Transient forced convection with viscous dissipation to power-law fluids in thermal entrance region of circular ducts with constant wall heat flux

MolaeiDehkordi, A ; Sharif University of Technology | 2009

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  1. Type of Document: Article
  2. DOI: 10.1016/j.enconman.2008.12.007
  3. Publisher: 2009
  4. Abstract:
  5. A numerical investigation was conducted on the transient behavior of a hydrodynamically, fully developed, laminar flow of power-law fluids in the thermally developing entrance region of circular ducts taking into account the effect of viscous dissipation but neglecting the effect of axial conduction. In this regard, the unsteady state thermal energy equation was solved by using a finite difference method, whereas the steady state thermal energy equation without wall heat flux was solved analytically as the initial condition of the former. The effects of the power-law index and wall heat flux on the local Nusselt number and thermal entrance length were investigated. Moreover, the local Nusselt number of steady state conditions was correlated in terms of the power-law index and wall heat flux and compared with literature data, which were obtained by an analytic solution for Newtonian fluids. Furthermore, a relationship was proposed for the thermal entrance length. © 2008 Elsevier Ltd. All rights reserved
  6. Keywords:
  7. Difference equations ; Fluid dynamics ; Fluids ; Heat flux ; Laminar flow ; Laws and legislation ; Nusselt number ; Thermography (temperature measurement) ; Vehicular tunnels ; Viscous flow ; Analytic solutions ; Axial conductions ; Circular ducts ; Constant wall heat fluxes ; Entrance regions ; Finite difference ; Initial conditions ; Literature datum ; Local Nusselt numbers ; Newtonian fluids ; Numerical investigations ; Power-law fluid ; Power-law indices ; Steady state ; Steady-state conditions ; Thermal energy equations ; Thermal entrance length ; Transient behaviors ; Transient forced convections ; Unsteady state ; Viscous dissipation ; Wall heat fluxes ; Forced convection
  8. Source: Energy Conversion and Management ; Volume 50, Issue 4 , 2009 , Pages 1062-1068 ; 01968904 (ISSN)
  9. URL: https://www.sciencedirect.com/science/article/pii/S0196890408004639