CN106524741B - Heat pump type double-circulation hot air drying system and control method thereof - Google Patents
Heat pump type double-circulation hot air drying system and control method thereof Download PDFInfo
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- CN106524741B CN106524741B CN201611170306.7A CN201611170306A CN106524741B CN 106524741 B CN106524741 B CN 106524741B CN 201611170306 A CN201611170306 A CN 201611170306A CN 106524741 B CN106524741 B CN 106524741B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
- F26B21/001—Drying-air generating units, e.g. movable, independent of drying enclosure
- F26B21/002—Drying-air generating units, e.g. movable, independent of drying enclosure heating the drying air indirectly, i.e. using a heat exchanger
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B30/00—Heat pumps
- F25B30/02—Heat pumps of the compression type
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B30/00—Heat pumps
- F25B30/06—Heat pumps characterised by the source of low potential heat
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B41/00—Fluid-circulation arrangements
- F25B41/40—Fluid line arrangements
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
- F26B21/06—Controlling, e.g. regulating, parameters of gas supply
- F26B21/08—Humidity
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
- F26B21/06—Controlling, e.g. regulating, parameters of gas supply
- F26B21/10—Temperature; Pressure
Abstract
A heat pump type double circulation hot air drying system and a control method thereof relate to a supply or control device of air or gas for drying solid materials or products, in particular to a heat pump type hot air drying system and a control method for the system, wherein a hot air cabinet is divided into a basic air temperature area and a reheating temperature rising area; the latent heat condenser and the sensible heat condenser are connected in series to form a double-section series condenser; the air supply circulation loop enters the air feeder from the drying room through the air return duct and the latent heat condenser, and is sent into the drying room through the air supply regulating valve, the sensible heat condenser and the air supply duct; the internal circulation loop returns to the blower from the blower through the internal circulation air valve, the internal circulation air duct, the return air duct and the latent heat condenser; by controlling the opening degrees of the internal circulation air valve and the air supply regulating valve, the internal circulation loop fully absorbs latent heat of condensation to improve the temperature of the basic air, and high-temperature hot air is prepared through secondary heat exchange of the air supply circulation loop, so that the temperature change requirement of the air outlet temperature drying room is met; the system has high heating efficiency and stable product operation condition.
Description
Technical Field
The present invention relates to a supply or control device of air or gas for drying solid materials or products, and more particularly, to a heat pump type hot air drying system and a control method for the same.
Background
At present, places needing hot air drying in the market are more and more, such as tobacco drying places, grain drying places, medicinal material drying places, fruit and vegetable drying places and the like, and the drying is mainly carried out by using a coal furnace, a gas furnace and an electric furnace. Coal and gas are non-renewable strategic energy sources, which is not the direction of national popularization, and the electric furnace is not suitable for batch popularization due to large energy consumption and high operating cost. The northern rural heating is performed by heating water by using coal furnaces before, and the country adopts a heat pump to replace the coal furnace for comprehensive popularization, thereby proving that the heat pump still has great market prospect in the aspect of heating. The heat pump has great development potential in the places with the hot air drying requirement. Taking tobacco leaf baking equipment in China as an example, the traditional natural ventilation type baking room with a civil structure is used for a long time, and although certain improvements and improvements are frequently made, the traditional mode is not separated. Intensive baking equipment adopting fuel oil and coal for direct heat supply and boiler heat supply is introduced from 90 s in 20 th century in China, and tests in various places reflect the advantages of simple baking operation technology, labor saving, capability of ensuring the baking quality of tobacco leaves and the like. The tobacco leaf baking is a large-scale heat consumption process, the coal is directly used for supplying heat for a common baking room, the heat utilization rate is low, the coal consumption is high, the coal consumption of 1kg of tobacco leaves baked normally is 1.5-2.5 kg of standard coal, and the environmental pollution is serious. The Chinese invention patent 'a tobacco curing barn using an air source heat pump as a heat source' (invention patent No. 200910044468.X, and an authorization publication No. CN101940358B) discloses a tobacco curing barn using an air source heat pump as a heat source, which comprises a heating chamber provided with a fresh air port, a drying chamber provided with a temperature and humidity probe, a moisture discharging port arranged above the curing barn, an air source heat pump and a condenser fan, wherein the value range of the ratio of the heat exchange area of the condenser to the input power of the compressor is 7-15m2/kw, and the condenser and an air suction type air supply fan thereof are arranged in the heating chamber; the drying chamber and/or the heating chamber are/is provided with an insulating layer. According to the technical scheme, the air source heat pump and the solar energy are used as novel heat sources of the tobacco curing barn, so that the application range of the air source heat pump and the solar energy is greatly expanded, the sulfur content of the atmosphere, the soil and the tobacco leaves can be reduced by large-scale popularization and use in a tobacco production area, the quality of the tobacco leaves is improved, and the tobacco curing barn has positive significance for saving energy and protecting the environment. However, in the baking process of tobacco, five-segment type, seven-segment type and six-segment type "double low" baking processes and the like have been proposed in various successive studies. In each curing process, the whole tobacco curing process is divided into a yellowing stage, a fixing stage and a drying stage, and specific temperature and humidity indexes are specified for each stage, which is shown in a multi-stage drying process diagram of part of tobacco varieties shown in fig. 9. Because the sections in the baking process are divided more and more finely, particularly, the tobacco leaves are divided into a plurality of layers, fuzzy and variable, and have no simple and definite key points, the technology is complex and is difficult to master, and the existing heat pump drying system can not meet the requirements of tobacco baking.
On the other hand, because some high-temperature drying time periods require hot air outlet temperature of more than 80 ℃, how to provide high-temperature hot air is another problem to be solved by the heat pump type hot air drying system. The Chinese invention patent application 'an ultra-high temperature heat pump drying system' (invention patent application No. 201510433292.2, publication No. CN105021015A) discloses an ultra-high temperature heat pump drying system, which comprises a drying room, a return air duct communicated with an air supply outlet and a return air duct of the drying room, a circulating fan arranged in the return air duct, an exhaust duct communicated with the return air duct, an exhaust fan arranged at a channel port of the exhaust duct, an air heat recovery device arranged at the intersection of the return air duct and the exhaust duct, and at least two sets of heat pump units used in parallel; the invention adopts two or more than two heat pump units to work in parallel, heats the drying room by absorbing the heat of low-grade ambient air at the initial stage of the drying operation process to raise the temperature, dehumidifies the high-temperature and high-humidity air discharged from the drying room after the temperature is raised to a certain degree, and recovers the sensible heat and latent heat contained in the air to the maximum extent. The system provides relatively higher air supply temperature by utilizing the difference of the temperature ranges of the circulating working media of the two heat pump units, and simultaneously ensures that the evaporation temperature of the drying unit is fully increased. However, the prior art scheme adopts two sets of heat pump units, which not only leads to the doubled investment of drying room equipment, but also increases the complexity of equipment maintenance by improving the air supply temperature by depending on the difference of the temperature range of the circulating working medium. Simultaneously, because the heat consumption demand of stoving in-process baking house changes greatly, this not only leads to heat pump set frequent start-stop, increases the operation power consumption of unit, reduces the efficiency of unit, still can make the temperature variation grow in the baking house, can influence off-the-shelf quality because of the stoving temperature variation is too big even.
