air enters the combustor. Preheating of the compressed air permits a small heat input to the combustor for a given power output of the engine. As an intercooler, a regenerator cools the gas between compressor stages. Less work is required to compress cool gas than is required to compress warm gas. Therefore, a regenerator intercooler can reduce the required work input to the compressor. Thus, regenerators can be used to increase the thermal efficiencies and power outputs of gas turbines. the backbones of high-performance re­ High-performance regenerators are generative gas turbines. In the past, lack of understanding of regenerator per­ formance has led to sub-optimal engine designs. Now this book gives com­ prehensive regenerator information. With this book, the designer can design regenerators that will yield gas turbines with maximum thermal efficiencies.