Conduction-radiation Interaction Research Articles

Spectral and boundary effects on coupled conduction-radiation heat transfer through semitransparent solids

The coupling of the conduction and radiation modes of heat transfer in a semitransparent solid such as glass is investigated in this study. In particular, the influence of the emission-reflection characteristics of the bounding surfaces, absorption spectrum and spectral absorption coefficient band model on the temperature distribution and heat transfer are examined. Numerical results based on a rigorous formulation of the equation of transfer and energy equation are presented for a large range of optical thickness and conduction-radiation interaction parameter. The error incurred with simplified techniques for predicting the heat transfer is also demonstrated.

Transient Combined Conductive and Radiative Heat Transfer

Transient simultaneous conductive and radiative transfer in a plane gray layer bounded by black walls is studied. The analytical development yields a nonlinear integro-differential equation which is numerically solved for a layer initially at a uniform temperature when the temperature of one wall is suddenly decreased. Instantaneous temperature and flux distributions illustrate the conduction–radiation interaction during cooling for a wide range of values for the influencing parameters which include layer optical thickness τ0 and the conduction–radiation interaction parameter N. Results are compared to those for an optically thin and optically thick medium, as well as to those for purely conductive and purely radiative transfer.

Heat transfer to laminar flow of nongray gases through a circular tube

Analyses are presented for infrared radiative energy transfer in gases when other modes of energy transfer simultaneously occur. Fully developed laminar flow of an absorbing emitting gas in a circular tube is considered under the conditions of uniform wall heat flux. Nongray as well as gray formulations are presented, and results are obtained for illustrative cases. Appropriate limiting solutions of the governing equations are obtained and conduction-radiation interaction parameters are evaluated. The influence of variable wall emittance (gray and nongray) upon radiative energy transfer in nongray gases is investigated. In particular, nongray results are obtained, in the large path length limit, for the flow of CO2 through stainless steel tubes of various compositions. Finally, a correlation is presented which can be utilized to extend all nongray results for the parallel plate geometry, already available in literature, to yield results for the corresponding case of a circular tube.

Effect of surface emittance and approximate kernels in radiation-conduction interaction

Representative results are presented for nongray radiation-conduction interaction in a radiating gas bounded by two gray infinite parallel plates. The effect of the surface emittanee on the interaction of radiation with conduction for diffuse surfaces and a special case of one black surface combined with a diffusely emitting, specularly reflecting surface is investigated. Additionally, the accuracy of the one-term exponential kernel approximation is examined.

The interaction of thermal conduction and infrared gaseous radiation

The present investigation is concerned with energy transfer in gases which transmit heat by the combined mechanisms of molecular conduction and infrared radiation. For illustrative purposes an analysis is presented for a gas bounded by two parallel black plates and within which there is a uniform heat source. Radiation-conduction interaction parameters, appropriate to both the optically thin and large path length limits, are presented for a number of gases. Numerical solutions for the gas centerline temperature have been obtained for CO, CO2, H2O, and CH4, and these are compared with limiting solutions.