CN112021630A - Heat accumulating type solar energy coupling air source heat pump tobacco leaf drying system and control method - Google Patents

Heat accumulating type solar energy coupling air source heat pump tobacco leaf drying system and control method Download PDF

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Publication number
CN112021630A
CN112021630A CN202010992656.1A CN202010992656A CN112021630A CN 112021630 A CN112021630 A CN 112021630A CN 202010992656 A CN202010992656 A CN 202010992656A CN 112021630 A CN112021630 A CN 112021630A
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China
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heat
drying
air
variable frequency
temperature
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段伦博
吴建雯
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Southeast University
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Southeast University
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    • AHUMAN NECESSITIES
    • A24TOBACCO; CIGARS; CIGARETTES; SIMULATED SMOKING DEVICES; SMOKERS' REQUISITES
    • A24BMANUFACTURE OR PREPARATION OF TOBACCO FOR SMOKING OR CHEWING; TOBACCO; SNUFF
    • A24B3/00Preparing tobacco in the factory
    • A24B3/04Humidifying or drying tobacco bunches or cut tobacco
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02BCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/52Heat recovery pumps, i.e. heat pump based systems or units able to transfer the thermal energy from one area of the premises or part of the facilities to a different one, improving the overall efficiency

Abstract

The invention relates to the technical field of tobacco leaf drying, in particular to a heat accumulating type solar energy coupling air source heat pump tobacco leaf drying system and a control method, wherein the drying system comprises: the drying system comprises a drying room, a solar drying system, an air source heat pump drying system and a control system. The solar heat pump and the air source heat pump are used as double heat sources, the heat storage water tank is used as an auxiliary heat source for solar heat collection, and the solar heat pump can be used for defrosting of an evaporator in winter, so that the maximum utilization of solar energy is realized. The controller reads each operation parameter in real time, adopts a variable frequency adjustment technology, adjusts and controls the operation equipment according to the set parameters, and selects a solar drying independent operation mode, a heat pump drying independent operation mode, a solar-heat pump drying combined operation mode or a heat storage water tank-heat pump drying combined operation mode. Thereby realizing continuous and stable operation under different climatic conditions. And the temperature and humidity in the drying chamber are accurately controlled by adopting a frequency conversion technology so as to improve the drying quality of the tobacco leaves.

Description

Heat accumulating type solar energy coupling air source heat pump tobacco leaf drying system and control method
Technical Field
The invention relates to the technical field of tobacco leaf drying, in particular to a heat accumulating type solar energy coupling air source heat pump tobacco leaf drying system and a control method thereof.
Background
The drying technology is widely applied in the fields of industry, agriculture and the like in China, is a very important process and is also a process link with the largest energy consumption. According to statistics, the drying energy consumption accounts for about 12% of the total national economic energy consumption. Tobacco leaf curing is also a drying process with high energy consumption involving complex heat and mass transfer. In addition, different curing procedures have a great influence on the tobacco drying rate and the tobacco quality. At present, the coal-fired curing barn is still commonly adopted in China to cure the tobacco leaves. The coal consumption of the common coal-fired curing barn is high, the heat efficiency is low, 1.5-2.5kg of standard coal is consumed for curing 1kg of tobacco leaves, and the cost for curing the tobacco leaves is gradually increased due to the rising of the coal price in recent years. In addition, the flue-curing barn is difficult to realize the automatic control of the temperature and the humidity, the temperature fluctuation is large, the phenomena of green curing and ash hanging are easy to occur, and the quality of the flue-cured tobacco is not high. But also can generate a large amount of harmful gas, has serious environmental pollution and is contrary to the development of an environment-friendly society. The use cost of fuel oil, fuel gas and electric heating curing barn is too high, and the economical efficiency is lower.
The heat pump drying technology can save a large amount of energy consumption, has a wide temperature adjusting range, can realize accurate control of temperature and humidity, and ensures the quality of tobacco leaf drying. The drying temperature of the tobacco leaves is between 38 and 70 ℃, the tobacco leaves are adaptive to low-temperature heat utilization of solar energy, and the tobacco leaves are clean and pollution-free. The solar drying and the heat pump drying technology are combined, so that the complementary advantages can be realized, the energy is saved by more than 30% compared with the single heat pump drying, and the solar drying and heat pump drying system has remarkable economic benefit, environmental benefit and energy-saving benefit. At present, the tobacco leaf drying by solar energy coupled with an air source heat pump mainly comprises the following modes: direct expansion, series, parallel, series-parallel. The direct expansion type can not dry the materials normally at night or in rainy days. The series-parallel system is complex, the initial investment cost is high, and the maintenance and overhaul cost of the equipment is high.
The air source heat pump is easy to frost in winter, particularly in severe cold areas, so that the heat exchange resistance of an evaporator is increased, and the energy efficiency ratio of the system is obviously reduced. The traditional reversing defrosting method and the hot gas bypass defrosting method have long defrosting time and poor system reliability, and easily cause temperature fluctuation in the drying chamber.
