THERMAL PERFORMANCE ANALYSIS FOR SOLAR COLLECTOR AIR HEATER ASSISTED SOLAR MODIFIED-QUONSET DRYER

Abstract

This paper presents an experimental analysis to study and test the thermal performance of a novel mixed mode solar dryer (modified-quonset form) with solar collector air heater that could be used to dry seedless grape. The solar dryer consists of a flat-plate solar collector and a solar dryer. The thermal performance analysis tests were carried out on the roof of Agricultural Engineering Department (latitude angle of 31.045oN, longitude angle of 31.37oE, and altitude of 14.5 m above the sea level) during summer season of 2015 (from 29/8/2015 to 3/9/2015). The thermal performance analysis of the mixed mode solar dryer (forced convection system) based on the energy balance equations was evaluated. The solar dryer with forced convection was operated under mass flow rate of 0.1172 kg/s (6.58 m3/min). The obtained data showed that, the daily average solar radiation recorded on the horizontal surface during the experimental period was 5.607 kWh/m2 whilst, the actual solar radiation recorded on the tilted surface of flat-plate solar collector was 8.109 kWh/m2. Consequently, the stationary non-tracking flat-plate solar collector increased the actual received solar radiation during that period by 44.62%. The daily averages solar radiation recorded outside and inside the solar dryer, respectively, were 5.607 and 4.570 kWh/m2 with cover effective transmittance of 81.51%. The daily averages solar energy available inside the flat-plate solar collector and the solar dryer were 16.217 and 9.141 kWh of which 10.895 and 5.514 kWh, respectively, converted into useful heat gain. These solar energy available inside the flat-plate solar collector and the solar dryer resulting in increasing the indoor air temperatures above the outdoor (31.1°C) by 10.5, and 16.1°C, and reduce the air relative humidity under the outside (60.8%) by 28.3%. The daily average overall thermal efficiencies of the flat-plate solar collector and the solar tunnel dryer during the drying period were 66.64% and 59.52%, consequently, 33.36% and 40.48% of the solar energy available were lost, respectively.