Design and development of a dual-purpose air cooler for space cooling and fruit/vegetable preservation

Abstract The authors have designed and developed a dual-purpose air cooler (DPAC) capable of both room cooling and refrigeration for storing fruits and vegetables. They proposed a design in which a box, made of mild steel plate and enveloped in jute cloth, is affixed at a specific distance from the cooler tank. This distance corresponds to the height at which the air temperature saturates. Water at saturation temperature is directed over the box to maintain its wetness, thereby indirectly cooling the interior space to prolong the freshness of stored items. The box's sidewall is perforated to introduce additional moisture, enhancing the preservation of vegetables and fruits. This innovative cooler was specifically designed for Raipur, Chhattisgarh, India, considering the region's maximum summer temperature (42 °C) and relative humidity ranging between 20 and 30% during the summer months. The authors conducted comprehensive computations to determine the optimal pad height, varying pad thickness from 10 to 15 cm, pad packing factor from 350 m 2 /m 3 to 450 m 2 /m 3 , and relative humidity from 20 to 30%. Additionally, the cooling potential of the cooler was numerically evaluated as part of the study.