Lab 5 Report
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School
Purdue University *
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Course
44000
Subject
Mechanical_engineering
Date
Apr 29, 2024
Type
Pages
5
Uploaded by DeaconElectronBuffalo36
Lab 5 –
Combustion Modeling 1.
How does the engine performance data for the Fixed Heat Release Model (Table 1) compare to the Predictive Combustion Model (Table 2) for all 3 cases? Using the plots for Apparent Burned Fuel (Fraction of Total Fuel) explain your reasoning. Gas Natural Gas Hydrogen
For the Gas and Hydrogen plots, the predicted performance was better than the measured. In these plots, more mass was burned. For natural gas, it was the opposite. More fuel was actually burned compared to the predicted amount. In the tables, the measured model has a higher brake torque and brake power, but lower BSFC. The measured performance also shows higher IMEP and BMEP. 2.
Using plots, compare the NOx formation for each of the three cases. Which case resulted in the maximum Nox produced? What about the least? Provide reasoning as to why. Gas Natural Gas
Hydrogen The gas simulation resulted in the highest NOx concentration while the natural gas resulted in the least. This is due to natural gas having a low fuel nitrogen content, while gasoline has a much higher nitrogen content. 3.
Using plots, compare the Flame Speeds for each of the three cases. Which case resulted in the fastest flame speed? What about the slowest? Provide reasoning as to why.
Gas Natural Gas Hydrogen The fastest flame speed occurred in the hydrogen simulation, while the lowest speed occurred in the natural gas simulation. This is because the hydrogen engine has faster reaction rates of the H2-O2 system. Alternatively, the reactions in the natural gas combustion equation take a longer time. 4.
Using plots, compare the Apparent Gross Heat Release for each of the three cases. Which case resulted in the longest heat release duration? What about the slowest? Provide reasoning as to why.
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Gas Natural Gas Hydrogen The hydrogen simulation had the longest heat duration while natural gas had the shortest heat release duration. This is because heat release duration is affected by a fuels specific heat, and hydrogen has a large specific heat while natural gas has a much lower specific heat. Table 1. Fixed Heat Release Model Gasoline Natural Gas Hydrogen Engine Speed RPM 2000 2000 2000 Brake Torque N-m 32.748 30.772 28.527 Brake Power kW 6.859 6.445 5.975 BSFC g/kWh 235.360 254.452 95.148 IMEP720 Bar 9.407 8.907 8.328
BMEP Bar 8.231 7.734 7.170 PMEP Bar -0.067 -0.061 -0.050 Volumetric efficiency, air % 77.324 69.314 55.595 Table 2. Predictive Combustion Model Gasoline Natural Gas Hydrogen Engine Speed RPM 2000 2000 2000 Brake Torque N-m 30.499 24.877 23.324 Brake Power kW 6.388 5.210 4.885 BSFC g/kWh 252.557 314.788 116.375 IMEP720 Bar 8.926 7.388 7.112 BMEP Bar 7.666 6.253 5.862 PMEP Bar -0.0866 -0.061 -0.049 Volumetric efficiency, air % 77.277 69.311 55.580 Table 3. Optimal Combustion and Turbulence Parameters Gasoline Natural Gas Hydrogen Production Term Multiplier 0.366 0.366 0.366 Geometric Length Scale Multiplier 1.942 1.942 1.942 Intake Term Multiplier 0.163 0.163 0.163 Spray/Jet Term Multiplier 0.771 0.771 0.771 Initial Spark Size 2.435 2.435 2.435 Dilution Effect Multiplier 1.904 1.904 1.904 Flame Kernel Growth Multiplier 3.686 3.686 3.686 Turbulent Flame Speed Multiplier 4.229 4.229 4.229 Taylor Length Scale Multiplier 2.034 2.034 2.034