Thermal design and model analysis of the Swiss-roll recuperator for an innovative micro gas turbine

For the advanced power systems based on the use of microturbines, the major considerations are higher power density as well as higher efficiency for energy-saving. In order to achieve higher efficiency, recuperated systems which recover the exhaust heat then become mandatory and the paramount requirements for the recuperator are high effectiveness and low pressure loss. Here, the thermal design and model analysis of a proposed Swiss-roll recuperator for future higher efficiency microturbines were made with both theoretical approach and numerical simulation. The proposed Swiss-roll recuperator is basically the primary surface type. It is composed of two flat plates that are wrapped around each other, creating two concentric channels of rectangular cross-section. The characteristics of Swiss-roll recuperator resemble the counter-flow spiral plate heat exchanger and have the excellent performance in effectiveness and pressure-loss. From a theoretical analysis, the thermal characteristics of the Swiss-roll recuperator were investigated and its preliminary designs at a given effectiveness for an innovative micro gas turbine were also demonstrated, including the determination of the number of turns, the corresponding channel widths and the required number of transfer unit (NTU). The consequent pressure loss through the recuperator was also predicted. For a given design of the recuperator, the model simulation was then made to provide the insights and needs for further improving the performance of the Swiss-roll recuperator. (C) 2008 Elsevier Ltd. All rights reserved.