Themal Characteristic And Control Study Of Radiant Cooling System

The radiant air conitioning(RAC) is a new air conditioning style. It has an advantage of convection air conditioning in high comfortable,high energy-saving and clearing. The radiant air conditioning include radiant ceilling , floor cooling and the raiant metal board, the text aimed the radiant cooling and floor cooling system ,research the characteristics and , analyzed the influent factors and influence for running results through researching the tip thermal characteristics of radiant ceiling project in Nanjing and floor cooling system in Handan, and got a control method for radiant air conditioning.In the analysis of heating thermal comfort, using physical models, mathematical model and numerical analysis and experimental analysis, the analysis thermal radiation system and the impact of factors and the indoor temperature changes, To identify the factors and the corresponding changes in the indoor temperature, and in the course of testing the various phenomena cause analysis.For thermal stability of the radiation system, the indoor temperature, radiant face average temperature and average temperature of cold media, there is a corresponding relationship, there are delays, the surface temperature of the indoor temperature has a direct impact on the relationship between the non-summer Obviously, the impact on more factors for backwater temperature and the temperature on the surface there is a delay, this delay on the end of the control system adverse, you can through other means to eliminate, outdoor thermal radiation is the environmental impact of air-conditioning systems Can not be ignored in an area, there are two kinds of direct and indirect role in the indoor temperature trend is the deciding factor. Building the type of system has also affected the operation and regulation, using energy-efficient construction is conducive to the normal operation of systems and energy conservation.Condensation problems isn't only infuence the appearance of the building, but also infuence the use of the building effects and human health, comfort, its control and temperature control is just as important. In radiant cooling system, condensing the impact of many factors, the literature that the increase in radiant face return water temperature to ensure that the indoor surface temperature is higher than the dew point temperature, or using the drying of displacement ventilation systems to prevent condensation. In essence analysis, to ensure that radiant face is not condensation, to meet the cooling capacity of the premise, as far as possible backwater of the increase in temperature, while use of air-drying treatment programme. The application of research at home and abroad, the displacement ventilation is the most commonly used, and existing projects in the fan-coil used to deal with air, so can guarantee that the indoor dry, but failed to meet health requirements. Another new type of material for the development and application of radiation to provide more cooling of the application of space.Though condensation of the ground experiments, found that condensing the reason is that the indoor dew point temperature is too high, do not meet design requirements, is not conducive to human health. If we can control indoor relative humidity within reasonable limits, can effectively prevent condensation. In addition to displacement ventilation and cooling radiation combination of theoretical and experimental analysis, come to the floor displacement ventilation systems can not solve the condensation problem, only to a certain extent, ease the severity of the condensation. And concluded that the replacement of fresh air ventilation for drying, its handling of station, and indoor and outdoor wet state of the environment related to its real-time monitoring and regulating the ground can do to prevent condensation.According to radiation at home and abroad for the operation of air-conditioning control, the control was part of the control parameters, input parameters and control of radioactive cooling in the parameters involved in the analysis of the parameters to compare the advantages arid disadvantages of the various control programmes to identify and radiation for a cold characteristics of control programme. Nanjing and the operation of a residential area of analysis, analysis of such control, the system's operating parameters to meet the requirements of the test analysis found that the indoor temperature and relative humidity requirements are met and to prevent condensation of radiant face.For the radiation air-conditioning, the winter's control is more simple than the summer, the impact factors is more than summer, and the change parameters, the control system is not easy to grasp, but with the development of control technology, multi-parameter control and intelligent The complexity of the control of which could be achieved. It also adopted the analysis of the causes of the factors to identify the essence of the existing problems between each other and the impact of radiation so that we can better understand the operation of air-conditioning the end of radiation characteristics, a more comprehensive grasp of the operating system, better able to control better Applicable to such a system for more work.Through some projects of RAC have a lot of qustion in practice .such as the condensation of floor ,the cooling floor is quite cold .the qustion is gardually solved and developed by the research ,and prospect is good .in south area,as the developed of economic and people's life quality,the project is get an widly accept,and begin to use the system.,get an good purpose. Radiant air conditioning is different from custom convection,radiant surfaces exchange energy with indoor air by radiant and convection, because of the results of radiance, it isn't horizontal temperature gradient.,connecting with replacement ventilation system, it can offer fresh and clean air in working area. On energy-saving, it can use natural source. In the same room, because of the radiance , the indoor air temperature is lower about 2℃than custom air conditioning, So the system can save about 20-50% energy. In the international environment of energy-lack, the comfortable and energy-saving air conditioning is developed, which is a new trend in the future. But the north Europe is different from our country in weather condition, and the successful advice can't be used in our projects. We have our different conditions, so we need more analysis of the project problems and the tip thermal characteristics, find the control methods and useful advise. It has an important meaning for the development of radiant air conditioning in China.