Question

0.75 kg of refrigerant-134a at 120 kPa and 20°C initially fills a piston-cylinder device. Heat is now transferred to the refrigerant from a source at 150°C, and the piston which is resting on a set of stops, starts moving when the pressure inside reaches 140 kPa. Heat transfer continues until the temperature reaches 90°C. Assuming the surrounding to be at 25°C and 100 kPa, determine (a) the work done, (b) the heat transfer, (c) the exergy destroyed, and (d) the second law efficiency of this process.

Answer #1

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0.75 kg of refrigerant-134a at 120 kPa and 20°C
initially fills a piston-cylinder device. Heat is now transferred
to the refrigerant from a source at 150°C, and the piston which is
resting on a set of stops, starts moving when the pressure inside
reaches 140 kPa. Heat transfer continues until the temperature
reaches 90°C. Assuming the surrounding to be at 25°C and 100 kPa,
determine (a) the work done, (b) the heat transfer, (c) the exergy
destroyed, and (d) the...

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.

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.

A piston - cylinder device, whose piston is resting on a set of
stops, initially contains 2 kg of air at 300 kPa and 27 degree C.
The mass of the piston is such that a pressure of 600 kPa is
required to move it. Heat is now transferred to the air until its
volume doubles.
a) Show the process on p - V and p - T diagrams.
b) Determine the work done by the air.
c) Determine the...

A piston cylinder system contains 2 kg of R-134a under conditions of 100 kPa and 0.5 dryness.
Heat is supplied to the system from a 500 K source. If the exergy destroyed is 20 kJ, the final situation
what? Environmental temperature 300 K.

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?

A piston-cylinder contains 2 kg of refrigerant R-134a at
temperature -20 degrees Celsius and a quality of 20% is heated in
device until it reaches a saturated mixture with quality 60%. a)
Show process on a P-v and P-T diagram b) What is the pressure? c)
What is the change in volume? d) What is the change in the internal
energy? e) Redo the problem if the piston-cylinder assembly is
replaced with a rigid container.

A
piston-cylinder device contains 3.2 kg of air at 400 kPa and 10°C.
Heat is transfered to air and the piston is allowed to expand at
constant pressure until its temperature reaches 50°C. The work done
during this expansion process is: Use kj units

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.

a plunger cylinder device contains 0.8 kg of water at 4 Mpa and
500 ° C, it begins to lose heat causing the piston to descend to a
set of stops inside the cylinder, at which point saturated steam is
obtained through an isobaric process. Cooling continues until the
cylinder contains water at 1 atm pressure. The heat transferred
during this process is kJ

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