Question

In: Mechanical Engineering

1. Methane and oxygen exist in a stoichiometric mixture at 500 kPa and 298 K. They...

1. Methane and oxygen exist in a stoichiometric mixture at 500 kPa and 298 K. They are ignited and react at constant volume. Combustion is complete.

a. Find the heat removed from the system per kmol of fuel if the final products are at 1500 K.

b. What is the final pressure?

c. Explain what assumptions made in this calculation are less accurate for constant volume combustion than for the constant pressure combustion we have studied before.

d. If the reaction above occurs in an insulated container, find the final temperature and pressure of the products.

e. If the same mixture reacts at constant pressure, find the final temperature.

f. Suppose the products from both #2 and #3 then undergo adiabatic expansion in a pistoncylinder device. Find the total work done for both processes in each problem and draw the P-v and T-s diagrams (two diagrams that include two processes for each problem).

g. If one approach produces more work than the other using the same amount of fuel, use the first and second law to explain why.

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