Latent and sensible heat thermal storage in a heat pipe-based evacuated tube solar dryer: A comparative performance analysis

Abstract

A new solar dryer system that can work with multiple heat storage mediums was developed and conducted a comparative performance analysis. Latent and sensible heat thermal storage mediums can be accommodated in the drying system. The solar dryer consist of evacuated tubes with thermal storage unified heat pipe solar collector. A new heat pipe layout was developed and placed inside the collector by linking the evaporator sections of the heat pipe with a single heat pipe condenser segment linked to a chamber that can accommodate various types of thermal energy storage mediums. Two heat storage mediums like benzoic acid and therminol-55 were used during the study. A maximum of 118 °C drying air temperature was obtained from the system with Therminol-55 heat storage medium. The collector and dryer system has a maximum energy efficiency of 29 % and 24 % respectively. The Benzoic acid stored a maximum of 3069 kJ energy whereas therminol-55 stored a maximum of 1881 kJ. Drying experiments conducted using therminol-55 as the thermal storage medium needed 16 h to dry 1 kg of apple to 45 g, whereas Benzoic acid required 17 h of drying time. The drying system performed well with therminol-55.