The Effects Of Radiation Asymmetry On Planar Radiation Air Conditioning And Countermeasures

As a new development direction of the air conditioning technology, planar radiation air conditioning has the advantages of high health, comfort and energy saving. Planar radiation air conditioning implement the counterpart of the grade of energy, temperature and the requirement of energy cascade utilization, so it is widely used.Planar radiation air conditioning technology does not impact on the thermal comfort of human body by heating or cooling air, but by raising or reducing wall temperature indoors to form certain radiation intensity, thus affecting the thermal comfort of human body. For plane radiation air conditioning system, radiant panel for installation reasons are not likely to be evenly laid in the walls of the room, so the temperature of each wall is different. Summer cooling conditions, for example, temperature of the wall equipped with radiant panel is lower than other wall that without laying radiation board, thus causes the radiation intensity of different wall in the face of the human body, resulting in a radiation asymmetry phenomenon. the thermal comfort index PMV equation deduced by the Fanger equation is not fully applied. Therefore, it is necessary to go into details of planar radiation air conditioning asymmetry phenomenon, to point out the asymmetric theoretically radiation’ s influence on planar radiation air conditioning, and thus making the PMV equation more suitable for asymmetric thermal comfort evaluation in radiation environment.This paper analyzes the asymmetry phenomenon of radiation in the planar radiation air conditioning system, and respectively analyzes the effect of the radiation on radiation heat exchange and the effect of clothing thermal resistance on human thermal comfort with asymmetric Airpark simulation.In this paper, evaluate the thermal comfort of human body comfort with the PMV value as the index, namely to analyze the effect of radiation heat exchange and clothing thermal resistance on PMV value. Theoretically, analysis the influence of asymmetric radiation on radiation heat transfer and thermal resistance, and carries on the revision to make it more suitable for thermal comfort evaluation in svmmetric radiation environment. This research is helpful to reduce the energy consumption of air conditioning system in our country, and to improve the thermal comfort in cold areas, promoting the low carbon economy.Firstly, this paper introduces the heat transfer mechanism of planar radiation in air conditioning room, analyzed the reason of asymmetric radiation under the conditions of heat radiation air conditioning theoretically. Introduces the Fanger theoretical derivation process of thermal comfort equation and the Fanger PMV index that is deduced by thermal comfort equation. Pointed out that because of the influence of the asymmetry of radiation, heat convection and the changes of clothing thermal resistance and PMV value changes. So it is necessary to make PMV equation more suitable for radiation environment environmental thermal comfort index.Secondly, in view of the asymmetry of planar radiation air conditioning system, the influence of the radiation phenomenon on radiation heat transfer is analyzed. Introduced the thermal comfort equation used in the radiation heat transfer model and analyses the applicability of the asymmetric radiation environment. The radiation heat transfer model does not consider the effects of wall surface emissivity on radiation, and does not consider the influence of Angle coefficient between palisade structure on radiation. when the window is in the exterior wall, its heat transfer coefficient is bigger, leading to the temperature difference between interior walls,so it is necessary to consider the outside window as a single heat exchange surface. New radiation heat transfer model is established according to the above factors, solve the radiation heat transfer under the new radiation heat transfer model. Because new radiation heat transfer model is many surface closed system,it is need to use a computer to solve. This article uses the Airpak to simulate the temperature, speed, PMV value distribution in two cases. When the outside window is consider as a separate calculation of retaining structures and set up the various surfaces according to boundary condition leading that the window outside and wall area is not comfortable. So at the time of calculating PMV value it is necessary to consider the outside windows and walls as a separate enclosure structure.Finally, the research analyzed the effect of asymmetric radiation on the thermal resistance of clothing and carries on the revision. Using C language programming calculation, and analyzes the effect of clothing thermal resistance on PMV value, therefore it is need to correct clothing thermal resistance under asymmetric radiation. Using the formula deduced the effect of asymmetric radiation on the thermal resistance of clothing, and define it as comprehensive clothing thermal resistance. The effect of asymmetric radiation on the thermal resistance of clothing mainly include the influence of clothing emissivity and wall emissivity on the clothing thermal resistance. This paper is divided into two cases:the clothing emissivity and surface emissivity is basic same, wall emissivity can be negligible in comparison with clothing emissivity. In both cases, simplify the synthetic clothing thermal resistance model respectively, and respectively analyze the influence of clothing emissivity on the thermal resistance of clothing and PMV value using C programming language.