Principles and Application of Evaporative Cooling Systems for Fruits and Vegetables Preservation

In order to extend the shelf life of fruits and vegetables, they need to be properly stored. Proper storage means controlling both the temperature and relative humidity of the storage area. The essence of storage is of great importance because not all the harvested vegetables or crops in general will be used immediately after harvest so, measures of preserving the vegetables before it exceeds its shelf life is of great importance. Most of the peasant farmers are not able to afford the cost of purchasing high tech storage equipments for their harvested crops. Evaporative cooling has been found to be an efficient and economical means of reducing temperatures and increasing humidity in an enclosure where the humidity is comparatively low. Minimizing deteriorative reactions in fruit and vegetables enhances their shelf lives, implying that the produce will be available for longer periods; this would reduce fluctuation in market supply and prices. Evaporative cooler works on the principle of cooling resulting from evaporation of water from the surface of the structure. The cooling achieved by this device also results in high relative humidity of the air in the cooling chamber from which the evaporation takes place relative to ambient air. The atmosphere in the chamber therefore becomes more conducive for fruit and vegetable storage. Therefore, this paper reviews the concept, principle, method and types of evaporative cooling. The evaporative cooling systems has prospect for use for short term preservation of fruits and vegetables after harvested. It reduces the storage temperature and also increases the relative humidity within the optimum level of the storage thereby helps in keeping the fruits and vegetables fresh. Potential improvements for evaporative cooling devices include improvements in materials used, mainly in absorbent pads and ceramic pots. Experimentation needs to be performed to identify more locally available materials that can successfully be used as absorbents.