Printed circuit heat exchanger performance analysis using non-uniform segmental design method

Abstract

Supercritical carbon dioxide (sCO2) is currently being studied as the working fluid in power producing Brayton cycles due to its excellent physical and thermodynamic properties, especially near the critical point. Printed circuit heat exchangers (PCHEs) are being considered for use as condensers and recuperators for this purpose due to their high strength and compact designs. The entire average data reduction method has traditionally been the means by which to evaluate the Nusselt number, Colburn factor, and Fanning friction factor for these heat exchangers. Then the segmental design method of data reduction was proposed which greatly improved the accuracy of these analyses. This paper examines, through computational fluid dynamics (CFD), the design and operating factors which influence the size of data sampling interval that must be used to accurately apply the segmental design method to zigzag-channel and straight-channel PCHEs. Then a non-uniform segmental design method is used and evaluated against several test cases. Data indicates that the interval size required for PCHEs data analysis is primarily driven by channel bend angle for zigzag-channel designs and by mass flow rate for straight-channel designs. The non-uniform segmental design method was of limited use for zigzag-channel heat exchangers operating near the critical point. The method was quite useful for reducing the number of required data sampling points for straight-channel PCHEs with low mass flow rates operating near the critical point.