Chemistry combustion question involving the use of Chemkin

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Nyrkn1274

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Four Questions as follows: (1) Use Chemkin’s (chemical kinetics software) built-in laminar flame speed calculator to explore the flame speed of methane for a range of pressures (1 to 50 atm), inlet temperatures (300 to 600 K), equivalence ratios (0.5 to 2.0). Use enough points over each range to be able to make good observations. a. Plot flame speed vs. equivalence ratio with temperature as a parameter for a few pressures b. Plot flame speed vs. equivalence ratio with pressure as a parameter for a few temperatures c. Plot flame speed vs. equivalence ratio with temperature as a parameter d. For the equivalence ratio = 0.8, inlet temp. = 300 K, pressure = 1 atm case, plot the spatial variation of the important species through the flame. e. Graphically estimate the laminar flame thickness. (2) Compute the laminar flame speed and thickness of a methane-air mixture for the case where equivalence ratio = 0.8, temperature = 600 K, and pressure = 20 atm. Compare the results of this calculation with the results from problem 1 (don’t need to use chemkin). (3) Use Chemkin’s perfectly stirred reactor model to explore the blow-out equivalence ratio limits of a propane-air combustor having Volume = 10,000 cm^3, temperature = 600 K, pressure = 30 atm, and mass flow rate (mdot) = 5 kg/s. Next, for Volume = 10,000 cm^3, temperature = 600 K, pressure = 30 atm, explore how the blow-out equivalence ratio changes with reactant mass flow rate. Vary the mass flowrate from 1 kg/s to 20 kg/s. (4) Use Chemkin’s plug flow reactor model to develop a plug-flow-reactor model. Assume the initial conditions corresponding to compression of a fuel-air mixture from 300 K and 1 atm to topdead-center for a compression ratio of 10:1. The initial volume before compression is 3.68 *10^4 m^3, which corresponds to an engine with both a bore and a stroke of 75 mm. Assume the reactor is adiabatic. Use the model to a. Determine the mass flow rate such that the reaction is 99 percent complete in a flow length of 10 cm for inlet temperature = 1000 K, inlet pressure = 0.2 atm, and equivalence ratio = 0.2. The circular duct has a diameter of 3 cm. b. Explore the effects of inlet pressure, inlet temperature, and equivalence ratio, on the flow length required for 99 percent complete combustion using the flow rate determined in part (a) The following may be assumed: (i) One-step global kinetics using the rate parameters for ethane (ii) The fuel, air, and products all have equal molecular weights of 29 (iii) The specific heats of the fuel, air, and products are constant & equal (1200 J/kg) (iv) The enthalpy of formation of the air and products are zero; the enthalpy of formation of the fuel is 4 * 10^7 J/kg (v) We assume that the stoichiometric air-fuel ratio is 16.0 and restrict combustion to stoichiometric or lean conditions.
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I will upload them now and if you have any question or want anything to be changed or added let me know I even insert screen shots of how to do it in the program

(1) Use Chemkin’s (chemical kinetics software) built-in laminar flame speed calculator to explore the
flame speed of methane for a range of pressures (1 to 50 atm), inlet temperatures (300 to 600 K),
equivalence ratios (0.5 to 2.0). Use enough points over each range to be able to make good
observations.
a. Plot flame speed vs. equivalence ratio with temperature as a parameter for a few pressures
b. Plot flame speed vs. equivalence ratio with pressure as a parameter for a few temperatures
c. Plot flame speed vs. equivalence ratio with temperature as a parameter
d. For the equivalence ratio = 0.8, inlet temp. = 300 K, pressure = 1 atm case, plot the spatial
variation of the important species through the flame.
e. Graphically estimate the laminar flame thickness.
In ChemKin, open the flame_speed_parameter_study. ckprj project. Figure below shows a screenshot of
how the project should look like once it opens.
Select the Reactor physical properties tab, and set the desired inlet temperature, pressure and equivalence
ratio by inserting the corresponding values in the “Unburnt gas temperature”, “Pressure” and “Gas reaction
rate multiplier”, respectively. You should ideally select 15 different combinations of the three values in the
target intervals (300-600K, 1-50 atm, 0.5-2.0 equival...


Anonymous
Just what I was looking for! Super helpful.

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