Experimental investigation and exergy and energy analysis of a forced convection solar fish dryer integrated with thermal energy storage

Abstract

Drying is an effective means of reducing post-harvest losses which increases the shelf life of products by reducing their moisture content to a safe storage level. An indirect mode forced convection solar dryer integrated with thermal energy storage was designed, developed and experimentally tested by drying fish. The components of the dryer are a double pass solar air heater, a paraffin wax-based shell and tube for latent heat thermal energy storage, a drying chamber and a blower. A maximum temperature of 69 ℃ was obtained at the outlet of the solar air heater, and the energy and exergy efficiencies were 25% and 1.5%, respectively. The latent heat storage reduces the fluctuations in the outlet temperature of the solar air heater and extends the drying process for two extra hours per day. The average energy and exergy efficiencies of the energy storage were 41.9% and 15.6%, respectively, whereas average energy and exergy efficiencies of the drying chamber were 35% and 52%, respectively. Moreover, 5 kg of fresh fish was effectively dried in the dryer within 21 hrs, reducing the moisture content of the fish from 75% to 12.5% by removing 3.57 kg of moisture. The specific energy consumption of the dryer was 7.3 kWh per kilogram of moisture, and the power consumed by the blower was 0.6 kWh per kilogram of moisture, which is 8.3% of the total energy consumption. The remaining 91.7% of the energy is harvested from the sun, and the overall efficiency of the drying system is 9.4%.