Disclosure of Invention
The invention aims to provide a heat pump type double-circulation hot air drying system which is used for solving the technical problem of providing high-temperature hot air by the existing heat pump hot air drying system.
The technical scheme adopted by the invention for solving the technical problems is as follows:
a heat pump type double-circulation hot air drying system comprises a heat pump unit, a hot air cabinet, a drying room and a control device for realizing microprocessor control of the hot air drying system; the method is characterized in that:
the heat pump type double-circulation hot air drying system also comprises a hot air double-circulation loop formed by an air supply circulation loop and an internal circulation loop;
an air supply regulating valve is arranged in the hot air cabinet to divide the hot air cabinet into a basic air temperature area and a reheating temperature-raising area;
the latent heat condenser arranged in the basic air temperature area and the sensible heat condenser arranged in the reheating temperature-raising area are connected in series through a refrigerant pipeline of a heat pump unit to form a double-section series condenser; the high-temperature gaseous refrigerant discharged by the compressor is sent into the sensible heat condenser for heat exchange and temperature reduction and then sent into the latent heat condenser;
the air supply circulation loop enters the hot air cabinet from the drying room through the return air duct, enters the air supply machine through the latent heat condenser arranged on the air inlet side of the basic air temperature zone, then reaches the sensible heat condenser of the reheating heating zone through the air supply regulating valve, and finally is sent into the drying room through the air supply duct;
the internal circulation loop enters an internal circulation air duct from an air outlet of the air feeder through an internal circulation air valve, then enters the hot air cabinet through a return air duct, reaches a latent heat condenser at the air inlet side of the basic air temperature zone, and finally returns to an air suction port of the air feeder;
the control device adjusts the circulating air quantity of the air supply circulation loop and the internal circulation loop by controlling the opening degrees of the internal circulation air valve and the air supply adjusting valve, and controls the air outlet temperature of the hot air cabinet.
The invention relates to a better technical scheme of a heat pump type double-circulation hot air drying system, which is characterized in that a heat pump unit comprises a main circulation pipeline of a refrigerant and a two-way unloading branch circuit connected to the main circulation pipeline; the main circulation pipeline starts from an exhaust port of the compressor, sequentially passes through the sensible heat condenser, the latent heat condenser, the expansion valve, the evaporator and the vapor-liquid separator and returns to an air suction port of the compressor; the two-way unloading branch is formed by connecting an unloading electromagnetic valve, a first throttle valve and a second throttle valve: the inlet of the unloading electromagnetic valve is connected to the outlet of the refrigerant pipeline of the latent heat condenser in parallel, the inlets of the first throttle valve and the second throttle valve are connected to the outlet of the unloading electromagnetic valve in parallel, the outlet of the first throttle valve is connected to the inlet of the evaporator, and the outlet of the second throttle valve is connected to the inlet of the vapor-liquid separator; the control device is connected to the first throttle valve, the second throttle valve and the unloading electromagnetic valve, a refrigerant circulating pipeline of the heat pump unit is dynamically changed according to the outlet air temperature, the exhaust temperature and the high-pressure side pressure of the compressor are reduced through the two-way unloading branch, and the double-circulation dynamic operation mode of the hot air drying system is realized.
The invention discloses a better technical scheme of a heat pump type dual-cycle hot air drying system, which is characterized in that the dual-cycle dynamic operation mode comprises a single-cycle conventional heating mode, a dual-cycle pressure reduction unloading mode, a dual-cycle temperature reduction unloading mode and a dual-cycle two-way unloading mode, wherein:
single cycle conventional heating mode: the unloading electromagnetic valve is closed, and the refrigerant circulates along the main circulation pipeline; the opening degree of the internal circulation air valve is 0 percent, the opening degree of the air supply adjusting valve is 100 percent, and the double-circulation hot air drying system prepares low-temperature hot air with the air outlet temperature lower than 45 ℃ through the air supply circulation loop; the control device controls the air outlet temperature by changing the running time interval or the running frequency of the compressor;
a double-cycle pressure reduction unloading mode: the unloading electromagnetic valve and the second throttle valve are opened, the first throttle valve is closed, and when the refrigerant circulates along the main circulation pipeline, one part of the refrigerant is shunted by the unloading electromagnetic valve and directly enters the vapor-liquid separator through the second throttle valve; the opening of the internal circulation air valve is 50-55%, and the opening of the air supply regulating valve is 50-45%; the control device controls the air outlet temperature by adjusting the circulating air quantity of the air supply circulating loop and the internal circulating loop, and prepares medium-temperature hot air with the air outlet temperature of 45-65 ℃;
a dual-cycle cooling unloading mode: the unloading electromagnetic valve and the first throttle valve are opened, the second throttle valve is closed, and when the refrigerant circulates along the main circulation pipeline, one part of the refrigerant is shunted by the unloading electromagnetic valve and enters the evaporator through the first throttle valve connected with the expansion valve in parallel; the opening of the internal circulation air valve is 55-65%, and the opening of the air supply regulating valve is 45-35%; the control device controls the air outlet temperature by adjusting the circulating air volume of the air supply circulating loop and the internal circulating loop, and prepares medium-high temperature hot air with the air outlet temperature of 65-75 ℃;
double-circulation double-path unloading mode: the unloading electromagnetic valve, the first throttle valve and the second throttle valve are opened, the refrigerant is shunted by the unloading electromagnetic valve while circulating along the main circulation pipeline, one part of the shunted refrigerant enters the evaporator through the first throttle valve connected with the expansion valve in parallel, and the other part of the shunted refrigerant directly enters the vapor-liquid separator through the second throttle valve; the opening degree of the internal circulation air valve is 65-75%, and the opening degree of the air supply regulating valve is 35-25%; the control device controls the air outlet temperature by adjusting the circulating air volume of the air supply circulating loop and the internal circulating loop, and high-temperature hot air with the air outlet temperature higher than 75 ℃ is prepared.
