Flat micro heat pipe-based shell and tube storage unit for indirect solar dryer: a pilot study

Poria cocos has been dried in an indirect solar drying system composed of a roughened solar air heater (RSAH), a shell and tube storage unit assisted with flat micro heat pipes fins, and a drying chamber. The main novelty in this study is using FMHPs as fins in shell and tube storage unit with paraffin wax and lack of investigations on Poria cocos solar drying as medicinal material used in Chinese medicine. First and second laws of thermodynamics are used to assess the performance of the system and the results indicated that the RSAH average thermal (?) and exergy efficiency (?(Ex)) were 73.9% and 5.1%, respectively, with averaged incident solar radiation of 671 W/m(2) under airflow rate of 0.0381 m(3)/s. Furthermore, the storing system showed 37.6% as averaged overall ? and 17.2% as averaged overall ?(Ex), as well as, discharging prolonged to 4 h with effective drying temperature. The overall ? of the dryer was 27.6% with specific energy consumption (SEC) of 8.629 kWh/kg moisture. The payback period of the system is 1.7 years.