EXPERIMENTAL INVESTIGATION OF IOT-BASED HUMIDITY-RESPONSIVE VENTILATION FOR ENHANCED SOLAR DRYER PERFORMANCE

Active solar dryers (ASD) often encounter limitations in thermal performance due to continuous ventilation without appropriate control mechanisms, which leads to unnecessary heat losses. To resolve the trade-off between thermal energy retention and moisture removal, this study experimentally investigates an automated Relative-Humidity-Controlled Solar Dryer (RH-SD) by implementing a feedback-based control system integrated with Internet-of-Things (IoT) technology. The performance of the RH-SD was evaluated in comparison with a Passive Solar Dryer (PSD) and an ASD operating under continuous ventilation mode. Experiments were conducted using pork as the test material, with an initial moisture content of 285% on a dry-basis, under real tropical environmental conditions. The results indicate that the proposed RH-SD strategy notably enhances energy efficiency without inducing adverse effects on the drying performance. Furthermore, the humidity-responsive ventilation strategy reduced fan energy consumption by 58.0% compared with the conventional ASD. Although the drying rate of the RH-SD exceeded that of the PSD by 20.0% and was comparable to the ASD (11.1% higher), the system achieved improved thermodynamic balance by reducing the specific energy consumption (SEC) by 14.3% and 12.9% relative to the PSD and ASD, respectively. These findings suggest that humidity-driven control provides a promising pathway for the development of solar drying systems that are energy-efficient and conducive to long-term sustainability.