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Unformatted text preview: Practice Exam 1
Closed book with four single—sided Self-prepared pages allowed 1. (15%) What are the two types of energy that are the focus of engineering thermodynamics ?
Then explain the relationship between these two types of energy that is the main topic of
engineering thermodynamic. Please use the steam power plant as an example for your explanation. 2. ‘ (15%) A tea kettle is placed on a stove and under a boiling condition (inside the kettle, it is 100
°C and steam is coming out from the spout, see schematic). If you consider the kettle is a
system, identify the mass flows (hot or cold) and energy transfers that enter or leave the
system. . 3. (15%) Two cylinders are connected by a piston, as shown in the picture below. Cylinder A is used
as a hydraulic lifter and is pumped'up to 500 kPa. The piston mass is 25 kg and there is a
standard gravity (9.81 m/sZ), what is the gas pressure in cylinder B ? 4. (15%) Complete the following Table foer'O : T in 0C P in kPa v in m3/kg x, quality in % Phase description
50 4.16 250 400 160 2000 5. (25%) A cylinder fitted with a frictionless piston contains 5 kg of superheated R-134a vapor at
1000 kPa and 140 ° C. The set up is cooled at constant pressure until the R—134a reaches a
quality of 25%, calculate the work done in the process ? Is it done by the system on the
surroundings ? 6. (15%) A piston/cylinder has a 1.5 kg ofair at 300 K and 150 kPa. Now it is heated in a two-stage
process : first a constant volume step to 1000 K (state 2), followed by a constant pressure step
to 1500 K (state 3) find the final volume and work done in the process. ...
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- Fall '08