Effect of water mist stimulation on dynamic thermal response of pedestrians in summer.

In order to reduce the heat stress caused by urban heat island and local overheating of the city, the spray cooling system is arranged in the streets. The purpose of this study was to reveal the dynamic physiological adjustment and thermal perception response of human body under heat stress with alternating exposure of sunlight and water mist. Fifteen subjects participated in the exposure test at different frequencies. Three kinds of data were collected, including meteorological parameters, skin temperature (T sk), and thermal perception. The results showed that the dynamic thermal perception was affected by the short-term thermal experience based on 2 or 5 min. The change of thermal sensation to cooling stimulation was approximately 1.5 times higher than that to warm stimulation. The increase of water mist exposure rate improved the neutral temperature of the universal thermal climate index (NUTCI) and the neutral temperature of the universal thermal climate index range (NUTCIR). In the step-change stages, air temperature (T a) and relative humidity (RH) were the meteorological parameters that significantly affected the thermal sensation, and the physiological parameter was the skin temperature of lower arm (T Arm). Dynamic models for predicting thermal sensation with T a , RH and T Arm change rate was established. Compared with the traditional regression prediction, BP neural network prediction had higher accuracy (RMSE = 0.229) and better fitting degree (R² = 0.856). • The dynamic thermal response to microclimate step changes was studied. • A short-term thermal experience of 2 or 5 min affected thermal sensation. • The sensitivity to cooling stimuli was 1.5-fold greater than that to warm stimuli. • The relationship between thermal sensation and multiple parameters was revealed. • Four methods for predicting dynamic thermal sensation were proposed. [ABSTRACT FROM AUTHOR]