Influence of misting system on the thermal environment and thermal comfort of seated people in semi-outdoor space in Xi’an, China

Abstract

In summer, factors such as solar radiation could make semi-outdoor spaces uncomfortable, and the use of misting systems for evaporative cooling is a low-energy improvement measure. To investigate the impact of misting system on the thermal environment and thermal comfort of seated people improvement, a field study was conducted at a semi-outdoor cafeteria in Xi’an. The results indicated that the misting system was capable of reducing the ambient air temperature by 2.4-4.9 ℃ and increasing the relative humidity by 17.1%-17.8%. Participants in misting condition reported lower thermal sensation and higher thermal acceptability, thermal preference, humidity sensation, humidity preference and humidity acceptability. In no misting condition, the upper SET* limit acceptable to 80% of the population was 28.5 ℃. However, in the misting condition, the acceptable percentage of participants in each SET) interval was more than 90%. When SET) was 22.1-23.7 ℃, the improvement in human thermal comfort through misting system was not significant. When SET) was 23.7-28.5 ℃, the misting system significantly improve human thermal comfort. Finally, two control temperature thresholds of the misting system were provided according to the relationship between 80%, the maximum (89.3%) acceptable percentage and the air temperature, which were 30.1 ℃ and 26.5 ℃, respectively.

Key words： Misting system; Thermal environment; Thermal response; Acceptable temperature; Control strategy