Recent Developments in Evaporative Cooling as an Energy Efficient Technology for the Short-Term Storage of Perishable Farm Goods: A Review

In storage of fruits and vegetables, temperature and humidity are important factors which affect nutritional value of fresh commodities. There are different technologies like cold storages, forced air cooling, hydro cooling, evaporative cooling, night air ventilation, controlled atmosphere and modified atmosphere to maintain the quality of fruits and vegetables and to prolong its shelf life. Cold storages, controlled atmosphere and modified atmosphere are the more effective techniques among the ones mentioned above, but cost of these technologies is high which makes them non-affordable to marginal farmers. Evaporative cooling is an old, economical, energy efficient and sustainable technology for the small farmers in hot and dry climate for the storage of fresh commodities. In this review paper, working principle, advantages and limitations, research achievements of different evaporative cooling system have been discussed. Effectiveness or efficiency of evaporative cooling can be increased by optimizing the fan speed, changing the cooling pad material and thickness, optimizing the water flow rate and controlling the system on/off operations according to climate conditions. With the evaporative cooling, it is possible to reduce the temperature by 5–12 and increase the relative humidity above the ambient humidity by 14% which helps to maintain the freshness of commodities. With developments in evaporative cooling, in the near future, energy consumption can be reduced and the possibility of energy efficient storing of the farm fresh horticultural commodities at farm level in tropical and subtropical regions could turn into reality.