We present a numerical analysis of the thermal behavior of a high-temperature rotary regenerator with a cordierite heat-exchange matrix which is rotated in an indexed fashion. Such an “indexing regenerator” has recently been proposed as a novel high-temperature high-effectiveness heat-exchange solution for microturbines and other heat engines. Our simulations indicate significant differences in the patterns of thermal gradient development between the indexing regenerator and its continuously rotating siblings (e.g. the Ljundstrom air preheater). These features are crucial in understanding the thermal stresses in the regenerator matrix, which in turn will allow designers to increase the longevity and overall reliability of such devices. In addition to the numerical analysis, we have used thermal-imaging techniques to support our simulations and examine in-plane thermal conditions on the inlet and outlet surfaces of the regenerator disk. The principal result of our study is an understanding of the development of thermal gradients in the matrix of an indexed-rotation regenerator. This understanding is fundamental to thermal stress management in the design and operation of indexed regenerators. Analysis indicates that, for the same operating conditions, indexed-rotation regenerators develop lower thermal gradients than continuous rotation regenerators, and thus have the potential for greater reliability. Design recommendations are made from the simulation and experience with a prototype unit.

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