Evaluation of an Active Evaporative Cooling Device for Storage of fruits and Vegetables

Abstract

An active evaporative cooling device for storage of fruits and vegetables was developed and evaluated. The cooling device was developed to improve the shelf life of fruits and vegetables. It consists of an inner wall (aluminum of 0.6 mm thickness), external wall (galvanized steel of 1mm thickness), one suction fan, water pump and three trays. The walls were lagged by polyurethane of 25 mm, and three trays. Water distribution network contains two water tanks of 20 litres capacity each, a PVC pipe of 25 mm diameter for conveying water, a 0.5 hp pump for circulating water from the tank to the overhead reservoir and a floated switch for controlling the pump. Water is discharged from the overhead tank through a tap and drains through a jute bag which serves as a cooling pad material. As water drips through the pad, a suction fan of 38 cm swept depth set air in motion and blow through the wetted part. The cooler was evaluated with sweet orange, green tomatoes, and red tomatoes for 7 days to determine firmness, colour changes and weight loss of the crops. Weight loss in the red and green tomatoes stored in the ambient was observed to be 47.20 % and 5.14% respectively while it was 8.65% for red tomatoes stored in the cooler. Cumulative weight loss recorded in sweet oranges was 9.25% for ambient and 4.27% for the cooling device. The cooler reduced the ambient temperature of 29.5 ^oC to 22.8 ^oC and increased ambient relative humidity to 95.7%.