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ÇANKAYA UNIVERSITY

MECHANICAL ENGINEERING DEPARTMENT

ME 215 FUNDAMENTALS OF THERMAL SYSTEMS

CHAPTER 6 EXAMPLES AND SOLUTIONS

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Q-2 Air enters an adiabatic nozzle steadily at 300 kPa, 200°C, and 30 m/s and leaves at 100 kPa and 180 m/s. The

inlet area of the nozzle is 80 cm2. Determine (a) the mass flow rate through the nozzle, (b) the exit temperature of

the air, and (c) the exit area of the nozzle.

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Q-3 Steam enters an adiabatic turbine at 10 MPa and 500°C and leaves at 10 kPa with a quality of 90 percent.

Neglecting the changes in kinetic and potential energies, determine the mass flow rate required for a power output

of 5 MW.

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Q-4 Helium is to be compressed from 120 kPa and 310 K to 700 kPa and 430 K. A heat loss of 20 kJ/kg occurs

during the compression process. Neglecting kinetic energy changes, determine the power input required for a mass

flow rate of 90 kg/m.

Q-5 Refrigerant-134a is throttled from the saturated liquid state at 700 kPa to a pressure of 160 kPa. Determine the temperature drop during this process and the final specific volume of the refrigerant.

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Q-6 A hot-water stream at 80°C enters a mixing chamber with a mass flow rate of 0.5 kg/s where it is mixed with a

stream of cold water at 20°C. If it is desired that the mixture leave the chamber at 42°C, determine the mass flow rate

of the cold-water stream. Assume all the streams are at a pressure of 250 kPa.

Q-7 A well-insulated shell-and-tube heat exchanger is used to heat water (cp = 4.18 kJ/kg · °C) in the tubes from 20 to

70°C at a rate of 4.5 kg/s. Heat is supplied by hot oil (cp = 2.30 kJ/kg · °C) that enters the shell side at 170°C at a rate of

10 kg/s. Determine the rate of heat transfer in the heat exchanger and the exit temperature of oil.

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Q-8

Energy balance: