Design and construction of an evaporative cooler for the preservation of fresh cabbages.

Abstract

A Solar Powered and Temperature Controlled Evaporative Cooler of 50 kg capacity was designed and constructed to increase the shelf life of fresh cabbages. The cooler was tested using green fresh cabbage and evaluated. The cooler operates on the principle of DEC. Fresh cabbage is highly perishable. The cooler was made up of a 1mm aluminum sheet and lagged with cotton with one side made of charcoal through which the water flew via a perforated quarter inch steel pipe from the reservoir located at the top of the cooler. A 12 V Lithium battery powered two DC fans inserted on the side opposite to the side of charcoal and a Thermostat controlled the fans. The temperature, RH and weight loss of cabbage were statistically analyzed using ANOVA and the results revealed that there was significant difference in using the cooler for preserving cabbages as compared to the shade. The average COP was 1.75. The temperature in the cooler reduced up to 12.8 o c when compared to the shade and the RH in a cooler chamber went up to 90%, However, the testing of the system disclosed that the cabbages can be stored for a minimum of three weeks with negligible changes in weight, color and no putrefying as compared to the shade which started with notable changes in weight, color and severe putrefying after 9 days. Hence, it is on advisable that market cabbage venders and cabbage processing factories adopt the use of an evaporative cooler for their preservation as this increases their shelf life.