The invention relates to an improved technical scheme of a heat pump type double-circulation hot air drying system, which is characterized in that a heat pump unit also comprises a second refrigerant circulation pipeline adopting a variable frequency compressor; the third condenser connected in the second refrigerant circulating pipeline is arranged in the hot air cabinet and is arranged on the air outlet side of the basic air temperature zone; when the required heat consumption of the drying room is less than 40%, the fixed-frequency compressor is stopped, the variable-frequency compressor is started, and the heat pump hot air drying system operates in a conventional variable-frequency heat pump mode; when the required heat consumption of the drying room is more than or equal to 40%, the constant-frequency compressor and the variable-frequency compressor are started simultaneously, and the heat pump hot air drying system operates in a constant-frequency and variable-frequency double-machine parallel mode; when the set temperature of the supplied air is higher than 75 ℃, the heat pump hot air drying system operates in a double-circulation double-path unloading mode, and the latent heat condenser, the third condenser and the sensible heat condenser form a three-stage heat exchange structure of the hot air cabinet; the circulating air flow of the internal circulation loop exchanges heat twice through the latent heat condenser and the third condenser, so that the basic air temperature of the basic air temperature area is further increased, and the outlet air temperature of the hot air cabinet is increased to over 75 ℃.
Another object of the present invention is to provide a control method for the heat pump type dual circulation hot air drying system. The technical scheme adopted by the invention for solving the technical problems is as follows:
a control method of the heat pump type double-circulation hot air drying system is used for the heat pump type double-circulation hot air drying system, and is characterized by comprising the following steps:
s100: configuring temperature control parameters and storing preset temperature control curve parameters;
s200: detecting and monitoring the air outlet temperature and the temperature and humidity of the drying room;
s300: dynamically adjusting the set temperature according to a preset temperature control curve;
s400: and selecting a double-circulation dynamic operation mode of the system according to the current set temperature.
A preferred technical solution of the control method of the heat pump type dual-circulation hot air drying system of the present invention is characterized in that the step S400 includes the following control operations:
s420: if the set temperature is less than 45 ℃, closing the unloading electromagnetic valve, and entering a single-cycle conventional heating mode; controlling the running time interval or running frequency of the compressor according to the outlet air temperature;
s440: if the set temperature is less than 65 ℃, opening the unloading electromagnetic valve and the second throttle valve, closing the first throttle valve, and entering a dual-cycle pressure reduction unloading mode; the air outlet temperature is controlled by adjusting the circulating air volume of the air supply circulating loop and the internal circulating loop;
s460: if the set temperature is more than or equal to 75 ℃, turning to the step S480; otherwise, opening the unloading electromagnetic valve and the second throttle valve, closing the first throttle valve, and entering a dual-cycle cooling unloading mode; the air outlet temperature is controlled by adjusting the circulating air volume of the air supply circulating loop and the internal circulating loop;
s480: opening an unloading electromagnetic valve, a first throttle valve and a second throttle valve, and entering a dual-cycle two-way unloading mode; the air outlet temperature is controlled by adjusting the circulating air volume of the air supply circulating loop and the internal circulating loop.
The invention has the beneficial effects that:
1. according to the heat pump type double-circulation hot air drying system and the control method thereof, the internal circulation loop with large air volume circulation is established, the condensation latent heat of the refrigerant is fully absorbed, the basic air temperature is increased, and high-temperature hot air is prepared through secondary heat exchange of the air supply circulation loop; the air outlet quantity is automatically adjusted and controlled by adopting double paths of air quantity, so that the requirement of the temperature change of the air outlet temperature drying room is met; the system has high heating efficiency and stable product operation condition.
2. The heat pump type dual-circulation hot air drying system and the control method thereof adopt the dual-section serial condenser formed by connecting the latent heat condenser and the sensible heat condenser in series to carry out heat exchange, the latent heat condenser of the internal circulation loop circularly prepares the basic air temperature, the sensible heat condenser of the air supply circulation loop directly prepares the high-temperature hot air, and the air outlet temperature can reach 90 ℃ without electric heating.
3. The heat pump type dual-circulation hot air drying system and the control method thereof adopt a multi-section temperature control curve to configure temperature control parameters of a drying room, dynamically adjust the set temperature according to the temperature control curve, select the operation mode of the system according to the current adjusted set temperature, and control the dual-circulation hot air drying system to realize full-automatic intelligent operation without manual operation; can meet the high-precision control requirements of temperature and humidity in the baking process.
Drawings
FIG. 1 is a schematic diagram of a dual cycle configuration of a heat pump type dual cycle hot air drying system;
FIG. 2 is a schematic diagram of a heat pump unit of the heat pump type dual-circulation hot air drying system;
FIG. 3 is a schematic diagram of a fixed-frequency and variable-frequency dual-cycle structure of a heat pump type dual-cycle hot air drying system;
FIG. 4 is a schematic diagram of a heat pump unit of a variable-frequency variable-capacity heat pump hot air drying system;
FIG. 5 is a schematic diagram of a control device of the heat pump hot air drying system;
FIG. 6 is a flow chart of a control method of the heat pump type dual circulation hot air drying system;
FIG. 7 is a flow chart of a control method of a variable frequency and variable capacity heat pump hot air drying system;
FIG. 8 is a schematic diagram of a multi-sectional temperature control curve and temperature control parameter configuration interface;
FIG. 9 is a multi-stage drying process diagram of a part of tobacco varieties of flue-cured tobacco;
FIG. 10 is a graph of heat consumption at each time interval during the tobacco curing process.
Reference numbers for components in the above figures: 1 is a compressor, 1-1 is a fixed frequency compressor, 1-2 is an inverter compressor, 2-1 is a first condenser, 2-2 is a second condenser, 2-3 is a third condenser, 21 is a latent heat condenser, 22 is a sensible heat condenser, 3 is an expansion valve, 3-1 is a first expansion valve, 3-1A is a first balance pipe, 3-1B is a first temperature sensing bulb, 3-2 is a second expansion valve, 3-2A is a second balance pipe, 3-2B is a second temperature sensing bulb, 4 is an evaporator, 4-1 is a first evaporator, 4-2 is a second evaporator, 4-3 is a third evaporator, 5 is a vapor-liquid separator, 5-1 is a first vapor-liquid separator, 5-2 is a second vapor-liquid separator, 6 is an evaporator fan, 7-1 is a first electromagnetic valve bank, 7-2 is a second electromagnetic valve group, 8 is a blower, 10 is a first throttle valve, 11 is a second throttle valve, 12 is an unloading electromagnetic valve, 23 is an internal circulation air valve, 24 is an air supply regulating valve, 100 is a heat pump unit, 200 is a hot air cabinet, 210 is an air supply duct, 220 is an internal circulation air duct, 230 is an air return duct, 400 is a drying room, 500 is a control device, 510 is an operation parameter setting module, 520 is a drying room temperature and humidity monitoring module, 521 is a dry bulb temperature sensor, 522 is a wet bulb temperature sensor, 530 is an air supply temperature monitoring module, 531 is an air outlet temperature sensor, 540 is an air valve opening controller, and 550 is a heat pump unit controller.
