Question

A piston-cylinder device with a set of stops initially contains 0.35 kg of steam at 1.0 MPa and 900 degrees C. The location of the stops corresponds to 44 percent of the initial volume. Now the steam is cooled. Determine the magnitude of the compression work if the final state is (A) 1.0 MPa and 600 degrees C and W=. kJ (B) 500 kPa. W=. kJ (C) Also determine the temperature at the final state in part (B). T2=. C

Answer #1

A piston-cylinder device contains 0.54 kg of steam at 300
degrees C and 3 MPa. Steam is cooled at constant pressure until
one-half of the mass condenses. (A) Find the final temperature (B)
Determine the volume change

A piston-cylinder device contains 0.9 kg of steam at
350⁰C and 1.4 MPa. Steam is cooled at constant
pressure until one-half of the mass condenses.
(a) show the process on a T-v and P-v diagrams,
(b) find the final temperature and
(c) determine the volume and entalphy changes.

A piston-cylinder device initially contains 75 g of saturated
water vapor at 340 kPa . A resistance heater is operated within the
cylinder with a current of 0.6 A from a 300 V source until the
volume doubles. At the same time a heat loss of 7 kJ occurs.
Part A)Determine the final temperature (T2).
Part B)Determine the duration of the process.
Part C)
What-if scenario: What is the final
temperature if the piston-cylinder device initially contains
saturated liquid water?

A piston cylinder device contains 0.15 kg of air initially at 2
MPa and 350 C. First, the air expands isothermally to a pressure of
500 kPa. Then, it is compressed polytropically back to the initial
pressure (2 MPa) with a polytropic exponent of 1.2. Find the work
performed or introduced by or to the air for each process. Express
it both times in kJ.

H3.3 A frictionless piston-cylinder device contains 2 kg of H2O
initially at T1 = 300◦C and p1 = 5 bar. The device is cooled at
constant pressure until the volume is ∀2 = 0.5 m3 . Assume a
quasiequillibrium process which occurs slowly with no acceleration
as the piston moves. Kinetic and potential energy effects are
negligible. Determine: a. work [kJ] during process (indicate
magnitude and direction) b. heat transfer [kJ] during process
(indicate magnitude and direction)

Entropy From Steam Tables
A piston-cylinder assembly contain 2 kg of water. The water is
initially at the pressure of 0.5 MPa and the temperature of 300°C.
The water is cooled down at constant pressure process until it is a
saturated vapor. Determine the change in the entropy of the
system.

A piston cylinder device contains air with a volume of 0.05 m3
at 25oC and 100 kPa pressure. The gas is now compressed to a final
temperature of 95oC at 250 kPa. This compression is polytropic and
follows PVn=constant.
a. Determine how much boundary work was added to the gas [in
kJ]
b. How much heat was added or removed from this system during
this process? [in kJ]

A piston cylinder device contains 5 kg of Refrigerant 134a at
800 kPa and 70 C. The refrigerant is now cooled at constant
pressure until it reaches a saturated vapor state. How much heat
was lost in the process? Express your result in kJ and you may
ignore the negative sign.

1-kg water in a frictionless piston-cylinder device is initially
at 250°C and 300 kPa (state
1). A total of 700 kJ of work is done ON the water
in order to isothermally reduce its volume to
1/20 of its initial volume (state 2). Determine the magnitude and
direction of the heat transfer
involved in this process.
Answer: -1147 kJ.

An insulated piston–cylinder device initially contains
20 L of air at 140 kPa and 27 °C. Air
is now heated for 10 min by a 100-W resistance heater placed inside
the cylinder. The pressure
of air is maintained constant during this process, and the
surroundings are at 27 °C and 100 kPa.
Determine the exergy destroyed during this process.

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