Research on Airflow Distributing Characteristic and Dynamic Thermal Comfort in Air-Conditioning Vehicle
|School||Central South University|
|Course||Heating, Gas Supply , Ventilation and Air Conditioning Engineering|
|Keywords||air-conditioning vehicle air quality thermal comfort subjective assessment PMV-PPD/PD index themoregulation model dynamics index of thermal comfort|
This dissertation takes the chamber environment as the main object of research and the thermal comfort and air quality to the chamber environment was researched. The works of this dissertation are related to heat transfer theory, fluid mechanics, thermodynamics, experimental fluid mechanics, ergonomics, man-machine-environmental engineering, statistics and evaluation methodology, etc.A questionnaire is designed to apply to vehicle cabin refer to the thermal environment ergonomics ISO10551 standard and the internationally universal indoor air quality questionnaire. The questionnaire survey were conducted on vehicle to collect subjective sensation responses levels concerning in vehicle thermal comfort and air quality. By contrasting and analyzing the result at different types air conditioning vehicle cabin, the actuality of air quality in vehicle cabin can be gripped. A new synthesize subjective evaluation model that related to air quality inside air conditioning vehicles for summer hot and winter cool region in China is established. The synthesize objective evaluation model(Votez) and percent of dissatisfied(PDz) were developed based on the PMV index and CO2 index. Gray relative analysis based on entropy is applied to analyse the survey results for four air-conditioning vehicles, and the calculated result indicates that the proposed method is reasonable and practical. According to living standard, racial difference, cultural background, psychological expectations, etc, the PMV-PPD index range is extended for summer hot and winter cool region in China.In this dissertation, all kinds of turbulence models were applied to the air-conditioning vehicle cabin applicability. The heat transfer of air-conditioning vehicle are analysed and described by using the physics equation of mathematics. The effect of solar radiation and body heat on airflow and temperature fields in the chamber is investigated, and the distribution of airflow, temperature and humidity fields are researched in different supply air temperature and different supply air velocity. PMV-PPD/PD indexes maked by using C language programme are applied in the research of body thermal comfort. The influences of supply air velocity, temperature and humidity on thermal comfort are respectively studied. The optimal supply air parameters are put forward for meeting the requirement of thermal comfort. Contaminant, the age of air and residual lifetime of air are simulated using a convection-diffusion equation, which are discretized and then solved by using the UDF technology in Fluent. Regularity of distribution for CO2 concentration field, air of age, residual lifetime of air, PAV and PDA indexes are using to study influence fact on air quality. The results provide supports for the optimized design of Ventilation and Air Conditioning system. The comparison is carried out between the simulated and the measured results of temperature, velocity, humidity and CO2 concentration. The agreement between them is quite well.These indexes of Votez and PDZ, thermal comfort and air quality are used to evaluate the air quality in the cabin on difference ventilation mode. The results that tow return air inlets layouted and air supply outlet augmented model can improve the air quality in vehicle cabin.The new thermoregulation model is developed, and compared to the literature data. The results indicated that the new model is reliability and effectiveness. Then the dissertation expound the algorithm coupling thermoregulation and CFD, and analyse the heat exchange between body and environment. Comparison of coefficient of the heat convection and radiation and published literature data is quite well.Based on the results of LES of the vehicle cabin, thermoregulation and Fanger’s thermal comfort theory, it is brought forward the concept of the series of dynamic thermal comfort evaluating indexes based on the thermoregulation, which can be divide into thermal comfort index with dynamic properties DPMV、DPPD、DPD. The dissertation also put forward the moving dynamic thermal comfort indexes taking into account human moving, which can be divide into thermal comfort index with dynamic properties MDPMV、MDPPD、MDPD. The new concepts are completed to thermal comfort theory.