Detailed Description
In order to better understand the technical solution of the present invention, the following detailed description is made with reference to the accompanying drawings and examples. Fig. 1 is an embodiment of a heat pump type dual-circulation hot air drying system, which includes a heat pump unit 100, a hot air cabinet 200 and a drying room 400, and a control device 500 for implementing microprocessor control of the hot air drying system; as shown in fig. 1, the heat pump type dual-circulation hot air drying system further includes a hot air dual-circulation loop formed by an air supply circulation loop and an internal circulation loop;
an air supply regulating valve 24 arranged in the hot air cabinet 200 divides the hot air cabinet 200 into a basic air temperature area and a reheating temperature-raising area;
a latent heat condenser 21 arranged in the basic wind temperature area and a sensible heat condenser 22 arranged in the reheating temperature area are connected in series through a refrigerant pipeline of the heat pump unit 100 to form a double-section series condenser; the high-temperature gaseous refrigerant discharged from the compressor is sent to a sensible heat condenser 22 for heat exchange and temperature reduction and then sent to a latent heat condenser 21;
the air supply circulation loop enters the hot air cabinet 200 from the drying room 400 through the return air duct 230, enters the air blower 8 through the latent heat condenser 21 arranged on the air inlet side of the basic air temperature zone, then reaches the sensible heat condenser 22 of the reheating and heating zone through the air supply regulating valve 24, and finally is sent into the drying room 400 through the air supply duct 210;
the internal circulation loop enters an internal circulation air duct 220 from an air outlet of the blower 8 through an internal circulation air valve 23, then enters the hot air cabinet 200 through a return air duct 230, reaches a latent heat condenser 21 at the air inlet side of a basic air temperature zone, and finally returns to an air suction port of the blower 8; the air flow entering the basic air temperature zone from the drying room 400 is partially returned to the return air duct 230 through the internal circulation air duct 220, is mixed with the drying room return air and then is sent to the latent heat condenser 21 to form an internal circulation loop with large air volume circulation, and the other part is sent to the sensible heat condenser 22 through the air supply regulating valve 24 to carry out secondary heat exchange and is sent to the drying room 400 through the air supply duct 210 to form an air supply circulation loop with small air volume circulation. Latent heat in the refrigerant is gradually transferred to the large-air-volume circulating airflow of the internal circulation circuit through the latent heat condenser 21, and the basic air temperature is increased by fully absorbing the condensation latent heat of the refrigerant; sensible heat in the gaseous refrigerant with the compressor discharge temperature reaching 130 ℃ is transferred to the small air volume circulating airflow of the air supply circulating loop through secondary heat exchange of the sensible heat condenser 22; the sensible heat condenser 22 can absorb about 30% of the system heat energy, and the outlet air temperature of the hot air cabinet 200 can reach 90 ℃.
The control device 500 controls the opening degrees of the internal circulation air valve 23 and the air supply regulating valve 24, regulates the circulation air volume of the air supply circulation loop and the internal circulation loop, and controls the air outlet temperature of the hot air cabinet 200.
According to the embodiment of the heat pump unit of the heat pump type dual-circulation hot air drying system shown in fig. 2, the heat pump unit 100 includes a main circulation pipeline of a refrigerant and a two-way unloading branch connected to the main circulation pipeline; the main circulation pipeline starts from an exhaust port of the compressor 1, sequentially passes through the sensible heat condenser 22, the latent heat condenser 21, the expansion valve 3, the evaporator 4 and the vapor-liquid separator 5, and returns to an air suction port of the compressor 1; the two-way unloading branch is formed by connecting an unloading electromagnetic valve 12, a first throttle valve 10 and a second throttle valve 11: the inlet of the unloading electromagnetic valve 12 is connected in parallel to the refrigerant pipeline outlet of the latent heat condenser 21, the inlets of the first throttle valve 10 and the second throttle valve 11 are connected in parallel to the outlet of the unloading electromagnetic valve 12, the outlet of the first throttle valve 10 is connected to the inlet of the evaporator 4, and the outlet of the second throttle valve 11 is connected to the inlet of the vapor-liquid separator 5; the control device 500 is connected to the first throttle valve 10, the second throttle valve 11 and the unloading electromagnetic valve 12, a refrigerant circulation pipeline of the heat pump unit is dynamically changed according to the outlet air temperature, the exhaust temperature and the high-pressure side pressure of the compressor 1 are reduced through the two-way unloading branch, and a double-circulation dynamic operation mode of the hot air drying system is realized.
According to an embodiment of the heat pump type dual-cycle hot air drying system of the present invention, the dual-cycle dynamic operation mode includes a single-cycle conventional heating mode, a dual-cycle pressure reducing and unloading mode, a dual-cycle temperature reducing and unloading mode, and a dual-cycle two-way unloading mode, wherein:
single cycle conventional heating mode: the unloading electromagnetic valve 12 is closed, and the refrigerant circulates along the main circulation pipeline; the opening degree of the internal circulation air valve 23 is 0%, the opening degree of the air supply adjusting valve 24 is 100%, and the double-circulation hot air drying system prepares low-temperature hot air with the air outlet temperature lower than 45 ℃ through the air supply circulation loop; the control device 500 controls the outlet air temperature by changing the operation time interval or the operation frequency of the compressor 1;
a double-cycle pressure reduction unloading mode: the unloading electromagnetic valve 12 and the second throttle valve 11 are opened, the first throttle valve 10 is closed, and while the refrigerant circulates along the main circulation pipeline, a part of the refrigerant is branched by the unloading electromagnetic valve 12 and directly enters the vapor-liquid separator 5 through the second throttle valve 11 so as to reduce the high-pressure side pressure; the opening degree of the internal circulation air valve 23 is 50-55%, and the opening degree of the air supply regulating valve 24 is 50-45%; the control device 500 controls the air outlet temperature by adjusting the circulating air volume of the air supply circulating loop and the internal circulating loop, and prepares medium-temperature hot air with the air outlet temperature of 45-65 ℃;
a dual-cycle cooling unloading mode: the unloading electromagnetic valve 12 and the first throttle valve 10 are opened, the second throttle valve 11 is closed, and while the refrigerant circulates along the main circulation line, a part of the refrigerant is branched by the unloading electromagnetic valve 12 and enters the evaporator 4 through the first throttle valve 10 connected in parallel with the expansion valve 3 to lower the exhaust temperature; the opening degree of the internal circulation air valve 23 is 55-65%, and the opening degree of the air supply regulating valve 24 is 45-35%; the control device 500 controls the air outlet temperature by adjusting the circulating air volume of the air supply circulating loop and the internal circulating loop, and prepares medium-high temperature hot air with the air outlet temperature of 65-75 ℃;
double-circulation double-path unloading mode: an unloading electromagnetic valve 12, a first throttle valve 10 and a second throttle valve 11 are opened, the refrigerant is shunted by the unloading electromagnetic valve 12 while circulating along a main circulation pipeline, one part of the shunted refrigerant enters the evaporator 4 through the first throttle valve 10 connected with the expansion valve 3 in parallel, and the other part of the shunted refrigerant directly enters the vapor-liquid separator 5 through the second throttle valve 11; the opening degree of the internal circulation air valve 23 is 65-75%, and the opening degree of the air supply regulating valve 24 is 35-25%; the control device 500 controls the air outlet temperature by adjusting the circulating air volume of the air supply circulating loop and the internal circulating loop, and prepares high-temperature hot air with the air outlet temperature higher than 75 ℃.
