Heat pump opening and closing integrated multi-mode efficient drying system based on double evaporators

Abstract

The invention discloses a heat pump opening and closing integrated multi-mode efficient drying system based on double evaporators, and relates to the technical field of agricultural product drying. When materials are dried at low temperature, fresh air enters along a first fresh air inlet, sequentially flows through an evaporator I and a condenser and then returns to an air inlet of a drying chamber; return air of the drying chamber is discharged into the atmosphere through the evaporator II; when materials are dried at high temperature, fresh air enters along the second fresh air inlet, passes through the condenser and then returns to the air inlet of the drying chamber, return air of the drying chamber passes through the evaporator II and then is exhausted into the atmosphere, and meanwhile the fresh air enters along the first fresh air inlet, passes through the evaporator I and then is exhausted into the atmosphere. By changing the flow direction, one set of drying system can be switched between the low-temperature drying mode and the high-temperature drying mode, then the drying quality of materials is guaranteed, and the technical problem that in an existing heat pump drying system, switching between the low-temperature drying mode and the high-temperature drying mode cannot be achieved through one set of drying system is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of agricultural product drying, and particularly to a high-efficiency drying system with an integrated heat pump opening and closing and multiple modes based on a dual evaporator. Background Art

[0002] Heat pump drying has developed with the heat pump technology. The heat pump has the remarkable advantage of high energy efficiency ratio, and at the same time can achieve the collaborative emission reduction effect of air pollutants and greenhouse gases. After years of development, the application of heat pumps in China almost covers all fields such as agricultural and sideline products, especially the field of grain drying is becoming more and more widely used.

[0003] Heat pump drying systems can be divided into open heat pump drying systems and closed drying systems according to the circulation mode of the drying medium. The performance of air-source heat pumps is relatively sensitive to the ambient temperature. When the ambient temperature is relatively low, a closed structure is more suitable to exclude the influence of harsh external environmental factors. In the first half of the drying process, the moisture content of the material is high, and the evaporator can recover a large amount of the latent heat of vaporization of water vapor, and the system energy efficiency is high. However, in the second half of the drying process, the moisture content of the material is low, and the heat recovered by the evaporator is insufficient. The heat source of the drying chamber mainly comes from electric energy, and the system energy efficiency is low. At the same time, during the operation of the closed heat pump drying equipment, the heat discharged by the condenser is always greater than the heat absorbed by the evaporator, so that the temperature of the drying chamber gradually rises with the increase of the drying time, resulting in the heat pump triggering the high-pressure protection mechanism and shutting down. Open heat pump drying equipment has certain regional and seasonal limitations in use and is greatly affected by the ambient temperature and humidity. When the ambient temperature is relatively low, it is very difficult to heat the circulating air to the required drying temperature. In addition, in the first half of the drying process, the moisture content of the material is high. After the heat pump operates for a period of time, the drying chamber needs to open the exhaust valve to dehumidify. The dehumidification process will not only cause the temperature in the drying chamber to drop sharply, but also the exhaust air will carry a large amount of waste heat, and the system energy efficiency is low. However, for the second half of the material drying process, the open dehumidification interval is long and the system energy efficiency is relatively high.

[0004] Among them, the drying of the second half of the material is particularly important for the drying quality of the material. Different material characteristics require appropriate drying modes for the second half, that is, the drying of the second half of the material needs to select a low-temperature drying mode or a high-temperature drying mode according to the material characteristics. However, when the existing drying system dries the second half of the material, it cannot adjust the drying mode of the second half. Generally, it is necessary to replace the drying system corresponding to the material characteristics for drying, and a set of drying system cannot realize the switching between the two drying modes. Therefore, how to realize the switching between a low-temperature drying mode and a high-temperature drying mode in a drying system is a technical problem to be solved. Summary of the Invention

[0005] Aiming at the deficiencies in the above background technology, the present invention proposes a heat pump opening and closing integrated multi-mode high-efficiency drying system based on a double evaporator, which solves the technical problem that a set of drying systems in the existing heat pump drying systems cannot achieve the switching between a low-temperature drying mode and a high-temperature drying mode.

