Arbitrary Wall Heat Research Articles

Thermal entrance solution for parallel plates with asymmetric arbitrary wall heat flux

Thermal entrance solution for parallel plates with asymmetric arbitrary wall heat flux

Mixed convection heat transfer of water about a vertical surface of variable heat flux with density inversion

Laminar mixed convection boundary layer flow of water about a vertical plate is studied including density inversion effects. The plate surface is subjected to an arbitrary heat flux that is a function of vertical distance from the leading edge. Both aiding and opposing mixed convection situations are considered in the study. The dimensionless forms of stream function and temperature are expanded in terms of perturbation elements and universal functions. The differentials of the heat flux, which are functions of vertical distance, are used as perturbation elements to obtain universal functions. The results for universal functions required to find temperature and velocity profiles are obtained. The obtained universal functions are valid for any arbitrary wall heat flux variation. The universal applicability of results is demonstrated for power-law variation of wall heat flux. The velocity and temperature variation, boundary layer thickness, Nusselt numbers and skin friction coefficient are presented for various values of mixed convection parameter, wall flux power index, for both aiding and opposing mixed convection. For a given combination of Grashof and Reynolds numbers, the heat transfer rates and skin friction coefficient are found to increase almost linearly with wall flux power index, in the parameter range of the study, for both the cases of aiding and opposing mixed convection. The present results of special cases are found to match well with the results available in the literature.

Transient laminar forced convection with arbitrary variation in the wall heat flux

The aim of the work is to present a detailed numerical study of the transient forced laminar convection flow over a flat plate, when thermal conditions are due to arbitrary wall heat flux variations in space. The energy governing equation is modelled using the Karman–Pohlhausen integral approach in the wide range of Prandtl numbers. The influence of both the thermal problem nature (transient heating and/or cooling processes) and the wall flux function on the resulting mathematical expressions is evidenced and the thermal boundary layer thickness behaviour is discussed. In addition, a particular attention has been focused on both the change in sign of the flux and the duration of the transient heating and cooling. Detailed thermal responses and convective heat coefficient evolutions due to the change of wall conditions are presented.

Laminar tube flow heat transfer in non-newtonian fluids under arbitrary wall heat flux

Analytical solutions are developed for the wall temperature profile of a power law fluid in laminar flow in a circular tube. This profile is first developed for the boundary condition involving uniformly constant heat flux at the wall. This is next extended for the boundary condition involving an arbitrarily varying heat flux at the wall. The computed results are finally compared with measured values obtained from a horizontal recirculating flow experimental unit.

Laminar Heat Transfer Data with a Step-Varying Wall Heat Flux

In 1958 Siegel et al. derived a thermal-entry-length integral solution for laminar flow in circular tubes with an arbitrary wall heat flux. From this we derived a solution for a step-varying flux. The objective of this research was to obtain experimental data to verify the accuracy of the above solution. The steps used were a good approximation of the sinusoidal heat flux, which exists along the cooling tube in nuclear reactors. The experimental results fell above the theoretical solution, the average difference being 10.9%. Thus, the step-varying wall heat flux solution may be used for the design of cooling systems within that uncertainty.

Laminar heat transfer in a round tube with variable circumferential or arbitrary wall heat flux

Laminar heat transfer in a round tube with variable circumferential or arbitrary wall heat flux

Heat transfer in a tube with forced convection, internal radiation exchange, axial wall heat conduction and arbitrary wall heat generation

Heat transfer in a tube with forced convection, internal radiation exchange, axial wall heat conduction and arbitrary wall heat generation

A Fully Integrated Solution of the Problem of Laminar or Turbulent Flow in a Tube With Arbitrary Wall Heat Flux

Technical Briefs A Fully Integrated Solution of the Problem of Laminar or Turbulent Flow in a Tube With Arbitrary Wall Heat Flux R. N. Noyes R. N. Noyes General Electric Company, ANP Department, Cincinnati, Ohio Search for other works by this author on: This Site PubMed Google Scholar Author and Article Information R. N. Noyes General Electric Company, ANP Department, Cincinnati, Ohio J. Heat Transfer. Feb 1961, 83(1): 96-98 (3 pages) https://doi.org/10.1115/1.3680480 Published Online: February 1, 1961 Article history Received: April 27, 1960