Optimization of Thermo-Flow in a Solar Food Dehydrator Using Computational Techniques

Abstract

A solar food dehydrator converts solar energy into heat required to remove moisture from food. This study involved development of an optimized design for a solar dehydrator using computational techniques. A computer-aided design of six (6) different configurations of the dehydrator was developed, and a remotely-installed heat capture device was modelled and analysed using MATLAB. The results show that the Parabolic Trough Collector (PTC) could be used in effectively transferring heat remotely to a dehydrator. The temperature of air leaving the heat exchanger increases in proportion to the increase in the temperature of the heating fluid entering the heat exchanger. Computational Fluid Dynamics (CFD) in Ansys Fluent was employed to aid in the study of airflow and temperature distribution. The hot air was simulated at 2 m/s and 350 K inlet conditions. The CFD simulation results showed significant variations in the air velocity distribution and temperature for different configurations of the dehydrator. The back inflow - front outflow configuration provided the most uniform distribution of heated air in the drying chamber, with minimal variation on each tray. This uniformity was also observed in the distribution of static temperature. The back inflow – side outflow configuration showed a similar performance in flow and temperature distribution. However, the bottom inflow – top outflow and bottom inflow – front outflow configurations showed uneven velocity and temperature distribution inside the drying chamber. Supply of airflow across the trays horizontally provides best airflow and temperature distribution in solar dehydrators and thus highly recommended.