Dynamic Modeling and Simulation of a Solar Air Heater Assisted by a Dehumidification System for an Agriculture Greenhouse

Abstract

Appropriate greenhouse microclimate control is essential for optimizing plant growth and food production. But, maintenance of a greenhouse microclimate generally requires an excessive amount of energy. According to a report published by Scott Sanford [1], the energy cost for greenhouses is considered the third highest annual cost, behind labor and plant materials. At northern latitudes, heating is the primary energy requirement needed in an agriculture greenhouse, comprising 70 to 80% of a typical greenhouse energy consumption [1]. A reduction of heating energy is necessary to ensure the economic viability of a greenhouse. This research investigates the potential energy savings associated with integrating a solar air heater assisted with a desiccant wheel in an agriculture greenhouse. This study has two main thrusts. The first is to demonstrate the energy effectiveness a solar air heater with a dehumidification system to maintain the internal climate. The second thrust is to develop a multi-linear regression model that can be used to predict the hourly heating requirement. Thereafter, the developed regression model can be used to conduct a parametric analysis to investigate the impact of changing greenhouse parameters on the total heating requirements. A case study has been considered for a greenhouse that is 30 m long and 24 m wide. The climate condition of the city of Dayton, OH was selected for this case. The predicted performance of the integrated system is compared with two other heating systems: electric and gas furnaces. The study reveals that heating energy savings in the proposed system is 51% and 30% when compared with the electric and gas furnaces, respectively. Aside from heating energy savings, the proposed system can be efficiently used to control indoor humidity in a way that ensures better crop yield.