Effect Of Internal Heat Generation Research Articles

Effects of heat generation and axial heat conduction in laminar flow inside a circular pipe with a step change in wall temperature

This study analyzes the effect of internal heat generation and axial heat conduction on the convective heat transfer characteristics of laminar flow in a circular pipe subjected to a step-change in wall temperature. Additionally, the flow is considered to be hydrodynamically fully developed and contains an internal heat generation density. The temperature field in the circular pipe is obtained analytically/ numerically from the energy equation by employing a straightforward approach using the Fourier transform technique. The effects of axial heat conduction and internal heat generation are included in this expression in both upstream and downstream directions for Peclet numbers ranging from 0 to ∞. The representative curves illustrating the variations of the bulk temperature and Nusselt numbers with pertinent parameters are plotted. In addition, the ratio of the Nusselt number with heat generation to that without heat generation is plotted against the dimensionless longitudinal coordinate. Furthermore, the Nusselt number is plotted against the dimensionless heat generation number for various Peclet numbers.

Effects of Internal Heat Generation and Variable Viscosity on Marangoni Convection

The problem of Marangoni convection in a horizontal fluid layer with internal heat generation is solved using the sequential gradient-restoration algorithm (SGRA) developed for optimal control problems. A general discussion of the method is given. The effects of the temperature-dependent surface tension and viscosity are studied by examining the critical Marangoni numbers and wave numbers. The validity of the method is established by comparison with the work in the literature for the case of a linear temperature profile across the fluid layer.

Investigation of temperature fields in heat exchangers of porous cylindrical boards

1. W. S. Minkler and W. T. Rouleau, The effects of internal heat generation on heat transfer in thin fins, Nucl. Sci. Enqng 7,400~406 (1960). 2. G. B. Melese and J. E. Wilkins, Efficiency of longitudinal fins of arbitrary shape with nonuniform surface heat transfer and internal heat generation, in Proceedings Third International Heat Trksfer Conference, Vol. Iii, DD. 272-280. A.1.Ch.E.. New York (19661. 3. G. Ahmadi and A. Raiani, Some dptimisation problems related to cooling fins, Int. J. Heat Mass Transfer 16, 2369-2375 (1973). 4. A. Aziz and S. M. Enamul Huq, Perturbation solution for convecting fin with variable thermal conductivity, J. Heat Transfer 97C, 300-301 (1975). 5. R. J. Krane, Discussion on a previously published paper by A. Aziz and S. M. Enamul Huq, J. Heat Transfer. FIG. 2. Optimisation chart for rectangular fin with uniform To be published. internal heat generation and temperature dependent thermal 6. D. Q. Kern and A. D. Kraus, Extended Surface Heat conductivity. Transfer, pp. 193-199. McGraw-Hill, New York (1972).

Subcritical convective instability Part 2. Spherical shells

In this paper we consider the effect of internal heat generation and a spatial variation of the gravity field on the onset of thermal convection in spherical shells. If the temperature gradient and gravity fields have the same spatial variation, then initially quiet fluids are subcritically stable. For these flows the effect of inertially non-linear disturbances is not destabilizing if the Rayleigh number is below the critical value set by linear theory plus ‘exchange of stabilities’. For subcritically-stable flows a principle of exchange of stabilities is not necessary; a stronger statement of stability for the same stability limit can be made. For the many cases calculated here in which subcritical instabilities can exist, the difference between the linear and energy limits is small and can be contracted only toward the energy limit by an improved linear theory.

The Effects of Internal Heat Generation on Heat Transfer in Thin Fins

Some of the differential equations of thin fin theory have been rewritten to include an internal heat generation term, and solutions have been obtained for fins of rectangular, triangular, and “optimum” profiles. Fin temperature distributions and heat removal rates are exhibited as functions of the other variables involved by means of dimensionless parameters. In addition, criteria are discussed for determining whether the use of fins is worthwhile in a given application where internal heat generation is present in the fins.The analysis presented here should find wide application, not only to actual fins, but to many other problems where thin fin theory applies, such as determination of the heat transfer characteristics of thin structural members used in reactors.