A Comparison of Some Heat Transfer Surfaces for Small Gas Turbine Recuperators

Abstract

For small gas turbines a recuperator is mandatory to achieve high thermal efficiencies, 30 percent and higher. As the recuperator represents 25–30 percent of the overall machine cost, efforts are now being focused on establishing new low cost recuperator concepts for gas turbine engines. In this paper a comparison of four different heat transfer surfaces is performed for a recuperator for a representative 50 kW micro turbine. Two standard methods of comparison, the so-called volume goodness factor and the flow area goodness factor, were used to choose several promising heat transfer surfaces for design calculations of a recuperator heat transfer matrix. Thus a direct comparison of recuperator matrix dimensions, volume and weight is possible for the selected surfaces. The hydraulic diameter is equal for all surfaces thus only their thermohydraulic performances are compared. In this paper details of the heat transfer surface geometries as well as the resulting recuperator matrix dimensions, volumes and weights are presented.