Disclosure of Invention
The technical problem is as follows: in order to overcome the defects in the prior art, the invention provides a heat accumulating type solar energy coupling air source heat pump tobacco leaf drying system and a control method thereof, wherein a solar energy and air source heat pump are used as double heat sources, a parallel connection mode is adopted, a heat accumulating water tank is used as an auxiliary heat source for solar heat collection, and four operation modes of solar energy independent operation, heat pump independent operation, solar energy-heat pump combined operation and heat accumulating water tank-heat pump combined operation can be realized; according to different climatic conditions, different operation modes are adopted, so that the continuous and stable operation of the drying system is ensured, and the power consumption of the system can be obviously saved.
The technical scheme is as follows: the heat accumulating type solar energy coupling air source heat pump tobacco leaf drying system comprises a drying room, a solar energy drying system, an air source heat pump drying system and a control system;
the solar drying system comprises a solar heat collector, a heat storage water tank, a first heat exchanger and a second heat exchanger; two ends of the solar thermal collector are connected with two ends of the heat storage water tank through a first three-way valve and a second three-way valve respectively to form a first circulation loop, and two ends of the heat storage water tank are connected with a second circulation water pump and a first heat exchanger in series through the first three-way valve and the second three-way valve respectively to form a second circulation loop; the other two ends of the heat storage water tank are connected with the first circulating water pump and the second heat exchanger in series through the first electromagnetic valve and the second electromagnetic valve respectively to form a third circulating loop; the second heat exchanger is used for heating air around the evaporator so as to prevent the evaporator from frosting in a low-temperature environment; the heat storage water tank is used as an auxiliary heat source for solar heat collection, provides heat for the first heat exchanger and the second heat exchanger, and is respectively used for tobacco leaf drying and evaporator defrosting;
the air source heat pump drying system is formed by sequentially connecting a condenser, an expansion valve, an evaporator and a variable frequency compressor in series to form a fourth circulation loop; the air inlet end of the condenser is connected with the air outlet end of the variable frequency compressor, the air outlet end of the condenser is connected with the air inlet end of the expansion valve, the air outlet end of the expansion valve is connected with the air inlet end of the evaporator, and the air outlet end of the evaporator is connected with the air inlet end of the variable frequency compressor;
the drying room comprises a heating chamber and a drying chamber, and the heating chamber and the drying chamber are separated by a partition wall; the drying rack is arranged in the drying chamber, can be freely stretched, and is convenient for taking and placing the tobacco leaves; the upper part in the drying room is provided with a first air distribution plate, and the lower part is provided with a second air distribution plate for promoting the uniform distribution of a temperature field and a wind speed field in the drying room; a full heat exchanger, a condenser and a first heat exchanger are arranged in the heating chamber; the total heat exchanger is used for recovering heat of moisture removal, when the humidity in the drying chamber reaches an upper limit, part of wet and hot air preheats fresh air through the total heat exchanger and is arranged to the evaporator; the condenser and the first heat exchanger are used as drying heat sources, and are arranged in the heating chamber from top to bottom for heating fresh air and return air; the hot air of the heating chamber adopts a mode of up-feeding and down-returning so as to avoid damaging the shape and quality of the tobacco leaves;
the control system comprises a process parameter acquisition system and an operating equipment regulation and control system; the process parameter acquisition system comprises a first temperature and humidity sensor, a second temperature and humidity sensor, a third temperature and humidity sensor, a first temperature sensor and a second temperature sensor; the first temperature sensor, the second temperature sensor and the third temperature sensor are respectively arranged at the air supply opening, the air return opening and the outside of the drying chamber, and the first temperature sensor and the second temperature sensor are respectively arranged at the outlet of the solar heat collector and in the heat storage water tank; the operation equipment regulation and control system comprises a controller, a first three-way valve, a second three-way valve, a first electromagnetic valve, a second electromagnetic valve, a first circulating water pump, a second circulating water pump, a variable frequency compressor, an expansion valve, a total heat exchanger, a first variable frequency fan and a second variable frequency fan; the controller reads each operation parameter in real time, adopts a variable frequency adjustment technology, adjusts and controls the operation equipment according to the set parameters, and selects a solar drying independent operation mode, a heat pump drying independent operation mode, a solar-heat pump drying combined operation mode or a heat storage water tank-heat pump drying combined operation mode.
The solar heat collector adopts a vacuum tube type, and the area of the heat collector is more than 40m2The mounting angle can be adjusted, so that the water temperature in the heat collector can reach more than 90 ℃ in clear summer; the volume of the heat storage water tank is more than 2.5 tons.
The refrigeration working medium adopted by the air source heat pump drying system is R134 a; the condenser and the evaporator adopt plate-fin heat exchangers.
The inner wall of the drying chamber is made of polyurethane foam board, and the heat conductivity coefficient is 0.02-0.025W/(m)2K), has good heat insulation and waterproof performance, and the outer wall adopts a color steel plate; the pipelines at all positions of the system are also covered with rock wool heat-insulating materials.
