Development of greenhouse cooling and heating technology by using seasonal thermal storage for alluvial aquifer

Abstract.

As research for technical development saving and using energy of greenhouse cooling and heating by using alluvial aquifer, this study investigated geological features of alluvial aquifer and the best target area of growing facility, and as a result, three greenhouses(2,100m²) of single-span of tomato farmhouse in Buyeo located in the ground of Guem River basin alluvial aquifer in Chungcheongnam-do, South Korea. System composition of greenhouse cooling and heating of alluvial aquifer is 30m-depth of Pumping well(200mm of pipe size), recharge well(200mm of pipe size), and 12 auxiliary pipe wells(50mm of pipe size) for recharging and gauging, and underwater pumps were installed in pumping well and recharge well to supply a system of greenhouse cooling and heating with underground water that is heat source water by exchanging roles of pumping well and recharge well in summer and winter. The composition of greenhouse cooling and heating system is heat pump 50RT, 40m² of thermal storage tank, pipe and circulation pump of a machine room, remote control, and monitoring system, so this system was practically installed on site. Flow rate was decided to be 300m³/day(15℃ of temperature difference of heat pump entering water and its leaving water) of cooling supply volume and 380m³/day(10℃ of temperature difference of heat pump entering water and its leaving water) of heating supply volume. From 20:30 p.m. to 24 a.m. in August 13, side window of greenhouse was closed and greenhouse was sealed, and greenhouse inside set temperature was 25℃, and heat pump cooling COP and temperature control effect in greenhouse were measured. In addition, the underground heat storage test putting underground water that was underground water passes heat pump so whose temperature increases into alluvial aquifer for greenhouse cooling from August 31 to September 22 was conducted. As a result of measuring cooling coefficient of performance of the seasonal thermal storage greenhouse cooling and heating system for alluvial aquifer, cooling COP was averagely 3.5, and on night cooling, when outdoor temperature was 29℃, 25℃ that is desired temperature in greenhouse was properly kept. In addition, as a result of underground storage test from August 31 to September 22, 850m³ of heat source water was put into ground-water zone. Injection water temperature was 30℃(15℃ of intake temperature), so 12.750,000kcal of calorie was injected. Temperature of ground-water zone where injection well is located was 25℃, and the measuring a temperature maintenance effect in ground-water zone of in-between seasons before the beginning of heating in winter is going to be conducted afterward.