1 Department of Processing & Agril. Structures, Punjab Agricultural University, Ludhiana. E-mail: akdevgan@rediffmail.com
Temperature and moisture play major role in storage of fruits and vegetables. Evaporative-cooling is the most economical way of reducing the temperature by humidifying the air. Three evaporatively cooled stores (double walled structures having sandfilled cavity between the walls) namely domestic indoor-store (1.89 x 1.28 x 0.07m), domestic outdoor store (2 x 2 x 0.75m) and a large outdoor store (5.5 x 5.5 x 3.5m) having storage spacefor 50 kg, 100 kg and 100 bags of potatoes respectively were evaluated throughout the year to observe the effect of size and external environment on performance of the store. The roofs of all the stores were covered with wet jute bags and sand between the cavities was kept wet. The temperature and humidity inside and outside the store were recorded thrice a day throughout the study. Relative humidity inside all the stores remained more than 90% throughout the year irrespective of ambient variations. The maximum drop in inside temperature (13–18°C) was observed in the hot and dry months of April to June followed by (9–10°C) in February and 6–8°C drop during July to December depending upon the ambient conditions. Maximum cooling was observed in domestic outdoor store as the temperature inside the store remained close to ambient wet bulb temperature. This was mainly because of low absorption of solar radiation because of small size. Temperature inside the large store was 1–2°C higher because of the large area exposed to solar radiations. Average inside temperature in domestic store was also higher by 1–2°C as compared to domestic outdoor store because the outside temperature around domestic store was always higher than actual ambient store.
