Performance, energy and exergy analysis of solar-assisted heat pump drying system with heat recovery: A comprehensive experimental study

Abstract

This study introduces an innovative solar-assisted heat pump drying (SAHPD) system incorporating multi-stage waste heat recovery technology to enhance energy efficiency, environmental sustainability, and economic feasibility for diverse drying applications. Through comprehensive experimental analysis under solar drying (SD), heat pump drying (HPD), and SAHPD modes, the SAHPD system achieved the highest performance metrics. The average coefficient of performance (COP) in SAHPD mode reached 2.49, a 34.59 % improvement over the HPD mode without heat recovery (1.85). Notably, the multi-stage heat recovery system demonstrated significant advantages, with a heat recovery rate of 5040.69 kJ/h, marking a 228.03 % increase compared to single-stage recovery. The condenser heating power increased from 8.83 kW to 10.93 kW, reflecting notable energy efficiency improvements. Additionally, the system's specific moisture extraction rate (SMER) was 1.53 kg/kWh, far surpassing HPD's 0.576 kg/kWh, highlighting its superior moisture extraction efficiency. The SAHPD system also proved highly cost-effective, with a payback period of just 0.97 years These results confirm the SAHPD system's potential as a sustainable, energy-efficient, and economically viable solution for agricultural products drying processes, setting a benchmark for integrating solar energy with heat recovery technologies.