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Differences in the persons’ individual parameters such as age, gender, weight, height and basal metabolic rate have a significant effect on the human body thermoregulation. Therefore, using the human thermal models that developed on the basis of large humanity population cannot lead to accurate results for specific individuals. Because, the individual parameters have not been considered in standard thermal comfort models and also available individual and local models are so complicated in applications; nowadays, the necessity of developing a simple and accurate individualized model is felt. In this study, some physiological parameters such as: body fat percentage, subcutaneous fat layer thickness, body heat capacity coefficient and tissue conductive resistances have been modeled from readily-available external measurement of individuals and these parameters are incorporated into three node-model algorithm structure to predict individual variations in thermal response between individuals. Three-node thermal comfort model is based on Gagge’s standard model that has been accurately estimated thermal sensation of the bare and clothed parts of the body. The model has been verified against the analytical and experimental results where a good agreement was found. In conclusion, the results indicate that the mean error in prediction of skin temperature is decreased from 1.2℃ for three-node model to 0.4℃ for the new individual model.

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The aim of this study is to compare the performance of floor displacement and overhead mixing ventilation systems in providing the thermal comfort conditions for bus passengers. For this reason, the flow and energy have been numerically simulated inside a Scania 4212 bus with its 45 passengers. In the case of displacement ventilation, the inlet diffusers have been located under the seats at the floor and for mixing ventilation mode, the inlet diffusers have been established overhead of passengers. In both cases, as mentioned in ASHRAE standard for public transportation, the inlet air rate of 5 lit/s has been provided for each passenger and the inlet air temperature has been controlled until the predicted mean vote index is within the allowable range of thermal comfort standards. In displacement ventilation because of locating the inlet diffusers on the floor and the buoyancy effects, the air temperature in foot region is about 18C, which is lower than other parts of body and vertical temperature difference in overhead mixing ventilation occurred less than floor displacement ventilation and the temperature difference between foot and head region is only 2C. In overhead mixing ventilation, air temperature near the head is about 24C while in floor displacement ventilation the temperature is about 26C that is not in neutral zone. The results of 65-nodes thermal comfort model indicate that the temperature difference between skin neutral temperatures of each segment in floor displacement mode is higher than overhead mixing ventilation

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Thermal sensation evaluation of occupants in a dense occupancy space can be an effective step for designing ventilation systems of these environments. In a dense occupancy environment, because of the presence of a large population and also differences in personal parameters such as age, gender, clothing, weight, and body mass index, providing the appropriate thermal comfort conditions is complicated. In this study, the individual characteristics effects on thermal comfort conditions of occupants in a dense occupancy environment is investigated by individualized three-node model. For this issue, a dense occupancy environment with displacement ventilation and inlet air diffusers on the floor is modeled and thermal sensation index for occupants who seated in middle row has been analyzed. Based on the results, the women are more sensitive than men under cold conditions. Also, effects of mass body index on thermal sensation are significantly noticeable. Compared with a healthy person, the thinner people have a cold sensation and fatter ones feel warmer. For example, in the mentioned case, difference between thermal sensation index of thin woman and obese man is 0.42 for the bare parts of the body, indicating noticeable effects on thermal sensation.

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In the present study, a new thermal comfort model based on cutaneous thermoreceptors has been developed by using non-Fourier heat transfer in biological tissue. The new model considers the concept of finite propagation speed of thermal disturbance by using non-Fourier equations. Since biological tissues consist of complicated and nonhomogeneous structure, the heat process is different from other materials. The dual phase lag (DPL) bioheat transfer model describes two time relaxations is a case of non-Fourier heat transfer application in biological tissue. In this study, the mentioned model has been utilized to evaluate the temperature distribution at the depth of skin thermoreceptors. The new thermal comfort model has been verified by comparisons with experimental data where a good agreement has found. As thermal response of the human cutaneous thermoreceptors depends on temperature and its change rate at the depth of thermoreceptors; therefore, it is very important to estimate these parameters with a good accuracy. In this paper, the previous models improved and effect of non-Fourier heat transfer on temperature derivative is investigated. It is found that the DPL model has a significant effect on change rate of temperature and thermal response of cutaneous thermoreceptors.