Graphite Foam Heat Exchanger Technology for Energy Recovery

The recovery of heat currently wasted in exhaust gases can reduce fuel consumption in almost every commercial and industrial sector. In the electricity generation sector alone, even modest improvements in energy recovery effectiveness would result in billions of dollars in savings annually. New materials made from conductive graphite have created a significant opportunity to produce heat exchangers for energy recovery from exhausts. This project seeks to advance this technology in preparation for the commercialization of energy recovery products, initially for microturbine generators and ultimately for thermal power generation by utilities. In Phase I, new elements made from conductive graphite materials performed beyond their thermal engineering and reliability expectations, demonstrating that they are ideal for exhaust heat recovery. Issues with bonding, sealing, pressure drop, thermal stresses, corrosion, and maintenance were overcome with solutions appropriate for commercial products. Phase II will extend these results and culminate in full-scale field studies. In particular, the conductive graphite materials will be optimized to maximize the recovery of energy from generator exhausts; robustness, reliability, and performance will be measured under practical operating conditions; and manufacturing tools will be advanced to optimize element fabrication. Commercial Applications and Other Benefits as described by the awardee: The graphite heat exchangers should enable more energy to be removed from exhausts because graphite does not corrode in condensing combustion products. Costs should be reduced because the graphite would significantly extend the lifespan of energy-recovery heat exchangers. In addition to electricity generation, the technology should be applicable to energy recovery in residential, commercial, and industrial refrigeration and air conditioning; chemical, petroleum, and industrial plants; and automobiles, trucks, trains, and aircraft.