Investigation of heat transfer and pressure drop characteristics in sinusoidal pipes

Investigation of Heat Transfer and Pressure Drop Characteristics in Sinusoidal Pipes In this study, heat transfer and pressure drop characteristics for hydrodinamically fully developed, thermally developing and folly developed laminar and turbulent flows in sinusoidal pipes having various amplitudes and periods have been investigated experimentally. The experiments have been performed for constant wall temperature boundary condition. Experiments were carried out for Reynolds numbers ranging from 75 to 23000 and the fluid used was air at atmospheric conditions. Nusselt number and friction factor values calculated by using experimental results were presented as a function of Reynolds number. Using the various correlations of these values, the variation of heat transfer and pressure drop characteristics with respect to straight pipe were determined and the effectivenesses of sinusoidal pipes were analyzed. Furthermore, in order to determine the performance of the sinusoidal pipes and estimate unavoidable errors in experimental results, entropy and uncertainty analyses have been performed. Comparing with straight pipe, heat transfer decreases and pressure drop increases in the low Reynolds number range ( Re< 1250 for laminar flow, and Re< 7500 for turbulent flow ). For high Reynolds numbers, heat transfer and pressure drop increase with increasing Reynolds number. For a constant Reynolds number, an increase in amplitude or period of Sine function results an increase in heat transfer and pressure drop. Key Words : Sinusoidal pipes, heat transfer enhancement, pressure drop, constant wall temperature, entropy analysis, uncertainty analysis.