Question

A vertical, insulated piston cylinder is filled with saturated liquid H2O at 50 kPa. A stirrer moves rapidly inside the cylinder until 22% of the H2O (by mass) evaporates. Determine the net work done (in kJ/kg), the change in entropy during this process (in kJ/kg-K) and the entropy generated during this process (in kJ/kg-K).

Answer #1

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?

Water, initially (state 1) a saturated liquid at
1100C, is contained in a piston-cylinder assembly. The
water undergoes a process to the corresponding saturated vapor
(state 2), during which the piston moves freely in the cylinder. If
the change of state is brought about by heating the water as it
undergoes an internally reversible process at constant pressure and
temperature, determine (a) heat transfer using first law of
thermodynamics in kJ/kg and (b) heat transfer using second law of
thermodynamics...

Air in a closed piston cylinder device is initially at 800 K and
at 250 kPa.
The air undergoes a process until it is at 2200 K and at 750
kPa.
What is the change in the air's specific entropy during
this process (kJ/kgK)?

Initially (state 1) a well-insulated rigid tank contains 20 kg
of a saturated liquid-vapor mixture of water at 100 kPa and half of
the mass is in the liquid phase. An electric resistance heater
placed in the tank is now turned on and kept on until all the
liquid in the tank is vaporized (state 2). Determine (a) the
initial specific volume in m3/kg, (b) the final specific
entropy in kJ/kg.K and (c) change of entropy in kJ/K.

Initially (state 1) a well-insulated rigid tank contains 20 kg
of a saturated liquid-vapor mixture of water at 100 kPa and half of
the mass is in the liquid phase. An electric resistance heater
placed in the tank is now turned on and kept on until all the
liquid in the tank is vaporized (state 2). Determine (a) the
initial specific volume in m3/kg, (b) the final specific
entropy in kJ/kg.K and (c) change of entropy in kJ/K.

500 g of saturated liquid water is contained in a
piston-cylinder arrangement. The inside diameter of the cylinder is
100 mm. The water is heated at a constant pressure of 150 kPa until
it becomes saturated vapor. Determine (a) the distance through
which the piston is raised, and (b) the amount of energy
transferred to the water.

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?

Air in a piston-cylinder device undergoes an isobaric expansion
process from 280 K and 245 kPa to 880 K. This is achieved by adding
heat to the system under quasi-equilibrium conditions. What is the
work done by the air during this process? (Use the appropriate sign
convention.) What is the amount of heat transferred for this
process? (Use the appropriate sign convention.) Considering the
actual variation in the specific heat of air during the process,
what is the change in...

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...

10 kg of H2O is reversibly compressed from 600 kPa and 600 oC to
1 MPa in an insulated piston- cylinder assembly. Calculate (a)
entropy change (kJ/K) of the system and (b) the final
temperature.

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