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

Abstract

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 ([Formula: see text]) and exergy efficiency ([Formula: see text]) were 73.9% and 5.1%, respectively, with averaged incident solar radiation of 671 W/m2 under airflow rate of 0.0381 m3/s. Furthermore, the storing system showed 37.6% as averaged overall [Formula: see text] and 17.2% as averaged overall [Formula: see text], as well as, discharging prolonged to 4h with effective drying temperature. The overall [Formula: see text] of the dryer was 27.6% with specific energy consumption (SEC) of 8.629 kWh/kg moisture. The payback period of the system is 1.7years.