Optimal design of a solar precooling system for small-scale producers

Abstract

The pre-cooling process (The removal of field heat)  is considered one of the most important post-harvest processes that directly affect the quality and production. Pre-cooling reduces microbial activity, respiration rates, and vital heat. This process reduces water loss and decomposition, thus, it helps to maintain quality and extend the shelf life of the fruits. This study aimed to provide the optimal design of a solar precooling system for small-scale producers. The working principle of the designed pre-cooling system was based on a solar energy system integrated with water cooling combined with indirect evaporative cooling. The total required time to reduce the water temperature from 25 to 15, 10, and 5 °C was 1.88, 2.63, and 3.4 hr, respectively. The total required power to reduce the water temperature from 25 to 15, 10, and 5 °C was 1.41, 1.98, and 2.54 kWh, respectively. Optimal operating conditions for a solar pre-cooler were 6 l/min water flow rate, 5 ^oC cooling water temperature, and 2.5 m.s^-1 air velocity. Solar pre-cooler corresponds to the demands of small and medium horticultural holdings. It maintains quality and extends the shelf life of the fruits, especially in cities with a very hot climate