[0006] The technical solution of the present invention is realized as follows: A heat pump opening and closing integrated multi-mode high-efficiency drying system based on a double evaporator includes an evaporator I, an evaporator II, a condenser, a first fresh air inlet, a second fresh air inlet, and a drying chamber for drying materials; when the materials in the drying system are in the second half of the low-temperature drying process, fresh air enters along the first fresh air inlet, flows through the evaporator I and the condenser in sequence, and then returns to the air inlet of the drying chamber, and the return air of the drying chamber flows through the evaporator II and then is discharged into the atmosphere; when the materials in the drying system are in the second half of the high-temperature drying process, fresh air enters along the second fresh air inlet, passes through the condenser and then returns to the air inlet of the drying chamber, the return air of the drying chamber flows through the evaporator II and then is discharged into the atmosphere, and at the same time, fresh air enters along the first fresh air inlet, passes through the evaporator I and then is discharged into the atmosphere. In the drying system of the present application, when the materials need to be dried at a low temperature, fresh air enters along the first fresh air inlet, flows through the evaporator I and the condenser in sequence, and then returns to the air inlet of the drying chamber, and the return air of the drying chamber flows through the evaporator II and then is discharged into the atmosphere; when the materials need to be dried at a high temperature, fresh air enters along the second fresh air inlet, passes through the condenser and then returns to the air inlet of the drying chamber, the return air of the drying chamber flows through the evaporator II and then is discharged into the atmosphere, and at the same time, fresh air enters along the first fresh air inlet, passes through the evaporator I and then is discharged into the atmosphere, so that the drying system of the present application can select a low-temperature drying mode or a high-temperature drying mode according to the material characteristics of the materials, and then realizes the switching between the low-temperature drying mode and the high-temperature drying mode of a set of drying systems by changing the flow direction, thereby ensuring the drying quality of the materials and solving the technical problem that a set of drying systems in the existing heat pump drying systems cannot achieve the switching between the low-temperature drying mode and the high-temperature drying mode.

[0007] When the materials of the drying system of the present application are in the second half of the low-temperature drying process, the temperature t range of the low-temperature drying is 15°C ≤ t ≤ 40°C. When the materials of the drying system of the present application are in the second half of the high-temperature drying process, the temperature T range of the high-temperature drying is 40°C < T ≤ 75°C.

[0008] A fan II is provided at the air inlet of the drying chamber, and the fan II is located between the drying chamber and the condenser. A fan does work on the gas by rotating the impeller, converting mechanical energy into gas kinetic energy and pressure energy to form a directional air flow. The setting of the fan II is to introduce the high-temperature gas pressurized by the fan II into the air inlet of the drying chamber and improve the rate of the high-temperature gas input into the drying chamber.

[0009] A blower I is connected to the inlet of the evaporator I. A blower does work on a gas by rotating an impeller, converting mechanical energy into the kinetic energy and pressure energy of the gas to form a directional air flow. The blower I is provided to allow fresh air to enter the evaporator I, thereby increasing the rate of fresh air entering the evaporator I.

[0010] When the drying system is preheating, fresh air enters along the first fresh air inlet, flows through the evaporator I and then is discharged into the atmosphere. The return air of the drying chamber flows through the evaporator II and the condenser in sequence and then returns to the air inlet of the drying chamber. At this time, the evaporator II does not work. Before drying the material, the drying system starts preheating, enabling the drying system to quickly heat the circulating air to the required drying temperature. And when the ambient temperature is relatively low, the drying system of the present application preheats the circulating air and quickly heats it to the required drying temperature, greatly reducing the influence of the ambient temperature and humidity on the drying system.

[0011] When the first half of the material in the drying system is being dried, the return air of the drying chamber flows through the evaporator II, the evaporator I and the condenser in sequence and then returns to the air inlet of the drying chamber. When the moisture content of the first half of the material is high during the first half of the drying process, a closed system is used for drying, which fully utilizes the energy-saving and high-efficiency operation of the closed system in the first half.

[0012] 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, realizing the adjustment of the two-stage circuit, and the damper can be used to control the switching between the low-temperature drying mode and the high-temperature drying mode of the drying system.

[0013] Among them, the dampers of the present application include damper I, damper II, damper III, damper IV, damper V, damper VI and damper VII. The specific damper control is as follows: Before drying the material in the present application, the drying system is preheated and operates in an open system. Fresh air enters along the first fresh air inlet, flows through damper III, is cooled after passing through the evaporator I under the action of blower I, and then flows through damper V and is discharged into the atmosphere. The return air of the drying chamber passes through the evaporator II (at this time, the evaporator II does not work), enters the condenser after passing through damper IV, and then enters the drying chamber for circulating heating under the action of blower II. When operating in this mode, damper I, damper II, damper VI and damper VII are closed, damper III, damper IV and damper V are open, the second control valve is closed, and the first control valve is open.

[0014] Initial closed - loop drying stage of materials: After the return air in the drying chamber is cooled and dehumidified by Evaporator II, it passes through Air Valve II, and then, under the action of Fan I, enters Evaporator I for further cooling and dehumidification. Then it enters the condenser through Air Valve VI to exchange heat and increase the temperature. The high - temperature and low - humidity air obtained enters the drying chamber under the action of Fan II to dry the materials, thus completing a cycle. When operating in this mode, Air Valve I, Air Valve III, Air Valve IV, Air Valve V, and Air Valve VII are closed.

