Application of Air Source Heat Pump Heating System in Greenhouse
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Update time : 2017-09-14 13:59:42
In recent years, the global problem of energy crisis and global warming has been the concern of all countries. In this context, heat pump technology has become one of the important technical means to solve global environmental problems. It has been developed and widely used. Heat pump technology in 1854 proposed in the mineral energy shortage in Europe and Japan, heat pump technology research and development has been in a leading position. Since the 1990s, the use of heat pumps is generally on the rise, especially in the 21st century, it is significant growth, which is the development of heat pump technology and national energy and environmental pressures are inseparable, while the heat pump market Development is also closely related to the level of national economic development.
In the greenhouse production in winter, heating fuel consumption, greenhouse gas emissions and dust pollution, since 2000 at home and abroad in the greenhouse heat pump heating has been a wide range of efforts, energy efficiency rate of 20% to 50%. sunmax summed up the use of heat pump technology to increase greenhouse production of the overall economic and social benefits, on basic principles of heat pump technology, based on the principle of heat pump energy-saving.
Heat pump heating principle
Heat pump is the consumption of mechanical work, the heat from the low temperature heat source to the high temperature heat source device, generally divided into water source heat pump and air source heat pump, the former by the water source to absorb heat to the high temperature transmission, which absorbs the ambient air heat to the high temperature transmission. Water source heat pump can be arranged horizontally on the ground, but also to the ground layout, known as ground source heat pump. Generally, the source heat pump saves the mechanical work from the ground heat. Due to the small air heat capacity, under the ground heat benefit is not significant, there is little under ground air source heat pump situation. Ground source heat pump to rely on the outside world to provide mechanical power from the low temperature environment sent to high temperature environment, transport the same heat, the greater the temperature difference, the greater the consumption of mechanical work, known as the pump, because it will heat from the low temperature To the high temperature, the working principle with the pump consumption of mechanical power from the low to mention similar high. Winter heating heating, the under ground temperature is higher than the ground temperature, so from the outdoor under the ground heat transfer to the indoor consumption of mechanical work is lower than the outdoor ground to the room through the same heat consumption of mechanical work, which is the ground source heat pump The reason for energy saving.
The heat pump mainly consists of a compressor, a heat exchanger, an expansion valve and an air heat exchanger. The compressor compresses the gaseous refrigerant medium into a liquid state while the compressed refrigerant medium is heated to reach the condenser (high temperature heat exchanger) To the heating end of the heat, and then through the expansion of the valve after the expansion of the valve from the liquid into a gas expansion, and quickly into the evaporator, where the absorption of heat, heat from the outdoor air, heat absorption of low-temperature heat medium gas refrigerant into the compressor Perform cyclic compression. Heat pump heating and heating performance is generally used heating coefficient COP (Coefficient of Performance) that the calculation process can be calculated by thermal engineering thermo-thermal entropy diagram to approximate, due to consumption of coal, oil, natural gas and direct electricity when heating Thermal efficiency is less than 1, so the heat pump system than other heating equipment, energy saving effect. Through the heat pump heating coefficient COP calculation can be seen to improve the output heat of the heat will reduce the heating coefficient of the heat pump COP, will consume more mechanical work; the use of ground heat pump or the use of industrial waste heat as a low temperature heat source to low heat absorption Increased temperature increases heating coefficient.
The air source heat pump uses the low temperature heat of the surface environment, the installation is convenient, the operation and management is simple, the initial investment is low, the application is more extensive, but the winter operation is easy to frost causes the unit efficiency is reduced, so it is suitable for use in the south of the Yangtze River in China. Ground source heat pump from the under the ground depth of the soil heat, the depth of the soil throughout the year the temperature is relatively constant, affected by the seasonal changes in the temperature of the small, good heat effect, but the construction of large, high initial investment system for the northern region of China greenhouse Winter heating and heating use.
