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 sy...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.展开更多
Occupants’thermal comfort in buildings may be affected by the cool wall and warm wall,which is attributed to the effect of asymmetric radiation.However,the previous majority of the researches on asymmetric radiation ...Occupants’thermal comfort in buildings may be affected by the cool wall and warm wall,which is attributed to the effect of asymmetric radiation.However,the previous majority of the researches on asymmetric radiation were mainly about the comfort limits under thermally neutral condition within 1∼1.5 h but had not considered the effect of exposure duration and the condition beyond neutral.To investigate the human thermal comfort under an asymmetric environment caused by the cool wall and warm wall,forty-four subjects were exposed to neutral air temperature with lateral radiant asymmetries in winter and summer for 3 h.The results indicated that the cool wall caused thermal discomfort easier than the warm wall because the thermal sensation decreased and deviated from neutral with time.Subjects’sensitivity of local parts to asymmetric radiation was affected in the conditions beyond neutral,thus their acceptability to asymmetric radiation decreased.The currently used limits of radiant temperature asymmetry tended to underestimate the local discomfort due to the walls.For the conditions tested,The limits of 5%dissatisfaction in radiant temperature asymmetry were 4.4°C(180 min)and 1.8°C(60 min and 120 min)for the warm wall,and 1.8°C at 60 min for the cool wall.展开更多
基金This study was supported by the Key Research and Development Program of Shaanxi,China(2018ZDCXL-SF-03-05).
文摘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.
基金The work was supported by"The 13th Five-Year"National Key R&D Program of China(2018YFC0704500)the National Natural Science Foundation of China under Grant No.51778439.
文摘Occupants’thermal comfort in buildings may be affected by the cool wall and warm wall,which is attributed to the effect of asymmetric radiation.However,the previous majority of the researches on asymmetric radiation were mainly about the comfort limits under thermally neutral condition within 1∼1.5 h but had not considered the effect of exposure duration and the condition beyond neutral.To investigate the human thermal comfort under an asymmetric environment caused by the cool wall and warm wall,forty-four subjects were exposed to neutral air temperature with lateral radiant asymmetries in winter and summer for 3 h.The results indicated that the cool wall caused thermal discomfort easier than the warm wall because the thermal sensation decreased and deviated from neutral with time.Subjects’sensitivity of local parts to asymmetric radiation was affected in the conditions beyond neutral,thus their acceptability to asymmetric radiation decreased.The currently used limits of radiant temperature asymmetry tended to underestimate the local discomfort due to the walls.For the conditions tested,The limits of 5%dissatisfaction in radiant temperature asymmetry were 4.4°C(180 min)and 1.8°C(60 min and 120 min)for the warm wall,and 1.8°C at 60 min for the cool wall.
