Partial cooling of strawberry plants by water tube utilizing geo-thermal heat pump
Faculty of Agriculture and Life Science, Hirosaki University, 3 Bunkyo, Hirosaki, Aomori, 036-8561, Japan. Professor Emeritus, Hirosaki University, Hirosaki, Aomori, Japan. Agriculture Research Institute, Aomori Prefectural Industrial Technology Research Center, 82-9 Tanaka, Kuroishi, Aomori, 036-0522, Japan.
DOI: https://doi.org/10.37855/jah.2017.v19i03.34
Key words: strawberry, cooling, geo-thermal energy, heat pump, temperature, greenhouse
Abstract: A commercial heat pump was utilized to cool strawberry plants using a heat exchanger well at 10 m of soil depth. Two lines of strawberry were planted to grow fully on a high bench of 20 m length. The cooling treatment was conducted through a water tube connected to the chiller tank of the heat pump. A single water tube was buried under the soil surface. Two kinds of set-up for the water tube on the soil surface were designed to cool the strawberry crown. Compared with that of the control, the temperature of crown and soil was effectively lowered by the two treatments. Regardless of the setup of the water tube, the temperature of soil and crown did not differ between the two treatments. Considering the high water temperature of the heat exchanger tank of the heat pump system, the length of the heat exchange well was insufficient for the extraction of sufficient geothermal energy in this experiment. However, the converted heat pump and facile establishment of wells achieved cooling of the 4 benches effectively and at a reasonable cost.
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