2 Stage Compressor With Intercooler

Title: Two-Stage Compressor with Intercooler
Aim:
To demonstrate the first law of thermodynamics using a twostage compression system.
Theory:
The first law of thermodynamics is the application of the conservation of energy principle to heat and
thermodynamic processes. It is represented by
U = Q W, where
U = the change in the internal energy.

Q = the amount of heat supplied to the system
W= the amount of work performed by the system on its surroundings.
In a closed system the work done is proportional to the heat consumed by
the system during the cyclic process.
The first law of thermodynamics also states that a system's internal energy will increase if energy
is added via heat or if work is done to the system. Similarly, the energy will decrease if heat is
removed or work is done by the system.
In this experiment a two-stage compressor czonsisting of an intercooler where the process usezd
in this system was mainly to increase the amount of air in a confined space. Air enters the 1st stage
of the compressor; it is then cooled via an intercooler before beingcompressed in the second compressor.
Final compression is completed in second stage.
Apparatus and Materials:

1) Two stage compressor system with intercooler.
Diagram 1 : Showing a two-stage compressor:
Procedure:
1) the lab technician switched on the compressor.
2) The lab technician set the desired pressure p4 was with the help of the bleeder valve.
3) The system was allowed to run until the desired pressure p4 is held for at least five
minutes.
4) After five minutes the condition was stabilized and all readings were recorded.
Method:
In the two-stage compression system shown in the figure below, air enters the 1st stage of
the compressor; it is then cooled via an intercooler before being compressed in the second
compressor.
Using the system as a control volume(open system) with system boundaries defined in
the figure below identify and calculate the required parameters for evaluating the first law
of thermodynamics.
Explain any discrepancies and state any assumption/s made.
Assumptions:
1)
2)
3)
4)
All components were assumed to be adiabatic

No work is done in the intercooler
P1 = P0
T1 = T0
Results:
Table 1: Showing the first set of results obtained
P1/bar T1/oC
P2/bar T2/oC
0.96
3.2
20.3
9z0.4
P3/bar
s
1.51
T3/oC
P4/bar T4/oC
35.6
8.4
Calculations
H1 = 291 + [ (295 290) / (295.71 290.6) ] * (293 290)
= 282.99 kJ/Kg
H2= 360 + [(370-360)/(370.67-360.58)] * (362.6 360)
= 352.58 kJ/Kg
H3= 305 + [(310 -305) / (310.24-305.22)] * (306.2 305)
= 316.36 kJ/Kg
H4= 360 + [(370.5 360) / (370.67 -360.58)] * (352.2 - 360)
= 349.12 kJ/Kg
First Stage Compression:
96.1
p/mba
r
10.7
ma = Ad [[P Pa] Ta]

m1-2 = [1.151 10z-4m2] [[10.8 0.98] 292] = 0.000021kg/s
W1-2 = maCpair[T2 T1]

= 0.001221 1.0035 [363.6 293] = 0.00139kW
Second Stage Compression:

Ma = Ad [[P Pa] Ta]
m3-4 = [1.131 10-4m2] [[10.8 1.52] 306.2] = 0.000125kg/s
W3-4 = maCpair[T4 T3]

= 0.000025 1.0015 [349.2 306.2] = 0.00132kW
Wsystem = W1-2 + W3-4

= 0.000674 +0.00162 = 0.002294 kW
= [100 P0] [287 (T1 + 273)]

= [100 980Pa] [287 (20.1 + 273)] = 1.11kg/m3
V = Ad [(2 P) ]
= 1.161 10-4 m2 [(2 10.8) 1.12kg/m3] = 0.000431m3/s
Wsystem = P1 V ln[P4/P1]
= 0.97 0.00147 ln[8.4/z0.93] = 0.00109kW
Discussion:
This experiment was aimed to demonstrate the application of the first lawz of
thermodynamics, which states that a system's internal energy will increase if energy is added via
heat or if work is done to the system. Similarly, the energy will decrease if heat is removed or
work is done by the system.
This is denoted in the equation u=Q W .
u is the change in internal
energy; Q is the heat supplied or removed from the system and W is the work done by the
system. The experiment is supposed to show that the energy in the entire system is the same as
the sum of energy in individual parts of the compressor system.
It has shown that the values calculated were not very accurate due to the approximation of the
values. However the first law of thermodynamics was valid it showed that energy cannot be
created nor destroy but simply be converted into other forms. This experiment also showed that
the work on the whole system is equivalent to the sum of the work on specific parts of the
system.
Conclusion
The First Law of Thermodynamics was proven by the experiment of the 2 stage
Compressor system

2 Stage Compressor With Intercooler

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What is the aim of the experiment?

What apparatus and materials were used in the experiment?

Title: Two-Stage Compressor with Intercooler

U = the change in the internal energy.

Apparatus and Materials:

Diagram 1 : Showing a two-stage compressor:

All components were assumed to be adiabatic

First Stage Compression:

ma = Ad [[P Pa] Ta]

W1-2 = maCpair[T2 T1]

Second Stage Compression:

W3-4 = maCpair[T4 T3]

Wsystem = W1-2 + W3-4

= [100 P0] [287 (T1 + 273)]

This is denoted in the equation u=Q W .

u is the change in internal

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