{'fraction_non_alphanumeric': 0.013486176668914362, 'fraction_numerical': 0.0, 'mean_word_length': 5.369098712446352, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Hybrid Flamelet/Progress Variable Approach for NO Prediction in Pulverized Coal Flames

The flamelet/progress
variable (FPV) approach is further extended
for a better prediction of NO emission in pulverized coal flames.
The predicted results are compared with detailed chemistry simulation
solutions for model evaluation. The results show that the original
FPV approach with a conventional progress variable consisting of major
species can predict the gas temperature and major products well but
can roughly predict the NO variation. Therefore, the extended FPV
approach with a modified progress variable including both NO and major
species is further evaluated. The results indicate that the prediction
accuracy of NO is sensitive to the proportion of NO introduced in
the modified progress variable. The best prediction of NO can be obtained
with the modified progress variable where the concentration of NO
is comparable to that of all major species. However, the predictions
of other quantities of interest are simultaneously deteriorated to
some extent. Based on these analyses, a hybrid FPV approach is developed
in which two flamelet libraries are constructed with conventional
and modified progress variables, respectively. The results indicate
that the hybrid FPV approach can predict both NO and other quantities
of interest quite well at the same time under various operating conditions
of strain rate, coal particle diameter, coal mass flow rate, and initial
temperature.