A Compartive Study on Two Different Evaporative Cooling Systems for Producting Cucumber Crop Under Hot-Humid Summer Conditions

Abstract

The influence of greenhouse evaporative cooling systems (based on misting, and fan pads cooling systems) on the microclimatic conditions of greenhouse cucumber was studied and investigated in two fiberglass greenhouses combined with roof shading black net screen situated on the roof of the Agricultural Engineering Department, University of Mansoura. Measurements were executed during several days (122 days) in the hot summer of 2009; (G1) with a mist system operating 15 sec every 15 min., (G2) with a pad-fan system. In order to compare between the cooling systems, air temperatures and relative humidity inside and outside the greenhouses were measured and recorded. Experimental data revealed that the pad-fan cooling system was able to keep the air temperature within the greenhouse at rather low levels. The internal air temperature stayed 8.0°C below outside, even during hot afternoons (Tao > 35°C). Whereas, the evaporative cooling using mist system kept the greenhouse air temperature above the set point temperature by an average of 4.9°C. Therefore, the internal air temperature stayed 4.2°C below outside. Due to the short length of the greenhouse (8 m), small temperature gradients (2.9°C) were observed from wet pads to extracting fan. The cooling system using fan-pad system inside the greenhouse (G2) was on the average more efficient than the misting system inside the greenhouse (G1) by 22.5% due to the cooling operation period for the greenhouse (2) was longer than that for the greenhouse (1), accordingly, the water temperature of cooling system (2) was lower than that in misting system (G1). The total fresh yield of cucumber crop per square meter for greenhouse (G1) and greenhouse (G2) was 3.805 and 5.491 kg/m 2 , respectively. Therefore, the greenhouse (G2) produced 1.686 kg /m 2 (44.31%) more than the greenhouse (G1).

Effects of the Organic Fertilizers and Modified Evaporative Cooling System on the Productivity of Tomatoes Greenhouse in Hot and Humid Regions

“…Mehmet and Hasan (2015) reported that the hourly mean cooling efficiency for fan-pad system was found to be 76.8%. In addition, Abdellatif et al, (2010) found that the daily average effectiveness of the fan-pad evaporative cooling system was 76.6%.…”

“…Excess heat causes air temperature to become hotter than the desired level resulting in detrimental effects on crop growth and production (Montero, 2006). Reducing temperatures is one of the main problems facing greenhouse management during daylight in hot-humid summer conditions such as in Egypt (Abdellatif et al, 2010), they mentioned also, that air temperatures in Egyptian greenhouses either covered with polyethylene or fiberglass reinforced plastic can easily exceed 50 °C during the hot summer if they are not equipped with evaporative cooling system.…”

Impact of Shade and Fogging on High Tunnel Production and Mineral Content of Organically Grown Lettuce, Basil, and Arugula in Georgia

“…Evaporative cooling systems, consisting of sprinklers that deliver mist or fog throughout a structure, reduce air temperatures within greenhouses [18][19][20]. In arid environments, such as in Egypt, mist/fogging systems reduced air temperatures up to 6.2 • C during summer months [21]. The effectiveness of mist or fogging for evaporative cooling varies based on climate, with the greatest impact occurring in regions with high air temperatures and low humidity [21].…”

“…In arid environments, such as in Egypt, mist/fogging systems reduced air temperatures up to 6.2 • C during summer months [21]. The effectiveness of mist or fogging for evaporative cooling varies based on climate, with the greatest impact occurring in regions with high air temperatures and low humidity [21]. Although well documented for use in greenhouses, less information is available evaluating the effectiveness of shade cloth and fogging/misting systems in passively cooled structures such as high tunnels in hot humid climates, such as the Southeastern United States, is limited.…”