The Development of Drawn Microchannel Flow Inserts for High Temperature Waste Heat Recuperators

Abstract

The U.S. Department of Energy has estimated that the opportunities for industrial waste heat recuperation far exceed the current installed base of renewable energy. Of greatest potential are high temperature applications of waste heat recovery including opportunities in emerging technologies such as solid oxide fuel cells and the solar thermal processing of fuels. High temperature recuperators are typically produced from nickel super-alloys. To improve the economics of high temperature recuperation, microchannels have been applied to reduce the size and weight of the recuperators. Machining of microchannel features into these alloys is not only difficult, but expensive due to low material utilizations. Efforts to form microchannel geometries require the use of highly porous, micro-scale pyramidal truss networks inserted into low pressure microchannel to resist fin deflection. Challenges include the formability of the superalloy and the need for precision registration to the dies. In this paper, we discuss the limitations of conventional drawing for producing a truss network made from a nickel superalloy.