Effects of Storing Commodity on the Inner Environment of Evaporatively Cooled Storage Structures

The effects of stored produce and its properties on the thermal environment in an evaporatively cooled (EC) storage structure for horticultural produce were analysed with the help of a computer model and limited field trials. It was observed that loading of the produce increased the inside temperature due to the respiratory heat generation and the increase in inside temperature was directly related to the amount of stored commodity. The daily temperature fluctuation was less in loaded structures than that in empty structures due to the heat generated within produce and the thermal inertia. Higher the rate of respiratory heat generation, more was the inside air temperature, and hence, the type of stored commodity and the amount of load would directly influence the inside thermal environment of the structure. When the ambient temperature varied between 20.1 and 40.5°C, the produce loaded at 40°C temperature took about 84 h to come to the steady periodic equilibrium storage temperature. The produce loaded at lower temperatures took less time, i.e. about 60 h and 36 h for produce loaded at 33 and 25°C, respectively. Hence, to get maximum advantage of the evaporative cooling system, the temperature of the produce should be as low as possible when loaded, i.e. precooling of the produce and/ or loading in early morning hours have been suggested.