The control method of the heat accumulating type solar energy coupling air source heat pump tobacco leaf drying system adopts a solar energy drying independent operation mode: if the solar irradiation is more than or equal to the irradiation required by independent operation, opening a channel a and a channel c of a first three-way valve and a second three-way valve, starting a second circulating water pump, heating the air in the heating chamber through a first heat exchanger, simultaneously opening a first variable frequency fan and a second variable frequency fan, and enabling the hot air to pass through a first air distribution plate and a second air distribution plate, so that the temperature field and the air speed field in the drying chamber are more uniform; the rotating speeds of the first variable frequency fan and the second variable frequency fan are adjusted through the control system, so that the air temperature in the drying chamber is controlled within a reasonable range;
a heat storage process: if the solar irradiation intensity is higher in the daytime, the solar irradiation amount is larger than or equal to the irradiation amount required by independent operation, and the water temperature at the outlet of the solar thermal collector-drying temperature is larger than or equal to 15 ℃, the channel b of the first three-way valve and the second three-way valve is opened, the valve opening degree of the channel c of the first three-way valve and the second three-way valve is properly reduced, so that part of water is circularly heated in the solar thermal collector-heat storage water tank; when the water temperature-drying temperature of the heat storage water tank is more than or equal to 15 ℃, closing a channel b of the first three-way valve and the second three-way valve; the tobacco leaves are dried while heat is stored.
The three-section five-step tobacco leaf baking process flow taking low-temperature slow yellowing as the core is adopted to obtain better tobacco leaf baking quality. The three sections are respectively: yellowing stage (about 38 ℃), fixing color stage (about 45-50 ℃) and drying tendon stage (about 68-70 ℃).
The control method of the heat accumulating type solar energy coupling air source heat pump tobacco leaf drying system adopts a solar energy-heat pump drying combined operation mode: if the minimum irradiation quantity required by the combined operation is less than or equal to the irradiation quantity required by the independent operation, adopting a solar energy-heat pump drying combined operation mode; opening a channel a and a channel c of the first three-way valve and the second three-way valve, and sending hot water in the solar heat collector to the first heat exchanger under the action of the second circulating water pump so as to heat air; simultaneously starting the inverter compressor 19 for circulation, and heating air through the condenser; after being sequentially heated by the first heat exchanger and the condenser, the hot air passes through the first variable frequency fan, the first air distribution plate, the material rack, the second air distribution plate and the second variable frequency fan to dry the tobacco leaves; the controller realizes the accurate control of the temperature and the humidity in the drying chamber by adjusting the variable frequency compressor, the first variable frequency fan and the second variable frequency fan.
The control method of the heat accumulating type solar energy coupling air source heat pump tobacco leaf drying system adopts a heat accumulating water tank-heat pump drying combined operation mode: if the solar irradiation is less than the minimum irradiation required by the combined operation and the water temperature-drying temperature of the heat storage water tank is more than or equal to 5 ℃, adopting a heat storage water tank-heat pump drying combined operation mode; opening a channel b and a channel c of the first three-way valve and the second three-way valve, and sending hot water in the hot water storage tank to the first heat exchanger under the action of the second circulating water pump so as to heat air; simultaneously starting the frequency conversion compressor to circulate, and heating air through the condenser; after being sequentially heated by the first heat exchanger and the condenser, the hot air passes through the first variable frequency fan, the first air distribution plate, the material rack, the second air distribution plate and the second variable frequency fan to dry the tobacco leaves; the controller realizes the accurate control of the temperature and the humidity in the drying chamber by adjusting the variable frequency compressor, the first variable frequency fan and the second variable frequency fan.
The control method of the heat accumulating type solar energy coupling air source heat pump tobacco leaf drying system adopts a heat pump drying independent operation mode: if the solar irradiation is less than the minimum irradiation required by the combined operation and the water temperature of the heat storage water tank-drying temperature is less than 5 ℃, independently drying the tobacco leaves by adopting a heat pump; starting the variable frequency compressor, enabling the refrigerant to absorb heat from the external environment, releasing heat to the air in the heating chamber through the condenser, and starting the first variable frequency fan and the second variable frequency fan to enable the hot air to forcibly flow in the drying chamber and the heating chamber; the controller realizes the accurate control of the temperature and the humidity in the drying chamber by adjusting the variable frequency compressor, the first variable frequency fan and the second variable frequency fan.
According to the control method of the heat accumulating type solar energy coupled air source heat pump tobacco leaf drying system, in the operation mode, when the relative humidity in the drying chamber reaches the upper limit set by the system, the full heat exchanger is started to perform dehumidification; the wet and hot air is preheated by the total heat exchanger and is discharged to the evaporator, the fresh air is mixed with the rest wet and hot air, and the mixture is heated by the first heat exchanger and the condenser and is sent into the drying chamber again to dry the tobacco leaves; the amount of the exhausted damp and hot air is equal to that of the fresh air sent into the heating chamber, and the moisture exhaust is stopped until the relative humidity of the air in the drying chamber meets the requirement.
In winter or in cold areas, if the temperature of air around an evaporator is lower than 5 ℃, a defrosting operation mode is started: the first electromagnetic valve and the second electromagnetic valve are opened, and the hot water in the heat storage water tank heats the air around the evaporator through the second heat exchanger under the action of the first circulating water pump, so that frosting is avoided, and the energy efficiency ratio of the system is improved.
Has the advantages that: the invention has the advantages that:
(1) the solar heat pump and the air source heat pump are used as double heat sources, a parallel connection mode is adopted, the heat storage water tank is used as an auxiliary heat source for solar heat collection, and four operation modes of solar energy independent operation, heat pump independent operation, solar energy-heat pump combined operation and heat storage water tank-heat pump combined operation can be realized; according to different climatic conditions, different operation modes are adopted, so that the continuous and stable operation of the drying system is ensured, and the power consumption of the system can be obviously saved.
