Development of the Metal Foam Electrical Resistance Heater

Abstract

This thesis presents a novel concept using a radial heating element made from porous Fe-Cr-Al metal foam in an air heater. Electrical resistance heating has been used extensively to convert the electrical energy into thermal energy. An analytic heat transfer model is first developed to estimate dimensions of the heating element. Four prototype Fe-Cr-Al metal foam electrical heaters with different levels of porosity and density are built. A more detailed computational fluid dynamics modeling of prototype heaters to include the temperature loss to the surroundings is developed. Experiments were conducted to evaluate effects of airflow rates and electrical current and measure the change of air inlet and outlet temperatures. The temperature rise in the airflow is directly proportional to electric current, and inversely proportional to the weight density of the foam. The temperature appears directly proportional to airflow rate in low density foams, while it is inversely proportional in foams of higher relative density. Experimental temperature measurements show reasonable agreement with modeling predictions. Finally, possible improvements to the initial concept are discussed.