[0015] In the later stage of material drying, an open - loop system is adopted: This mode can be further divided into a low - temperature drying open - loop mode and a high - temperature drying open - loop mode. Which mode to adopt specifically needs to be selected according to the material characteristics.

[0016] Among them, in the low - temperature drying open - loop mode: Fresh air enters along the first fresh - air inlet, passes through Air Valve III, and enters Evaporator I for cooling and dehumidification under the action of Fan I. Then it enters the condenser through Air Valve VI to be heated and increase the temperature. The low - temperature and dry air obtained enters the drying chamber under the action of Fan II to dry the materials. The high - humidity air after drying flows through Evaporator II for cooling and dehumidification, and then is discharged into the atmosphere through Air Valve I. In this working mode, Air Valve II, Air Valve IV, Air Valve V, and Air Valve VII are closed.

[0017] Among them, in the high - temperature drying open - loop mode: Fresh air enters along the second fresh - air inlet, passes through Air Valve VII, and enters the condenser to exchange heat and increase the temperature. The high - temperature air obtained enters the drying chamber under the action of Fan II to dry the materials. The high - humidity air containing the moisture of the materials is discharged from the drying chamber, enters Evaporator II to be cooled and dehumidified, and then is discharged into the atmosphere through Air Valve I. At the same time, fresh air enters along the first fresh - air inlet, passes through Air Valve III, and enters Evaporator I to be cooled and then discharged into the atmosphere. In this working mode, Air Valve II, Air Valve IV, and Air Valve VI are closed.

[0018] A refrigerant circulation loop is provided on the drying system. The setting of the refrigerant circulation loop is to realize the circulation of the refrigerant on the drying system.

[0019] The refrigerant circulation loop includes a refrigeration compressor. The outlet of the refrigeration compressor is connected to the condenser. The inlets of Evaporator I and Evaporator II are respectively connected to the outlet of the condenser. The outlets of Evaporator I and Evaporator II are respectively connected to the inlet of the refrigeration compressor. A first control valve is provided between the inlet of Evaporator I and the outlet of the condenser, and a second control valve is provided between the inlet of Evaporator II and the outlet of the condenser. The first control valve is used to control the refrigerant flow between Evaporator I and the condenser, and the second control valve is used to control the refrigerant flow between Evaporator II and the condenser. After the low-pressure refrigerant gas is compressed by the refrigeration compressor, the obtained high-pressure refrigerant gas enters the condenser to exchange heat with air and is cooled into a high-pressure liquid. Then it is divided into two paths. One path passes through the first control valve for throttling and pressure reduction, and the obtained low-temperature and low-pressure wet steam enters Evaporator I to exchange heat with air. After that, the low-pressure wet steam refrigerant is completely vaporized. The other path passes through the second control valve for throttling and pressure reduction, and the obtained low-temperature and low-pressure refrigerant wet steam enters Evaporator II to exchange heat with air. The low-pressure liquid refrigerant is completely vaporized. The low-pressure refrigerant gas after the two paths of low-pressure liquid refrigerant are completely vaporized and mixed is sucked into the refrigeration compressor, thus completing a cycle.

[0020] A check valve I is provided between the outlet of Evaporator I and the inlet of the refrigeration compressor, and a check valve II is provided between the outlet of Evaporator II and the inlet of the refrigeration compressor. After the low-pressure refrigerant gas is compressed by the refrigeration compressor, the obtained high-pressure refrigerant gas enters the condenser to exchange heat with air and is cooled into a high-pressure liquid. Then it is divided into two paths. One path passes through the first control valve for throttling and pressure reduction, and the obtained low-temperature and low-pressure wet steam enters Evaporator I to exchange heat with air. After the low-pressure wet steam refrigerant is completely vaporized, it then flows through the check valve I. The other path passes through the second control valve for throttling and pressure reduction, and the obtained low-temperature and low-pressure refrigerant wet steam enters Evaporator II to exchange heat with air. After the low-pressure liquid refrigerant is completely vaporized, it flows through the check valve II and mixes with the refrigerant flowing through the check valve I. The mixed low-pressure refrigerant gas is sucked into the refrigeration compressor, thus completing a cycle.

[0021] Both the first control valve and the second control valve are electromagnetic expansion valves. The functions of the electromagnetic expansion valve mainly include throttling and pressure reduction, controlling superheat, and regulating refrigerant flow. 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 valve and the second control valve are electromagnetic expansion valves to regulate the refrigerant flow using the electromagnetic expansion valve.