(2) When the solar irradiance is large in the daytime, the heat storage water tank stores redundant heat of the system, and can be used as an auxiliary heat source for drying tobacco leaves when the solar heat collector supplies insufficient heat, so that the maximum utilization of solar energy is realized; in addition, when the outdoor temperature is lower in severe cold areas or winter, the defrosting device can be used for defrosting the evaporator, and the normal operation of the system is ensured.
(3) The invention adopts the total heat exchanger to recover the heat of dehumidification, can recover 70 percent of heat, reduces the heat loss of dehumidification, and discharges the damp and hot air after heat exchange to the evaporator, thereby improving the energy efficiency ratio of the system.
(4) The control system can realize the switching of different operation modes according to the process parameters collected in the system, and adopts a frequency conversion technology to realize the accurate control of the temperature and the humidity in the drying chamber, thereby improving the quality of the tobacco leaf drying; in addition, the problems of electric energy consumption, temperature fluctuation in the drying chamber and damage to the service life of the heat pump caused by frequent starting and stopping of the heat pump can be avoided.
Drawings
Fig. 1 is a schematic structural diagram of a tobacco leaf drying system of a solar energy coupled air source heat pump according to the invention.
The figure shows that: the drying room comprises a drying room 1, a heating chamber 2, a drying chamber 3, a first air distribution plate 4, a second air distribution plate 5, a first temperature and humidity sensor 6, a second temperature and humidity sensor 7, a third temperature and humidity sensor 8, a first variable frequency fan 9, a second variable frequency fan 10, a drying rack 11, a total heat exchanger 12, a partition wall 13, a first heat exchanger 14, a second heat exchanger 15, a condenser 16, an expansion valve 17, an evaporator 18, a variable frequency compressor 19, a first circulating water pump 20, a second circulating water pump 21, a first electromagnetic valve 22, a second electromagnetic valve 23, a first temperature sensor 24, a second temperature sensor 25, a heat storage water tank 26, a first three-way valve 27, a second three-way valve 28, a solar heat collector 29 and a controller 30.
Detailed Description
In order to better understand the technical means, the implementation purpose and the effect of the invention, the heat accumulating type solar energy coupling air source heat pump tobacco leaf drying system of the invention is specifically described below with reference to the accompanying drawings.
The first air distribution plate 4 and the second air distribution plate 5 adopt dense hole plates, the hole patterns are circular, and the small holes are uniformly distributed;
first temperature and humidity sensor 6, second temperature and humidity sensor 7, 8 models of third temperature and humidity sensor: DG-WDO 11; temperature range: -40 ℃ to 80 ℃; humidity range: 0-100% RH;
first frequency conversion fan 9, second frequency conversion fan 10 model: g-450A; the power is 1.1kW, the rotating speed is 1400r/min, and the air volume is 8500m3H, wind pressure 85Pa, protection grade IP 54;
total heat exchanger 12 model: RXH-D12; electric power: 320W; heat exchange efficiency: 70 percent; air volume: 2000m3/h;
The first heat exchanger 14 and the second heat exchanger 15 adopt finned tubes; the model is as follows: JN-1;
the condenser 16 adopts a plate-fin type, and the circulating air volume is 19000 kg/h;
type 17 of expansion valve: TRAE +13 MC;
the evaporator 18 adopts a plate-fin type, and the circulating air quantity is 9300 kg/h;
the type of the inverter compressor 19: YH-30 ZV; the power is 22 kW;
models of the first and second circulating water pumps 20 and 21: 25ZDB 6-35-1.1; power: 1.1kW, maximum lift: 35 m;
models of the first electromagnetic valve 22 and the second electromagnetic valve 23: 2W-200-20;
the first temperature sensor 24 and the second temperature sensor 25 comprise a Pt100 thermal resistor;
first three-way valve 27, second three-way valve 28 model: Q911F-16, DN 25;
the solar heat collector 29 adopts a full-glass vacuum tube type solar heat collector; the model is as follows: Q-B-J-1-355/5.85/0.05; the glass material is high borosilicate, and the heat collection area is more than 40m2
The controller 30 adopts a PLC controller; the model is as follows: OMRON C200 HE;
as shown in fig. 1, a heat accumulating type solar energy coupled air source heat pump tobacco leaf drying system is provided, which comprises a drying room, a solar energy drying system, an air source heat pump drying system and a control system.
The solar drying system comprises a solar heat collector 29, a heat storage water tank 26, a first heat exchanger 14 and a second heat exchanger 15; the solar heat collector 29 is connected with the hot water storage tank 26 through a first three-way valve 27 and a second three-way valve 28; the hot water storage tank 26 is connected with the second heat exchanger 15 through the first electromagnetic valve 22, the second electromagnetic valve 23 and the first circulating water pump 20; the second heat exchanger 15 is used for heating the air around the evaporator 18, so as to avoid the evaporator frosting in a low-temperature environment; the heat storage water tank 26 is used as an auxiliary heat source for solar heat collection, can provide heat for the first heat exchanger 14 and the second heat exchanger 15, and is respectively used for tobacco leaf drying and defrosting of the evaporator 18, so that the maximum utilization of solar energy is realized; the outlet c of the first three-way valve 27 is connected to the inlet of the second circulating water pump 21.
