| Summary: | 碩士 === 國立屏東科技大學 === 車輛工程系所 === 100 === This thesis investigates the air conditioning system and manikin temperature distribution in the cabin of a new generation of a two-seat electric car as well as manikin comfort through PMV and PPD analyses. The cabin model used was based on an electric car developed in our department. This work studied the effect of roof ventilation system and air-conditioning sytem on the temperature rise and passengers comfort when the cabin is continuously exposed to the sun.
This study combined the cabin geometric factor and the air-conditioning system to simulate the temperature and flow fields in the cabin and to analyze the manikins comfort using PMV and PPD analyses. Different from other numerical studies related to the air-conditioning of cabin, this thesis takes into account the solar radiation and manikin model with an additional ventilation system. The manikin model could be divided into five parts including the head, the body, the hip, the hands, and the legs. Present numerical approach applied the k-ε turbulence model and DTRM radiation model. The manikins were assumed to have two different rates of metabolism and various clothings. Then, the PMV and PPD analyses were performed to determine the thermal comfort.
Based on current numerical results, the cabin roof ventilation system is capable of effectively cooling down the cabin temperature warmed by solar radiation. The cabin temperature depends on the time the cabin exposed to solar radiation and the orientation of the car. If the car is facing north, the driver’s hands and legs as well as the right side of the front passenger body will be exposed to the intense solar radiation. Results also show that the exchange of cabin air with its ambient through the ventilation system is still difficult to reduce the thermal energy the persons generate at high rate of metabolism and therefore the surface temperature of the manikins continue to rise. According to the PMV analysis, manikins with short clothes and low metabolism rates enter the cabin, which has been exposed to the sun for an hour, would feel comfortable after activating the air-conditioning system for 30 seconds. If the manikins wear heavy clothes or engage in high metabolic activities, the PMV index may deviate from the range between ±0.5 leading to an increase in PPD index and double the time it takes for the manikins to achieve comfort level. The recirculation of cabin air through a vent at the cabin roof was also been investigated. Though this scheme was unable to reduce PPD index effectively, it could make the PPD indeces at different parts of the manikin more uniform and hence reduce the feeling of discomfort.
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