Thermodynamics

calculate the internal energy and enthalpy variations of an ideal gas (in btu / lb) when it changes state from 50 °c to 150 °c, with gas properties k = 1.4

Δu= 29.82  Btu/lb

Explanation:

Given that gas temperature changes from  50 °C to 150 °C.

K=1.4

We know that

K=1.4  it means that it is air.

We know that for air

We know that internal energy for gas given as

KJ/kg

Δu= 0.71 x (150-50) KJ/kg

Δu=71 KJ/kg

We know that

1 KJ/kg=0.42 Btu/lb

So 71 KJ = 29.82  Btu/lb

Δu= 29.82  Btu/lb