In order to solve the problems of frequent start and stop of the heat pump unit and reduction of energy efficiency caused by large change of heat consumption requirement of the drying room in the drying process, in one embodiment of the heat pump hot air drying system, the heat pump unit 100 further comprises a second refrigerant circulating pipeline adopting a variable frequency compressor; a third condenser 2-3 connected in the second refrigerant circulation pipeline is arranged in the hot air cabinet 200 and is arranged on the air outlet side of the basic air temperature zone, see fig. 3; when the required heat consumption of the drying room is less than 40%, the fixed-frequency compressor is stopped, the variable-frequency compressor is started, and the heat pump hot air drying system operates in a conventional variable-frequency heat pump mode; when the required heat consumption of the drying room is more than or equal to 40%, the constant-frequency compressor and the variable-frequency compressor are started simultaneously, and the heat pump hot air drying system operates in a constant-frequency and variable-frequency double-machine parallel mode; when the set temperature of the supplied air is higher than 75 ℃, the heat pump hot air drying system operates in a double-circulation double-path unloading mode, and the latent heat condenser 21, the third condensers 2-3 and the sensible heat condenser 22 form a three-stage heat exchange structure of the hot air cabinet 200; the circulating air flow of the internal circulation loop exchanges heat twice through the latent heat condenser 21 and the third condenser 2-3, so that the basic air temperature of the basic air temperature area is further increased, and the outlet air temperature of the hot air cabinet 200 is increased to over 75 ℃.
Fig. 4 shows an embodiment of a heat pump unit of a variable-frequency and variable-capacity heat pump hot air drying system, where the heat pump unit 100 includes a fixed-frequency compressor 1-1, a variable-frequency compressor 1-2, a fixed-frequency circulation pipeline and a variable-frequency circulation pipeline connected in parallel, and a heat exchanger variable-capacity branch controlled and connected with the fixed-frequency compressor 7-2 through a first electromagnetic valve bank 7-1 and a second electromagnetic valve bank; the fixed-frequency circulating pipeline starts from an exhaust port of the fixed-frequency compressor 1-1, sequentially passes through the first condenser 2-1, the first expansion valve 3-1, the first evaporator 4-1 and the first gas-liquid separator 5-1, and returns to an air suction port of the fixed-frequency compressor 1-1; the variable frequency circulating pipeline starts from an exhaust port of the variable frequency compressor 1-2, sequentially passes through a third condenser 2-3, a second expansion valve 3-2, a third evaporator 4-3 and a second gas-liquid separator 5-2, and returns to an air suction port of the variable frequency compressor 1-2; the variable-capacity branch of the heat exchanger comprises a second condenser 2-2 and a second evaporator 4-2, wherein the second condenser 2-2 is connected in parallel to the first condenser 2-1 through a first solenoid valve bank 7-1, and is connected in parallel to a third condenser 2-3 through a second solenoid valve bank 7-2; the second evaporator 4-2 is connected in parallel to the first evaporator 4-1 through a first electromagnetic valve bank 7-1, and is connected in parallel to the third evaporator 4-3 through a second electromagnetic valve bank 7-2; the control device 500 is connected to the first electromagnetic valve group 7-1 and the second electromagnetic valve group 7-2, and the connection mode of the variable-capacity branch of the heat exchanger is changed by controlling the opening states of the first electromagnetic valve group 7-1 and the second electromagnetic valve group 7-2, so that the heat pump hot air drying system is controlled to enter a double-machine variable-capacity operation mode; the control device 500 controls the running frequency of the variable frequency compressor 1-2 according to the set temperature of the outlet air; according to the variable-frequency and variable-capacity heat pump hot air drying system, the heat exchange area of the heat exchanger (comprising the evaporator and the condenser) is enlarged through the variable-capacity operation mode, the overall heat exchange effect of the heat pump unit 100 can be obviously improved, and the system energy efficiency is improved.
According to an embodiment of the present invention, the dual-machine variable-capacity operation mode includes a variable-frequency constant-capacity mode, a variable-frequency variable-capacity mode, a constant-frequency variable-capacity + variable-frequency constant-capacity parallel operation mode, a variable-frequency constant-capacity mode + variable-frequency variable-capacity parallel operation mode, and a constant-frequency constant-capacity + variable-frequency variable-capacity parallel operation mode, wherein:
frequency conversion constant volume mode: starting the variable frequency compressor 1-2, circulating a refrigerant along a variable frequency circulating pipeline, and closing the first electromagnetic valve bank 7-1 and the second electromagnetic valve bank 7-2;
variable frequency variable capacity mode: starting the variable frequency compressor 1-2, and circulating a refrigerant along a variable frequency circulating pipeline; the first electromagnetic valve group 7-1 is closed, the second electromagnetic valve group 7-2 is opened, the variable-capacity branch of the heat exchanger is connected to the variable-frequency circulating pipeline in parallel, and the variable-capacity compressor 1-2 enters a variable-capacity operation mode;
a constant-frequency variable-capacity + variable-frequency constant-capacity parallel operation mode: the fixed-frequency compressor 1-1 and the variable-frequency compressor 1-2 are started simultaneously, and the refrigerant circulates along the fixed-frequency circulating pipeline and the variable-frequency circulating pipeline in a double-way mode simultaneously; the first electromagnetic valve group 7-1 is opened, the second electromagnetic valve group 7-2 is closed, the variable-capacity branch of the heat exchanger is connected to the fixed-frequency circulation pipeline in parallel, and the fixed-frequency compressor 1-1 enters a variable-capacity operation mode;
a fixed-frequency fixed-volume and variable-frequency variable-volume parallel operation mode: the fixed-frequency compressor 1-1 and the variable-frequency compressor 1-2 are started simultaneously, and the refrigerant circulates along the fixed-frequency circulating pipeline and the variable-frequency circulating pipeline in a double-way mode simultaneously; the first electromagnetic valve group 7-1 is closed, the second electromagnetic valve group 7-2 is opened, the variable-capacity branch of the heat exchanger is connected to the variable-frequency circulating pipeline in parallel, and the variable-capacity compressor 1-2 enters a variable-capacity operation mode.
