Experimental and numerical investigations of a modified designed baseboard radiator using an air gap enhancing free convection heat transfer

The present study aims to improve the thermal performance of conventional radiant baseboard heating systems by proposing a novel and modified design with the least cost and complexity. The convection to radiation ratio for conventional and modified baseboard designs is compared by several experimental tests and numerical simulations of heat transfer between internal pipe flow and indoor air convective flow. By examining the temperature and velocity profiles of both radiant baseboards, it is revealed that the total thermal power of the modified radiant baseboard is 34% higher than that of the conventional one, especially at the occupied zone which has raised indoor air temperature by up to 2 degrees C in different resident postures such as standing, sitting and sleeping. Also, the results show that the convection contribution of the modified design of radiant baseboard is greater than the conventional one, more than 45% in the same conditions, while radiation contribution also grows considerably. The results of 3D steady-state numerical simulations show that heat output from the modified radiant baseboard per cm of panel height is 3 times more than that of the conventional one. Consequently, it is indicated that the modified radiant baseboard has a lower supply temperature, leading to energy-space saving, while its capability to overcome cold air down draught flow is more, which can be of interest to experts in the thermal comfort field. Furthermore, by choosing a modified radiant baseboard, the required length of the baseboard will be reduced by 50% compared to the conventional one, and this can have a significant impact on the architectural and economic limitations of the building industry.