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CE Topic 2 & 3

The document contains questions and problems related to thermodynamics concepts including: 1) Five questions related to the first law of thermodynamics including specific heat, the Bernoulli equation, and adiabatic processes. 2) Five questions related to the second law of thermodynamics and entropy including defining a cycle, reversible processes, entropy, and the principle of entropy increase. 3) Five thermodynamics problems related to topics like work, heat, efficiency, and Carnot cycles.

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CARL IJADE PINO
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60 views2 pages

CE Topic 2 & 3

The document contains questions and problems related to thermodynamics concepts including: 1) Five questions related to the first law of thermodynamics including specific heat, the Bernoulli equation, and adiabatic processes. 2) Five questions related to the second law of thermodynamics and entropy including defining a cycle, reversible processes, entropy, and the principle of entropy increase. 3) Five thermodynamics problems related to topics like work, heat, efficiency, and Carnot cycles.

Uploaded by

CARL IJADE PINO
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as DOCX, PDF, TXT or read online on Scribd
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Answer/Solve the following questions/problems.

The First Law of Thermodynamics

QUESTIONS:

1. When a fluid is vaporized, the temperature does not change during the process as heat is added.
What is the specific heat for this process?
2. Discuss the problems associated with the Bernoulli equation.
3. With all of the problems associated with the Bernoulli equation, why is it still used?
4. An automobile engine consists of a number of pistons and cylinders. If a complete cycle of the
events that occur in each cylinder can be considered to consist of a number of nonflow events,
can the engine be considered a nonflow device?
5. Can you name or describe some adiabatic processes?

PROBLEMS (Show your Solution/s)

Unless indicated otherwise, use gc = 32.174 lbm·ft./lbf ·s 2 and g = 32.174 ft./s2 or 9.81 m/s2

1. If a nonflow process is carried out so that 30 kJ/kg of work is removed while 75 kJ/kg is added as
heat, determine the change in internal energy of the fluid.
2. A gas that is contained in a cylinder is made to undergo a constant-pressure expansion from a
volume of 0.1 m3 to a volume of 0.4 m 3. If the piston moves to keep the pressure constant at
400 kPa, determine the work in kilojoules.
3. Two kilograms of a gas receive 200 kJ as heat at constant volume. If the temperature of the gas
increases by 100°C, determine the cv of the process.
4. A gallon is a volume measure of 231 in3. Determine the velocity in a pipe 2 in. in diameter when
water flows at the rate of 20 gal./min in the pipe.
The Second Law and Entropy

QUESTIONS:

1. Define a cycle.
2. Do you know of any process in nature that is reversible?
3. How does the combination of the work of Kelvin and Carnot help in the design of power cycles?
4. Other than being a property, what else does entropy represent?
5. What is the principle of the increase of entropy? Why is it important?

PROBLEMS:

1. A reversible engine produces 10 hp as work while 1270 Btu/min enter the engine as heat.
Determine the energy rejected and the thermal efficiency of the cycle.
2. A Carnot power plant operates between a high-temperature reservoir at 1500°F and a low-
temperature reservoir at 70°F. Determine the heat addition if the plant produces 1000 MW of
power.
3. An internal combustion engine uses 0.38 lbm/h of gasoline for each horsepower that it
produces. If the gasoline has an energy content of 19 500 Btu/lbm, determine the thermal
efficiency of the engine.
4. A Carnot cycle is operated between 1000°F and 500°F. If the upper temperature is increased to
1100°F, what is the efficiency of the cycle? If the lower temperature is decreased to 400°F, what
is the efficiency of the cycle?
5. A Carnot engine operates between 1350°F and 125°F. If it rejects 55 Btu as heat, determine the
work output.

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