Experimental study of radiation and free convection in an enclosure with a radiant ceiling heating system

Participation of the radiation and free convection in the heat transferred from the ceiling surface of a room to other internal surfaces has been investigated in this study. A model enclosure representing a room was constructed and equipped with a radiant ceiling heating system. In order to have a thermal map over both internal and external surfaces of the enclosure, 108 elements were specified over the walls, floor and ceiling of the enclosure. Temperatures at both sides of the elements were measured using an infrared thermometer and k-type thermocouples under steady state heat flow condition. Using the measured temperatures, conductive heat transfer through the compartment elements was first calculated. 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 radiation and conduction for each element. Based on the results, more than 90% of the heat is transferred by the radiation from the heated ceiling to the other surfaces of enclosure. The participation of the radiation increases slightly as the ceiling temperature is increased.