[0022] The beneficial effects of the present invention: 1. When the material needs to be dried at a low temperature, fresh air enters along the first fresh air inlet, flows through evaporator I and condenser in sequence, and then returns to the air inlet of the drying chamber. The return air of the drying chamber flows through evaporator II and then is discharged into the atmosphere. When the material needs to be dried at a high temperature, fresh air enters along the second fresh air inlet, passes through the condenser and then returns to the air inlet of the drying chamber. The return air of the drying chamber flows through evaporator II and then is discharged into the atmosphere. At the same time, fresh air enters along the first fresh air inlet, passes through evaporator I and then is discharged into the atmosphere. This enables the drying system of the present application to select a low-temperature drying mode or a high-temperature drying mode according to the material characteristics of the material, and then realizes the switching between the low-temperature drying mode and the high-temperature drying mode by changing the flow direction, thereby ensuring the drying quality of the material and solving the technical problem that a single heat pump drying system cannot realize the switching between the low-temperature drying mode and the high-temperature drying mode in the existing heat pump drying system.

[0023] 2. This system can achieve an integrated heat pump on-off drying. When the moisture content of the material is high in the first half, a closed system is used for drying. When the moisture content of the material decreases in the second half, an open system is used. This gives full play to the advantages of high energy efficiency in the operation of the closed system in the first half and high energy efficiency in the operation of the open system in the second half. Compared with a single heat pump open system and a heat pump closed system, the system has a significant energy-saving effect and improves the drying rate.

[0024] 3. This system adopts a parallel dual-evaporator system. Before the material is dried, it exchanges heat with outdoor fresh air through an external evaporator, which can quickly increase the temperature of the drying chamber and greatly shorten the system stabilization time.

[0025] 4. During the closed operation of this system, the high-humidity air discharged from the drying chamber is cooled and dehumidified by passing through two evaporators in sequence. The moisture content of the dehumidified air is lower than that of the traditional single-evaporator dehumidification. At the same time, the hot-end condenser can obtain more heat (a large amount of latent heat of vaporization is released when water vapor is cooled to liquid water). Therefore, this system has a higher drying efficiency and a shorter drying time compared with the traditional heat pump drying system.

[0026] 5. During the open operation of this system, fresh air first passes through the evaporator to cool and dehumidify to obtain low-moisture-content air, and then flows through the condenser to heat to obtain high-temperature and low-humidity air for drying the material, which can greatly improve the drying rate of the material. The high-temperature and high-humidity air after drying flows through another evaporator to cool and dehumidify and then is discharged into the atmosphere. Therefore, this system not only fully recovers the waste heat of the high-temperature and high-humidity air discharged from the drying chamber, but also has high drying efficiency and is more energy-saving.

[0027] 6. When the system operates in the open mode, there are two operating modes. In the first mode, the fresh air is cooled and dehumidified by passing through the evaporator in sequence, and then heated and raised in temperature by passing through the condenser to dry the material. This drying mode is low-temperature drying. In another mode, the fresh air passes through another pipeline and directly enters the condenser to be heated and raised in temperature before drying the material. This mode is high-temperature drying. Therefore, the system has a wider application range for drying different materials and can achieve a cascade drying mode combining high-temperature mode and high-temperature drying with low-temperature drying, as well as the low-temperature drying mode.

[0028] 7. When the system operates in the open mode, the exhaust air from the drying chamber exchanges heat through the evaporator and is discharged into the atmosphere after heat recovery, which overcomes the defect that a large amount of heat is wasted during moisture discharge in a conventional open heat pump system. In addition, when the system operates in the open mode, both evaporators work. The heat source of the drying air comes from two parts. One part is the outdoor fresh air, and the other part is the high-humidity exhaust air from the drying chamber. This mode reduces the influence of the outdoor environment on the open system, the system operates more stably, can obtain a higher drying temperature, improve the drying rate, and further improve the system energy efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the 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 drawings can be obtained based on these drawings.

[0030] Figure 1 It is a schematic diagram of the present invention.

