1. The document contains 4 problems involving compressed gases and thermodynamic processes. Problem 1 involves determining the pressure reading of a manometer connected to a tank containing compressed air and oil. Problem 2 involves determining the air pressure in a storage tank using the pressure reading in a pipe containing a different fluid. Problem 3 involves calculating the work done and heat transferred during an isothermal expansion process of air in a piston cylinder device. Problem 4 involves sketching and analyzing an isothermal compression followed by a constant pressure compression process of air on PV and TS diagrams.

1. ME 12 F1
QUIZ NO. 3
PROBLEM SOLVING
1. A closed tank contains compressed air and oil (S = 0.90) as shown in the figure.a U – tube manometer using
mercury (S = 13.6) is connected to the tank as shown. For column heights h1 = 90 cm; h2 = 15 cm and h3 = 22
cm, determine the pressure reading of the gage.
2. In the figure pipe A contains carbon tetrachloride (S = 1.60) and the closed storage tank B contains a salt brine
(S =1.15). Determine the air pressure in tank B in KPa if the gage pressure in pipe A is 1.75 kg/cm2
.
3. A piston cylinder device, whose piston is resting on a set stops, initially contains 3 kg of air at 200 KPa and 27C.
The mass of the piston is such that a pressure of 400 KPa is required to move it. Heat is now transferred to the air
until its volume doubles. Determine the work done by the air and the total heat transferred to the air during this
process. Also show the process on a P-V diagram.
Given:
m = 3 kg
P1 = 200 KPa
T1 = 27 + 273 = 300 K
P = 400 KPa
V2 = 2V1
4. Air which is initially at 120 KPa and 320K occupies 0.11 m3
. It is compressed isothermally until the volume is
halved and then compressed it at constant pressure until the volume decreases to ¼ of the initial volume. Sketch
the process on the PV and TS diagrams. Then determine the pressure, the volume and temperature in each state.
Q
P
V
1
2 3