Creare has recently delivered a heat exchanger that was used to successfully recover waste heat from the exhaust gas stream from an RR-250 gas turbine engine. Creare teamed with Innovative Automation Inc., Electratherm, and the United States Naval Academy to demonstrate waste heat recovery and conversion to electrical power at the USNA Gas Turbine Laboratory.
Gas turbine engines are used extensively for marine and shore applications for the production of electrical power. The turbine engines are typically less than 40% efficient at full power and significantly less at part power. At normal operating conditions, the temperature of the exhaust gas is quite high and can exceed 1000º F. Consequently, the high temperature exhaust gas contains heat energy that could be converted to electrical power if a reliable means was available for capturing it. By converting some of this waste heat to electrical power, the overall system efficiency is increased, and a reduction in fuel consumption or increase in power production can be realized.
One approach to utilizing this waste heat is to capture and deliver it to a bottoming cycle. Several prior efforts by the U.S. Navy to recover waste heat have shown promise, but various reliability issues were encountered associated with the exhaust gas heat exchanger. This heat exchanger must be able to withstand the high temperature corrosive gas turbine exhaust, endure thermal transients and shock, and withstand the high pressures of the bottoming cycle working fluid that flows through the heat exchanger as it picks up energy from that gas turbine exhaust flow.
Creare Heat Exchanger Development and Demonstration
Over the past several years, Creare has developed and demonstrated prototype heat exchangers for this demanding application. The effort involved contributions from multiple team members to conduct design performance analyses, fabrication trials, assembly of the heat exchanger units, and performance testing. Most recently, Creare teamed with Innovative Automation Inc., Electratherm, and the United States Naval Academy to successfully demonstrate waste heat recovery and conversion to electrical power at the USNA Gas Turbine Laboratory. Creare delivered a heat exchanger that was installed to recover waste heat from the exhaust gas of a RR-250 gas turbine engine. Water circulating through a loop picked up the waste heat from the exhaust gas heat exchanger and delivered the heat to an Electratherm Power+ Generator that produced almost 50 kW of electrical power. Additional testing is planned to exercise the system to further evaluate performance.
The funding for this effort was provided by the Office of Naval Research and the Office of the Deputy Assistant Secretary of Defense for Operational Energy under Contract No. N00014-16-C-2059. Their generous support is greatly appreciated. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the view of the Office of Naval Research or the Office of the Deputy Assistant Secretary of Defense for Operational Energy.