Energy and Drying Performance Evaluation of a PCM ‐Integrated Hemispherical Solar Dryer With Pretreated Grape
Abstract
This study experimentally evaluated the drying performance of a solar tracking‐free hemispherical solar dryer integrated with vertically arranged collector‐storage units, phase change material (PCM), and chemical pretreatment for grape drying. Paraffin wax as the PCM was used as the thermal energy storage medium to improve thermal stability and extend drying beyond sunshine hours, while chemical pretreatment using potassium carbonate (K 2 CO 3 ) and olive oil enhanced moisture removal. Four drying conditions: chemical pretreatment, PCM‐assisted drying, combined PCM with pretreatment, and passive drying were investigated. The combined application of PCM and pretreatment exhibited the best performance, reducing the drying duration from 15 to 7 days and achieving the highest drying efficiency (13.17%) and moisture removal rate (0.3906 kg/h). PCM extended the effective drying period by up to 2 h 25 min after sunset. Statistical analysis confirmed the significant effects of PCM, pretreatment, and their interaction on drying performance ( p < 0.001). The results demonstrate that integrating thermal energy storage with pretreatment effectively improves the performance and economic viability of solar drying for grape processing.