Problem 1 A 60-L rigid tank initially contains a saturated mixture of water at 100 kPa and 3 percent quality. The contents in the tank can exchange heat with the surroundings, which is at 20C The tank is connected by a valve to a supply line that carries steam at 10 MPa and 900C The valve is opened, and steam from the supply line is allowed to enter the tank. The valve is shut when all the liquid water in the tank is just vaporized, at which point the temperature in the tank is 300C. Determine (a) the heat transfer of this process (kJ). indicating the direction of heat flow. and (b) the entropy generation (kJIK). Steam at 10 MPa and 900C Problem 2 Steam enters an adiabatic turbine at 8 MPa and 500C, and exits at 200 kPa and 150C If the power outp ut of the turbine is 8 MW, determine (a) the mass flow rate of the steam, and (b) the isentropic efficiency of the turbine. Assume that changes in potential and kinetic energies are negligible. Problem 3 An air-standard cycle is executed in a closed system and is composed of the following four processes: 1+2: Constant 1) heat addition from 100 kPa and 300 K in the amount of 700 lekg. 243: Constant P heat addition to 1800 K. 3>4: lsentropic expansion to 100 kPa. 41: Constant P heat rejection to the initial state. (a) Show the cycle on a P - v diagram. (b) What is the total heat input per unit mass? Assume cold-air-standard (i.e. constant specific heats with values given by those at 300 K). (c) Determine the thermal efficiency of the cycle. Problem 4 A gas-turbine power plant operates on a simple Brayton cycle with air as working fluid. Air enters the turbine at 850 kPa and 1000 K, and exits at 100 kPa. Heat is rejected to the surroundings at a rate of 5000 kW, and the air mass flow rate is 20 kgls. Using cold-air standard. and assuming (i) the turbine is ideal, and (ii) the compressor is adiabatic with an isentropic efficiency of 80 percent, determine (a) the net power output (MW). and (b) the thermal efficiency of the power plant