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Q9 In a mixture of methane (CH4) and air there are three volumes of oxygen to one volume of methane.

The mixture is isentropically compressed through a volume ratio of five to one from initial conditions of 1 bar and 102°C.

Calculate EACH of the following:

(a) the gravimetric analysis of the mixture; (4)

(b) the molecular mass of the mixture; (2)

(c) the adiabatic index of the mixture; (4)

(d) the work done per unit mass of the mixture. (6)

Note: The universal gas constant = 8.3145 kJ/kmol K.

For each constituent gas the values of Cp at 375 K are:

Oxygen = 0.934 kJ/kg, Methane = 2.442 kJ/kg K,

Nitrogen = 1.042 kJ/kg K .

Atomic mass relationships: H = 1, C = 12, N = 14, 0 = 16.

Air contains 21% oxygen by volume.