Study Of The Heat Dissipation Characteristics Of An Enhanced-convection Overhead Radiant Floor Heating System

Heating energy consumption is an important part of building energy consumption,the proportion of the total energy consumption in the country increased year by year.In many heating modes,the low temperature radiant floor heating has been widely used because of its advantages of high energy saving and high comfort.At present,the low temperature hot water floor radiant heating commonly used in the continuous heating building is mostly buried pipe type structure.This heating mode embed the heating pipe in the filling layer and makes strong heat storage capacity and good thermal stability.However,this heating unit has some problems such as long heating time and poor adjustability in the intermittent heating building.For the research on floor radiation heating system,it is significant to consider the different heating demand and flexible regulation while the advantages have been also taken into account.Based on these,this paper puts forward a kind of an enhanced-convection overhead radiant floor heating system(EORFHS).The experiment system of EORFHS was built,and the test was carried out in the artificial climate chamber.The heat dissipation characteristics of the system during preheating period,intermittent period and stable state were analyzed in different operating conditions of the pipe water temperature,the coil spacing and the opening area.Comparing the EORFHS with conventional radiant overhead radiant floor heating system,it was found that the floor surface temperature and the room temperature of the EORFHS were more responsive during the preheating period;the indoor temperature reached 20°C ahead of about one hour than the conventional radiant floor heating system.Furthermore,during stable state,the floor surface temperature of the EORFHS was increased by 2.7°C,the surface heat flux of the floor was increased by about 10 W/m2,and the heating capacity was significantly enhanced.The pipe spacing had the strongest effect on the preheating time of the overhead radiant floor heating system,and the water temperature of the coil was less effected.The pipe spacing and pipe water temperature had the same effect on the preheating time for the EORFHS.The floor surface mean temperature of the EORFHS is rapidly increasing within 1.5 h.The relationship of the two systems between the intermittent period and the preheating period was also obtained.Analysis the heat transfer process of the EORFHS by its thermal resistance node.Set up the control equation of the heat transfer in floor and the heat balance of the up and lower floor surfaces.Analysis the flow model and heat transfer model of the air in interlayer and indoor.The simulation is carried out to study the distribution of surface temperature and heat flux in the stable operation of the overhead floor under different pipe spacing and pipe water temperature.Analysis the indoor thermal environment of the EORFHS and the conventional overhead radiant floor heating system.And found that the indoor air temperature with EORFHS is 1 °C higher than that of the conventional overhead radiant floor heating system.The distribution of indoor air temperature of these two kinds of system.The heat dissipation of the EORFHS is 5% higher than that of the conventional overhead radiant floor heating system.The indoor wind velocity of the EORFHS is less than 0.2 m/s and that is meeting the comfort requirements of personnel.According to the experimental study,theoretical analysis and numerical simulation,the heat dissipation characteristics and indoor thermal environment characteristics of the EORFHS under different pipe spacing,pipe water temperature and the density of the hole are systematically studied,which laid the foundation for strengthening the design,application and popularization of EORFHS.