Air source heat pump winter greenhouse heating system mainly by the greenhouse air source heat pump module unit and the greenhouse heat transfer pipeline 2 parts. Greenhouse internal air source heat pump module unit is mainly for the heat pump module unit, water tank heat pump; greenhouse heat transfer pipeline is divided into hot water transport water and hot air evacuation airway two parts, water and air through the liquid - gas heat exchanger Together. Air source heat pump winter greenhouse heating system works is: air source heat pump module unit from the greenhouse outside the environment to absorb heat, through the power consumption of mechanical power to heat the use of hot water in the form of hot water pipe to the greenhouse heat transfer, greenhouse The hot water pipe feeds heat into each of the liquid-gas heat exchangers where the hot water exchanges heat into the interior of the greenhouse, exchanging the heat of the cooler water back through the return pipe to the air source heat pump module unit Circulating heat of heat, when the water leakage occurs, through the water tank for the hot water supply water; for the greenhouse hot air evacuation air, first through the heat transfer fan to drive air through the liquid - gas heat exchanger, so that heat After the heat is obtained, the hot air is blown into the hot air blower from the middle of the liquid-gas heat exchanger. The hot air is introduced into the greenhouse at both ends, and then the hot air is driven by the circulating fan arranged at both ends of the greenhouse. Evacuated to various parts of the greenhouse, in order to achieve uniform greenhouse warming purposes.
Greenhouse summer cooling can be mainly through the inside and outside the shade net for shading, high temperature season and then add SUNMAX wet curtain - fan cooling system cooling, extreme high temperature weather with spray cooling, under this condition can basically guarantee the greenhouse temperature is not higher than 30 ℃, so you can not use the air source heat pump module unit for summer cooling operation.
The hot air blower is arranged on the liquid-gas heat exchanger, and the other end of the hairdryer is extended to the greenhouse, and the heat transfer fan is connected with the heat exchanger. , The heat in the greenhouse is driven by the heat exchanger and the heat is transferred to the edge of the greenhouse. Heat pump, hot air blower and circulation fan control area of 8m × 24m greenhouse area, in addition, the hot air can also be extended to the greenhouse wall, open end closed, and in accordance with certain laws along the send Hair dryer length on both sides of the direction of the wind hole, to achieve uniform transport along the heat, so you can avoid the use of circulating fan.
In order to reduce the heating load inside the greenhouse, reduce the heat loss, add two layers of plastic film inside the greenhouse in winter, increase the thermal resistance and reduce the heating space. Figure 8f is the two-layer film added in the greenhouse, Increase the top two layers of plastic film insulation, in the 8m × 24m area to form a more confined space. Winter rely on the air source heat pump heating system for heating the greenhouse heating, the greenhouse can be cultivated within the regional temperature maintained at 20 ℃ or more, to ensure that the flower seed production on the ambient temperature needs.
Heat pump heating system energy saving effect is remarkable. In the past, the use of coal for heating greenhouse heating, the use of 1,500 yuan / t or so advanced anthracite, resulting in winter heating greenhouse heating fuel costs are very high. After the use of air source heat pump system, a winter heating heating operation fee reduced to 50% of the original.
(2) heating control precision, simple operation. Air source heat pump heating system heating control using microcomputer control, heating and heating can be set according to the environmental requirements of the installation of heating temperature, ambient temperature automatic adjustment, compared with the traditional coal-fired hot blast furnace heating and heating methods, heat pump heating system can be automatically controlled Start and stop, the operation process is simple, rapid heating adjustment, greatly improving the greenhouse environment temperature control accuracy.
(3) air source heat pump heating system is compact, compared with the traditional coal-fired boiler room and coal field, the area is greatly reduced, almost no energy materials and personnel management.
(4) air source heat pump heating system equipment and air conditioning technology, high technology maturity, compared with the traditional coal-fired heating equipment failure rate is greatly reduced.
(5) As the heat pump power from the power, no waste emissions to the environment, completely put an end to the dust and other pollution to the environment emissions, improve the previous winter coal dust emissions affect the living environment of nearby residents, social benefits significantly. Greenhouse air source heat pump heating in winter there are many advantages, but its one-time investment is still relatively large, the size of the air source heat pump heating system, a 5000m2 unit of the overall investment of more than 500,000 yuan, through the operation Of the economic benefits of estimated, about 3 to 4 years can be recycled costs, payback period with the geographical environment, greenhouse insulation and other factors are directly related. Therefore, heat pump heating system in recent years, the actual application of the greenhouse situation, the current heat pump heating system only in the flower and other industries with high economic efficiency widely used.