A Study on Greenhouse Heating System with Air Source Heat Pump

Abstract

Energy conservation is an essential issue in greenhouse farming. Since greenhouseoperations use significant amounts of fossil fuel oil, energy conservation is expected toprotect farmer's profit and reduce global warming. To have good environmental conditions,several variables must be regulated. Inside a greenhouse, temperature, humidity, and lightare the most significant parameters to be regulated, especially in winter and at lowtemperatures at night. This study was conducted greenhouse heating for using heat pumpsystem that surplus air source and outdoor air source. The greenhouse experiment systemperformed on December 08, 2020, and December 13, 2020, selected days in similarenvironments of condition and experiment to measure the required parameters to be used in agreenhouse with a length, width, and height was 10.0m, 5.4m, 4.6m and located in JejuNational University, Korea. This system consists of a heat pump system including heatstorage tanks, fan-coil-units in the greenhouse, and an electric heater for supplementalheating. The experiment condition was to run a heat pump system using a surplus air sourceand outdoor air source each day. The experiment of greenhouse inside the set temperaturewas between 12℃ to 15℃. The greenhouse heating system has two modes. The first modewas heating mode, the greenhouse inside temperature lower than 12℃ and heat it until 15℃.The second mode was storage mode that stored heat from heat pump to storage tanks whenthe greenhouse temperature was higher than 15℃. In the results storage mode: surplus heatsource system was performed the average power consumption and COP were, 3.8 kW and3.7 and outdoor heat source system was the average power consumption and COP were 3.7kW and 2.9. Heating mode: The surplus heat source system evaluated with average powerconsumption and COP was 3.8 kW and 3.7 and outdoor heat source system. The averagepower consumption and COP were 3.7 kW and 2.9, respectively. In conclusion, experimentalresults show that surplus heat source of heat pump system was a high estimated averagecapacity 12.8 kW, while the outdoor heat source of heat pump system was 10.6 kW.Greenhouse heating system of surplus heat source energy saved 7.6 % than an outdoor heatsource system. Furthermore, it saved power consumption by 16.6 % than the outdoor heatsource system when heating mode performed. In COP of surplus heat source system installedan average of 3.6 and outdoor heat source system average of 2.7. The surplus heat source ofheat pump was 0.9 higher than the outdoor heat source heat pump.