Coke removal in fuel-cooled thermal management systems

In hydrocarbon fuel cooling technology, the coke deposits, which may form in heat exchangers and reactors and on the inside surfaces of fuel system components, degrade heat-transfer, catalyst activity, and fuel-flow characteristics and can lead to system failure. Therefore, in situ regeneration of fouled surfaces was investigated as a practical approach for reducing the impact of coke formation on aircraft thermal management systems. Various surface regeneration techniques, such as carbon burnoff in air or oxygen and carbon gasification using CO2 or steam, were investigated. The most practical technique for in situ surface regeneration of the heat exchangers is the carbon burnoff method. Although the burnoff method is simple and cost-effective, care must be taken to control strong exothermic reactions. For this reason, a kinetic model has been developed and its successful application to regenerate a fouled multiple-channel heat-exchanger/reactor panel from a scramjet test engine is discussed in the paper.