Thermal performance of a multi-loop pump-driven heat pipe as an energy recovery ventilator for buildings

Building energy consumption could benefit from air-to-air energy recovery ventilators. A triple-loop pump-driven heat pipe system was developed for energy recovery from exhaust air in buildings. The thermal performances of the single-loop and triple-loop systems were studied and compared experimentally under winter and summer conditions. The improvement of loop number and the uniformity of temperature difference distribution was discussed. Results indicated that heat transfer capacity and coefficient of performance increased with indoor and outdoor temperature difference, and the variation of temperature effectiveness depended on working conditions. The energy recovery performance of the triple-loop system was better than the single-loop system. The heat transfer capacity, temperature effectiveness, and coefficient of performance of the triple-loop system increased by 3.0%, 0.6%, and 56.7% in summer conditions with an indoor and outdoor temperature difference of 7.5 °C, and by 22.4%, 22.6%, and 53.5% in winter conditions with an indoor and outdoor temperature difference of 31.9 °C. The uniformity of temperature difference distribution could be improved clearly with increasing loop number in winter conditions but not obviously in summer conditions. The variation coefficient of temperature difference decreased from 17.2% to 10.2% in winter conditions, and from 4.5% to 3.9% in summer conditions.