According to one embodiment, preferably used for a heat pump hot air drying system requiring a higher drying temperature, the hot air cabinet 200 includes a basic air temperature zone and a reheating temperature raising zone separated by the air supply regulating valve 24; refrigerant pipelines of the first condenser 2-1 and the second condenser 2-2 are connected in series to form a double-section series condenser; the first condenser 2-1 is used as a sensible heat condenser and is arranged in a reheating temperature-rising area, the second condenser 2-2 is used as a latent heat condenser and is arranged on the air inlet side of a basic air temperature area, and the third condenser 2-3 is arranged on the air outlet side of the basic air temperature area; the hot air cabinet 200 is provided with an internal circulation loop communicated with a basic air temperature area, which is shown in fig. 3; the hot air output by the heat pump hot air drying system is subjected to secondary heat exchange through the internal circulation loop and the air supply circulation loop, so that the outlet air temperature can reach 90 ℃.
An embodiment of a control device 500 of a heat pump type dual-circulation hot air drying system according to the present invention is shown in fig. 5, and includes an operation parameter setting module 510 for configuring temperature control parameters and saving preset temperature control curve parameters, a drying room temperature and humidity monitoring module 520 and an air supply temperature monitoring module 530 for detecting and monitoring an air outlet temperature and a drying room temperature and humidity, an air valve opening controller 540 for driving an air valve, and a heat pump unit controller 550 for controlling a compressor and an electromagnetic valve; the input end of the drying room temperature and humidity monitoring module 520 is connected to the operation parameter setting module 510, the dry bulb temperature sensor 521 and the wet bulb temperature sensor 522; the output end of the drying room temperature and humidity monitoring module 520 is connected to the heat pump unit controller 550; the output of the heat pump unit controller 550 is connected to the control solenoids in the compressor and refrigerant lines; the input end of the air supply temperature monitoring module 530 is connected to the operation parameter setting module 510 and the air outlet temperature sensor 531; the output of the supply air temperature monitoring module 530 is connected to an air valve opening controller 540, and the output of the air valve opening controller 540 is connected to the internal circulation air valve 23 and the supply air adjusting valve 24. The control electromagnetic valve comprises an unloading electromagnetic valve 12, a first throttle valve 10, a second throttle valve 11, a first electromagnetic valve bank 7-1 and a second electromagnetic valve bank 7-2 which are connected in a refrigerant pipeline.
According to an embodiment of the heat pump type dual-cycle hot air drying system of the present invention, the control device 500 employs a single-chip microprocessor having multiple a/D conversion interfaces and multiple PWM output interfaces to implement program control, and the operation parameter setting module 510, the drying room temperature and humidity monitoring module 520, and the air supply temperature monitoring module 530 are software functional modules provided by the microprocessor; the dry bulb temperature sensor 521, the air outlet temperature sensor 531 and the wet bulb temperature sensor 522 are connected to the single-chip microprocessor through an A/D conversion interface of the microprocessor; the control device 500 provides an air valve opening control output signal for the air valve opening controller 540 by utilizing the PWM output of the microprocessor, and provides frequency conversion control output signals of the frequency conversion compressor and the frequency conversion fan by the heat pump unit controller 550; the control device 500 utilizes the PIO port of the microprocessor to program and output the switch output signals of the electromagnetic valve and the compressor, and the heat pump unit controller 550 performs switch control on the compressor and the electromagnetic valve in the system.
According to the embodiment of the heat pump hot air drying system control method of the invention shown in fig. 6, the method comprises the following steps:
s100: configuring temperature control parameters and storing preset temperature control curve parameters;
s200: detecting and monitoring the air outlet temperature and the temperature and humidity of the drying room;
s300: dynamically adjusting the set temperature according to a preset temperature control curve;
s400: and selecting a double-circulation dynamic operation mode of the system according to the current set temperature.
Example 1:
fig. 8 shows an embodiment of a multi-segment temperature control curve and a temperature control parameter configuration interface, in which the multi-segment temperature control curve is a 10-segment heating curve, and the control device 500 configures the set temperature and the temperature stabilizing time of each time segment to control the dual-circulation hot air drying system to realize intelligent full-automatic operation without manual operation.
According to the embodiment of the method for controlling a heat pump type dual circulation hot air drying system of the present invention as shown in fig. 6, the step S400 includes the following control operations:
s420: if the set temperature is less than 45 ℃, closing the unloading electromagnetic valve 12 and entering a single-cycle conventional heating mode; in the mode, the opening degree of the internal circulation air valve 23 is 0%, and the opening degree of the air supply regulating valve 24 is 100%; controlling the operation time interval or operation frequency of the compressor 1 according to the outlet air temperature; the temperature control range of this step corresponds to the 1 st to 5 th sections of the 10-section heating curve shown in fig. 8, and the set outlet air temperatures are 20 ℃, 25 ℃, 30 ℃, 35 ℃ and 40 ℃.
S440: if the set temperature is less than 65 ℃, opening the unloading electromagnetic valve 12 and the second throttle valve 11, closing the first throttle valve 10, and entering a dual-cycle pressure reduction unloading mode; the air outlet temperature is controlled by adjusting the circulating air volume of the air supply circulating loop and the internal circulating loop; in the mode, the opening degree of the internal circulation air valve 23 is 40-60%, and the opening degree of the air supply regulating valve 24 is 60-40%; the temperature control ranges in this step correspond to the 6 th and 7 th sections of the 10-section heating curve shown in fig. 8, the outlet air temperatures are set to 50 ℃ and 60 ℃, the corresponding openings of the internal circulation air valve 23 are 50% and 55%, and the openings of the air supply regulating valve 24 are 50% and 45%, respectively.
S460: if the set temperature is more than or equal to 75 ℃, turning to the step S480; otherwise, opening the unloading electromagnetic valve 12 and the second throttle valve 11, closing the first throttle valve 10, and entering a dual-cycle cooling unloading mode; the air outlet temperature is controlled by adjusting the circulating air volume of the air supply circulating loop and the internal circulating loop; in the mode, the opening degree of the internal circulation air valve 23 is 55-65%, and the opening degree of the air supply regulating valve 24 is 45-35%; the temperature control range in this step corresponds to the 8 th segment of the 10-segment heating curve shown in fig. 8, the outlet air temperature is set to 70 ℃, and the opening degrees of the corresponding internal circulation air valve 23 and the corresponding air supply regulating valve 24 are 60% and 40%, respectively.
S480: opening an unloading electromagnetic valve 12, a first throttle valve 10 and a second throttle valve 11, and entering a dual-cycle two-way unloading mode; the air outlet temperature is controlled by adjusting the circulating air volume of the air supply circulating loop and the internal circulating loop; in the mode, the opening degree of the internal circulation air valve 23 is 60-80%, and the opening degree of the air supply adjusting valve 24 is 40-20%. The temperature control ranges in this step correspond to the 9 th and 10 th sections of the 10-section heating curve shown in fig. 8, the outlet air temperatures are set to 80 ℃ and 90 ℃, the corresponding openings of the internal circulation air valves 23 are 65% and 75%, and the openings of the air supply regulating valves 24 are 35% and 25%, respectively.
