A heat pump coupled soil-air heat exchange system and operation method

Abstract

The present invention relates to a soil-air heat exchange system for hot air and heat pump coupling in a greenhouse and its operation method, including a heat exchange mechanism, a heat pump unit and a control system; the heat exchange mechanism includes an air inlet pipe, an air outlet pipe and a plurality of heat exchange pipes laid underground in the greenhouse, and a fan is installed at the upper end of the air inlet pipe; the heat pump unit includes a heat pump, a pumping well and a recharging well, the water inlet of the heat pump is connected to the pumping well through the heat pump inlet pipe, the water outlet of the heat pump is connected to the recharging well through the outlet pipe, and the air outlet of the heat pump is connected to the heat exchange pipe through the heat pump outlet pipe; the control system includes a control host, an air temperature and soil temperature sensor installed in the greenhouse, a first solenoid valve and a second solenoid valve. The present invention can be used for both warming up the greenhouse in winter and cooling down the greenhouse in summer, and can automatically adjust the temperature environment in the greenhouse, and is an energy-saving, environmentally friendly and multifunctional agricultural temperature control system.

Description

Technical Field

[0001] The present invention relates to the field of facility environment control, and in particular to a soil-air heat exchange system for hot air and heat pump coupling in a greenhouse and an operation method thereof. Background Art

[0002] Solar greenhouses and plastic greenhouses are the main types of facilities for the protection and production of horticultural crops in my country at present. In winter, solar greenhouses and plastic greenhouses have limited heat preservation and heat storage capacity, and low temperature and high humidity often occur at night, affecting crop yield and quality; high temperatures inside greenhouses in summer are also not conducive to crop growth, causing most greenhouses to be idle, resulting in a waste of resources and reduced farmers' income.

[0003] In order to meet the growth of solar greenhouses and greenhouse crops and improve the annual utilization efficiency of greenhouses, heating or cooling equipment is needed for environmental control. Common greenhouse heating methods include fossil energy combustion heating, electric heating and solar energy heating. Fossil energy combustion heating has high costs and is prone to environmental pollution; electric heating has low conversion efficiency and higher costs; although solar energy is low-cost and environmentally friendly, it is greatly affected by the weather and cannot meet the needs of all-weather heating. The main forced cooling methods for greenhouses in summer are mechanical ventilation, shading and evaporative cooling. Mechanical ventilation consumes a lot of energy; shading and cooling have limited effects; evaporative cooling can easily lead to excessive air humidity and induce crop diseases. Therefore, it is of great significance to study low-cost, high-efficiency and environmentally friendly temperature control systems. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a soil-air heat exchange system for hot air and a heat pump coupled to a greenhouse and an operating method thereof.

[0005] The present invention is realized by the following technical scheme: A soil-air heat exchange system coupled with hot air and a heat pump comprises three parts: a heat exchange mechanism, a heat pump unit and a control system.

[0006] The heat exchange mechanism includes an air inlet pipe, an air outlet pipe and a plurality of heat exchange pipes laid underground in the greenhouse, and a fan is installed at the upper end of the air inlet pipe; the heat pump unit includes a heat pump, a pumping well and a recharge well, the water inlet of the heat pump is connected to the pumping well through the heat pump water inlet pipe, the water outlet of the heat pump is connected to the recharge well through the water outlet pipe, and the air outlet of the heat pump is connected to the heat exchange pipe through the heat pump outlet pipe; the control system includes a control host, an air temperature sensor and a soil temperature sensor installed in the greenhouse, a first solenoid valve installed on the air inlet pipe of the heat exchange mechanism, and a second solenoid valve on the air outlet pipe of the heat pump.

[0007] As an optimization, the air inlet pipe is arranged in the middle or north of the greenhouse span direction, and the heat exchange pipes extend to both ends of the greenhouse span direction and are connected with the air outlet pipes buried at both ends to make the soil and air temperature distribution more uniform.

[0008] As an optimization, the heat exchange pipes are buried in parallel, and air outlets are arranged at intervals on the pipes to facilitate heat exchange with the soil above the pipes, so that the heat distribution of the soil is uniform. A heat insulation layer is laid under the heat exchange pipes to reduce the conduction of heat to the soil below the pipes.

