Assessing the variable performance of fan-and-pad cooling in a subtropical desert greenhouse

Abstract

The cooling performance of a fan and pad system applied in a subtropical desert greenhouse (in Ahvaz-Iran) was evaluated during the critical climatic period from May to October using validated Computational Fluid Dynamics (CFD) method. The boundary and initial conditions of the models were set based on regional meteorological reports. Pad was separately simulated inside a wind tunnel and the porous media properties were extracted and applied in the greenhouse model. Transient fan and pad saturation efficiency, indoor temperature and its homogeneity in comparing to natural ventilation were considered for this evaluation. The regional meteorological reports, as well as physical experiments, approved the accuracy of the CFD models. 15–25 °C temperature reduction with a higher temperature heterogeneity was observed at the crop region in comparing with naturally ventilated from May to October. A transient fan and pad saturation efficiency from 57% to 77% was observed during the warmest day of the year (16 July 2019). Comparing indoor microclimate at the solar noon during the critical period of the year, showed a variable fan and pad saturation efficiency from 58% to 75% due to the variable solar heat load and dynamic seasonal climatic conditions.