Investigation of Direct and Indirect Evaporative Cooling Options for Greenhouse Air Conditioning in Multan (Pakistan)

Extreme sensible and latent load inside a greenhouse is a challenge faced in greenhouse farming which ultimately affects the crop yield and adds into food insecurity. In this regard, proper ventilation and air-conditioning is required to control the atmosphere inside the greenhouse. In this study, three experimental evaporative cooling (EC) (i.e. direct (DEC), indirect (IEC), and Maisotsenko cycle (MEC)) systems were thermodynamically analyzed for potential application of greenhouse air-conditioning for the climatic conditions of Multan. According to American Society of Agricultural Engineers (ASAE), temperature inside a greenhouse should be 30-32°C. From a year-long experiment, results of 15^th May showed that DEC, MEC, and IEC resulted in process air of 27°C, 20°C, and 31.4°C at 40°C ambient temperature, respectively. The DEC and MEC systems performed better as compared to the IEC system. The results indicate that the DEC and MEC systems perform optimally for greenhouse air-conditioning according to ASAE standards.