[0009] A method for operating a soil-air heat exchange system coupled with hot air and a heat pump comprises the following steps:

[0010] In the low temperature season, on sunny days during the day, the hot air heat exchange mechanism is operated first to allow the soil to accumulate heat. When the temperature rises to the preset temperature T1, the control system opens the first solenoid valve, closes the second solenoid valve, and runs the fan of the air inlet pipe to exchange heat with the soil through the underground heat exchange pipe. When the temperature drops to the preset temperature T2, the fan of the air inlet pipe stops running; on rainy and snowy days, when the temperature in the greenhouse drops to the preset temperature T3, the heat pump unit is operated, the control system opens the second solenoid valve, closes the first solenoid valve, and the heat pump extracts heat energy from the groundwater to heat the air. The hot air enters the greenhouse after heat exchange with the soil through the underground heat exchange pipe, raising the ground temperature and air temperature. When the air temperature rises to the preset temperature T4, the heat pump stops running;

[0011] At night, when the indoor temperature of the greenhouse is lower than the preset temperature T5 and the ground temperature is greater than the preset temperature T6, the heat exchange mechanism will be operated first to bring out the heat accumulated in the soil to increase the indoor temperature of the greenhouse; when the heat exchange mechanism alone cannot maintain the suitable temperature of the greenhouse T7, the fan of the air inlet duct will stop running and the heat pump unit will be operated. When the indoor temperature of the greenhouse is higher than the preset temperature T8, the heat pump will stop running.

[0012] In the hot season, when the daytime temperature rises to the preset temperature T9, the heat pump unit is operated to reduce the indoor temperature and ground temperature of the greenhouse. When the temperature drops to the preset temperature T10, the heat pump stops. At night, when the indoor temperature of the greenhouse is higher than the preset temperature T11, the heat pump unit is operated. When the indoor temperature of the greenhouse is lower than the preset temperature T12, the heat pump stops.

[0013] The beneficial effects of the present invention are as follows: the hot air and heat pump coupled soil-air heat exchange system is a soil hot air exchange system combined with a shallow water source heat pump device. The system not only reduces the load of a single shallow water source heat pump, but also compensates for the weather influence of the heat collection method of a single soil-air heat exchange system. It not only solves the problem of warming up the greenhouse in winter, but also solves the problem of cooling down the greenhouse in summer, thereby being able to effectively regulate the indoor temperature environment of the greenhouse, and has the advantages of energy saving, low cost, ecological protection, and diverse functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the structure of the present invention;

[0015] Figure 2 is a cross-sectional view of the present invention;

[0016] As shown in the figure:

[0017] 1. Air inlet pipe; 2. Air outlet pipe; 3. Heat exchange pipe; 4. Fan; 5. Heat pump; 6. Pumping well; 7. Recharge well; 8. Water inlet pipe; 9. Water outlet pipe; 10. Heat pump air outlet pipe; 11. Control host; 12. Air temperature sensor; 13. Soil temperature sensor; 14. First solenoid valve; 15. Second solenoid valve. DETAILED DESCRIPTION

[0018] In order to clearly illustrate the technical features of this solution, the solution is described below through specific implementation methods. Figure 1~2 As shown, a heat pump coupled soil-air heat exchange system of the present invention includes a heat exchange mechanism, a heat pump unit and a control system.

[0019] The heat exchange mechanism includes an air inlet pipe 1, an air outlet pipe 2, and a plurality of heat exchange pipes 3 laid underground in the greenhouse, wherein the air inlet pipe 1 is arranged in the middle or north of the greenhouse span direction, the lower end of the air inlet pipe 1 is connected to the underground heat exchange pipe 3, and a fan 4 is installed at the upper end of the air inlet pipe 1. The heat exchange pipe 3 includes a heat dissipation main pipe in the length direction of the greenhouse and a heat dissipation branch pipe in the span direction of the greenhouse. The air inlet pipe 1 is connected to the heat dissipation main pipe, and the heat dissipation branch pipes extend to both ends of the greenhouse span direction and are connected to the air outlet pipes 2 buried at both ends.

