Development of physiological human model considering mist wettedness for mist-spraying environments

The thermal state of the human body is closely related to thermal sensations and thermal comfort and can be estimated using a physiological human model. However, the feasibility of its prediction models in a mist-spraying environment has not been examined. The present study confirmed the applicability of existing prediction models (two-node model (2NM) and three-node model (3NM)) in outdoor and mist-spraying environments. Additionally, the evaporative heat loss caused by mist wetting in the human body (mist wettedness)—which has been overlooked—was measured using a heating globe thermometer controlled at the skin-temperature level, and on the basis of the results, the existing prediction models were modified. In the outdoor environment, the existing and modified models predicted the skin temperature identically, with errors of 0.30 °C (2NM) and 0.24 °C (3NM), for 10 min. In the mist-spraying environment, the skin-temperature results for the existing models stabilized and did not reflect the continuously decreasing experimental results, but the modified models reflected the continuously decreasing tendency of the experimental skin-temperature results, with errors of 0.52 °C (2NM) and 0.56 °C (3NM). When the effective area factor (ηmist = 0.5) of the mist droplets was applied to the modified prediction models, the mist wettedness contributions to the total heat loss from the body surface were 40.4% (2NM) and 37.9% (3NM). Therefore, the mist wettedness was identified as a significant environmental factor affecting the heat loss on the human body, and these models can provide better understandings of the physical phenomena in mist-spraying environments.