Influencing Factors Used for Performance Evaluation of Solar Dryers

Due to the rapid growth in human energy demand, research and development in renewable energy sources have become a top priority. Solar energy, as a renewable energy source, is widely used in the drying industry. This study examines the factors that influence the performance evaluation of solar dryers. The dryer consists of an air collector, a drying chamber, and a chimney. Experiments were conducted at the Solar Energy Laboratory of the Hungarian University of Agriculture and Life Sciences in Hungary (47.59° N, 19.36° E). The drying behaviour of single-pass and double-pass solar dryers was compared under the same environmental conditions. The analysis results indicate that the maximum solar radiation value is 950 W/m2 at 12:00. The maximum temperature difference between the top and bottom channels of the double-pass solar air collector is 9.5 °C. The average humidity in the environment, single-pass, and double-pass drying chambers is 31%, 26.5%, and 24%, respectively. The instantaneous efficiency of the single-pass solar collector reaches a peak of 56%, while the double-pass collector’s instantaneous efficiency peaks at around 60%. The collector performance curves show that the double-pass collector has a more stable performance.