Experimental study of radiation and free convection in an enclosure with under-floor heating system

Contribution of free convection and radiation in the heat transfer from the heated floor of a room to the other internal surfaces has been investigated in the present study. A model enclosure representing a room was constructed and equipped with the under-floor heating system. In order to have a thermal map over both the internal and external surfaces of the enclosure, 104 elements were specified over the walls, floor and ceiling of the enclosure. Temperatures of both sides of the elements were measured using an infrared thermometer under steady state heat flow condition. Assuming one-dimensional conduction, heat transfer through the elements was first calculated using the measured temperatures. A model based on the net-radiation method was employed to compute the radiation exchanges between internal surfaces of the elements. Convection participation was also specified using specified radiation and conduction for an element. Based on the results, 75–80% of the heat is transferred by the radiation from the heated floor to the other surfaces of the enclosure. The contribution of the radiation decreases slightly as the floor temperature is increased.

► Contribution of free convection and radiation was examined using floor heating system.
► Typically, 75–80% of heat transfer is accomplished by the radiation.
► Participation of the radiation decreases as the floor temperature is increased.