An innovative window heat recovery (WHR) system with heat pipe technology: Analytical, CFD, experimental analysis and building retrofit performance

This paper addresses the numerical and experimental performance analysis of a windows heat recovery system made of heat pipes. For modelling, the heat pipe is considered as a pseudo solid material with high value of effective thermal conductivity. An experimental investigation using a window heat recovery prototype was carried out to predict the value of effective thermal conductivity of the heat pipes and to validate the numerical model. After validation, a parametric analysis was conducted to investigate the performance of the recovery system for different working conditions (mass flow rate and temperature difference between exhausted and supplied air). Based on the performance obtained in the parametric analysis, energy performance in building and the impact on velocity and pressure distributions are also evaluated with the support of CFD analysis. It is found that the effectiveness of window heat recovery made of heat pipes depends on ventilation rate and temperature difference between exhausted and supplied air. Increasing ventilation rates and temperature differences decrease the effectiveness. For ventilation rate between 10–60 m 3/h and temperature difference 10–30 °C, effectiveness between 65%–95% and pressure drop 4–80 Pa are obtained. For performance in building, the power consumption can be reduced between 3%–24% and the thermal comfort increased. •Effectiveness of window heat recovery depends on ventilation rate and temperature.•Ventilation rates have the most significant impact on effectiveness.•Higher ventilation rate and temperature difference decrease the effectiveness.•The increase of ventilation rate could enlarge the monthly heating demand.•Window heat recovery can improve the thermal comfort in building.