Oxygen at 50 lbf/in.2, 200 F is in a piston/cylinder arrangement with a volume of 4 ft3. It is now compressed in a polytropic process with exponent, n = 1.2, to a final temperature of 400 F. Calculate the heat transfer for the process.

The value of heat transfer during the process Q = - 29.49 KJ

Explanation:

Given data

= 50 = 344.7 k pa

= 0.113

F = 366.4 K

= 477.6 K

Poly tropic index n = 1.2

gas constant for oxygen = 0.26

From ideal gas equation

= m R

Put all the values in above equation we get

⇒ 344.7 × 0.113 = m × 0.26 × 366.4

⇒ m = 0.408 kg

Heat transfer in poly tropic process is given by

Q =

Put all the values in above formula we get

⇒ Q =

⇒ Q = 2.5 × 0.408 × 0.26 × ( 366.4 - 477.6 )

⇒ Q = - 29.49 KJ

This is the value of heat transfer during the process & negative sign shows that  heat is lost during the process.

a and b sometimes have a positive value

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