"Second Law Analysis of Viscous Flow in
Nature of Work: Analytical and Numerical (the software Matlab can be used for the numerical solution).
The main objective of this study is to investigate analytically the entropy generation for a fully developed turbulent viscous fluid flow such as crude oil in a circular pipe during a heating process. The pipe wall boundary conditions are considered to be either constant temperature or uniform heat flux. The temperature dependence on the viscosity will be taken into consideration in the analysis. Thus, the availability losses (exergy destruction) as a result of entropy generation in the viscous fluid flowing through the pipe will be determined.
Description of the Problem:
The irreversibilities (entropy generation) associated with fluid flow through a duct are usually related to heat transfer and viscous friction. The irreversibility associated with viscous friction is directly related to the viscosity of the fluid in both laminar and turbulent flows. Therefore, its is necessary to investigate the effect of a change of viscosity during a heating process for an accurate determination of entropy generation. This is important for efficient thermal operation in industrial sector handling and processing viscous fluids such as petrochemical and process industries.
Second law analysis work on viscous fluids found in the literature mostly deal with constant viscosity assumption. However this is not true for highly viscous fluids and for situations where considerable temperature variation exist. Almost no study can be found in the literature dealing with second law (exergy) analysis using variable thermal properties. Since the significant variation of viscosity affect the viscous friction related irreversibilities considerably, it is necessary to analyze the entropy generation considering the variable viscosity model. This gives an accurate determination of exergy losses due to the entropy generation. This is the aim of this study.