Development of an active evaporative cooling system for short-term storage of fruits and vegetable in a tropical climate

Abstract

An active evaporative cooler for short-term storage of fruits and vegetable has been developed to improve the shelf life of fruits and vegetables for small holder farmers in Southern Nigeria.  The evaporative cooler uses palm fruit fiber as cooling pad material which is considered a waste in palm oil production in Nigeria and consists of three suction fan, automatic water control switch, water pump and evaporative cooling chambers.  The performance of cooler was evaluated in terms of temperature drop, efficiency of the evaporative cooling and cooling capacity.  The temperature drop ranged from 4⁰C to 13⁰C while the relative humidity of the ambient air was increased to 96.8%.  The cooler could drop the temperature close to wet bulb depression of ambient air and provided up to 98% cooling efficiency with a maximum cooling capacity of 2,529 W.  At an ambient temperature of 37⁰C, the evaporative cooler provided the storage conditions of 23.2 temperature and 85.6% – 96.8% relative humidity, which can enhance the shelf life of wide range of fruit and vegetables of moderate respiration rates.  The power consumption of the cooler was half that of a typical vapour compression refrigerator of the same volume.

Keywords: cooling capacity, cooling efficiency, evaporative cooling, temperature drop

cerun:yes'> A throughput capacity of 66.06 kg h^-1 was obtained at moisture content of 12.5% wet basis and 405 r min^-1 while throughput capacity of treadle thresher was 55.51 kg h^-1 at moisture content of 17% wet basis and 610 r min^-1.

Keywords: cowpea, mechanical damage, moisture content, threshing efficiency, variety