Question

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.

Answer #1

V = 0.01 m3 = 10 L

sat water at 200°C, x = 0.4

Q = ? until x = 1

find H

this is deffinetively an isobaric process

so

Q = m*Cp*dT

since this is at equilibrium

Q = Hf-Hi

Hf = saturated vapor , 1.0 quality

Hi = sat. liquid, 0.4 quality

a)

step 1, find Pressure saturation

at T = 200°C, P = 1.5538 MPA (from thermo tables)

H of liquid = 852.45 kJ/kg

H of gas = 2793.2 kJ/kg

Hfg = 1940.7 kJ/kg

We need the mixed Enthalpy:

H = x*Hfg + Hf

H = 0.4*1940.7 + 852.45 + = 1628.73kJ/kg

then

we need mass of system

vf = 0.001157 ---> 0.01 m3

mass = vf/V = 0.01 m3 /0.001157 m3 / kg *= 8.6430 kg

Q = m(Hf-Hi)

substitute data

Q = 8.6430* (2793.2 -1628.73) = 10064.51421 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 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Saturated water vapor at 260 C is slowly withdrawn through a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...

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.

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.

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 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.

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?

A 0.6-m3 rigid tank is filled with saturated
liquid water at 170
°C. A valve at the bottom of
the tank is now opened, and one-half of the total mass is withdrawn
from the tank in liquid
form. Heat is transferred to water from a source of 210 °C so that
the temperature in the tank
remains constant. Determine (a) the amount of heat transfer and (b)
the reversible work and
exergy destruction for this process. Assume the surroundings to...

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, initially saturated vapor at 14.6 bar, fills a closed,
rigid container. The water is heated until its temperature is
200°C. For the water, determine the heat transfer, in kJ/kg.
Kinetic and potential energy effects can be ignored.

ADVERTISEMENT

Get Answers For Free

Most questions answered within 1 hours.

ADVERTISEMENT

asked 7 minutes ago

asked 11 minutes ago

asked 15 minutes ago

asked 19 minutes ago

asked 21 minutes ago

asked 22 minutes ago

asked 22 minutes ago

asked 22 minutes ago

asked 29 minutes ago

asked 29 minutes ago

asked 38 minutes ago

asked 45 minutes ago