Study On Asymmetry Capillary Radiation Air Conditioning

The energy efficiency and comfort make capillary radiation air conditioning a good prospect for development. Since the radiation apparatus can not evenly arranged on the interior wall surfaces, making the temperature difference between the surfaces of wall high, such that the radiation heat transfer between the human body and the wall surfaces are quite different, hence, the human body will get asymmetric radiation. When the angle coefficient between human body and radiating surface is large, or when the distance between human body and radiating surface is short, it can affect human comfort. Therefore, the in-depth study on asymmetric radiation phenomena in summer radiant cooling is necessary. By experiment and simulation, the effects from asymmetric radiation to the indoor thermal environment was studied. Besides, the thermal sensation of human beings on both local part of body and whole body, thermal comfort and other thermal reaction, and their relationship in the environment of asymmetric radiation were analyzed. furthermore, the evaluation model of human thermal acceptable degree was obtained.Firstly, this paper introduces the principle of radiant heat transfer, and analyzes the reasons of asymmetric radiation phenomenon. By comparing the existing methods of evaluating human thermal comfort in asymmetric radiation environment, it pointing out that the experimental method is the most appropriate way. It analyzes the vote values of thermal sensation and thermal comfort to obtain the relationship between human thermal responses.Secondly, based on the established asymmetric radiation room model, the simulation software Airpak is used to calculate, simulate and analysis the distribution of air temperature, velocity, velocity vector, and PMV values in different conditions. The experiment can verify the effectiveness of the use of model. The analysis shows that within 0.5m, the closer to the capillary mat, the lower the air temperature, and the more effective on the surrounding air temperature from symmetric radiation. In this case, the human body feel uncomfortable. On the other side, it shows the temperature gradient at vertical direction is pretty small and the PMV values are within the range of human comfort. Thus, the closer to the capillary mat, the greater impact on the air temperature and comfort from the surface of it.Finally, by the way of questionnaires, under different conditions, the thermal comfort vote values in local parts of human body and the whole body were obtained. Meanwhile, the relationship between each of the heat reaction was analyzed. The studies show that in the same conditions, the thermal sensation and thermal comfort vote values from different local parts of human body are significant different; in the asymmetric radiant cooling environment, the temperature of capillary surface greatly affects thermal comfort of human body; with the distance between the testers and the capillary mat increases, the temperature of capillary mat surface increases. The vote values in local parts of human body and whole body increase; the most unfavorable localized parts of the body determines the overall sensation of heat and thermal comfort; by analyzing the relationship among maximum value of different thermal comfort for local body; the sensation of whole body; thermal comfort of whole body and the acceptability, the model for evaluate overall thermal acceptability based on the total thermal comfort is established.