Question

A rigid container with a volume of 2 m3 initially contains 0.05 m3 of liquid and 1.95 m3 of vapor at 125 kPa. Heat is transferred from a 3000C source to the contents of the vessel until the pressure in the container reaches 4 MPa. The contents of the vessel are now cooled in a surrounding temperature of 250C until the contents reach its initial state.

Determine total entropy generated (Sgen) during the cycle.

Answer #1

A 0.1-m3 rigid tank contains saturated liquid-vapor mixture of
water, initially at 150 kPa and 52 percent quality. Heat is now
transferred to the tank until the system becomes superheated vapor
and the pressure reaches 300 kPa. Determine (a) the total mass of
the mixture in the tank and (b) the amount of heat transferred.

A rigid container of volume 0.2 m3 contains 5 kg of water at 20
◦C. The maximum allowable pressure of the container is set at 10
MPa. The system is now connected to a heat source, which transfers
heat at a rate of 1000 W to the container. How long will the
container survive?

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.

A rigid tank has a volume of 0.01 m3. It
initially contains saturated water at a temperature of 200
oC and a quality of 0.4. The top of the
tank contains a pressure regulating valve which maintains the vapor
at constant pressure. This system undergoes a process where it is
heated until all the liquid vaporizes. How much heat in (kJ) is
required? You may assume there is no pressure drop in the exit
line.

A 1.2 m3 rigid tank initially contains steam at 8 MPa and 400
◦C. The steam slowly comes out through a hole at the bottom until
the pressure drops to P0 while
keeps the temperature constant. Making the pertinent considerations
determines:
a) the heat transferred, in kJ when P0 = 2 MPa.
b) graph the heat transfer, in kJ, versus P0 from 0.5 to 8.0
MPa

Steam is contained in a closed rigid container with a volume of
2 m3 . Initially, the pressure and the temperature of the steam are
7 bar and 400°C, respectively. The temperature drops as a result of
heat transfer to the surroundings. i. Determine the temperature at
which the condensation first occurs in °C. [6 marks] ii. Evaluate
the fraction of the total mass that has condensed when the pressure
reaches 0.75 bar. [4 marks] iii. Calculate the volume in...

Steam is contained in a closed rigid container with a volume of
2 m3 . Initially, the pressure and the temperature of the steam are
7 bar and 400°C, respectively. The temperature drops as a result of
heat transfer to the surroundings. i. Determine the temperature at
which the condensation first occurs in °C. [6 marks] ii. Evaluate
the fraction of the total mass that has condensed when the pressure
reaches 0.75 bar. [4 marks] iii. Calculate the volume in...

A rigid container of volume 1 m3 contains saturated water at 1Mpa.
If the quality is 0.10, what is the volume occupied by the
vapor?

Q3. A tank with rigid walls and a volume of
0.05 m3 initially has a two-phase liquid- vapor mixture of ammonia
at a pressure of 4 bar and a quality of 10%. The tank is then
heated such that the pressure is kept constant through a
pressure-regulating valve that allows saturated vapor to escape.
The heating continues until the quality of the mixture in the tank
is 40%. Assume kinetic and potential energy changes are
insignificant. Determine:
(i) The final...

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