Example

Steam enters a turbine at 1200 kPa and 350°C and it exits at 100 kPa, 150°C. The water mass flow rate through the turbine is 2 kg/s. Determine the power produced by the turbine, in kW, and state any assumptions that you made.

Charging and Discharging Processes

An insulated, freely moving piston cylinder device contains 10 kg of water, 6 kg of which is in the vapor phase. The mass of the piston is such that it maintains a constant pressure of 200 kPa. Now, steam at 0.5 Mpa and 350oC is allowed to enter the cylinder from a supply line until all the liquid has vaporized. Determine the final temperature in the cylinder and the mass of steam that entered.

Charging and Discharging Processes

A 2 m3 rigid tank initially contains air at 100 kPa and 22oC. The tank is connected to a supply line through a valve. Air is flowing in the supply line at 600 kPa and 22oC. The valve is opened, and air is allowed to enter the tank until the pressure in the tank reaches the line pressure, at which point the valve is closed. A thermometer placed in the tank indicates that the air temperature at the final state is 77oC. Determine the mass of air that entered the tank and the amount of heat transfer.

Second Law (Ch. 6) Concepts

Introduction to 2nd LawThermal Energy Reservoir – Source and SinkHeat Engines – Four CharacteristicsKelvin Plank Statement of 2nd LawRefrigerators and Heat Pumps – COPTons of Refrigeration, EER, SEERClausius Statement of 2nd LawPerpetual MotionReversibility

Second Law (Ch. 6) Concepts

Reversibility and Examples of IrreversibilitiesCarnot Cycle – All Reversible ProcessesCarnot PrinciplesThe Quality of Energy

Calculations – Heating Value

Example

An automobile consumes fuel at a rate of 28 L/hr delivers 60 kW of power to the wheels. If the fuel has a heating value of 44,000 kJ/kg and a density of 0.8 g/cm3, what is the efficiency of this engine?

Example

A coal burning steam power plant produces a net power of 300 MW with an overall thermal efficiency of 32%. The actual air fuel ratio is 12 kg air/kg fuel and the heating value of the coal is 28,000 kJ/kg. Determine the amount of coal consumed in a 24 hr period and the rate of air flowing through the furnace.

Example

A 3.5 ton A/C unit has an EER rating of 15. Determine the power consumed by the unit in KW and the amount of heat rejected to the environment over the course of 1000 hours of operation, in kJ.