Stratum-air-distributed radiant-convective room air conditioner for heating.

• Stratum-air-distributed radiant-convective room air conditioner is proposed. • First time for stratum ventilation to be applied to room air conditioner. • First time for radiant-convective heater to be integrated with advanced air distribution like stratum ventilation. • Enlarged heat output and advanced air distribution result in improved thermal comfort and energy efficiency. The radiant-convective room air conditioner has been demonstrated to improve the coefficient of performance and the heating capacity effectively. However, the applicability of the radiant-convective room air conditioner in modulating the indoor thermal environment is unclear. This study proposes a stratum-air-distributed radiant-convective room air conditioner and evaluates its effectiveness for providing thermal comfort under heating mode with experimentally validated CFD simulations. Results show that the heat output of the radiant panel of the room air conditioner accounts for 20.7 %- 34.5 % of the total heat output. The supply airflow rate should be properly determined to balance the highly coupled heat output and air distribution. Compared with the conventional room air conditioner, the proposed room air conditioner under proper operation more effectively warms the occupied zone because of the enlarged heat output and improved air distribution, thereby increasing the predicted mean vote from −0.15 to −0.02, reducing the vertical air temperature difference from 6.7℃ to 0.8℃, and enhancing the thermal utilization effectiveness from −0.09 to 0.25. In addition, the draft rating and radiant temperature asymmetry of the proposed room air conditioner are thermally acceptable. Therefore, the proposed room air conditioner can modulate the indoor thermal environment energy-efficiently from the aspects of both overall and local thermal comfort. [ABSTRACT FROM AUTHOR]