1. EXERCISE 1
CHAPTER 12

2. QUESTION 1
kg of a saturated vapor is converted to a saturated liquid by being cooled in a weighted piston-cylinder device maintained at 350 kPa. During the phase conversion, the system volume decreases by 0.04 m3; 250 kJ of heat are removed; and the temperature remains fixed at -10°C. Estimate the boiling point temperature of this substance when its pressure is 420 kPa.
350 kPa
-10°C
0.22 kg
sat. vapor

3. Using the finite difference approximation,
Solving for T2,
350 kPa
-10°C
0.22 kg
sat. vapor

4. QUESTION 2
2. Determine the change in the enthalpy of air, in kJ/kg, as it undergoes a change of state from 100 kPa and 20°C to 600 kPa and 300°C using the equation of state P(v-a) = RT where a = 0.01 m3/kg, and compare the result to the value obtained by using the ideal gas equation of state.

5. 2. Determine the change in the enthalpy of air, in kJ/kg, as it undergoes a change of state from 100 kPa and 20°C to 600 kPa and 300°C using the equation of state P(v-a) = RT where a = 0.01 m3/kg, and compare the result to the value obtained by using the ideal gas equation of state. Solving the equation of state for v, Differentiating the equation, For enthalpy change,

6. Integrating ; For ideal gas,

7. QUESTION 3
3. Methane is compressed adiabatically by a steady-flow compressor from 0.8 MPa and -10°C to 6 MPa and 175°C at a rate of 0.2 kg/s. Using the generalized charts, determine the required power input to the compressor.
6 MPa
175°C Ẇ
CH4
ṁ = 0.2 kg/s
0.8 MPa
-10°C

8. 6 MPa
175°C Ẇ
CH4
ṁ = 0.2 kg/s
0.8 MPa
-10°C