Studies on thermal performance of electrical heaters by using porous materials

This paper is devoted to the subject of new configurations of electrical heaters that use porous media. Thermal performance of two innovative designs are estimated and compared with that of the conventional ones. In the first design, airway is filled with a porous insert while the second heater uses a porous heating element instead of the conventional solid ones. The coupled differential equations for both solid and gas phase are solved simultaneously by a control-volume based procedure along with the corresponding boundary conditions, using SIMPLE algorithm. Results reveal that for equal air flow rates, equal heater masses, and the same energy generation rates, the heating element in the porous heater attains the lowest temperature. Surprisingly, this heater also achieves the lowest pressure drop, which is a result of lower air velocity inside the heater. The results also show that at the same aforementioned conditions, the heater with porous insert suffers from the highest temperature while it has a medium pressure drop with respect to the other designs.