Numerical study on forced convection in the exhaust problem using the spectral line-based weighted sum of gray gases model

Abstract

In this work, influences of thermal radiation on forced convection in the Exhaust problem are effectively simulated by application of the spectral line-based weighted sum of gray gases (SLW) model. The Exhaust problem includes an abrupt contraction in a horizontal channel. The working fluid of this problem is an air mixture with 10% CO2 and 20% H2O mole fractions. This mixture is regarded as an emitting, absorbing and non-scattering medium. In addition, the gray model is utilized to simulate the radiative medium based on total emissivity. Then, the findings of this model are compared with the results of SLW model as the main case to attain the error rate of gray model in simulating the Exhaust problem. The results clearly show the differences between the gray and SLW models to simulate the thermal behaviors are strongly dependent on the radiation-conduction parameter (25 ≤ RC ≤ 50) and wall emissivity (0 ≤ ɛw ≤ 1). In this regards, the gray model is unable predict the real results in many cases.