Preferably, the solar heat collector 29 adopts a vacuum tube type, and the area of the heat collector is 40m2The installation angle of the heat collector can be adjusted according to the local latitude, and the water temperature in the heat collector can reach more than 90 ℃ in clear summer.
Preferably, the volume of the hot water storage tank 26 is 2.5 tons, and the operation can be continuously performed for more than 5 hours.
The air source heat pump drying system comprises a condenser 16, an expansion valve 17, an evaporator 18 and a variable frequency compressor 19; the air inlet end of the condenser 16 is connected with the air outlet end of the variable frequency compressor 19, the air outlet end of the condenser 16 is connected with the air inlet end of the expansion valve 17, the air outlet end of the expansion valve 17 is connected with the air inlet end of the evaporator 18, and the air outlet end of the evaporator 18 is connected with the air inlet end of the variable frequency compressor 19.
Preferably, the refrigerant adopted by the air source heat pump drying system is R134 a.
The drying room 1 comprises a heating chamber 2 and a drying chamber 3 which are separated by a partition wall 13; a drying rack 11 is arranged in the drying chamber 3, can be freely stretched, and is convenient for taking and placing tobacco leaves; the top of drying room 1 is equipped with first air distribution plate 4, and the bottom is equipped with second air distribution plate 5 for promote the even distribution of temperature field and wind speed field in the drying chamber. The heating chamber 2 comprises a total heat exchanger 12, a condenser 16 and a first heat exchanger 14; the total heat exchanger 12 is used for recovering heat of humidity discharge, when the humidity in the drying chamber 3 reaches an upper limit, part of the damp and hot air preheats fresh air through the total heat exchanger 12 and is arranged to the evaporator 18; the condenser 16 and the first heat exchanger 14 are used as drying heat sources, and are arranged up and down for heating fresh air and return air; a first variable frequency fan 9 and a second variable frequency fan 10 are respectively arranged at an air supply outlet and a return air inlet in the heating chamber 2; the hot air is sent from top to bottom so as to avoid damaging the shape and quality of the tobacco leaves.
Preferably, the dimensions of the drying chamber 3 are: 4.5m long, 2.5m wide and 4m high, the inner wall of the drying chamber adopts a polyurethane foam plate with the thickness of 50mm, and the heat conductivity coefficient is 0.02-0.025W/(m)2K), has good heat insulation and waterproof performance, and the outer wall adopts a color steel plate; the pipelines at all positions of the system are also covered with rock wool heat-insulating materials.
The control system comprises a process parameter acquisition system and an operating equipment regulation and control system; the process parameter acquisition system comprises a first temperature and humidity sensor 6, a second temperature and humidity sensor 7, a third temperature and humidity sensor 8, a first temperature sensor 24 and a second temperature sensor 25, wherein the first temperature and humidity sensor 7, the second temperature and humidity sensor 8 and the third temperature and humidity sensor 9 are respectively arranged at the air supply opening, the air return opening and the outside of the drying chamber, and the first temperature sensor 24 and the second temperature sensor 25 are respectively arranged at the outlet of the solar heat collector 29 and in the heat storage water tank 26; the operation equipment regulation and control system comprises a controller 30, a first three-way valve 27, a second three-way valve 28, a first electromagnetic valve 22, a second electromagnetic valve 23, a first circulating water pump 20, a second circulating water pump 21, a variable-frequency compressor 19, an expansion valve 17, a total heat exchanger 12, a first variable-frequency fan 9 and a second variable-frequency fan 10, wherein the controller 30 reads each operation parameter in real time, adopts a variable-frequency regulation technology, regulates and controls operation equipment according to the set parameters, and selects different operation modes; the operation modes comprise: the system comprises a solar drying independent operation mode, a heat pump drying independent operation mode, a solar-heat pump drying combined operation mode and a heat storage water tank-heat pump drying combined operation mode.
Solar drying individual operating mode: if the solar radiation amount is larger than or equal to the radiation amount required by independent operation, the channel a and the channel c of the first three-way valve 27 and the second three-way valve 28 are opened, the second circulating water pump 21 is started, the air in the heating chamber 2 is heated through the first heat exchanger 14, the first variable frequency fan 9 and the second variable frequency fan 10 are simultaneously started, and the hot air passes through the first air distribution plate 4 and the second air distribution plate 5, so that the temperature field and the air speed field in the drying chamber are more uniform. The rotating speed of the fan is adjusted through the control system, so that the air temperature in the drying chamber is controlled within a reasonable range
A heat storage process: if the solar irradiation intensity is higher in the daytime, the solar irradiation amount is larger than or equal to the irradiation amount required by independent operation, and the water temperature at the outlet of the heat collector-the drying temperature is larger than or equal to 15 ℃, the channel b of the first three-way valve 27 and the channel c of the second three-way valve 28 are opened, the valve opening degrees of the channel c of the first three-way valve 27 and the channel c of the second three-way valve 28 are properly reduced, and part of water is circularly heated in the solar heat collector-; when the water temperature-drying temperature of the heat storage water tank is more than or equal to 15 ℃, closing a channel b of the first three-way valve 27 and the second three-way valve 28; the tobacco leaves can be dried while storing heat.
