Radiative Property Study Of High Temperature And Pressure Syngas Based On Wide Band K-distribution Model

There are three main kinds of methods to calculate high temperature gasradiation heat transfer according to the number of the calculation spectral band:Line-by-Line, Spectral Band Model and Full Spectral Model. There has been manymethods to calculate high temperature radiation heat transfer, k-distribution modelhas been developing in recent years，its principle is to rearrange the absorptioncoefficient in the calculation spectrum interval，then we can use the cumulativek-distribution function to transfer the absorption coefficient curve to a single increasecurve in [0-1] area. Wide Band k-distribution Model (WBK), Narrow Bandk-distribution Model (NBK) and Full Spectral k-distribution Model (FSK) are themain k-distribution models. The NBK model has many calculation spectrumintervals because the wave number of the spectrum interval is small，it needs longcalculation time, the advantage of the FSK model is short calculation time，but itscalculation precision is low; the WBK model is used widely for its perfectcalculation time and calculation precision.In the WBK model, the value of the Planck function changes a lot because thecalculation interval is broad, it will have an affect on the result. In this paper，we willcalculate the radiation properties and radiation heat transfer of the syngas in theradiant syngas cooler(RSC) by using the WBK model with weighted Planck functionand then fit the absorption coefficient as temperature and pressure functions. Themain contents are as follows:(1)Introduce the WBK model with weighted Planck function, then use thismodel to calculate the radiation properties of syngas in RSC，including the effectivebandwidth of typical spectral bands of the syngas, the average Planck absorptioncoefficient of full spectral area and the total emission rate of the syngas. The resultsshow the advantage of the WBK model.(2)Divide the wide band spectrum intervals of the syngas spectral area, thencalculate the radiation heat transfer of one-dimension isothermal gas layer andnon-isothermal gas layer by using the WBK model and discuss the proportion of COand CH4in radiation heat transfer. The results show that the advantage of the WBKmodel compare to other calculation models and we can ignore the effect of CO orCH4in engineering calculation, it will reduce the calculation greatly.(3)When the temperature and the pressure of the syngas change, the absorption coefficient should be calculated again, it needs long calculation time. In this paper,we calculate the absorption coefficient of syngas at1.0-4.0MPa(P=0.2MPa) and600-1700K(T=20K)according to the obtained parameters of syngas in RSC andthen fit the Gauss points absorption coefficient at1.0MPa as temperature functionsand the Gauss points absorption coefficient at1.0-4.0MPa as pressure functionsusing the absorption coefficient of Gauss points at1.0MPa as standard.(4)Using the fitted coefficients of temperature and pressure to calculateone-dimension and two-dimension radiation heat transfer and compare the results tothe previous. The results show that the coefficients of temperature and pressure areright, it will reduce the calculation time at certain precision. We can use thecoefficients of temperature and pressure directly in future calculation, it will reducethe calculation greatly.