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301 Sample_Test_1

301 Sample_Test_1 - a rigid well insulated tank until only...

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SAMPLE 1 MAE 301: Engineering Thermodynamics I Spring 2010 Test 1 (15% of final grade) February 16, 2010 Closed books & notes Problem 1. (25 points) A fan driven by an electrical motor is to accelerate quiescent air to a velocity of 10 m/s. The mass flow rate of air is 5 kg/s. The combined efficiency of the fan-motor assembly is 80 %. Determine the electric power that must be supplied to the motor. Problem 2. (25 points) In a hydroelectric power plant, 100 m 3 /s of water flows from an elevation of 70 m to a turbine-generator assembly, where electric power is generated. The efficiency of turbine is 90%, and efficiency of generator is 95%. Determine the energy losses in water piping if 50 MW of electrical power output is produced. Problem 3. (25 points) A two-phase, liquid-vapor mixture of water with quality of 0.68 is stirred in
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Unformatted text preview: a rigid, well insulated tank until only saturated vapor remains. Determine the amount of energy transfer by work, if the volume of tank is 1 m 3 and the initial pressure is equal to 100 kPa. Problem 4. (25 points) A 1-m long sealed cylindrical tank is divided in half by a piston with negligible weight. The top and bottom sections are filled with argon with P = 100 kPa and T = 300 K. The top section is gradually heated to 900 K. The bottom section is maintained at 300 K. Find the resulting displacement x of the piston. Closed System First Law: net net W Q U − = Δ Ideal Gas Relations: M R RT Pv mRT PV u = = = Quality relations: total g m m x = fg f xh h xu xv v + = + = + = Energy Efficiency: total in useful out total in useful out Power Power E E / / / / = = η 1 m x...
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