THERMODYNAMICS - Speech or Presentation Example

d) If the driver needs to bring back the gauge pressure to its original value, what mass (units grams) of air must be released from each tyre (at 50°C) in order to bring each tyre back to its safe operating pressure. Q2) A piston cylinder device is used to expand water. The process occurs isothermally at 200°C and the starting volume of the water is 1 m3. The water is in a saturated liquid state at its initial state. At the end of the isothermal expansion process, the water has a quality of x = 0.8. Q3) A diffuser is used to decelerate a stream of air from 230m/s to 30m/s.

The air stream moves steadily through this diffuser at a rate of 1.7kg/sec, whereby its (absolute) pressure at the inlet is 80kPa and outlet 100kPa, respectively. At the inlet port, the air is at 127°C. Note1: Ensure you refer to Figure 6-22 (page 199) in the text book for a “tip” clarifying the equivalence of J/kg and m2/s2 units. You will need this to ensure the units are equivalent between enthalpy and kinetic energy in your solution within this problem)! Note2: You can solve this problem either using constant specific heats or variable specific heats.

You should know the difference between the two solution methods, even though you are required to use only of these methods (not both) in your