Study On Influences Of Indoor Relative Humidity And Air Supply Modes On Thermal Comfort Of Human Body

With the development of economy and the improvement of people’s living standard, people’s demand for the indoor air quality is more and more high. As an air conditioning system of controlling the indoor thermal and wet environment, it is necessary to maintain the indoor temperature field and velocity field, and to control the indoor air relative humidity. The indoor air relative humidity, temperature and air flow rate are not only related to the human body thermal comfort, but also has a significant impact for indoor air quality. However, at present, there are few studies on the effect of relative humidity. In view of this, under the six air supply models of top-supply and down-return, top-supply and up-return, side up-supply and down-return, down-supply and up-return, mechanical displacement ventilation, stratum ventilation, and five kinds of interior design relative humidity of 40%、50%、60%、70%、80%, in this thesis, the numerical simulation and experimental study would be used to explore and compare the influence of the indoor thermal and wet environment change of being caused by the different air supply modes and indoor relative humidity on the thermal comfort of human body.In the study subject, the FLUENT was selected as the numerical simulation software, and the geometric model was established according to the actual size of artificial environment chamber comprehensive experimental bench, and t hen, the grids were divided; the control equations and flow model were selected; the initial and boundary conditions were set. And next, the numerical simulation calculation was carried out. The experimental bench was designed and built; the air relative humidity, temperature and flow rate in a X=3m plane were measured and collected by the temperature and humidity transmitter and wind speed probe The numerical simulation and experimental study were used to explore and analyse the subject contents, and the experimental results were used to verifie the correctness and feasibility of numerical simulation results. Within the scope of this study, using the mathematical method of л theorem and multiple linear regression analysis fitted a empirical formula of PPD in the human activity areas with air temperature, relative humidity and velocity, and some main conclusions could be came and were as follows:(1) With the numerical simulation results and experimental datas being compared and analyzed, it could be fould that the relative humidity values of simulation and experiment were basically consistent; the maximum error was 8.2%, and the errors were within the acceptable range in the different air supply modes and different interior design relative humidity. Thus, the mathematical models and numerical simulation methods used in the study of this thesis could be used in the related contents study.(2) With the numerical simulation, it was found that the air distribution was different in different air supply modes and when the air flowed through the simulated heat source, it would be affected a lot by the thermal buoyancy force under the different air supply modes. With the numerical model geometric size referencing for the experimental bench size, under the same air supp ly volume, the air supply velocity of mechanical displacement ventilation and stratum ventilation conditions was lower and was only 0.11m/s, therefore, the air flow velocity in the two kinds of air supply models was lower.(3) The temperature around the human body was obviously higher than that of other areas, and the gradient was larger, and the temperature in the air supply intlet was lowest under the different air supply modes. The indoor temperature was relatively higher under the down-supply and up-return air supply mode, and up to 29°C.(4) From the numerical simulation results found that the relative humidity distribution gradient in the remote area from human body was relatively lower and the gradient around human body was relatively greater. The experimental study found that the highest air relative humidity was located in the location of Z=0.50 m under the five kings of air supply models of top-supply and down-return, top-supply and up-return, down-supply and up-return, mechanical displacement ventilation, stratum ventilation. Under six groups air supply conditions, the difference of maximum average relative humidity of seven measuring points was 5.5%, which appeared in the air supply condition of mechanical displacement ventilation, and the minimum difference was 2.1%, which appeared in the air supply condition of top-supply and down-return, thus, the indoor air relative humidity distribution gradient was largest unde the air supply model of mechanical displacement ventilation, ang it was lowest unde the air supply model of stratum ventilation.(5) The numerical simulation showed that the air relative humidity in the air supply inlet was highest under the air supply models of top-supply and down-return, top-supply and up-return, and they were the key parts of prewenting condensation. The experiment found that when the indoor design relative humidity was higher, the relative humidity of close to the roof was relatively lower relative to other measuring points under the mechanical ventilation mode, and obviously, this kind of air supply model could effectively prevent roof condensation.(6) Under the condition of office standard interior design relative humidity 50~60%, the PMV values were between-0.5~0.5 under the four kings of air supply models of top-supply and down-return, top-supply and up-return, side up-supply and down-return, mechanical displacement ventilation, and it meetd the thermal comfort requirements of the human body. With the interior design relative humidity was 60% under the air supply model of down-supply and up-return, the PMV value was 0.57, and the human body would feel slightly warm. With the interior design relative humidity was 50% under the air supply model of stratum ventilation, the PMV value was-0.52, and the human body would feel slightly cool.(7) The energy use efficiency in human activity areas under different air supply modes was analyzed with the interior design relative humidity 60% as an example. It was found that the energy use efficiency in the activity areas was highest under the air supply models of mechanical displacement ventilation and stratum ventilation, and it was 1.5. It was only 0.9 under the air supply models of top-supply and down-return, side up-supply and down-return.