Gas Radiation - Emissivity Value

[CFDFEAGURU]

I work in the field of high temperature equipment and I am using Hottel's curves from his classical book "Radiative Transfer" then I bought a much newer book by Michael F. Modest, "Radiative Heat Transfer" and this book uses curves by Leckner. I rewrote the FORTRAN code from Modest's book into a C++ program, debugged it and verified the results. Both Hottel and Leckner only work for H2O, CO2 and a combination of them.

My question is:

Has anyone really noticed a difference between the two methods?

Thanks
Matt

 

[Achy47]

Hello Matt,

Thank you for sharing your experience with using Hottel's and Leckner's curves for radiative heat transfer. As a fellow scientist in the field, I can understand your curiosity about the differences between the two methods.

To answer your question, yes, there have been studies and comparisons between Hottel's and Leckner's curves for radiative heat transfer. In general, both methods have been found to provide accurate results for the specific gases and combinations that they were designed for. However, there are some differences in the assumptions and approximations used in each method, which can lead to variations in the results.

One study by Garg and Modest (1995) compared the two methods for a range of temperatures and gas compositions. They found that Hottel's method tends to overestimate the radiative heat transfer for high temperatures and low pressures, while Leckner's method tends to underestimate it. Additionally, Hottel's method assumes a uniform temperature distribution in the gas, while Leckner's method takes into account temperature gradients. This can lead to differences in the results, especially for non-uniform temperature distributions.

Overall, it is important to carefully consider the assumptions and limitations of each method and choose the one that is most appropriate for your specific application. It is also recommended to validate the results with experimental data, as you have done with your C++ program.

I hope this helps answer your question. Keep up the good work in your research!