Solar energy-heat pump drying combined operation mode: if the minimum irradiation quantity required by the combined operation is less than or equal to the irradiation quantity required by the independent operation, adopting a solar energy-heat pump drying combined operation mode; the specific working mode is as follows: opening the paths a and c of the first three-way valve 27 and the second three-way valve 28, and sending the hot water in the solar heat collector 29 to the first heat exchanger 14 under the action of the second circulating water pump 21 so as to heat the air; at the same time, the heat pump cycle is started, heating the air by the condenser 16. After being sequentially heated by the first heat exchanger 14 and the condenser 16, the hot air passes through the first variable frequency fan 9, the first air distribution plate 4, the material rack 11, the second air distribution plate 5 and the second variable frequency fan 10 to dry the tobacco leaves; the controller 30 adjusts the variable frequency compressor 19, the first variable frequency fan 9 and the second variable frequency fan 10, so as to realize accurate control of the temperature and humidity in the drying chamber 3.
The heat storage water tank-heat pump drying combined operation mode is as follows: if the solar irradiation is less than the minimum irradiation required by the combined operation and the water temperature-drying temperature of the heat storage water tank is more than or equal to 5 ℃, a heat storage water tank-heat pump drying combined operation mode is adopted. The specific working mode is as follows: the passage b and the passage c of the first three-way valve 27 and the second three-way valve 28 are opened, and the hot water in the hot water storage tank 26 is sent to the first heat exchanger 14 by the second circulating water pump 21, so that the air is heated; at the same time, the heat pump cycle is started, and air is heated by the condenser 16; after being sequentially heated by the first heat exchanger 14 and the condenser 16, the hot air passes through the first variable frequency fan 9, the first air distribution plate 4, the material rack 11, the second air distribution plate 5 and the second variable frequency fan 10 to dry the tobacco leaves; the controller 30 adjusts the variable frequency compressor 19, the first variable frequency fan 9 and the second variable frequency fan 10, so as to realize accurate control of the temperature and humidity in the drying chamber 3.
Heat pump dry stand alone mode of operation: if the solar irradiation is less than the minimum irradiation required by the combined operation and the water temperature of the heat storage water tank-drying temperature is less than 5 ℃, the tobacco leaves are independently dried by adopting a heat pump. The refrigerant absorbs heat from the external environment, releases heat to the air in the heating chamber 2 through the condenser 16, and starts the first variable frequency fan 9 and the second variable frequency fan 10 to promote the forced flow of the hot air in the drying chamber 3 and the heating chamber 2; the controller 30 adjusts the variable frequency compressor 19, the first variable frequency fan 9 and the second variable frequency fan 10, so as to realize accurate control of the temperature and humidity in the drying chamber 3.
In the above four operation modes, when the relative humidity in the drying chamber 3 reaches the upper limit set by the system, the total heat exchanger 12 is opened to perform dehumidification; the damp and hot air preheats fresh air through the total heat exchanger 12 and is arranged to the evaporator 18, the fresh air is mixed with the rest damp and hot air, and the mixture is heated through the first heat exchanger 14 and the condenser 16 and is sent into the drying chamber 3 again to dry the tobacco leaves; the amount of the exhausted damp and hot air is equal to that of the fresh air sent into the heating chamber, and the moisture exhaust is not stopped until the relative humidity of the air in the drying chamber 3 reaches the requirement.
In the winter or cold regions, if the air temperature around the evaporator 18 is below 5 ℃, the defrost mode of operation is initiated: the first electromagnetic valve 22 and the second electromagnetic valve 23 are opened, and the hot water in the hot water storage tank 26 heats the air around the evaporator 18 through the second heat exchanger 15 under the action of the first circulating water pump 20, so that the frost formation is avoided, and the energy efficiency ratio of the system is improved.

