying bin 14 through the fan II 13 to dry the material, completing one cycle. At the same time, under the action of the fan I 7, the fresh air enters the condensation section of the heat exchange tube 5 to be heated, and then is heated by the condenser I 2. The obtained high-temperature air enters the dehumidification rotor 8 to regenerate the ineffective dehumidification material, and then is cooled and dehumidified by the evaporator II 10 and discharged into the atmosphere. In this operation stage, the temperature of the air sent into the drying bin 14 can meet the requirements of different drying modes such as high-temperature drying, low-temperature drying, and high-temperature and low-temperature cascade drying of the material by adjusting the opening of the second control part 12 on the second circulation loop and the compression ratio of the compressor II 9.

[0041] Heat pump cycle: The first circulation loop: After the low-pressure refrigerant gas is compressed by the compressor I 1, the obtained high-pressure refrigerant gas enters the condenser I 2 to exchange heat with the air and is cooled into a high-pressure liquid. Then, after throttling and pressure reduction by the first control part 4, the obtained low-temperature and low-pressure refrigerant wet steam enters the evaporator I 3 to exchange heat with the air. The low-pressure liquid refrigerant is completely vaporized and then enters the compressor I 1 to be compressed again, thus completing one cycle. Corresponding to the ventilation and preheating stage, the heat pump cycle 1 does not work.

[0042] The second circulation loop: After the low-pressure refrigerant gas is compressed by the compressor II 9, the obtained high-pressure refrigerant gas enters the condenser II 11 to exchange heat with the air and is cooled into a high-pressure liquid. Then, after throttling and pressure reduction by the second control part 12, the obtained low-temperature and low-pressure refrigerant wet steam enters the evaporator II 10 to exchange heat with the air. The low-pressure liquid refrigerant is completely vaporized and then enters the compressor I 1 to be compressed again, thus completing one cycle.

[0043] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high-efficiency heat pump drying system based on condensation-rotary cascade dehumidification, characterized in that It includes a condenser I (2), an evaporator I (3), a heat exchanger (5), the drying area of a dehumidification wheel (8), an evaporator II (10), a condenser II (11), and a drying bin (14) for drying materials. When the drying system is drying, the return air of the drying bin (14) flows through the evaporation section of the heat exchanger (5), the evaporator I (3), the drying area of the dehumidification wheel (8), and the condenser II (11) in sequence and then returns to the air inlet of the drying chamber (14). At the same time, the fresh air flows through the condensation section of the heat exchanger (5), the condenser I (2), the regeneration area of the dehumidification wheel (8), and the evaporator II (10) in sequence and then is discharged into the atmosphere.

2. The heat pump high-efficiency drying system based on condensation-rotary step dehumidification according to claim 1, characterized in that: The heat exchanger (5) is a heat pipe heat exchanger.

3. The heat pump high-efficiency drying system based on condensation-rotary cascade dehumidification according to claim 2, wherein: A fan II (13) is provided at the air inlet of the drying chamber (14), and the fan II (13) is located between the drying chamber (14) and the condenser II (11); a fan I (7) is connected to the inlet of the fresh air.

4. The heat pump high-efficiency drying system based on condensation-rotary cascade dehumidification according to claim 3, characterized in that: A air valve for controlling the flow direction is provided on the drying system.

5. The heat pump high-efficiency drying system based on condensation-rotary cascade dehumidification according to claim 4, characterized in that: A first circulation loop is connected to the condenser I (2).

6. The heat pump high-efficiency drying system based on condensation-rotary step dehumidification according to claim 5, wherein: The first circulation loop includes a compressor I (1). The outlet of the compressor I (1) is connected to the condenser I (2). The liquid outlet of the condenser I (2) is communicated with the liquid inlet of the evaporator I (3). A first control member (4) for adjusting the refrigerant flow rate is provided on the connecting pipe between the condenser I (2) and the evaporator I (3).

7. The heat pump high-efficiency drying system based on condensation-rotary cascade dehumidification according to any one of claims 3 to 6, characterized in that: A preheating unit is provided on the drying system; the preheating unit includes a condenser II (11). When the drying system is preheating, the return air of the drying chamber (14) passes through the condenser II (11) and the fan II (13) in sequence and then returns to the air inlet of the drying chamber (14). At the same time, the fresh air passes through the fan I (7) and the evaporator II (10) in sequence and then is discharged into the atmosphere.

8. The heat pump high-efficiency drying system based on condensation-rotary step dehumidification according to claim 7, characterized in that: A second circulation loop is connected to the condenser II (11).

9. The heat pump high-efficiency drying system based on condensation-rotary step dehumidification according to claim 8, wherein: The second circulation loop includes a compressor II (9). The outlet of the compressor II (9) is connected to the condenser II (11). The liquid outlet of the condenser II (11) is communicated with the liquid inlet of the evaporator II (10). A second control member (12) for adjusting the refrigerant flow rate is provided on the connecting pipe between the evaporator II (10) and the condenser II (11).

10. The heat pump high-efficiency drying system based on condensation-rotary step dehumidification according to claim 9, characterized in that: Both the first control member (4) and the second control member (12) are electromagnetic expansion valves.

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