Example 2:
the size of a certain tobacco drying room is as follows: 8 multiplied by 2.8 multiplied by 2.2m, the amount of the tobacco leaves dried in one time is 350 rods, and the total amount is 10500kg of the tobacco leaves per 30kg of the rods. The variable-frequency variable-capacity heat pump hot air drying system is formed by connecting 6 fixed-frequency compressors 1-1 and 6 variable-frequency compressors 1-2 in parallel, the maximum heating capacity is 50kW, and the variable-frequency variable-capacity connecting structure of the unit is shown in figure 4. The temperature control curve of the tobacco curing process refers to the multi-stage drying process chart shown in fig. 9, and the heat consumption in each stage is shown in fig. 10. The control device 500 selects an appropriate operation mode through comparative analysis to achieve maximum operation efficiency.
According to the embodiment of the method for controlling a variable-frequency and variable-capacity heat pump hot air drying system shown in fig. 7, in step S300, the required heat consumption in the current time period is dynamically set according to a preset temperature control curve; in this embodiment. The required heat consumption is expressed by the percentage of the heat consumption of the drying room in unit time in the current time period and the maximum heating capacity of the heat pump unit;
step S400 selects the dual-machine variable capacity operation mode of the system according to the required heat consumption in the current time period, and includes the following control operations:
s420: if the required heat consumption is less than 25%, starting the variable-frequency compressor 1-2, closing the first electromagnetic valve bank 7-1 and the second electromagnetic valve bank 7-2, and entering a variable-frequency constant-volume mode; the temperature control range of the step corresponds to the first half stage of the tobacco drying-yellowing period shown in fig. 9, the baking time in fig. 10 is 0-10 h, and the heat consumption of a drying room is 10 kw; the inverter compressor 1-2 is operated at a frequency of 20 Hz.
S440: if the required heat consumption is less than 35%, starting the variable-frequency compressor 1-2, closing the first electromagnetic valve group 7-1, opening the second electromagnetic valve group 7-2, and entering a variable-frequency variable-capacity mode; the temperature control range of the step corresponds to the later half stage of the tobacco drying-yellowing period shown in fig. 9, the baking time in fig. 10 is 10-60 h, and the heat consumption of a drying room is 15 kw; the inverter compressor 1-2 is operated at a frequency of 30 Hz. In the first stage (yellowing stage) of tobacco drying, the temperature in the drying room is required to be kept between 35 and 38 ℃, the load is relatively small at the moment, and the requirement of the tobacco leaf yellowing stage can be better met through the mode.
S460: if the required heat consumption is more than or equal to 70 percent, turning to step S480; otherwise, simultaneously starting the fixed-frequency compressor 1-1 and the variable-frequency compressor 1-2, starting the first electromagnetic valve bank 7-1, closing the second electromagnetic valve bank 7-2, and entering a fixed-frequency variable-capacity + variable-frequency constant-capacity parallel operation mode; the temperature control range of the step corresponds to the tobacco drying-color fixing period shown in fig. 9, the drying time in fig. 10 is 60-80 h, the heat consumption of a drying room is 15-35 kw, the capacities of a condenser and an evaporator of a fixed-frequency compressor 1-1 are increased, and the maximum heating capacity is obtained; the frequency conversion compressor 1-2 operates at a frequency of 30-50 Hz.
S480: and simultaneously starting the fixed-frequency compressor 1-1 and the variable-frequency compressor 1-2, closing the first electromagnetic valve bank 7-1, opening the second electromagnetic valve bank 7-2, and entering a parallel operation mode of fixed-frequency fixed capacity and variable-frequency variable capacity. The temperature control range of the step corresponds to the first half stage of the tobacco drying-color fixing period and the dry rib period shown in the figure 9, the baking time in the figure 10 is 80-120 h, the heat consumption of a drying room is 35-50 kw, the air outlet temperature is controlled to be 65-68 ℃, and the wet bulb temperature is controlled to be 40-43 ℃; the water content of the leaves is 5-6% and the water content of the veins is 7-8% after baking; the variable frequency compressor 1-2 runs at the frequency of 50-100 Hz, and the heat requirement of tobacco drying can be met under the working condition of the maximum loading capacity. At this time, the fixed-frequency compressor 1-1 has no difference from the ordinary operation condition, and mainly has the effect of increasing the whole heat exchange amount. The double-system parallel operation overcomes the defect that the traditional drying unit cannot reach high air outlet temperature and needs to introduce electric heating, so that the system operation energy efficiency can be greatly improved.
It should be appreciated by those skilled in the art that the above embodiments are only for illustrating the technical solutions of the present invention, and not for limiting the present invention, and any changes and modifications to the above embodiments based on the spirit of the present invention will fall within the protection scope of the claims of the present invention.
Claims (4)
1. The utility model provides a heat pump type dual cycle hot air drying system, includes heat pump set, hot-blast rack and baking house to and be used for realizing the controlling means of hot air drying system microprocessor control, its characterized in that:
the heat pump type double-circulation hot air drying system also comprises a hot air double-circulation loop formed by an air supply circulation loop and an internal circulation loop;
an air supply regulating valve is arranged in the hot air cabinet to divide the hot air cabinet into a basic air temperature area and a reheating temperature-raising area;
the latent heat condenser arranged in the basic air temperature area and the sensible heat condenser arranged in the reheating temperature-raising area are connected in series through a refrigerant pipeline of a heat pump unit to form a double-section series condenser; the high-temperature gaseous refrigerant discharged by the compressor is sent into the sensible heat condenser for heat exchange and temperature reduction and then sent into the latent heat condenser;
the air supply circulation loop enters the hot air cabinet from the drying room through the return air duct, enters the air supply machine through the latent heat condenser arranged on the air inlet side of the basic air temperature zone, then reaches the sensible heat condenser of the reheating heating zone through the air supply regulating valve, and finally is sent into the drying room through the air supply duct;
the internal circulation loop enters an internal circulation air duct from an air outlet of the air feeder through an internal circulation air valve, then enters the hot air cabinet through a return air duct, reaches a latent heat condenser at the air inlet side of the basic air temperature zone, and finally returns to an air suction port of the air feeder;
the control device regulates the circulating air quantity of the air supply circulation loop and the internal circulation loop by controlling the opening degrees of the internal circulation air valve and the air supply regulating valve, and controls the air outlet temperature of the hot air cabinet;
the heat pump unit comprises a main circulation pipeline of a refrigerant and a two-way unloading branch connected to the main circulation pipeline; the main circulation pipeline starts from an exhaust port of the compressor, sequentially passes through the sensible heat condenser, the latent heat condenser, the expansion valve, the evaporator and the vapor-liquid separator and returns to an air suction port of the compressor; the two-way unloading branch is formed by connecting an unloading electromagnetic valve, a first throttle valve and a second throttle valve: the inlet of the unloading electromagnetic valve is connected to the outlet of the refrigerant pipeline of the latent heat condenser in parallel, the inlets of the first throttle valve and the second throttle valve are connected to the outlet of the unloading electromagnetic valve in parallel, the outlet of the first throttle valve is connected to the inlet of the evaporator, and the outlet of the second throttle valve is connected to the inlet of the vapor-liquid separator; the control device is connected to the first throttle valve, the second throttle valve and the unloading electromagnetic valve, a refrigerant circulating pipeline of the heat pump unit is dynamically changed according to the outlet air temperature, the exhaust temperature and the high-pressure side pressure of the compressor are reduced through the two-way unloading branch, and the double-circulation dynamic operation mode of the hot air drying system is realized.
