Date:

2025-04-30

Title of Paper:

Investigation of evaluation criterion of axial wall heat conduction under two thermal boundary conditions

Journal:

Applied Energy

Summary:

The influence of axial wall heat conduction has been investigated in circular tube laminar flow and heat transfer under two classical thermal boundary conditions. Moreover, the effect of heat losses through the tube end is also considered beside of the adiabatic boundary conditions of the tube end. Three-dimensional numerical simulations are conducted with wall materials, wall thicknesses and tube lengths. A wide range of Peclet number is considered from 7 to 14000. Three parameters including the modified axial conduction number, the so-called axial conduction number and the temperature gradient number are comprehensively studied. Meanwhile, under the thermal boundary condition of uniform outside heat flux, the criterion for judging whether the axial wall heat conduction can be negligible is also discussed and modified. Under the constant outside wall temperature boundary condition, the temperature gradient number is presented to assess the relevance of the axial wall heat conduction. The approximate range of effect of axial wall heat conduction on the local Nusselt number for fully developed flow is obtained to provide a reference for judging whether the axial heat conduction can be negligible.

Co-author:

Mei. Lin, Qiu Wang Wang, Zhi Xiong Guo

Volume:

162

Page Number:

1662-1669

Translation or Not:

No

Date of Publication:

2016-06-05