Effect of Radiation Heat Transfer on Naturally Driven Flow Through Parallel-Plate Vertical Channel

The present study deals with the effect of radiative heat transfer, which is often neglected, on the flow and heat transfer characteristics in naturally driven flow through vertical parallel plates. The effect of radiation on the naturally driven flow has been investigated by a newly developed numerical model which was validated by comparing numerical models with the experimental data from the literature. Realizable k–ε (RKE) model, Low-Rek–ε model and Low-Re Stress-Omega model are utilized to model the turbulence and compared with the experimental values for the case radiative-convective transport as well as purely convective transport. Initially, we have considered surface-to-surface radiation, assuming the fluid is radiatively non-participating. The case was extended to study the effect of having participating medium (like carbon dioxide and water vapor) on the temperature and velocity pattern inside the channel. Various cases from Rayleigh number ranging from 2.5 × 10 ⁶ to 9.6 × 10 ⁶ have been studied. It was found that radiation has a significant effect on the natural convection process even at lower operating temperatures. All the three turbulent models give satisfactory results; however, RKE was found to be the closest to the experimental data. Presence of participating medium has significant effect on the velocity pattern and temperature distribution inside the channel.