Promoting food security and sustainability with a transportable indirect evaporative solar pre-cooler

Abstract

Perhaps one of the most important goals of sustainable development for developing countries is to enhance the utilization of renewable energy sources in all sectors in general and the agricultural sector in particular. The pre-cooling process helps to maintain quality and extend the shelf life of the fruits and vegetables. The aim of this study was to fabricate an indirect evaporative solar precooler (IESP) to reduce post-harvest loss for agricultural products. Tomato crop was chosen to be pre-cooled as an example of agricultural value chains. Experimental variables included three temperatures of cooling water (15, 10 and 5 °C) and two air velocities that passed through the cooling cabinet (1.5 and 2.5 m s-1). The results showed that at 1.5 m s-1 air velocity, the actual coefficient of performance was 19.4, 25.5 and 34.7% at cooling water temperatures 15, 10 and 5 °C, respectively. At 2.5 m s-1 air velocity, the actual coefficient of performance was 23.1, 28.8 and 37.2% at cooling water temperatures 15, 10 and 5 °C, respectively. The performance of the IESP under these conditions was 15.4 °C, 91.5% RH, 0.338 TR refrigeration load and 37.2% COPcyc. Total energy consumption was 6.4 kWh day-1. The solar pre-cooler performance proved a very feasible solution to the demands of small and medium horticultural holdings, especially in cities with a very hot climate to keep vegetables and fruits from deteriorating after harvest.