“Development and Performance Evaluation of a Hybrid Solar Dehydration System for Food Preservation”

Abstract

This study explores the creation and performance assessment of a hybrid solar drying system aimed at improving food preservation through energy-efficient methods. The system combines a flat plate solar collector, paraffin wax as a Phase Change Material (PCM) for storing thermal energy, IoT-based monitoring for real-time data collection, and optional forced convection elements like blowers, infrared (IR) bulbs, and electric heaters. The main objective is to facilitate continuous drying, especially during periods of low solar irradiance or at night, and to evaluate the efficiency of natural versus forced convection drying modes. Experiments were conducted on five vegetables: chili, onion, potato, spinach, and grapes, under different configurations. In the natural drying mode, which relies solely on solar-heated PCM, moisture removal of 80–85.6% was achieved within 70 to 105 minutes for chili, onion, and potato. Conversely, forced drying, which incorporates blowers and IR bulbs, significantly shortened drying time, achieving 80% moisture reduction in spinach in just 40 minutes, and consistent drying of chili and onion within 2 to 2.5 hours even in less than ideal sunlight conditions. The drying of grapes took longer due to their high moisture and sugar content. The IoT integration allowed for continuous monitoring of temperature, humidity, and airflow, optimizing drying conditions and enhancing process control. Comparative results suggest that the natural PCM-based mode is more appropriate for small-scale, energy-efficient applications, while the forced mode provides faster, uniform drying suitable for larger or commercial-scale operations. This research highlights the effectiveness of a hybrid solar dehydration system in offering a sustainable, adaptable, and efficient solution for agricultural drying and food preservation, with potential applications in rural and off-grid areas.