Living spece air heating is essential in most of the cold contries. Generally, natural gas is fired with partially premixed burner in the heating system. Nowadays, the emissions from fossile fuel firing applications are of primary concerns. Hence, CFD simulations are carried out to infere regions in the system for NOx formation and also compare it against experimental NOx data from a similar system. A simplified geometry of a gas heat system has been taken for this study and simulations are carriedout using ANSYS-FLUENT commercial software. For the simulations, combined models of non-premixed combustion which solves for mixture fraction using Probability Density Function (PDF) approach and premixed type, which involves method of reaction progress variable for turbulent flames have been adopted. The simulations provided a clear picture on the structure of the flame and flame temperatures inside the heat exchanger tubes. For the range of interest in equivalence ratio variation from about 0.75 to 1.1, the NOx level is increased from about 33 ppm to about 72 ppm. This prediction is about 10% lesser than experiments with similar system at slightly lean mixture conditions.
Space Heating, Partially Premixed Combustion, CFD, Natural Gas, Equivalence Ratio, NOx Emissions
