灰气体加权和辐射模型综合评估及分析

在O_2/CO_2气氛下,参与性介质的非灰气体辐射特性表现出不同于空气气氛下的特性,因此,非灰气体辐射模型的选择和应用在换热过程中将变得十分重要.基于统计窄谱带模型,本文综合评估近年发展应用较广的灰气体加权和(WSGG)模型.结果表明,几种WSGG模型的预测值总体趋势正确,但仍存在着一定的差别.对于发射率,Dorigon等(2013 Int.J.Heat Mass Transfer 64 863)和Bordbar等(2014 Combust.Flame 161 2435)的WSGG模型与基准模型符合较好,相对误差小于20%.与离散坐标法结合,本文求解了PH_2O/PCO_2=1,2时的一维平行平板间辐射换热问题.结果显示,由Dorigon等和Bordbar等的WSGG模型得到的辐射热源和热流密度分布的相对误差均较小(10%左右).Johansson等(2011 Combust.Flame 158893)和Bordbar等的WSGG模型具有更广的适用范围.

Comprehensive evaluation and analysis of the weighted-sum-of-gray-gases radiation model

In oxy-fuel combustion with CO₂ recycle, the non-gray gas radiative heat transfer characteristics of gaseous participating media are different from those in air-fuel combustion. Therefore, the choice of a non-gray gas radiation model should be carefully made since it plays an important role in modeling the oxy-fuel combustion system. Using the statistical narrow-band model as a benchmark, in this paper we provide a comprehensive assessment of the development of the weighted-sum-of-gray-gase (WSGG) model, which has been achieved in recent years. The results show that the predicted values obtained by the WSGG model are generally reasonably accurate, though some significant differences still exist. For the total emissivity, the WSGG models by Dorigon et al. (2013 Int. J. Heat Mass Transfer 64 863) and Bordbar et al. (2014 Combust. Flame 161 2435) are consistent well with the benchmark model, within a relative error of less than about 20%. Under the conditions of P_H2O/P_CO2=1 and 2, the magnitudes of radiative heat transfer between two planar plates are calculated using the discrete-ordinate method and WSGG model. It is found that the radiative source and radiative net heat flux obtained using the WSGG model parameters of Dorigon et al. and Bordbar et al. are more accurate than using other parameters developed in the literature (about 10% relative errors). It is worth noting that the WSGG model parameters of Jonhansson et al. (2011 Combust. Flame 158 893) and Bordbar et al. have a wider range of applications.