Design, Construction And Testing Of A Passive Evaporative Cooler For Short-Term Preservation Of Fresh Tomato

ABSTRACT

A passive evaporative cooler for short-term storage of tomato was developed to improve the shelf life of tomato. The evaporative cooler. uses jute bags as cooling pad material. The developed evaporative cooler consists of cooling chamber, water recycling pan, overhead pan, jute bag, trays. The design is a direct evaporative cooler of the passive type which uses wet jute bag as a cooling pad to cool dry air thereby reducing the inlet temperature and increasing the humidity of the inlet air that passes through the sides of the perforated evaporative cooler. The aim of the evaporative cooler that reduces the temperature and increases the relative humidity is to maintain a favorable condition that will prolong the shelf-life of the tomato since the tomato performs best in a reduced temperature and high relative humidity. It was found out that the temperature of the evaporative cooler at some hours in some days maintained a temperature range of 0°C- 21°C which is the proposed temperature for the storage of tomato (Lerner et al., 2001). The evaporative cooler, tends to maintain the temperature up till afternoon when there is a rise in the temperature of the evaporative cooler which remains in close range with that of the ambient temperature till evening. The evaporative cooler achieved a maximum relative humidity of 73% which is in close range with the proposed relative humidity of 80% - 95% (L.R. Castro etal., 2005). After the recording of the temperature and relative humidity of both evaporative cooler and ambient, the tomatoes in the evaporative cooler lasted more than the tomatoes in ambient with a duration of 16 days while the tomatoes in the room stayed for 10 days.