2. A heat pump type dual cycle hot air drying system according to claim 1, wherein the dual cycle dynamic operation modes include a single cycle conventional heating mode, a dual cycle pressure reducing and unloading mode, a dual cycle temperature reducing and unloading mode, and a dual cycle two-way unloading mode, wherein:
single cycle conventional heating mode: the unloading electromagnetic valve is closed, and the refrigerant circulates along the main circulation pipeline; the opening degree of the internal circulation air valve is 0 percent, the opening degree of the air supply adjusting valve is 100 percent, and the double-circulation hot air drying system prepares low-temperature hot air with the air outlet temperature lower than 45 ℃ through the air supply circulation loop; the control device controls the air outlet temperature by changing the running time interval or the running frequency of the compressor;
a double-cycle pressure reduction unloading mode: the unloading electromagnetic valve and the second throttle valve are opened, the first throttle valve is closed, and when the refrigerant circulates along the main circulation pipeline, one part of the refrigerant is shunted by the unloading electromagnetic valve and directly enters the vapor-liquid separator through the second throttle valve; the opening of the internal circulation air valve is 50-55%, and the opening of the air supply regulating valve is 50-45%; the control device controls the air outlet temperature by adjusting the circulating air quantity of the air supply circulating loop and the internal circulating loop, and prepares medium-temperature hot air with the air outlet temperature of 45-65 ℃;
a dual-cycle cooling unloading mode: the unloading electromagnetic valve and the first throttle valve are opened, the second throttle valve is closed, and when the refrigerant circulates along the main circulation pipeline, one part of the refrigerant is shunted by the unloading electromagnetic valve and enters the evaporator through the first throttle valve connected with the expansion valve in parallel; the opening of the internal circulation air valve is 55-65%, and the opening of the air supply regulating valve is 45-35%; the control device controls the air outlet temperature by adjusting the circulating air volume of the air supply circulating loop and the internal circulating loop, and prepares medium-high temperature hot air with the air outlet temperature of 65-75 ℃;
double-circulation double-path unloading mode: the unloading electromagnetic valve, the first throttle valve and the second throttle valve are opened, the refrigerant is shunted by the unloading electromagnetic valve while circulating along the main circulation pipeline, one part of the shunted refrigerant enters the evaporator through the first throttle valve connected with the expansion valve in parallel, and the other part of the shunted refrigerant directly enters the vapor-liquid separator through the second throttle valve; the opening degree of the internal circulation air valve is 65-75%, and the opening degree of the air supply regulating valve is 35-25%; the control device controls the air outlet temperature by adjusting the circulating air volume of the air supply circulating loop and the internal circulating loop, and high-temperature hot air with the air outlet temperature higher than 75 ℃ is prepared.
3. A heat pump type dual cycle hot air drying system control method for the heat pump type dual cycle hot air drying system of claim 2, characterized by comprising the steps of:
s100: configuring temperature control parameters and storing preset temperature control curve parameters;
s200: detecting and monitoring the air outlet temperature and the temperature and humidity of the drying room;
s300: dynamically adjusting the set temperature according to a preset temperature control curve;
s400: and selecting a double-circulation dynamic operation mode of the system according to the current set temperature.
4. A heat pump type dual circulation hot air drying system control method according to claim 3, wherein the step S400 comprises the following control operation steps:
s420: if the set temperature is less than 45 ℃, closing the unloading electromagnetic valve, and entering a single-cycle conventional heating mode; controlling the running time interval or running frequency of the compressor according to the outlet air temperature;
s440: if the set temperature is less than 65 ℃, opening the unloading electromagnetic valve and the second throttle valve, closing the first throttle valve, and entering a dual-cycle pressure reduction unloading mode; the air outlet temperature is controlled by adjusting the circulating air volume of the air supply circulating loop and the internal circulating loop;
s460: if the set temperature is more than or equal to 75 ℃, turning to the step S480; otherwise, opening the unloading electromagnetic valve and the second throttle valve, closing the first throttle valve, and entering a dual-cycle cooling unloading mode; the air outlet temperature is controlled by adjusting the circulating air volume of the air supply circulating loop and the internal circulating loop;
s480: opening an unloading electromagnetic valve, a first throttle valve and a second throttle valve, and entering a dual-cycle two-way unloading mode; the air outlet temperature is controlled by adjusting the circulating air volume of the air supply circulating loop and the internal circulating loop.
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| CN106989573B (en) * | 2017-05-27 | 2022-09-09 | 中原工学院 | Closed-circuit type heat pump drying system with internal radiation heat transfer function |
| CN107036405B (en) * | 2017-05-27 | 2022-09-09 | 中原工学院 | Heat recovery type air-cooled heat pump drying system suitable for big difference in temperature |
| CN107014173B (en) * | 2017-05-27 | 2022-09-09 | 中原工学院 | Direct-expansion solar-assisted closed-circuit heat pump drying system |
| CN107024033B (en) * | 2017-05-27 | 2023-02-03 | 中原工学院 | Closed-circuit heat pump drying system with dehumidification function |
| CN109631561A (en) * | 2018-12-20 | 2019-04-16 | 南京智升源建筑环境科技有限公司 | A kind of three-level recuperation of heat closed cycle Analysis of Heat Pump Drying System and technique |
| CN109899944B (en) * | 2019-01-28 | 2020-10-02 | 广州七号家族节能科技有限公司 | Regional dynamic circulation refrigeration and heating system |
| CN114543234A (en) * | 2022-02-22 | 2022-05-27 | 山西省安装集团股份有限公司 | Energy-concerving and environment-protective idle call heat supply ventilation system |
| CN116847641B (en) * | 2023-08-31 | 2023-11-21 | 空间液态金属科技发展(江苏)有限公司 | Ventilation and heat dissipation system for standard experiment cabinet in space station cabin |
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| KR101071313B1 (en) * | 2009-01-20 | 2011-10-10 | 김동현 | Multipurpose drying apparatus using heat pump system |
| CN105066666A (en) * | 2015-07-22 | 2015-11-18 | 合肥淘能环境科技有限公司 | Heat pump drying device with humidity and temperature adjusting function |
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