[0020] The air inlet pipe 1 is a 200mm PVC plastic pipe; the fan 4 is directly connected to the air inlet pipe 1 through a diameter change. The heat dissipation main pipe is a 160mm PVC plastic pipe, and the heat dissipation branch pipe and the air outlet pipe 7 are both 110mm PVC plastic pipes. The heat dissipation branch pipes are arranged side by side with a spacing of 0.8~1.2m, the buried depth of the heat exchange pipe 3 is 0.5~0.7m, and a heat insulation layer is laid under the heat exchange pipe 3.

[0021] When laying the heat exchange pipe 3, trenches are excavated according to the pipe spacing. In this embodiment, the heat exchange pipe 3 spacing is 1m, the trench width is 50cm, and the depth is 80cm. The original soil foundation is compacted and 3cm of pearl cotton is buried. Pearl cotton is used as a heat insulation layer, and the heat exchange pipe 3 is laid with 20cm of soil on the pearl cotton. Six rows of 30mm diameter holes are evenly distributed along the circumference, and the spacing in the pipe extension direction is 150mm. In order to prevent the soil from clogging the pipe holes, a layer of 2mm thick non-woven fabric is wrapped outside the heat dissipation branch pipe.

[0022] The heat pump unit includes a heat pump 5, a pumping well 6 and a recharging well 7. The water inlet of the heat pump 5 is connected to the pumping well 6 through a heat pump inlet pipe 8, and the water outlet of the heat pump 5 is connected to the recharging well 7 through a water outlet pipe 9. The heat pump 5 is a shallow water source heat pump, and shallow water is pumped out through the pumping well 6 into the heat pump 5 for heat exchange and then returned to the ground from the recharging well 7.

[0023] The air outlet of the heat pump 5 is connected to the heat exchange pipe 3 through the heat pump air outlet pipe 10. In this embodiment, the heat pump air outlet pipe 10 is connected to the lower end of the air inlet pipe 1 at 60 cm from the ground, so as to achieve communication with the heat exchange pipe 3. The heat pump air outlet pipe 10 is a 200 mm PVC plastic pipe, and the heat pump water inlet pipe 8 and water outlet pipe 9 are both 32 mm PPR hot melt pipes.

[0024] The control system includes a control host 11, an air temperature sensor 12 installed in the greenhouse, a soil temperature sensor 13, a first solenoid valve 14 installed on the air inlet pipe of the heat exchange mechanism, and a second solenoid valve 15 on the air outlet pipe of the heat pump. The control host 11 receives signals from the air temperature sensor 12 and the soil temperature sensor 13 and controls the first solenoid valve 14 and the second solenoid valve 15 to open and close.

[0025] The operating method of the embodiment of the present invention is as follows: in the low temperature season, the hot air heat exchange mechanism is preferentially operated on sunny days to allow the soil to accumulate heat. When the temperature rises to a preset temperature T1, the control system opens the first solenoid valve 14, closes the second solenoid valve 15, and operates the air inlet fan 4 to exchange heat between the hot air at the top of the greenhouse and the soil through the heat exchange pipe 3. When the temperature drops to a preset temperature T2, the air inlet fan 4 stops running; on rainy and snowy days, when the temperature in the greenhouse drops to a preset temperature T3, the heat pump system is operated, the control system opens the second solenoid valve 15, closes the first solenoid valve 14, and the heat pump 5 is raised The heat energy in the groundwater is used to heat the air. The hot air enters the greenhouse after heat exchange with the soil through the underground heat exchange pipe 3, raising the ground temperature and air temperature. When the air temperature rises to the preset temperature T4, the heat pump 5 stops running; at night, when the air temperature in the greenhouse is lower than the preset temperature T5 and the ground temperature is higher than the preset temperature T6, the hot air heat exchange mechanism is operated first to bring out the heat accumulated in the soil and increase the air temperature in the greenhouse; when the heat exchange mechanism alone cannot maintain the appropriate air temperature T7 in the greenhouse, the fan 4 at the air inlet pipe stops running and the heat pump system is operated. When the air temperature in the greenhouse is higher than the preset air temperature T8, the heat pump 5 stops running.