[0031] In the figure: 1. Evaporator I, 2. Evaporator II, 3. Condenser, 4. Fan I, 5. Check valve I, 6. Check valve II, 7. First control valve, 8. Second control valve, 9. Air valve I, 10. Air valve II, 11. Air valve III, 12. Air valve IV, 13. Air valve V, 14. Air valve VI, 15. Air valve VII, 16. Fan II, 17. Drying chamber, 18. Refrigeration compressor. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0033] Embodiment 1, a heat pump open-close integrated multi-mode high-efficiency drying system based on a double evaporator, as Figure 1As shown in the figure, it includes an evaporator I 1, an evaporator II 2, a condenser 3, a first fresh air inlet, a second fresh air inlet, and a drying chamber 17 for drying materials. When the materials in the drying system are in the second half of the low-temperature drying stage, fresh air enters along the first fresh air inlet, flows through the evaporator I 1 and the condenser 3 in sequence, and then returns to the air inlet of the drying chamber 17. The return air of the drying chamber 17 flows through the evaporator II 2 and then is discharged into the atmosphere. When the materials in the drying system are in the second half of the high-temperature drying stage, fresh air enters along the second fresh air inlet, passes through the condenser 3, and then returns to the air inlet of the drying chamber 17. The return air of the drying chamber 17 flows through the evaporator II 2 and then is discharged into the atmosphere. At the same time, fresh air enters along the first fresh air inlet, passes through the evaporator I 1, and then is discharged into the atmosphere. In the drying system of the present application, when the materials need to be dried at a low temperature, fresh air enters along the first fresh air inlet, flows through the evaporator I 1 and the condenser 3 in sequence, and then returns to the air inlet of the drying chamber 17. The return air of the drying chamber 17 flows through the evaporator II 2 and then is discharged into the atmosphere. When the materials need to be dried at a high temperature, fresh air enters along the second fresh air inlet, passes through the condenser 3, and then returns to the air inlet of the drying chamber 17. The return air of the drying chamber 17 flows through the evaporator II 2 and then is discharged into the atmosphere. At the same time, fresh air enters along the first fresh air inlet, passes through the evaporator I 1, and then is discharged into the atmosphere. This enables the drying system of the present application to select a low-temperature drying mode or a high-temperature drying mode according to the material characteristics of the materials, and then realize the switching between the low-temperature drying mode and the high-temperature drying mode through changing the flow direction, thereby ensuring the drying quality of the materials and solving the technical problem that a single drying system in the existing heat pump drying system cannot achieve the switching between the low-temperature drying mode and the high-temperature drying mode.

[0034] When the materials in the drying system of the present application are in the second half of the low-temperature drying stage, the temperature t of the low-temperature drying ranges from 15°C ≤ t ≤ 40°C. When the materials in the drying system of the present application are in the second half of the high-temperature drying stage, the temperature T of the high-temperature drying ranges from 40°C < T ≤ 75°C.

[0035] Embodiment 2. On the basis of Embodiment 1, a heat pump on-off integrated multi-mode high-efficiency drying system based on a double evaporator, as Figure 1 shown, a fan II 16 is provided at the air inlet of the drying chamber 17, and the fan II 16 is located between the drying chamber 17 and the condenser 3. A fan does work on the gas by rotating the impeller, converting mechanical energy into gas kinetic energy and pressure energy to form a directional air flow. The setting of the fan II 16 is to introduce the high-temperature gas pressurized by the fan II 16 into the air inlet of the drying chamber 17 and improve the input rate of the high-temperature gas into the drying chamber 17.

[0036] Embodiment 3. On the basis of Embodiment 2, a heat pump on-off integrated multi-mode high-efficiency drying system based on a double evaporator, as Figure 1As shown in the figure, a blower I 4 is connected to the inlet of the evaporator I 1. A blower does work on the gas by rotating the impeller, converting mechanical energy into gas kinetic energy and pressure energy to form a directional air flow. The blower I 4 is provided to allow fresh air to enter the evaporator I 1, thereby increasing the rate of fresh air entering the evaporator I 1.

[0037] Embodiment 4: On the basis of Embodiment 3, a heat pump on-off integrated multi-mode high-efficiency drying system based on a double evaporator, as Figure 1 shown in the figure. When the drying system is preheating, fresh air enters along the first fresh air inlet, flows through the evaporator I 1 and then is discharged into the atmosphere. The return air of the drying chamber 17 flows through the evaporator II 2 and the condenser 3 in sequence and then returns to the air inlet of the drying chamber 17. At this time, the evaporator II 2 does not work. Before drying the material, the drying system starts preheating, enabling the drying system to quickly heat the circulating air to the required drying temperature. And when the ambient temperature is relatively low, the drying system of the present application is used to preheat the circulating air and quickly heat it to the required drying temperature, greatly reducing the influence of the ambient temperature and humidity on the drying system.

[0038] Embodiment 5: On the basis of Embodiment 4, a heat pump on-off integrated multi-mode high-efficiency drying system based on a double evaporator, as Figure 1 shown in the figure. When the material in the drying system is dried in the first half, the return air of the drying chamber 17 flows through the evaporator II 2, the evaporator I 1 and the condenser 3 in sequence and then returns to the air inlet of the drying chamber 17. When the moisture content of the material in the first half is large during the first half of the material drying, a closed system is used for drying, thus giving full play to the energy-saving and high-efficiency operation of the closed system in the first half.

[0039] Embodiment 6: On the basis of Embodiment 5, a heat pump on-off integrated multi-mode high-efficiency drying system based on a double evaporator, as Figure 1 shown in the figure. A wind valve for controlling the flow direction is provided on the drying system. The wind valve is provided to adjust the flow direction of the air flow on the return circuit of the drying system, thereby controlling whether the drying system is in the preheating stage or the material drying stage, realizing the adjustment of the two-stage circuit, and the drying system can be controlled by the wind valve to switch between the low-temperature drying mode and the high-temperature drying mode.

