Question

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 (*T*2).

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?

Answer #1

A piston-cylinder contains 25 g of saturated water vapor and
kept at 300 kPa. We add to the saturated water vapor an amount of
electrical work of 7.2 kJ (via a resistance heater).
Simultaneously, we lose 3.7 kJ from the water.
1.Show the path on a PV diagram.
2.Determine the change in internal energy, the PV work, and the
enthalpy of the system.
3.Determine the final temperature of the system

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

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.

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...

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?

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 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 of water in a piston cylinder arrangement is initially in a
saturated liquid state at 1 bar. It undergoes expansion at constant
pressure due to external heat supply to it, to a final state of
saturated vapor.
(i) What is the initial temperature of water in C? (a) 93.50 (b)
96.71 (c) 99.63 (d) 111.4 (e) 12.2
(ii) What is the change in enthalpy of water (kJ/kg-K)? (a)
417.46 (b) 2258.0 (c) 2675.5 (d) 2506.1
(iii) What is...

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