Evaluation of Pond Water Performance for Greenhouse Irrigation Cooling: A Case Study in Southwestern Ontario, Canada

Abstract

Irrigation water temperature plays an essential role in yield and quality of greenhouse products. In the summer, the irrigation water can be warming than desirable, leading to certain problems such as root diseases. In this paper, the performance of using stormwater pond to cool irrigation water for a commercial greenhouse was studied using the Transient System Simulation (TRNSYS) software. The irrigation water system was simulated according to the reference greenhouse data in Leamington, Ontario, Canada. The model was validated with actual average temperature of the treated water tank and heat exchanger operation time data. The effect of changes in freshwater temperature, pond water temperature, the cold and hot side flow rate of the heat exchanger, and heat transfer coefficient of the heat exchanger were investigated. Incorporating pond water and heat exchanger reduce the treated water temperature by 1.5° in June and 0.5 °C in July. Sensitivity analysis showed that the pond water temperature had the greatest impact among other parameters in the studied ranges. Thus, a three-degree drop in pond water will reduce heat exchanger operating hours by 70% in July and 14% in June.