Study On Theoretical Calculation Of Comprehensive Heat Transfer Coefficient Of Radiant Heating Floor Surface

With the rapid development of society,the country is paying more and more attention to energy saving and emission reduction.A large proportion of building energy consumption comes from air-conditioning system.Therefore,the green development of air-conditioning system is of great practical significance to the road of green sustainable development in China.At present,China's building energy consumption is relatively severe,and the annual growth rate of building energy consumption greatly exceeds the growth rate of energy production in China,which seriously damages the ecological environment.As a new air-conditioning system,radiation heating system not only has the advantages of low noise and high comfort,but also has lower energy consumption compared with central air-conditioning system,which is getting more and more serious in modern society.More and more people like and accept it.The key to energy saving and consumption reduction is to make full use of the thermal performance of the heat transfer terminal device.Therefore,a systematic study of the heat transfer process of the radiant floor and the thermal process of the room,mastering the characteristics of the waiting points and temperature changes in the heat transfer process,will be conducive to giving full play to its good thermal comfort and energy saving characteristics,will help its popularization in China,and provide a basis for the formulation of the system operation control scheme.According to the radiant heating system of the floor,taking the inner wall surface of the room as the research object,based on the first law of thermodynamics,the theoretical calculation mathematical model of each wall surface under steady state condition is established,and the programming calculation is carried out by Matlab;The accuracy of theoretical calculation method and Matlab programming is compared with the results of Fluent simulation calculation under the same conditions.The comparison shows that the simulation results are consistent with the theoretical results,which verifies the correctness and feasibility of the theoretical solution.On this basis,based on theory The mathematical model is calculated to explore the influence of influence factors such as room height,outdoor temperature,wall thickness and floor emissivity on the surface temperature of the room and the comprehensive heat transfer coefficient of the radiant panel.The analysis and calculation results have the design and application of the radiant heating room.Must learn from the meaning.The results of calculation and analysis show that,on the premise of keeping the indoor design temperature unchanged,with the increase of outdoor temperature,the floor temperature decreases gradually,but the comprehensive heat transfer coefficient of the floor decreases greatly.The ground temperature basically maintains at about 22?.The temperature of the inner surface of the outer wall increases gradually and the growth trend is linear,and the temperature of the inner surface of the outer wall changes with the increase of the temperature of the inner surface of the outer wall.The rate of change is higher than the rate of floor temperature decrease;the change of room height has a relatively greater impact on the heat transfer coefficient of the floor panel,while the influence on the inner surface temperature and floor temperature of the external wall is relatively small.With the increase of room height,the growth trend of the comprehensive heat transfer coefficient and floor temperature are almost linear,and the overall temperature of the inner wall is decreasing.With the increase of thermal resistance of exterior wall,the decreasing trend of comprehensive heat transfer coefficient is close to linear change,and the temperature of interior surface of exterior wall increases with the increase of thermal resistance of exterior wall also approximates linear change;the higher the emissivity of floor,the lower the floor temperature required,and the floor temperature is determined by the temperature of water supply and return,so lower water supply temperature is needed,which is conducive to energy saving.In addition,the floor with high emissivity is adopted.It can also reduce the temperature of the inner surface of the outer wall,so the heat consumption of the room through the outer envelope structure will be reduced,saving energy.Therefore,in the design and construction of the floor surface,the floor with high emissivity will be selected as far as possible.With the increase of the number of exterior walls,the growth trend of floor temperature and comprehensive heat transfer coefficient is linear,and the decrease trend of the average temperature of non-heating surface is also linear.The overall fluctuation of operating temperature is not large,basically stable at about 18.4?,indicating that the temperature that people feel indoors is relatively stable.