Evaporative cooling technologies for greenhouses: a comprehensive review

Abstract

Excessive heat generation by the high solar radiation is the major issue for agricultural greenhouses in hot climatic regions. This issue has been of great concern to summer greenhouses and has continuously been under study. Effective cooling of greenhouses has to be undertaken to minimize the issue. There are several techniques of greenhouse cooling and among them, evaporative cooling has completely revolutionized the system of cooling in greenhouses since the nineteenth century and still it is being used around the world. The current paper presents a review study covering the past and the latest kinds of evaporative cooling techniques, which have been utilizing for agricultural greenhouses in summer. The paper attempted to show the performance characteristics of the individual cooling systems, like fan-pad systems, fog-cooled systems, roof cooling systems, dissector pad-fan systems, two-stage cooling system and seawater greenhouse systems. A brief survey of literature revealed that evaporative cooling could be applicable to any environmental condition to reduce greenhouse excess thermal load depending upon the types of the system. Finally, some innovative cooling ideas have been given for further studies.