Investigating performance of a new design of forced convection solar dryer

Abstract

Drying is a common practice for delaying deterioration, preserving quality, and easier prolonged storage of agricultural products. According to the climatic and geographical conditions of Arsanjan County, Fars, Iran. So far, many studies have been conducted on the design and use of various barriers on absorber plates with the aim of increasing heat exchange and subsequently increasing the efficiency of air heaters and solar dryers. However, the effect of using the metal of the sewing machine bobbin on the performance of these dryers has not been studied yet. Therefore, in this study, for the first time, this metal and also pipes containing PCM (phase change material) were used as a barrier on the absorber plate. The results showed that using bobbin absorber plate and PCM in the dryer improves the average collector efficiency and the average dryer efficiency by 28.5% and 52.1% respectively compared to flat absorber plate without PCM, 26.4% and 36.3% compared to bobbin absorber plate without PCM, and 12.2% and 12.9% compared with flat absorber plate with PCM. Although it took about 4.5 h on average to reach the target moisture content with the dryer, it took about 3 days to achieve the same moisture content when parsley was dried in the shade. After fitting the experimental data with nine drying kinetics models and comparing the results in terms of RMSE and R2, it was found that Midilli model can provide reasonably accurate estimates of the drying curve for drying of parsley in fabricated solar dryer.