Result of Thermal Energy Supply to Greenhouses by Water Source Heat Pump System Using Heat from Running Water in Irrigation Canals

― Performance of a flowing water heat pump system evaluated from the primary side (heat source side) ―

Abstract

In this study, a sheet-type heat exchanger was installed in an irrigation canal in Nasushiobara City, Tochigi Prefecture, and a demonstration test was conducted to supply thermal energy using a heat pump to a greenhouse for growing strawberries adjacent to the canal, in order to establish an operational technology for a flow-through heat pump system for an irrigation canal. The heating and cooling tests using the heat pumps with agricultural water as the heat source showed that the thermal energy can be supplied stably even in an irrigation canal. When the heat pump system was heated using running water with a water temperature of 1.7°C as the heat source, it was confirmed that the heat pump system could stably supply thermal energy at an overall heat pump system coefficient of performance (SCOP) of 2.4 to 2.5 without shutting down. The results also showed that the heat pump system could supply heat efficiently with a SCOP of 5.4 to 6.0 if the irrigation canal water could be used as a heat sink.