ABSTRACT An exergetic analysis of three basic types of solar drying systems is presented. The analysis is used to find the available useful energy and the quality of energy that is obtainable from the dryers. The dryers were installed side by side and tested simultaneously to eliminate influence of solar radiation and environmental changes in comparing their performances. The results obtained show that mixed mode and indirect mode solar dryers are more effective in utilizing the captured energy than direct mode dryer, and mixed mode has a slight edge in superiority over indirect mode system. 78.1% and 77% of energy collected in the mixed mode and indirect mode systems, respectively, were available as useful energy, while direct mode system could only convert 49.3% of collected energy to useful energy. The overall exergetic efficiencies of mixed mode, indirect mode and direct mode systems were found to be 55.2%, 54.5% and 33.4%, respectively.
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