[0040] Among them, the wind valves of the present application include a wind valve I 9, a wind valve II 10, a wind valve III 11, a wind valve IV 12, a wind valve V 13, a wind valve VI 14 and a wind valve VII 15. The specific wind valve control is as follows: Before drying the materials, the drying system is preheated and operates in an open system. Fresh air enters along the first fresh air inlet and flows through the air valve Ⅲ11. Under the action of the fan Ⅰ4, it passes through the evaporator Ⅰ1 for cooling, and then flows through the air valve Ⅴ13 and is discharged into the atmosphere. The return air from the drying chamber passes through the evaporator Ⅱ2 (at this time, the evaporator Ⅱ2 is not working), enters the condenser 3 through the air valve Ⅳ12, and then enters the drying chamber 17 under the action of the fan Ⅱ16 for circulating heating. When operating in this mode, the air valves Ⅰ9, Ⅱ10, Ⅵ14, and Ⅶ15 are closed, the air valves Ⅲ11, Ⅳ12, and Ⅴ13 are open, the second control valve 8 is closed, and the first control valve 7 is open.

[0041] Closed drying stage for the initial stage of materials: The return air from the drying chamber 17 passes through the evaporator Ⅱ2 for cooling and dehumidification, then passes through the air valve Ⅱ10, and then enters the evaporator Ⅰ1 under the action of the fan Ⅰ4 for further cooling and dehumidification. Then it enters the condenser 3 through the air valve Ⅵ14 for heat exchange and temperature rise. The obtained high-temperature and low-humidity air enters the drying chamber 17 under the action of the fan Ⅱ16 to dry the materials, thus completing a cycle. When operating in this mode, the air valves Ⅰ9, Ⅲ11, Ⅳ12, Ⅴ13, and Ⅶ15 are closed.

[0042] The open system is adopted in the later stage of material drying: This mode can be further divided into a low-temperature drying open mode and a high-temperature drying open mode. Which mode to adopt specifically needs to be selected according to the material characteristics.

[0043] Among them, the low-temperature drying open mode: Fresh air enters along the first fresh air inlet and passes through the air valve Ⅲ11. Under the action of the fan Ⅰ4, it enters the evaporator Ⅰ1 for cooling and dehumidification, then enters the condenser 3 through the air valve Ⅵ14 for heating and temperature rise. The obtained low-temperature drying air enters the drying chamber 17 under the action of the fan Ⅱ16 to dry the materials. The high-humidity air after drying passes through the evaporator Ⅱ2 for cooling and dehumidification, and then is discharged into the atmosphere through the air valve Ⅰ9. In this working mode, the air valves Ⅱ10, Ⅳ12, Ⅴ13, and Ⅶ15 are closed.

[0044] Among them, the high-temperature drying open mode: Fresh air enters along the second fresh air inlet and enters the condenser 3 through the air valve Ⅶ15 for heat exchange and temperature rise. The obtained high-temperature air enters the drying chamber 17 under the action of the fan Ⅱ16 to dry the materials. The high-humidity air with the moisture of the materials is discharged from the drying chamber 17 and then enters the evaporator Ⅱ2 to be cooled and dehumidified, and then is discharged into the atmosphere through the air valve Ⅰ9. At the same time, fresh air enters along the first fresh air inlet and flows through the air valve Ⅲ11. Under the action of the fan Ⅰ4, it enters the evaporator Ⅰ1 to be cooled and then is discharged into the atmosphere. In this working mode, the air valves Ⅱ10, Ⅳ12, and Ⅵ14 are closed.

[0045] Example 7, based on any one of Examples 1 to 6, a heat pump open-close integrated multi-mode high-efficiency drying system based on a double evaporator, as Figure 1As shown, a refrigerant circulation loop is provided on the drying system. The setting of the refrigerant circulation loop is to realize the circulating flow of the refrigerant on the drying system.

[0046] Example 8, based on Example 7, a heat pump opening / closing integrated multi-mode high-efficiency drying system based on a dual evaporator, as Figure 1 As shown, the refrigerant circulation loop includes a refrigeration compressor 18. The outlet of the refrigeration compressor 18 is connected to the condenser 3. The inlets of the evaporator I 1 and the evaporator II 2 are respectively connected to the outlet of the condenser 3. The outlets of the evaporator I 1 and the evaporator II 2 are respectively connected to the inlet of the refrigeration compressor 18. A first control valve 7 is provided between the inlet of the evaporator I 1 and the outlet of the condenser 3, and a second control valve 8 is provided between the inlet of the evaporator II 2 and the outlet of the condenser 3. The first control valve 7 is used to control the refrigerant flow between the evaporator I 1 and the condenser 3, and the second control valve 8 is used to control the refrigerant flow between the evaporator II 2 and the condenser 3. After the low-pressure refrigerant gas is compressed by the refrigeration compressor 18, the obtained high-pressure refrigerant gas enters the condenser 13 to exchange heat with air and is cooled into a high-pressure liquid. Then it is divided into two paths. One path passes through the first control valve 7 for throttling and pressure reduction, and the obtained low-temperature and low-pressure wet steam enters the evaporator I 1 to exchange heat with air. After that, the low-pressure wet steam refrigerant is completely vaporized. The other path passes through the second control valve 8 for throttling and pressure reduction, and the obtained low-temperature and low-pressure refrigerant wet steam enters the evaporator II 2 to exchange heat with air. The low-pressure liquid refrigerant is completely vaporized. The low-pressure refrigerant gas after the two paths of low-pressure liquid refrigerant are completely vaporized and mixed is sucked by the refrigeration compressor 18, thus completing a cycle.

