Building Performance & Environmental Systems Lab.

논문 초록 (Abstract)

Recently, the demand for energy-efficient air cooling and dehumidification systems for retrofitting existing buildings has grown. In conventional vapor-compression systems, substantial cooling energy is required to lower air temperature below its dew point for dehumidification, followed by reheating to meet the supply air setpoint. This process leads to significant energy inefficiency, especially in buildings with low sensible heat ratio. To address this, a run-around heat recovery coil (RAC)-assisted air-conditioning system is proposed as a practical retrofit solution. The system integrates two heat recovery coils before and after the cooling coil to precool and reheat the supply air using a circulating working fluid. Beyond the component-level analysis, this study evaluates the energy-saving potential of the RAC-assisted system through building energy simulations that incorporate part-load operation and climatic variability. The effectiveness–NTU approach was developed to characterize the heat recovery performance under varying air and water flow rates. Using these results, building energy simulations were conducted across multiple climates. In the representative climate of Seoul (Korea), the RAC system reduced thermal loads on the cooling and reheating coils by 13.5% and 55.5%, respectively, achieving total energy savings of up to 27.2% despite added fan and pump energy. Further analysis under various climatic conditions and corresponding building loads showed that energy savings increased to 35.4% in buildings under a humid continental climate. These findings demonstrate the potential of the RAC system as an energy-efficient retrofitting strategy.