Question

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 m^{3}/kg, (b) the final specific
entropy in kJ/kg.K and (c) change of entropy in kJ/K.

Answer #1

An initially empty, well insulated, rigid tank with a volume of
2 m3 is fitted with a mixing device. The tank has two inlets and
zero outlets. One inlet is water at 1 MPa and 600◦C while the other
is saturated liquid water. Both enter the tank slowly. If the
amount of work done by the mixing device is 300 kJ, what must the
temperature of the saturated liquid water be if the same mass is
added through both inlets...

Water of mass 2 kg in a closed, rigid tank is initially in the
form of a twophase liquid-vapor mixture. The initial temperature is
50° C. The mixture is heated until the tank contains only saturated
vapor at 110° C.
(i) Find the initial pressure, in kPa.
(ii) Find the work for the process, in kJ.
(iii) Find the heat transfer for the process, in kJ.

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...

A 50 kg copper block initially at 350 oC is quenched in a
closed, rigid insulated tank containing 120 L of liquid water at 25
oC. Specific heat of copper, Cc = 385 J/(kgK), specific heat of
liquid water, Cw = 4180J/(kgK). (i) Calculate the entropy change
(kJ/K) of copper block. (ii) Determine the entropy change (kJ/K) of
liquid water.

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.

(10 pts) A 10 m3 rigid storage tank contains oxygen
gas (R = 0.2598 kJ/kg.K, cp = 0.918 kJ/kg.K,
cv = 0.658 kJ/kg.K). The tank is initially 200 kPa and
600o It is cooled to 25oC in 35 minutes.
Determine:
(3 pts) The mass of oxygen in the tank, in kg.
(3 pts) The final pressure in the tank, in kPa.
(4 pts) The rate of heat transfer from the oxygen, in kW.

A tank having a volume of 0.85 m^3 initially contains water as a
two-phase liquid vapor mixture at 260 C and a quality of 0.7.
Saturated water vapor at 260 C is slowly withdrawn through a
pressure-regulating valve at the top of the tank as energy is
transferred by heat to maintain the pressure constant in the tank.
This continues until the tank is filled with saturated vapor at 260
C. Determine the amount of heat transfer in kJ. Neglect...

A closed, rigid tank is filled with water. Initially, the tank
holds 1.0 lb of saturated vapor and 7.0 lb of saturated liquid,
each at 212°F. The water is heated until the tank contains only
saturated vapor. Kinetic and potential energy effects can be
ignored. Determine the volume of the tank, in ft3, the temperature
at the final state, in °F, and the heat transfer, in Btu.

A rigid, well-insulated tank contains 100 kg of liquid water at
21°C. The tank is connected through a valve to a steam main where
the pressure is 1 MPa. The valve is opened and steam enters the
tank until the water temperatuere rises to 65 °C, at which time the
valve is closed. It is determined that there are now 107.96 kg of
water in the tank. Estimate the quality of steam in the main.

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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