Question

A cylinder contains 0.45 m3 of gas at 1 bar and 800C. The gas is compressed to a volume of

0.13 m3. The final pressure being 5 bar. Take γ = 1.4 and R = 294.2 J/kg0C. What is the index

of compression?​

Answer 1

Answer:

$\sf{Answer}$

Given that :

Specific Internal energy at beginning of expansion,

u1 = 500 kJ/kg

Heat rejected by air during expansion process

Q = -130 kJ/kg (-ve sign is there because heat is rejected)

Work done by air during expansion

W = 150 kJ/kg (expansion work is positive)

Applying first law of thermodynamics to the expansion process 1-2

Q = W + (u²-u1)

-130 = 150 + (u² � 500)

Or

u²= 500-130-150= 220 kJ/kg

Answer 2

Given that :

Specific Internal energy at beginning of expansion,

u1 = 500 kJ/kg

Heat rejected by air during expansion process

Q = -130 kJ/kg (-ve sign is there because heat is rejected)

Work done by air during expansion

W = 150 kJ/kg (expansion work is positive)

Applying first law of thermodynamics to the expansion process 1-2

Q = W + (u²-u1)

-130 = 150 + (u² � 500)

Or

u²= 500-130-150= 220 kJ/kg