Performance evaluation of solar and condensing heat recovery systems for air reheating and humidification in industrial buildings

Abstract

Ensuring precise control of temperature and humidity is critical for maintaining process reliability and energy efficiency in industrial building environments. However, conventional heating, ventilation, and air conditioning (HVAC) systems often overlook the recovery of low-grade waste heat and the integration of renewable energy, resulting in low operational efficiency and high energy costs. To address this issue, this study proposes an air conditioning system that integrates solar energy and condensation heat recovery, and establishes a coupled heat and humidity control strategy that simultaneously utilizes recovered heat for both air reheating and humidification. The system’s performance is comprehensively evaluated from the perspectives of energy, exergy, and economic efficiency. Furthermore, a multi-objective optimization framework combining artificial neural networks (ANN) and the multi-objective grey wolf optimizer (MOGWO) is developed to determine the optimal capacity configuration. The results demonstrate that, compared with traditional electric reheating systems, the proposed waste heat recovery (WHR) air conditioning system achieves a coefficient of performance (COP) of 6.08 and reduces the levelized cost of heat (LCOH) to 0.079 USD/kWh during the heating season, highlighting substantial improvements in energy efficiency and cost-effectiveness. In the non-heating season, the system also exhibits stable operation and effective cost control. Based on the technique for order preference by similarity to ideal solution (TOPSIS) decision-making method, a representative configuration optimized for the heating season is recommended for year-round operation, featuring a thermal storage tank volume of 59  m³ and a solar collector area of 594  m². This configuration ensures an annual COP of at least 4.3, an exergy efficiency above 0.18, and an LCOH not exceeding 0.081 USD/kWh. This study confirms the feasibility of coupling low-grade waste heat with renewable energy in HVAC systems and provides a high-efficiency, cost-effective, and scalable solution for achieving low-carbon building operations in industrial environments.