[0026] In the hot season, when the daytime temperature rises to the preset temperature T9, the heat pump system is operated to reduce the temperature in the greenhouse and the ground temperature. When the temperature drops to the preset temperature T10, the heat pump 5 stops operating. At night, when the temperature in the greenhouse is higher than the preset temperature T11, the heat pump system is operated. When the temperature in the greenhouse is lower than the preset temperature T12, the heat pump 5 stops operating.

[0027] Of course, the above description is not limited to the above examples. Technical features not described in the present invention can be achieved by or by using existing technologies, which will not be described here. The above embodiments and drawings are only used to illustrate the technical scheme of the present invention and are not limitations of the present invention. The present invention is described in detail with reference to the preferred implementation methods. Ordinary technicians in this field should understand that changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention do not depart from the purpose of the present invention, and should also fall within the scope of protection of the claims of the present invention.

Claims

1. A hot air and heat pump coupled soil-air heat exchange system, characterized in that: The invention comprises a heat exchange mechanism, a heat pump unit and a control system; the heat exchange mechanism comprises an air inlet pipe (1), an air outlet pipe (2) and a plurality of heat exchange pipes (3) laid underground in a greenhouse, and a fan (4) is installed at the upper end of the air inlet pipe; the heat pump unit comprises a heat pump (5), a water pumping well (6) and a recharging well (7); the water inlet of the heat pump is connected to the water pumping well (6) through a heat pump water inlet pipe (8), the water outlet of the heat pump is connected to the recharging well (7) through a water outlet pipe (9), and the air outlet of the heat pump is connected to the heat exchange pipe (3) through a heat pump air outlet pipe (10); the control system comprises a control host (11), an air temperature sensor (12) and a soil temperature sensor (13) installed in the greenhouse, a first solenoid valve (14) installed on the air inlet pipe (1) of the heat exchange mechanism, and a second solenoid valve (15) installed on the air outlet pipe (10) of the heat pump; Operation method of the hot air and heat pump coupled soil-air heat exchange system: In the low-temperature season, on sunny days during the day, the hot air heat exchange mechanism is preferentially operated to allow the soil to accumulate heat. When the temperature rises to a preset temperature T1, the control system opens the first solenoid valve (14), closes the second solenoid valve (15), and operates the fan (4) of the air inlet pipe to exchange heat with the soil through the underground heat exchange pipe (3). When the temperature drops to a preset temperature T2, the fan (4) of the air inlet pipe stops operating. On rainy and snowy days, when the temperature in the greenhouse drops to a preset temperature T3, the heat pump unit is operated. The control system opens the second solenoid valve (15), closes the first solenoid valve (14), and the heat pump (5) extracts heat energy from the groundwater to heat the air. The hot air passes through the underground heat exchange pipe (3) and exchanges heat with the soil before entering the greenhouse, thereby raising the ground temperature and air temperature. When the air temperature rises to a preset temperature T4, the heat pump (5) stops operating. At night, when the temperature in the greenhouse is lower than a preset temperature T5 and the ground temperature is higher than a preset temperature T6, the heat exchange mechanism is operated first to remove the heat accumulated in the soil and increase the temperature in the greenhouse. When the heat exchange mechanism alone cannot maintain the appropriate temperature in the greenhouse T7, the fan (4) of the air inlet duct stops running and the heat pump unit is operated. When the temperature in the greenhouse is higher than the preset temperature T8, the heat pump (5) stops running. In the hot season, when the daytime temperature rises to a preset temperature T9, the heat pump unit is operated to lower the indoor temperature and ground temperature of the greenhouse. When the temperature drops to a preset temperature T10, the heat pump (5) stops operating. At night, when the indoor temperature of the greenhouse is higher than a preset temperature T11, the heat pump unit is operated. When the indoor temperature of the greenhouse is lower than a preset temperature T12, the heat pump (5) stops operating.

2. A hot air and heat pump coupled soil-air heat exchange system according to claim 1, characterized in that: The air inlet pipe (1) is arranged in the middle or north of the greenhouse in the span direction, and the heat exchange pipe (3) extends to both ends of the greenhouse in the span direction and is connected to the air outlet pipes (2) buried at both ends.

3. A hot air and heat pump coupled soil-air heat exchange system according to claim 1, characterized in that: The heat exchange pipes (3) are buried in parallel, and air outlet holes are arranged at intervals on the pipes.

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