Design of a high effectiveness ceramic micro-channel heat recuperator for micro-turbine application
A highly effective recuperator with a low-pressure drop is a key enabling technology to increase the efficiency of the micro-turbine. To achieve an isentropic cycle efficiency of 35%, the average micro-turbine would require a recuperator that achieves close to 99% effectiveness with a pressure drop as low as 2%. A previous theoretical work shows that a micro heat exchanger designed for a cryocooler can achieve effectiveness of greater than 97% with a pressure drop of 3%. A similar heat exchanger could be used as a recuperator in a micro-turbine as an alternative to the metallic primary surface recuperators currently used, achieving at the highest 90% effectiveness. This paper presents the design and analysis of such a micro heat exchanger. The proposed design will be a counter flow, multi-layer pile of parallel ducts with wall thickness of 50 µm (according to limitations of micro-fabrication) and will be constructed with SiCN polymer derived ceramic, fabricated using micro-stereo lithography technology. Two designs, the square cross-section channel and the equilateral triangle cross-section channel, are proposed and compared. The resulting heat exchanger designs from optimization achieve an effectiveness of 96.4% and pressure loss of 3% for the square cross section and an effectiveness of 97.2% with a pressure loss of 2.4% for the triangle cross section. The triangle cross-section design is able to achieve maximum performance for the turbine cycle of 40%. Both designs require a volume of0.125 m3 are structurally stable, and can withstand temperatures up to 1500°C.
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Bachelor of Science (B.S.)
College of Engineering
Dissertations, Academic -- Engineering;Engineering -- Dissertations, Academic;Heat exchangers;Heat transfer media -- Mathematical models
Length of Campus-only Access
Honors in the Major Thesis
Carman, Bradley Gene, "Design of a high effectiveness ceramic micro-channel heat recuperator for micro-turbine application" (2002). HIM 1990-2015. 304.