A piston–cylinder device contains 0.85 kg of refrigerant-134a at
-10°C. The piston that is free to move has a mass of 12 kg and a
diameter of 25 cm. The local atmospheric pressure is 88 kPa. Now,
heat is transferred to refrigerant-134a until the temperature is
10°C. Determine (a) the final pressure, (b) the change in the
volume of the cylinder, and (c) the change in the enthalpy of the
100 kg of R-134a at 320 kPa are contained in a piston-cylinder
device whose volume is 7.530 m3. The piston is now moved
until the volume is one-half its original size. This is done such
that the pressure of the R-134a does not change. Determine the
final temperature and the change in the total internal energy of
the R-134a. (Round the final answers to two decimal places.)
One kilogram of water is contained in a piston-cylinder device
at 100 degC. The piston rests on lower stops such that the volume
occupied by the water is 0.835 m3. The cylinder is fitted with an
upper set of stops. When the piston rests against the upper stops,
the volume enclosed by the piston-cylinder device is 0.841 m3. A
pressure of 200 kPa is required to support the piston. Heat is
added to the water until the water exists as...
One kilogram of Refrigerant 134a vapor initially at 2 bar and
20°C fills a rigid vessel. The vapor is cooled until the
temperature becomes -24°C. There is no work during the
Let To = 20°C, po = 0.1 MPa and ignore the
effects of motion and gravity.
2. For the refrigerant, determine the change in exergy, in
Note: for part 1: q=-98.086kj please find part two- the change
in exergy in kj
A mass of 0.3 kg of saturated refrigerant-134a is
contained in a piston-cylinder device at 240 kPa.
Initially, 70 percent of the mass is in the liquid phase. Now heat
is transferred to the refrigerant at
constant pressure until the cylinder contains vapor only.
(a) show the process on a P-v and T-v diagrams with respect to
saturation lines. Determine;
(b) the volume occupied by the refrigerant initially,
(c) the work done, and
(d) the total heat transfer.
The volume of 1 kg of helium in a piston-cylinder device is
initially 7 m3 . Now helium is compressed to 3 m3 while its
pressure is maintained constant at 150 kPa. Determine the initial
and final temperatures of helium as well as the work required to
compress it, in kJ. You may assume deal gas behavior.
A piston–cylinder device initially contains 2 kg water in 1 m3
at 500 kPa. The system then cools down and the volume drops to half
and pressure of 300 kPa. At this state, the piston is resting on a
set of stops, and the mass of the piston is such that a pressure of
500 kPa is required to move it. (a) Show the process on a P-v, T-v
and P-T diagrams with respect to saturation lines and determine,
One-quarter kilogram of air is compressed in a piston-cylinder
device from 350 K and 150 kPa to 550 K and 900 kPa. Determine
a. The entropy change, in KJ/K.
b. The direction of any heat transfer by using the entropy
c. What-if scenario: If this process occurs adiabatically, is
this process reversible, irreversible, or impossible process?
Please answer the nature of this process and why.
Two moles of gas are confined in a piston–cylinder device.
Initially, the temperature is at 300 K and the pressure is 1 bar.
The gas is compressed isothermally to 5 bar. If the ideal gas heat
capacity is C ig P = 7R/2, find Q, W, ?U, ?H, and ?S if:
(a) the gas is ideal, or
(b) the gas satisfies the van der Waals equation of state with a
= 5.0 × 106 bar · cm6/mol2 and b =...