Question

**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 mass of the mixture in the tank (in kg)

(ii) The amount of heat transfer (kJ) during the heating.

[**Note:** The working substance is not water. Use the
appropriate table from the red book.]

Answer #1

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.

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transferred by heat to maintain the pressure constant in the tank.
This continues until the tank is filled with saturated vapor at 260
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(i) Find the initial pressure, in kPa.
(ii) Find the work for the process, in kJ.
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Determine total entropy generated (Sgen) during the cycle.

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Steam is contained in a closed rigid container with a volume of
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