Claims (10)

1. The utility model provides a heat accumulation formula solar energy coupling air source heat pump tobacco leaf drying system which characterized in that: the system comprises a drying room, a solar drying system, an air source heat pump drying system and a control system;
the solar drying system comprises a solar heat collector (29), a heat storage water tank (26), a first heat exchanger (14) and a second heat exchanger (15); two ends of the solar heat collector (29) are respectively connected with two ends of the heat storage water tank (26) through a first three-way valve (27) and a second three-way valve (28) to form a first circulation loop, and two ends of the heat storage water tank (26) are respectively connected with a second circulation water pump (21) and the first heat exchanger (14) in series through the first three-way valve (27) and the second three-way valve (28) to form a second circulation loop; the other two ends of the heat storage water tank (26) are connected with the first circulating water pump (20) and the second heat exchanger (15) in series through a first electromagnetic valve (22) and a second electromagnetic valve (23) respectively to form a third circulating loop; the second heat exchanger (15) is used for heating air around the evaporator (18) so as to avoid the evaporator (18) from frosting in a low-temperature environment; the heat storage water tank (26) is used as an auxiliary heat source for solar heat collection, provides heat for the first heat exchanger (14) and the second heat exchanger (15), and is respectively used for drying tobacco leaves and defrosting the evaporator (18);
the air source heat pump drying system is formed by sequentially connecting a condenser (16), an expansion valve (17), an evaporator (18) and a variable frequency compressor (19) in series to form a fourth circulation loop; the air inlet end of the condenser (16) is connected with the air outlet end of the variable frequency compressor (19), the air outlet end of the condenser (16) is connected with the air inlet end of the expansion valve (17), the air outlet end of the expansion valve (17) is connected with the air inlet end of the evaporator (18), and the air outlet end of the evaporator (18) is connected with the air inlet end of the variable frequency compressor (19);
the drying room (1) comprises a heating chamber (2) and a drying chamber (3), and the heating chamber (2) and the drying chamber (3) are separated by a partition wall (13); a drying rack (11) is arranged in the drying chamber (3) and can be freely stretched, so that the tobacco leaves can be conveniently taken and placed; a first air distribution plate (4) is arranged at the upper part in the drying room (1), and a second air distribution plate (5) is arranged at the lower part and used for promoting the uniform distribution of a temperature field and a wind speed field in the drying room; a total heat exchanger (12), a condenser (16) and a first heat exchanger (14) are arranged in the heating chamber (2); the total heat exchanger (12) is used for recovering heat of moisture removal, when the humidity in the drying chamber reaches an upper limit, part of wet and hot air preheats fresh air through the total heat exchanger and is arranged to the evaporator; the condenser (16) and the first heat exchanger (14) are used as drying heat sources, and the heating chamber (2) is internally provided with an up-down arrangement mode for heating fresh air and return air; a first variable frequency fan (9) is arranged at an air supply outlet for supplying air to the drying chamber (3) from the heating chamber (2), a second variable frequency fan (10) is arranged at an air return inlet for returning air to the heating chamber (2) from the drying chamber (3), and the hot air in the heating chamber (2) is fed upwards and returned downwards so as to avoid damaging the shape and quality of tobacco leaves;
the control system comprises a process parameter acquisition system and an operating equipment regulation and control system; the process parameter acquisition system comprises a first temperature and humidity sensor (6), a second temperature and humidity sensor (7), a third temperature and humidity sensor (8), a first temperature sensor (24) and a second temperature sensor (25); the first temperature and humidity sensor (6), the second temperature and humidity sensor (7) and the third temperature and humidity sensor (8) are respectively arranged at the air supply opening, the air return opening and the outside of the drying chamber, and the first temperature sensor (24) and the second temperature sensor (25) are respectively arranged at the outlet of the solar heat collector (29) and in the heat storage water tank (26); the operation equipment regulation and control system comprises a controller (30), a first three-way valve (27), a second three-way valve (28), a first electromagnetic valve (22), a second electromagnetic valve (23), a first circulating water pump (20), a second circulating water pump (21), a variable frequency compressor (19), an expansion valve (17), a total heat exchanger (12), a first variable frequency fan (9) and a second variable frequency fan (10); the controller (30) reads each operation parameter in real time, adopts a frequency conversion adjustment technology, adjusts and controls the operation equipment according to the set parameters, and selects a solar drying independent operation mode, a heat pump drying independent operation mode, a solar-heat pump drying combined operation mode or a heat storage water tank-heat pump drying combined operation mode.
2. The heat accumulating type solar energy coupled air source heat pump tobacco leaf drying system of claim 1, characterized in that: the solar heat collector (29) adopts a vacuum tube type, and the area of the heat collector is more than 40m2The mounting angle can be adjusted, so that the water temperature in the heat collector can reach more than 90 ℃ in clear summer; the volume of the heat storage water tank (26) is more than 2.5 tons.
3. The heat accumulating type solar energy coupled air source heat pump tobacco leaf drying system of claim 1, characterized in that: the refrigeration working medium adopted by the air source heat pump drying system is R134 a; the condenser (16) and the evaporator (18) adopt plate-fin heat exchangers.
4. The heat accumulating type solar energy coupled air source heat pump tobacco leaf drying system of claim 1, characterized in that: the inner wall of the drying chamber is made of polyurethane foam board, and the heat conductivity coefficient is 0.02-0.025W/(m)2K), has good heat insulation and waterproof performance, and the outer wall adopts a color steel plate; the pipelines at all positions of the system are also covered with rock wool heat-insulating materials.
5. The control method of the heat accumulating type solar energy coupling air source heat pump tobacco leaf drying system according to claim 1, characterized by adopting a solar energy drying independent operation mode: if the solar radiation amount is larger than or equal to the radiation amount required by independent operation, opening a channel a and a channel c of a first three-way valve (27) and a second three-way valve (28), starting a second circulating water pump (21), heating air in a heating chamber (2) through a first heat exchanger (14), simultaneously opening a first variable frequency fan (9) and a second variable frequency fan (10), and enabling the hot air to pass through a first air distribution plate (4) and a second air distribution plate (5), so that a temperature field and a wind speed field in a drying chamber (3) are more uniform; the rotating speeds of the first variable frequency fan (9) and the second variable frequency fan (10) are adjusted through a control system, so that the air temperature in the drying chamber (3) is controlled within a reasonable range;
a heat storage process: if the solar irradiation intensity is high in the daytime, the solar irradiation amount is larger than or equal to the irradiation amount required by independent operation, and the water temperature-drying temperature at the outlet of the solar heat collector (29) is larger than or equal to 15 ℃, the channels b of the first three-way valve (27) and the second three-way valve (28) are opened, the valve openings of the channels c of the first three-way valve (27) and the second three-way valve (28) are properly reduced, and part of water is circularly heated in the solar heat collector-heat storage water tank; when the water temperature-drying temperature of the heat storage water tank is more than or equal to 15 ℃, closing a channel b of the first three-way valve and the second three-way valve; the tobacco leaves are dried while heat is stored.
