Research On Water-source Heat Pump Control System Of Greenhouse Based On CFD

With the development of technology, facilities agriculture has been an important symbol of agricultural modernization. Modern greenhouse is one of the realization forms of facilities agriculture. As an energy-intensive industry, greenhouse requires energy input in winter and summer (especially in winter) to maintain the temperature indoor at a relatively steady state. Our scarce existing resources can not meet the demand of production. To save energy, the research on how to choose the most appropriate heating system for greenhouse, and how to develop the control strategies is significant.In this dissertation, a Venlo-type greenhouse heating system is built, by using water-source heat pump as the heat source, circulating water pump as the driving force, fan coil unit and low-temperature hot water radiant floor system as the heating device. On this basis, the control strategy of the heating system is made. Practice proves that this system is stable and easy control. The main worksand results of this paper are shown as follows:1. According to variety of physical processes of the greenhouse, the greenhouse temperature model is established based on conservation of energy and matter. 2. As the most important part in the the warter-source heat pump system, fan coil unit need to be researched significantly. After using CFD to establish greenhouse model and validating the correctness of the model, the best order to open the fan coil units is obtained through simulation, which can increase the efficiency of energy furthest. 3. A fuzzy control system based on prediction model of greenhouse is designed. The input of the fuzzy controller is temperature deviation and the rate of change of temperature deviation, the output is the expected rate of change of temperature. 4. According to the quantity of heat figured out from temperature model of heat and the best order to open the fan coil units, the control strategies of water-source heat pump, fan coil units and circulating pump are developed. 5. A control system of water-source heat pump in Venlo-type greenhouse is designed and used in target greenhouse. 6. Finally, a summary of the text and some future prospects for further study are present.