Experimental study of the heat transfer coefficient between human skin and the flowing water during showering

Showering, as an indispensable part of modern people’s daily routine, is closely related to people’s comfort and energy consumption. To get an insight into these relationships and further improve people’s comfort and energy efficiency, it is crucial to understand the heat transfer coefficient between human skin and the flowing water during showering. Although it was investigated by several studies before, the value varied significantly (from 43.2 to 588 W/(m2·℃)) among these studies, and no consistent conclusion can be identified. Therefore, this study conducted a series of experiments to deeply understand the heat transfer coefficient under different showering conditions. This experiment used a skin model made of an insulated Styrofoam board and a thin aluminium sheet to simulate human skin exposure to the flowing water. Four showerheads with different patterns, three water temperatures (35, 38, and 41 ℃), and three water flow rates (5, 6, and 7 L·min-1) were investigated. Results indicated that the heat transfer coefficient increased significantly with the water flow rate. Moreover, this value also differed with various water patterns. For the same showerhead, the higher the pattern’s nozzle area ratio, the higher the heat transfer coefficient. These findings could help to identify the most effective showering condition with the highest heat transfer coefficient between human skin and flowing water and contribute to people’s thermal comfort and energy saving during showering.