Metal Foam Electrical Resistance
ABSTRACT
COOKSON, EDWARD JAMES. Development of the Metal Foam Electrical Resistance
Heater. (Under the Direction of Dr. Albert Shih.)
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.
Development of the Metal Foam Electrical Resistance Heater by Edward James Cookson
A thesis submitted to the Graduate Faculty of
North Carolina State University in partial fulfillment of the requirements for the Degree of
Master of Science
Mechanical & Aerospace Engineering
Raleigh
2003
APPROVED BY:
________________________________ _________________________________
________________________________
Chair of Advisory Committee ii Personal Biography
Edward Cookson was born in Opelika, Alabama on March of 1979, and is the son of Edward and Madeline Munn and Jim and Alison Cookson. His brother is Brian Cookson. He grew up in Gastonia,
COOKSON, EDWARD JAMES. Development of the Metal Foam Electrical Resistance
Heater. (Under the Direction of Dr. Albert Shih.)
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.
Development of the Metal Foam Electrical Resistance Heater by Edward James Cookson
A thesis submitted to the Graduate Faculty of
North Carolina State University in partial fulfillment of the requirements for the Degree of
Master of Science
Mechanical & Aerospace Engineering
Raleigh
2003
APPROVED BY:
________________________________ _________________________________
________________________________
Chair of Advisory Committee ii Personal Biography
Edward Cookson was born in Opelika, Alabama on March of 1979, and is the son of Edward and Madeline Munn and Jim and Alison Cookson. His brother is Brian Cookson. He grew up in Gastonia,
References: Ashby, M., Fleck, N.A., Hutchinson, J.W., Gibson, L.J., Wadley, H., Evans, A.G., Wadley, H.N., 2000, Metal Foams - A Design Guide, Butterworth-Heinemann. Banhart, J., 2001, “Manufacture, Characterization and Application of Cellular Metals and Metal Foams,” Progress in Material Science, Vol Blacker, T., 1996, “The Cooper Tool,” 5th International Meshing Roundtable, Sandia National Laboratories, pp 13-30. Erickson, C. J., 1995, Handbook of Electrical Heating for Industry, IEEE Press. Floyd, D., 2001, Fluid Properties of Open Cell Sintered Iron Based Porous Metal Structures, Experimental Results and Discussion, Porvair Fuel Cell Technical Report. Hegbom, T., 1997, Integrating Electrical Heating Elements in Appliance Design, Marcel Dekker, New York. Incropera, F., Dewitt, D., 2002, Introduction to Heat Transfer, Wiley, New York. Kanthal, 2001, Kanthal Handbook – Heating Alloys for Electric Household Appliances, Kanthal AB. Lu, T. J., Stone, H. A., Ashby, M. F., 1998, “Heat Transfer in Open-Cell Metal Foams,” Acta Materialia, Vol Qu, J., Shih, A. J., and Scattergood, R. O., 2002, “Development of the Cylindrical Wire Electrical Discharge Machining Process: Part I: Concept, Design, and Material Removal Yoro, K., Itsauaki, S., Saito, H., Nakajima, S., and Okamoto, S., 1998, “Diesel Particulate Filter Made of Porous Metal”, Diesel Exhaust Aftertreatment , SAE Special Publications, Vol. 1313, SAE Paper # 980187, pp. 17-23, SAE, Warrendale, PA.