Development of a natural ventilation windcatcher with passive heat recovery wheel for mild-cold climates: CFD and experimental analysis

User demand for increased internal thermal comfort conditions have resulted in rising energy costs for space-heating consumption. The present study aims to recover the thermal energy in ventilation exhaust air and transfer the energy to the incoming air, to be redistributed using natural ventilation windcatcher. A comprehensive review was carried out to explore heat recovery systems that can potentially be incorporated with natural ventilation wind catchers. A rotary heat recovery device suitable to be incorporated with a roof mounted multi directional windcatcher system was developed. Computational Fluid Dynamics (CFD) modelling and laboratory experimental tests were conducted to investigate the proposed system. In the first phase, a full-scale prototype of the passive rotary thermal wheel device was developed and tested in a crossflow channel to initially assess the concept and performance of the design. Two configurations of the passive heat recovery wheel were tested: 20 and 32 radial blades. The second phase focused on investigating the integration of heat recovery wheel into a windcatcher system. CFD modelling and scaled wind tunnel testing were conducted to assess the airflow and temperature distribution around the multi-directional windcatcher with a passive rotary wheel. The results showed that the addition of the heat recovery wheel rotating at 15 rpm reduced the indoor airflow speed between 14 and 30%, depending on the outdoor wind conditions. The system was able to provide the recommended fresh air rates when the outdoor wind speed was 1.5 m/s and higher. In addition to sufficient ventilation, the heat recovery system had a positive impact on the indoor air temperature, raising the temperature up to 3.7 degrees C depending on the indoor/outdoor conditions. (C) 2020 Elsevier Ltd. All rights reserved.