R.I.T DUBAI
Rochester Institute of Technology
THE PERFORMANCE OF a HYDROCARBON
MIXTURE REFRIGERANT AS A
SUBSTITUTE FOR R22
Firas M. Younis* and Ghalib Y. Kahwaji**
*Department of Mechanical Engineering University of Mosul
** Rochester Institute of Technology, Dubai
R.I.T DUBAI
Rochester Institute of Technology
A word about the research
- This work started in summer 1997
- At the Norther oil company- Iraq
- The company engineers were looking at a
cheap, locally available substitute to make up
for depleting resources of R-22 and R-502
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R.I.T DUBAI
Rochester Institute of Technology
What did they find?
- They looked at the natural hydrocarbons available
at their disposal
- After many trials and properties analyses, they
came up with a mixture of Propane and Isobutene
R.I.T DUBAI
Rochester Institute of Technology
The data….
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R.I.T DUBAI
Rochester Institute of Technology
• In summer 1997, after a quick property analysis, we
started charging 1.5 and 2 TR window type units with
the proposed refrigerant.
The units performed well. And kept working until
2003.
To the best of my knowledge, no accidents were
reported.
R.I.T DUBAI
Rochester Institute of Technology
Present research:

Later we decided to look at the
performance of refrigerant when
used in R-22 systems.

Refrigerant properties were
correlated analytically.

Modeled a basic 1.5 TR window
type unit with the following:
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Rochester Institute of Technology
• Physical data from an existing system were used.
• Polytropic compression was assumed
• Three section condenser model.
• Valve pressure drop and cylinder heating was
considered in volumetric efficiency model.
• Constant degree of super heat was assumed for
consistency.
• MatLab- Simulink was used to do the simulation.
R.I.T DUBAI
Rochester Institute of Technology
Results
variable
R22 Pd=1.57x10-3
HC mix Pd=1.57x10-3
HC mix % variation
mR
0.03238
0.01569
-51.5
Te
5.2
7
34.6
Tc
49.5
47.35
-4.3
P2/P1
3.262
2.787
-14.6
T2
88.5
68.4
-22.7
0.866
0.879
1.5
Toe
10.87
11.88
9.3
WC
1315.43
1043.35
-20.7
QE
5353.8
4757.67
-11.1
COP
4.07
4.56
12.0
v
4
R.I.T DUBAI
Rochester Institute of Technology
Operation with increased piston displacement
R22
Pd=1.57x10-3
HC mix with 120% piston
displacement
% variation
mR
0.03238
0.01809
-44.1
Te
5.2
5.85
12.5
Tc
49.5
48.2
-2.6
P2/P1
3.262
2.94
-9.9
T2
88.5
69.9
-21.0
0.866
0.871
0.6
Toe
10.87
10.8
-0.6
WC
1315.43
1267
-3.7
QE
5353.8
5429.14
1.4
COP
4.07
4.285
5.3
variable
v
R.I.T DUBAI
Rochester Institute of Technology
comparison
R-22
HC mix at original piston
displacement
% variation
HC mix with 120% piston
displacement
% variation
0.03238
-51.5
-44.1
Te
5.2
34.6
12.5
Tc
49.5
-4.3
-2.6
P2/P1
3.262
-14.6
-9.9
T2
88.5
-22.7
-21.0
variable
mR
0.866
1.5
0.6
Toe
10.87
9.3
-0.6
WC
1315.43
-20.7
-3.7
QE
5353.8
-11.1
1.4
COP
4.07
12.0
5.3
v
5
R.I.T DUBAI
Rochester Institute of Technology
Refrigeration applications


The same exercise was conducted for a system in
freezing applications.
The results were very similar where COP increased by
8% only.
R.I.T DUBAI
Rochester Institute of Technology
Conclusions:

Using the HC mix in existing R-22 systems resulted in:






11.1% reduction in the capacity
12% increase in COP
50% less charge
14.6% reduction in the pressure ratio
22.7% decrease in the compressor outlet temp.
Increasing the compressor speed by 20% restored the
lost capacity while maintaining the a 3.7% decrease in
the compression power.
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R.I.T DUBAI
Rochester Institute of Technology
Thanks for your patience
R.I.T DUBAI
Rochester Institute of Technology
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