A simplified dynamic model based on response factor method for thermal performance analysis of capillary radiant floors

Abstract

Capillary radiant floors are much thinner and lighter than concrete radiant floors by embedding capillary tubes in insulation layers to supply heat, so that they can respond to temperature adjustment more quickly. In this study, a simplified dynamic model for the thermal performance analysis of capillary radiant floors was developed based on the response factor method. Next an experiment was conducted, the results of which were compared to results predicted by the model. The calculation results agree well with experimental data. The maximum deviation between the calculated surface temperatures and the experimental mean surface temperatures is 0.4 °C during the period of the starting and the maximum deviation of heat flux of the water side in the first minute is 8%, respectively. The developed dynamic model can calculate the surface temperature of the capillary tube and the heat fluxes of both the water side and the indoor air side directly if the water temperature and the indoor temperature are known regardless of whether they are constant or varied. The transient heat supplied by water and the heat stored in the floor can also be determined then. The model can be used to calculate the upward heat flow into the room above the floor and the downward heat flow into the room below the floor. At last, the effects of the surface layer and the tube spacing on surface temperature, heat flux, and time constants of capillary radiant floors are also analyzed by the simplified dynamic model.