Design feasibility study of an innovative solar chiller/heater for thermal management of greenhouse water supplies

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Water is a critically essential resource in the greenhouse industry. Greenhouse profitability is directly influenced by the cost of water. The primary supply of water for many greenhouses is the municipality. The expansion and/or replacement of municipal water infrastructure is currently compounding already costly water rates. Subsequently, it is advantageous for greenhouse operators to utilize as much reclaimed water as possible. Greenhouse owners are also concerned about the environmental implications of their water usage. Thus, where possible, water that has already cycled through the irrigation system is collected and added to storm water collected from the greenhouse roofs and property. The collected water is often stored in a central repository like a pond. Modern greenhouses are automated and tightly regulated environments that are very sensitive to changes in growing conditions. This includes the temperature of the water required to sustain the plants. Water drawn in winter months must be heated prior to distribution. In warm months, pond water temperatures cross a maximum threshold that prohibits the water from being used to irrigate the greenhouses. Presently, the only available alternative for operators in these months is to switch to the more temperate municipal water supply. The increased cost of this option cuts significantly into farm profits. The current proposal describes a study that will investigate the technical and financial feasibility of an innovative integrated solar-driven irrigation thermal management system. The proposed solution incorporates established absorption cycle principals with leading edge heat transfer and photovoltaic advancement technology under development at the University of Windsor. The in-situ solar absorptive chiller/heater system will allow the farm to significantly reduce their reliance on costly municipal water supplies. Secondly, in addition to providing power for self-sustenance, these processes may yield excess power to be utilized in greenhouse operations, further reducing dependency on local utilities. The overarching objective of this work is to minimize greenhouse dependency on municipal fresh water supplies.