A Study on the Efficiency of Solar Radiation Collectors Applying for Agricultural Products and Food Drying

Reducing the use of conventional energy in agricultural production and food processing via using renewable energy is one of the key points to protect our environment. Solar radiation might be an excellent source for replacing traditional heat sources in drying technology. This study aims to analyze and investigate the efficiency of different solar radiation collectors to apply for agricultural products and food drying. Seven solar radiation collectors have been developed and manufactured for experimental investigation. The first is a flat plate solar collector. The second is a pipe collector covered by transparent polyethylene. The third is a copper pipe collector placed on the focus of a parabolic trough. The fourth is a glass pipe collector placed on the focus of the parabolic trough (Experimental testing with fluid is air). The fifth is a glass pipe collector placed on the focus of the parabolic trough (Experiment testing with fluid is water). The sixth is the pipe collector placed on the focus of the parabolic cylinder with no extent to the collector (the parabola is insulated). The last is the pipe collector placed on the focus of the parabolic cylinder with an extended collector (the parabola is insulated). The experimental investigation results indicate that the collector efficiency depends on the solar radiation intensity, the mass flow rate of heating receiver substances, and the structure of the solar collectors. The high solar radiation intensity generates high efficiency. The Pipe collector is placed on the focus of the parabolic cylinder with an extension of the collector (the parabola is insulated); the highest solar collector efficiency with 50.58% at the air flow rate is 0.218 kg/s while the Glass pipe collector placed on the focus of parabolic trough (Experiment testing with fluid is air) has the lowest efficiency as 4.55%.