Research On Energy Supply System And Heating Load Forecasting Of Air Source Heat Pump In Solar Greenhouse

The demand for crops such as fruits and vegetables,which have been planted in the greenhouse against the seasons,is increasing.Considering the climatic characteristics of our country,greenhouses in most parts of China should be heated or cooled in different seasons.In order to ensure high quality and efficient production of crops,reduce energy consumption,research and development of energy conservation and environmental protection system is very important.In this research,a new type of air source heat pump energy supply system for solar greenhouse in cold area was built,and experimental research was carried out to verify the operation effect of energy supply system in solar greenhouse.Low-temperature air source heat pump unit is used in the system heat source.The terminal units combine the radiant floor heating and the fabric duct air supplying systems,which takes heat from air directly and distribute the heat to the indoor air and soil to improve the energy utilization efficiency,and enhance the solar greenhouse's ability to withstand the low temperature in winter.Moreover,the same system is used in summer to cool down,providing crops with suitable growth conditions.In order to guide the equipment selection and system control,a method of greenhouse heating load forecasting is proposed.During the winter operation of the system,the average temperature in the solar greenhouse can be raised to 18?or above,and the heating effect is remarkable,the temperature distribution of the east-west of the solar greenhouse is more uniform,and the temperature of the north-south direction is rising from north to south.At night,the floor heating system directly heats the soil,raising the average soil temperature from 20.3?to 22.2?,which satisfies the requirements of most crops for the optimum growth temperature of the root zone.The system has significant cooling effect,which can maintain in the indoor temperature from 28.4?to 31.2?,while outdoor temperature is close to 37?.So,the same system can be used in winter and summer for air condition.Based on the depth belief network(DBN),the model of accurate prediction of greenhouse heating load is established,the determination coefficient is 0.9402,the mean square root error is 0.0620,and the thermal load is well approximated to the actual heat load and has high stability.By comparing with different greenhouse heating system in recent years,it is found that the heating quantity of the system is 1073.162 kJ/(m~2·d)the relative heating cost is0.072 yuan/(m~2·d)and the energy-saving effect and economy are remarkable.In addition,the different heat sources and same terminal unit of the system has been comprehensively evaluated,the system has a large advantage in energy-saving and environmental protection,comprehensive evaluation is also the best solution.This research provides a new solution for winter heating and summer auxiliary cooling in solar greenhouse,which extends the application field of air source heat pump and has wide application prospects in greenhouse crop production.