6. The control method of the heat accumulating type solar energy coupling air source heat pump tobacco leaf drying system according to claim 1, characterized by adopting a solar energy-heat pump drying combined operation mode: if the minimum irradiation quantity required by the combined operation is less than or equal to the irradiation quantity required by the independent operation, adopting a solar energy-heat pump drying combined operation mode; opening the channels a and c of the first three-way valve and the second three-way valve, and sending hot water in the solar heat collector (29) to the first heat exchanger (14) under the action of the second circulating water pump (21) so as to heat air; simultaneously, starting a variable frequency compressor (19) for circulation, and heating air through a condenser (16); the hot air is heated by a first heat exchanger (14) and a condenser (16) in sequence and then passes through a first variable frequency fan (9), a first air distribution plate (4), a material rack (11), a second air distribution plate (5) and a second variable frequency fan (10) to dry the tobacco leaves; the controller (30) is through adjusting inverter compressor (19), first variable frequency fan (9) and second variable frequency fan (10) to the realization is to the accurate control of the drying chamber internal temperature and humidity.
7. The control method of the heat accumulating type solar energy coupling air source heat pump tobacco leaf drying system according to claim 1, characterized by adopting a heat accumulating water tank-heat pump drying combined operation mode: if the solar irradiation is less than the minimum irradiation required by the combined operation and the water temperature-drying temperature of the heat storage water tank is more than or equal to 5 ℃, adopting a heat storage water tank-heat pump drying combined operation mode; opening a channel b and a channel c of a first three-way valve (27) and a second three-way valve (28), and sending hot water in the heat storage water tank (26) to the first heat exchanger (14) under the action of a second circulating water pump (21) so as to heat air; simultaneously, starting a variable frequency compressor (19) for circulation, and heating air through a condenser (16); the hot air is heated by a first heat exchanger (14) and a condenser (16) in sequence and then passes through a first variable frequency fan (9), a first air distribution plate (4), a material rack (11), a second air distribution plate (5) and a second variable frequency fan (10) to dry the tobacco leaves; the controller (30) is through adjusting inverter compressor (19), first variable frequency fan (9) and second variable frequency fan (10) to the realization is to the accurate control of the drying chamber internal temperature and humidity.
8. The control method of the heat accumulating type solar energy coupled air source heat pump tobacco leaf drying system according to claim 1, characterized by adopting a heat pump drying independent operation mode: if the solar irradiation is less than the minimum irradiation required by the combined operation and the water temperature of the heat storage water tank-drying temperature is less than 5 ℃, independently drying the tobacco leaves by adopting a heat pump; starting the variable frequency compressor (19), absorbing heat from the external environment by the refrigerant, releasing heat to the air in the heating chamber (2) by the condenser (16), and starting the first variable frequency fan (9) and the second variable frequency fan (10) to force the hot air to flow in the drying chamber (3) and the heating chamber (2) forcibly; the controller (30) is through adjusting inverter compressor (19), first variable frequency fan (9) and second variable frequency fan (10) to the realization is to the accurate control of the drying chamber internal temperature and humidity.
9. The control method of the heat accumulating type solar energy coupling air source heat pump tobacco leaf drying system according to the claim 5, 6, 7 or 8, characterized in that in the operation mode, when the relative humidity in the drying chamber (3) reaches the upper limit set by the system, the total heat exchanger (12) is opened for dehumidification; the damp and hot air preheats fresh air through the total heat exchanger (12), and is arranged to the evaporator (18), the fresh air is mixed with the rest damp and hot air, and the mixture is heated through the first heat exchanger (14) and the condenser (16) and is sent into the drying chamber (3) again to dry the tobacco leaves; the amount of the exhausted damp and hot air is equal to that of the fresh air sent into the heating chamber (2), and the moisture exhaust is not stopped until the relative humidity of the air in the drying chamber (3) meets the requirement.
10. The control method of the heat accumulating type solar energy coupled air source heat pump tobacco leaf drying system according to claim 6, 7 or 8, characterized in that: in winter or cold regions, if the air temperature around the evaporator (18) is below 5 ℃, the defrost mode of operation is initiated: and the first electromagnetic valve (22) and the second electromagnetic valve (23) are opened, and the hot water in the hot water storage tank (26) heats the air around the evaporator through the second heat exchanger (15) under the action of the first circulating water pump (20), so that the frosting is avoided, and the energy efficiency ratio of the system is improved.
CN202010992656.1A 2020-09-21 2020-09-21 Heat accumulating type solar energy coupling air source heat pump tobacco leaf drying system and control method Pending CN112021630A (en)

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