[0047] Example 9, based on Example 8, a heat pump opening / closing integrated multi-mode high-efficiency drying system based on a dual evaporator, as Figure 1 As shown, a check valve I 5 is provided between the outlet of the evaporator I 1 and the inlet of the refrigeration compressor 18, and a check valve II 6 is provided between the outlet of the evaporator II 2 and the inlet of the refrigeration compressor 18. After the low-pressure refrigerant gas is compressed by the refrigeration compressor 18, the obtained high-pressure refrigerant gas enters the condenser 13 to exchange heat with air and is cooled into a high-pressure liquid. Then it is divided into two paths. One path passes through the first control valve 7 for throttling and pressure reduction, and the obtained low-temperature and low-pressure wet steam enters the evaporator I 1 to exchange heat with air. After the low-pressure wet steam refrigerant is completely vaporized, it then flows through the check valve I 5. The other path passes through the second control valve 8 for throttling and pressure reduction, and the obtained low-temperature and low-pressure refrigerant wet steam enters the evaporator II 2 to exchange heat with air. After the low-pressure liquid refrigerant is completely vaporized, it flows through the check valve II 6 and mixes with the refrigerant flowing through the check valve I 5. The mixed low-pressure refrigerant gas is sucked by the refrigeration compressor 18, thus completing a cycle.

[0048] Example 10, based on Example 9, a heat pump opening / closing integrated multi-mode high-efficiency drying system based on a dual evaporator, asFigure 1 As shown, both the first control valve 7 and the second control valve 8 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 valve 7 and the second control valve 8 are electromagnetic expansion valves to regulate the refrigerant flow rate.

[0049] When Example 10 is implemented, before the material is dried, the drying system is preheated and operated in an open system. Fresh air enters along the first fresh air inlet and flows through the air valve III 11. Under the action of the fan I 4, it passes through the evaporator I 1 for cooling and then flows through the air valve V 13 and is discharged into the atmosphere. The return air of the drying chamber 17 passes through the evaporator II 2 (at this time, the evaporator II 2 is not working), then passes through the air valve IV 12 and enters the condenser 3, and then enters the drying chamber 17 for circulating heating under the action of the fan II 16. When operating in this mode, the air valve I 9, the air valve II 10, the air valve VI 14, and the air valve VII 15 are closed, the air valve III 11, the air valve IV 12, and the air valve V 13 are open, the second control valve 8 is closed, and the first control valve 7 is open.

[0050] Closed drying stage for the material in the early stage: The return air of the drying chamber 17 passes through the evaporator II 2 for cooling and dehumidification, then passes through the air valve II 10, and then enters the evaporator I 1 for further cooling and dehumidification under the action of the fan I 4. Then it passes through the air valve VI 14 and enters the condenser 3 for heat exchange and temperature rise. The obtained high-temperature and low-humidity air enters the drying chamber 17 under the action of the fan II 16 to dry the material, thus completing a cycle. When operating in this mode, the air valve I 9, the air valve III 11, the air valve IV 12, the air valve V 13, and the air valve VII 15 are closed.

[0051] Open system is adopted in the later stage of material drying: This mode can be further divided into a low-temperature drying open mode and a high-temperature drying open mode. Which mode to adopt specifically needs to be selected according to the material characteristics.

[0052] Among them, the low-temperature drying open mode: Fresh air enters along the first fresh air inlet and passes through the air valve III 11. Under the action of the fan I 4, it enters the evaporator I 1 for cooling and dehumidification, then passes through the air valve VI 14 and enters the condenser 3 for heating and temperature rise. The obtained low-temperature drying air enters the drying chamber 17 under the action of the fan II 16 to dry the material. The high-humidity air after drying passes through the evaporator II 2 for cooling and dehumidification and then passes through the air valve I 9 and is discharged into the atmosphere. In this working mode, the air valve II 10, the air valve IV 12, the air valve V 13, and the air valve VII 15 are closed.

