Exploring the Airflow Generated by Ceiling Fans on a Human Body: An Experimental Study with a Thermal Manikin

Ceiling fans can provide comfort cooling in low-energy buildings, enabling the use of warmer room temperature set-points. While increased air movement through ceiling fans is an effective way to provide comfort in warm and humid conditions, the localized cooling impact on individual body parts can vary significantly based on the speed and direction of the airflow. This variability can influence local thermal sensation and hence the overall comfort. This study investigates how a ceiling fan impacts the heat flux and convective heat transfer coefficient of the different body-parts, using a thermal manikin in a living-room setting. This study explores the heat transfer dynamics around a clothed thermal manikin in a controlled ambient with a typical dining room furniture arrangement. The thermal manikin, operating in PI controller mode, measured the heat flux required by 27 different body-parts to maintain a constant skin temperature. The ceiling fan‘s impact is examined under two flow directions (Direct and Reverse), across three fan speed levels, and two seated positions around a dining table setup. Measured parameters include heat flux of each body part, air temperature, and air velocity near the manikin at four heights, which were used to calculate the convective heat transfer coefficient for each body part, allowing for a detailed analysis of the fan‘s cooling effect on specific body segment. The findings reveal distinct differences in the convective heat transfer coefficients under Direct and Reverse flow directions and across the two positions, suggesting potential variations in thermal sensation. Direct airflow correlates with increased cooling effect, particularly affecting the head, face, forearms, and hands, while reverse airflow enhances air velocity at feet level. The detailed characterization of localized cooling effects under various fan configurations enables more accurate modeling of human thermal response, leading to optimized control strategies for ceiling fans.