Question

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)

Answer #2

answered by: anonymous

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.

Carbon dioxide (CO2) is compressed in a
piston–cylinder assembly from p1 = 0.7 bar,
T1 = 280 K to p2 = 14 bar.
The initial volume is 0.2 m3. The process is described
by pV1.25 = constant.
Assuming ideal gas behavior and neglecting kinetic and potential
energy effects, determine the work and heat transfer for the
process, each in kJ, using constant specific heats evaluated at 300
K, and data from Table A-23.

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

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.

An insulated cylinder is initially divided into halves by a
frictionless, thermally conducting piston. On one side of the
piston is 1 m3 of a gas at 300 K, 2 bar. On the other
side is 1 m3 of the same gas at 300 K, 1 bar.The piston
is released and equilibrium is attained, with the piston
experiencing no change of state. Employing the ideal gas model for
the gas, determine
(b) the final pressure, in bar.
(c) the amount...

A cylinder fitted with a frictionless, massless piston contains
compressed liquid water at a temperature T1=20C. The atmospheric
pressure on the outside of the system is P=1.0 bar. Heat is then
added until the water is completely converted to saturated
vapor.
(a) What are the changes in specific volume, v2-v1
(m3/kg) and internal energy, u2-u1 (kJ/kg) of the water
for this process?
(b) How much specific work, if any, is done by the system?
(c) What is the amount of...

A 0.2 m3 piston-cylinder initially contains 400 K air. A heavy
frictionless piston maintains a pressure of 500 kPa abs. Then, a
weakness in the cylinder wall blows out and creates a hole. Air
escapes through the hole until the piston drops far enough to cover
the hole. At that point, the volume is half the initial volume.
During this process, 75 kJ of heat is transferred to the 100 kPa,
300 K surroundings. Using Cp = 1.005 kJ/kg-K and...

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.

Frictionless piston-cylinder system.
Initially contains 167 L of saturated liquid
Refrigerant-134a.
The piston can move freely in such that it maintains pressure at
877 kPa, an Isobaric process.
The Refrigerant-134a is heated until its temperature rises to 70
℃
Determine:
The work was done during the process in (kJ) units?

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