Thermo Hydraulic Performance of Brazed Plate Heat Exchangers computational and experimental studies

Abstract

vii newline1 ABSTRACT newlineBrazed plate heat exchangers are widely known for their compactness and efficient heat newlinetransfer. The geometry of the brazed plate heat exchanger is quite complex compared to newlinethat of some common heat exchanger types. Extensive research is necessary to document newlinethe thermos-hydraulic response of the heat exchanger. Experimental research requires the newlinefabrication of many heat exchanger units covering a wide range of geometrical newlineparameters. That can be expensive. That is why most university research on the subject newlinelimit experimental studies, and compensate the loss by extensive simulation studies. newlineNumerical studies are also expensive in terms of time and computational resources. This newlinecan be conquered by employing innovative computational schemes. newlineTo tackle these two problems, a simulation model has been created employing the concept newlineof periodicity and using the periodic boundary condition in ANSYS Fluent. Dimensions newlineof the geometrical features have been varied over reasonable ranges, and the thermoshydraulic newlineperformance has been simulated using this condition, thus ensuring a small newlinenumber of fluid elements and an efficient solution process. The corrugation pitch was newlinevaried between 4 and 8 mm; the amplitude-to-pitch ratio was chosen between 0.1 and newline0.3. The chevron angle was varied between 15 and 75 degrees. Simulation results show newlinethat the effect of the chevron angle is significant over the entire range, while the newlinecorrugation pitch and amplitude affect heat transfer and pressure drop only at higher newlineReynolds numbers. Velocity vectors and temperature contours have been plotted to newlineunderstand the reason behind the superior heat transfer performance of the brazed plate newlineheat exchanger. An experimental setup was made to study brazed plate exchangers over newlinelimited ranges of Reynolds numbers and heat fluxes. The measured data have been newlineanalysed and compared with the computed results. Approximate general correlations for newlineindustrial use have been worked out for the Nusselt number and the friction factor as newlinefunctions of Reynolds number, and several dimentionless geometrical parameters. newline