[0053] Among them, in the high-temperature drying open mode: fresh air enters along the second fresh air inlet and exchanges heat and warms up through the air valve Ⅶ 15 and enters the condenser 3. The obtained high-temperature air enters the drying chamber 17 under the action of the fan Ⅱ 16 to dry the materials. The high-humidity air with the moisture of the materials is discharged from the drying chamber 17 and then enters the evaporator Ⅱ 2 to be cooled and dehumidified, and then is discharged into the atmosphere through the air valve Ⅰ 9. At the same time, fresh air enters along the first fresh air inlet and flows through the air valve Ⅲ 11 and enters the evaporator Ⅰ 1 under the action of the fan Ⅰ 4 and is discharged into the atmosphere after being cooled. In this working mode, the air valves Ⅱ 10, Ⅳ 12 and Ⅵ 14 are closed.

[0054] 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 heat pump on-off integrated multi-mode efficient drying system based on a dual evaporator, characterized in that, It includes evaporator Ⅰ (1), evaporator Ⅱ (2), condenser (3), the first fresh air inlet, the second fresh air inlet, and a drying chamber (17) for drying materials; when the materials in the drying system are undergoing the second half of low-temperature drying, fresh air enters along the first fresh air inlet, flows through evaporator Ⅰ (1) and condenser (3) in sequence, and then returns to the air inlet of the drying chamber (17). The return air of the drying chamber (17) flows through evaporator Ⅱ (2) and then is discharged into the atmosphere; when the materials in the drying system are undergoing the second half of high-temperature drying, fresh air enters along the second fresh air inlet, passes through condenser (3), and then returns to the air inlet of the drying chamber (17). The return air of the drying chamber (17) flows through evaporator Ⅱ (2) and then is discharged into the atmosphere. Meanwhile, fresh air enters along the first fresh air inlet, passes through evaporator Ⅰ (1), and then is discharged into the atmosphere.

2. The heat pump on-off integrated multi-mode high-efficiency drying system based on a dual evaporator according to claim 1, wherein: A fan Ⅱ (16) is provided at the air inlet of the drying chamber (17), and the fan Ⅱ (16) is located between the drying chamber (17) and the condenser (3).

3. The heat pump on-off integrated multi-mode high-efficiency drying system based on a dual evaporator according to claim 2, wherein: A fan Ⅰ (4) is connected to the inlet of the evaporator Ⅰ (1).

4. The heat pump on-off integrated multi-mode high-efficiency drying system based on a dual evaporator according to claim 3, characterized in that: When the drying system is preheating, fresh air enters along the first fresh air inlet, flows through evaporator Ⅰ (1), and then is discharged into the atmosphere. The return air of the drying chamber (17) flows through evaporator Ⅱ (2) and condenser 3 in sequence and then returns to the air inlet of the drying chamber (17). At this time, evaporator Ⅱ (2) does not work.

5. The heat pump on-off integrated multi-mode high-efficiency drying system based on a double evaporator according to claim 4, characterized in that: When the materials in the drying system are undergoing the first half of drying, the return air of the drying chamber (17) flows through evaporator Ⅱ (2), evaporator Ⅰ 1, and condenser (3) in sequence and then returns to the air inlet of the drying chamber (17).

6. The heat pump opening and closing integrated multi-mode high-efficiency drying system based on a dual evaporator according to claim 5, wherein: A air valve for controlling the flow direction is provided on the drying system.

7. The heat pump on-off integrated multi-mode high-efficiency drying system based on a dual evaporator according to any one of claims 1 to 6, characterized in that: A refrigerant circulation loop is provided on the drying system.

8. The heat pump opening and closing integrated multi-mode high-efficiency drying system based on a dual evaporator according to claim 7, characterized in that: The refrigerant circulation loop includes a refrigeration compressor (18). The outlet of the refrigeration compressor (18) is connected to the condenser (3). The inlets of the evaporator Ⅰ (1) and the evaporator Ⅱ (2) are respectively connected to the outlet of the condenser (3). The outlets of the evaporator Ⅰ (1) and the evaporator Ⅱ (2) are respectively connected to the inlet of the refrigeration compressor (18). A first control valve (7) is provided between the inlet of the evaporator Ⅰ (1) and the outlet of the condenser (3), and a second control valve (8) is provided between the inlet of the evaporator Ⅱ (2) and the outlet of the condenser (3).

9. The heat pump on-off integrated multi-mode high-efficiency drying system based on a dual evaporator according to claim 8, characterized in that: A check valve Ⅰ (5) is provided between the outlet of the evaporator Ⅰ (1) and the inlet of the refrigeration compressor (18), and a check valve Ⅱ (6) is provided between the outlet of the evaporator Ⅱ (2) and the inlet of the refrigeration compressor (18).

10. The heat pump on-off integrated multi-mode high-efficiency drying system based on a dual evaporator according to claim 9, characterized in that: Both the first control valve (7) and the second control valve (8) are electromagnetic expansion valves.

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