| The low-temperature water floor radiant heating system can make the system saveheating energy consumption without influencing the room thermal comfort throughreasonable control under intermittent operation. How to conduct reasonable control ofthe system needs to master the temperature change rule of intermittent operating system.It is important to study the heat transfer process and master the influences of stepdisturbance during heat charge and discharge process and double outside disturbancecaused by outside air temperature and sun radiation.Two-dimensional stable and unstable convection models are built, they aresimplified on the basis of the characteristics of heat release and heat absorption processand one-dimensional mathematical model are built. The heat transfer quantity andtemperature distribution formulas are obtained.Test the heating process with numericalsimulation, it is found that the results of one-dimensional simplified model are close tothe simulation results in calculating heat release of heated floor, while more differentfrom the simulation results in calculating heat absorption. Modify the floor surfacetemperature on the basis of numerical simulation results. The revised results are close tothe simulation results.Study the floor surface average temperature fluctuation during heat release bynumerical simulation, it is found that larger temperature decrease will be caused byhigher supply and return water average temperature, smaller coil distance and smallerfilling layer thickness, it took short time for floor heat release tending to stable. Afterabout13h, the floor heat release tends to be constant, after20h it is considered to becompletely released. After2.5h,4.5h and6h, the floor heat storage tends to be constant when oil distance is100mm,200mm and300mm respectively, after4.5h,8h and9h,floor heat storage close to the end.Governing equations of envelope such as walls and roofs are established and theformula of heat transfer is given, energy balance equations of inside wall and room airare established and the treatment method to indoor thermal Boundary Condition isproposed, which supply scientific foundation to the research on heat environment.A common civil architecture in xi’an is selected as research target, study the effectof supply and return water average temperature, coil distance, floor thickness anddifferent intermittent models to intermittent running heated room temperature withEnergyplus. The results indicate that the higher supply and return water averagetemperature is, the larger room temperature range is during warm-up period or initialstage of heat release. The smaller the coil distance, the faster the room temperature rises,dramatic rise happens2h before heating when coil distance is100mm,200mm and300mm respectively, the rise tends to be relatively stable after3h,3.5h and4h.Whencoil distance is200mm, the system opens again3h,6h,9h and12h after stoppingoperation, the room temperature changes differently and the rise of room temperaturetends to be stable after1.5h,2h,4h and5h.For the house faces the north, starting heating10h after stopping at7:00, roomtemperature can reach indoor comfort by increasing supply and return water averagetemperature3℃-4℃and preheating for2h,or preheating in advance for2h when thewater average temperature remains constant. Other time heating18h can meet mostusers when chose to stop heating during7:00-10:00and13:00-16:00. It suggests thedefinite period should be14:00-15:00for those who spend too long time at home, whichcan meet indoor comfort after stopping heating for2h.For the house faces the south, indoor temperature can reach indoor comfort bystopping heating for2h-3h at0:00and stopping heating for7h at11:00, everydayheating12h-13h other time can meet most users. At the same time it can prevent theroom from being over-warm. Compared with the intermittent model, the indoortemperature will be relatively better in which the heating period remain unchanged andheating in advance as well as stopping heating. |
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