Design, Construction and Evaluation of an Evaporative Cooler for the Storage of Mango in the Bawku West District of the Upper East Region of Ghana.

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2015-02-20
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The design, construction and evaluation of a conventional evaporative cooler were carried out in the Bawku West District of the Upper East Region of Ghana for the storage of mango. The hexagonal shaped, sloped roofed non-circulating conventional evaporative cooler is of area 3.9m2 and height of 2.5m with a capacity of about 1.6MT. It was made from neem poles and sawn wood, a spear grass roof and a cemented floor. The cooler had a door of about 1.5m × 0.7m dimension, a 25 litres vegetable oil container as a water reservoir and a U-shaped header on top of walls of about 1.5m long and 20cm base diameter to supply water evenly throughout the walls. It has a total constructional cost of about three hundred and sixty-four Ghana Cedis, fifty Ghana pesewas (GH¢ 364.50). The daily ambient and internal temperatures were recorded using wet and dry bulb thermometer, and relative humidity of ambient air, inside the cooler and storage room was measured with a hygrometer. The results indicated that the evaporative cooler’s water requirement was about 8.79 litres of water per hour, with about 82% of the water applied evaporated. The wet bulb depression of the working air was 8.3 and the temperature drop inside the cooler was 7.6 ̊C resulting in a cooling efficiency of 91%. There was about 4.8 ̊C drop in product air temperature and 9.6% humidity increase when compared with the storage room. For Jaffna mango fruits stored in both storageroomand evaporative cooler, out of 300 fruits stored in the storage room 206 well ripened fruits were obtained at the end of a storage period of 11 days, as against 260 out of 300 stored in evaporative cooler at the end of 17 days. Eighty-eight (88) fruits showed signs of rot as against 40 fruits stored in the evaporative cooler, and 19 fruits showed signs of water loss as against zero in the evaporative cooler respectively during the storage period. Out of 300 Keitt mango fruits stored in the storage room, 173 well ripened fruits were obtained at the end of a storage period of eight (8) days, as against 219 fruits obtained from those stored in the evaporative cooler for a period of 13 days. About 101 fruits stored in the storage room showed signs of rot for the same storage period, as against 81 fruits stored in the evaporative cooler.About 16 fruits from the storage room showed signs of water loss as against zero from the evaporative cooler over the period.  
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A Thesis submitted to the Department of Agricultural Engineering, Kwame Nkrumah University of Science and Technology, Kumasi. in partial fulfillment of the requirement for the award of the degree of Master of Science in Food and Postharvest Engineering,
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