A Study of Thermal Comfort in the Fan Assisted Air Conditioned Environment

• Main Authors: Jian-Wei Laio, 廖健瑋
• Other Authors: Liang-Han Chien
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/9k22rd

碩士 === 國立臺北科技大學 === 能源與冷凍空調工程系碩士班 === 99 === In this study, thermal comfort of fan assisted air-conditioned room have been investigated numerically, and compared with the survey of the thermal comfort questionnaire in measured temperature and wind speed. Nine kinds of fan locations were simulated. The simulation shows that the skin temperature of the body is the coolest when the fan is blowing towards head or back, and second by blowing towards abdomen. To prevent discomfort causing by blowing towards human head, the questionnaire are conducted by blowing towards the abdomen. In the comfortable test, with wind speed and temperature are control parameters. The temperature ranged from 23.9 to 28.1℃,and humidity varied from 60 to 73.5%. The temperature has been divided to three zones,and tested with wind speed 0.1 m/s, 2.18 m/s, 2.36 m/s and 2.54 m/s for each temperature zone. The simulation shows that the PMV values were 1.18、1.08 without fan and with fan, respectively under the condition of: the amount of clothing 0.5 clo, the metabolic rate of 1.2 met (sedentary), the radiant temperature is 28℃, humidity of 70% and indoor dry-bulb temperature 28℃. The PPD value calculate is 38% without fan,and 30% with fan. These results indicate that both, enviroments are hot and the fan has limited influence on thermal comfort. The simulation also shows that the fan location has negligible influence on the environment PMV. However, the questionnaire survey in this study shows that the satisfaction of thermal comfort was as high as 90% under the same environment of the simulation especially for the fan speed at 2.18 m/s, 2.36 m/s, 2.54 m/s. The thermal comfort increased with increasing air flow rate. Hence, the PMV simulation yields considerable error for the case having a fan in the air-conditioned space. By regression analysis of the questionnaire in thermal comfort experiments, an empirical correlation was obtained. The correlation predicted the comfort index with a maximum uncertainty of 0.53, and it predicted satisfaction percentage with a maximum uncertainty of ±17%. By applying the results of this study, the air-conditioning unit can be set at 28℃ with a fan. Compared with a setting of 26℃, approximately 12% electric power can be saved. Although the use of fans may result in extra power consumption, power consumption of fans is relatively small as compared with the air-conditioning power consumption. Hence, this method is expected to save at least 10% of electricity.