A novel thermal energy storage integrated evacuated tube heat pipe solar dryer for agricultural products: Performance and economic evaluation

In this study, the design, development, and performance analysis of novel thermal energy storage integrated evacuated tube heat pipe solar dryer was investigated. A new common condenser heat pipe system having thermal energy storage was incorporated into the solar collector of the dryer. Therminol 55 was used as the thermal storage medium. The performance analysis was carried out with air mass flow rates between 0.003 kg/s to 0.02 kg/s and a combination of two mass flow rates 0.015 kg/s and 0.0065 kg/s. The maximum outlet temperature of the air delivered by the solar collector during the study was 118 degrees C. The average energy and exergy efficiency of the solar collector varied between 10%-30% and 1.9%-5.6% respectively. Agricultural products like tomatoes and carrots were dried in the dryer. The effect of moisture diffusivity variation for tomatoes and carrots with the mass flow rate of air and product thickness was analyzed in this study. The Newton model fairly demonstrated the solar drying characteristics of tomatoes. The combined mass flow rate method increased the average collector outlet temperature to 67 degrees C against 56 degrees C during a single mass flow rate and decreased the drying time by 2 h. The payback period for the dryer was 2.6 years. (C) 2021 Elsevier Ltd. All rights reserved.