Microturbines have proven to be a vital part of the distributed power generation field due to their low emissions, compact size, high reliability and low maintenance. However, microturbines operate at low pressure ratios and relatively low turbine inlet temperatures that limit cycle efficiency. In order to overcome these limitations, microturbines often utilize a recuperator or regenerator to achieve the optimal balance between improved heat rates and reduced pressure ratios across the turbine. Recuperator design aims to achieve maximum effectiveness while staying reasonably compact, which creates the need to study novel heat transfer surfaces for compact heat exchanger application. In this study, experimental data of heat transfer augmentation and friction factor augmentation values for various turbulator geometries is used to determine the required heat exchanger volume to achieve 85%, 90%, and 95% effectiveness. A parametric analysis of various recuperator channel surface areas and turbulator geometry data will be utilized to determine the feasibility of increasing thermal efficiency while remaining compact to avoid large, negative effects on power density for a hypothetical gas turbine modeled after the Turbine Technologies, Ltd. SR-30 Turbo-Jet Engine. The turbulators considered in this study consist of 4 wedges, 4 ribs, and a dimpled geometry. The results will highlight the applicability of surface features in recuperator designs that can improve overall efficiency for microturbines. Results present the power density, thermal efficiency, and specific fuel consumption as functions of heat exchanger channel Reynolds number for heat exchangers implementing different turbulators. It is shown that dimples at low Reynolds numbers yield 85% effectiveness with only a 8% reduction in power density and 90% effectiveness with only a 12% reduction in power density. Ribs and wedges also perform well but suffer from high pressure losses due to their obtrusive design.

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