Study of Refrigerator Performance Through Variation of Capiler
Pipe Length
Jufra D. J. Abanat, Jhon Arnoldos Wabang and Edwin P. D. Hattu
Machine Engineering, State Polytechnics of Kupang, Adisucipto Street, Kupang, Indonesia
Keywords: Cooling System, Capillarity Tube.
Abstract: In the cooling system (AC), there are a series of main components to support the working system, namely the
compressor, condenser, filter drayer, capillary pipe or expansion valve and evaporator. The five components
of concern in this study are the capillary tube. The function of the capillary tube is to lower the pressure and
lower the temperature of the system. The results showed that the performance of the refrigerator with length
of capillary pipe 150 cm, diameter 0.031 inch, Coeficient of Performance (COP) was 3.28, Refrigeration
Efficiency 86.47%, refrigeration effect 130.17 kJ/kg. and pressure ratio 6,22. For refrigerator with length of
capillary pipe 200 cm, diameter 0.031 inch, Coeficient of Performance (COP) was 3.41, Refrigeration
Efficiency 79.68%, refrigeration effect 128.66 kJ/kg. and pressure ratio 6,33. In refrigerator with length of
capillary pipe 250 cm, diameter 0.031 inch, Coeficient of Performance (COP) was 3.25, Refrigeration
Efficiency 77.27%, refrigeration effect 127.02 kJ/kg. and pressure ratio 6,77. Based on the results of the
analysis of the three types of capillary pipes, capillaries with a length of 150 mm have better performance
than the other two types of capillary pipes.
1 INTRODUCTION
Air conditioning is a condition that continues to be a
concern because this system is needed in almost all
fields, therefore the application of components that
can work effectively and efficiently continues to be
researched in order to get an AC working system that
can provide comfort for users in their daily activities
all day and every where (Anwar et al., 2010).
In the cooling system, a series of main
components to support the working system, namely
the compressor, condenser, filter drayer, expansion
valve or capillary tube and evaporator.The five
components that are of concern in this study are the
variation of length of capillary tube. this is due to the
difference that there are several refrigerators that have
capillary pipe sizes that are not the same length
(Anwar, 2010); (Bowo, 2013).
In this study using variations of three types of pipe
lengths, namely capillary pipes with a length of 150
mm, 200 mm and 250 mm respectively with the same
diameter, namely 0.031 inchi.
These three types of capillary tube will be tested
using the refrigerators. The refrigerant material used
is refrigerant (R234a) (Wang et al., 2017). The basis
for choosing this material is because the refrigerators
compressor is only suitable for using R134a.
The test model used is to vary the three types of
capillary tube to determine the performance of the
system in the form of Coeficient of Performance
(COP), refrigeration effect, system efficiency and
pressure ratio (Wardika, 2018).
2 RESEARCH METHODOLOGY
This research was conducted in the Refrigeration
Engineering laboratory, with the set up as follows:
Figure 1: Set Up Experimental.
154
Abanat, J., Wabang, J. and Hattu, E.
Study of Refrigerator Performance Through Variation of Capiler Pipe Length.
DOI: 10.5220/0011729700003575
In Proceedings of the 5th International Conference on Applied Science and Technology on Engineering Science (iCAST-ES 2022), pages 154-157
ISBN: 978-989-758-619-4; ISSN: 2975-8246
Copyright © 2023 by SCITEPRESS – Science and Technology Publications, Lda. Under CC license (CC BY-NC-ND 4.0)

The implementation of this research followed the
flow chart as shown below in fig.2. From this set up
of experiments, a system test is performed with steps
such as the following flow chart:
Figure 2: Flow Charts.
3 RESULT AND DISCUSSION
3.1 Result
This test is carried out on a split AC with the
following specifications:
1. The mass of refrigerant = 40gr
2. Testing time = 120 Minutes
Based on the research flow, the test results of the three
type of length of capillary pipe can be seen in the
following table below :
Table 1: Test results for length of capillary pipe 150 cm,
diameter 0.031 inch.
No
Time
(Men
ute)
Mass
refrig
erant
(gr)
Temperature ( ᵒC )
Low
Press
ure
(psi)
Evap
orator
Con
den
ser
Env
iron
men
t
1
30 10 18,5 33,1 30,8 -10
2
30 20 16 34,2 31 0
3
30 30 -11,7 38,8 31,2 3
4
30 40 -13 42,5 31 9
Table 2: Test results for length of capillary pipe 200 cm,
diameter 0.031 inch.
No
Time
(Men
ute)
Mass
refrig
erant
(gr)
Temperature ( ᵒC )
Low
Press
ure
(psi)
Evap
orator
Con
den
ser
Env
iron
men
t
1
30 10 15,7 33,5 31 -6
2
30 20 -11,4 38 30,9 0
3
30 30 -16 42,1 30,9 5
4
30 40 -16,5 43,5 30,9 10
Table 3: Test results for length of capillary pipe 250 cm,
diameter 0.031 inch.
No
Time
(Men
ute)
Mass
refrig
erant
(gr)
Temperature ( ᵒC )
Low
Press
ure
(psi)
Evap
orator
Con
den
ser
Env
iron
men
t
1
30 10 13,1 33,8 30,7 -8
2
30 20 -6,2 36 30 -2
3
30 30 -18,5 42,6 30,5 5
4
30 40 -19 41,4 30,2 8
Start
System Check
Test Preparation
Refrigerant
R134a
Measuring
Instruments
(Pressure,
humidity,
Refrigerator
(includes
Variation in
length of
Refrigerant
Charging and
System
Vacuum S
y
stem
Test
Result
Data
Report
Data Analysis
End
Study of Refrigerator Performance Through Variation of Capiler Pipe Length
155

3.2 Discussion
The test results based on variations in the length of
the capillary tube in the table 1, table 2 and table 3
above can be calculated the performance of
refrigerator with R134a refrigerant as follows:
a. Length of capillary pipe 150 cm, diameter 0.031
inch.
Based on the test results in the table 1 above, it
appears that at minute 120 with a refrigerant mass of
40 gr, the evaporator temperature reaches a
temperature of -13 at a low pressure of 9 Psi.
The data from this test, plotted in the coolpack
application, obtained a graph as shown in the figure
below:
Figure 3: Graph of p-h diagram for Length of capillary pipe
150 cm, diameter 0.031 inch.
The graph in this figure shows the enthalpy values as
follows:
h
1
= 390.09 kJ/kg h
3
= 259,92 kJ/kg
h
2
= 429,75 kJ/kg h
4
= 259,92 kJ/kg
The performance of the refrigerator based on the
eltalpy values is as follows:
1. Specific work by the Compressor (Q
w
).
39,66 kJ/kg
2. The heat is released by the condenser (q
k
)
169,83 kJ/kg
3. Refrigeration Effect (q
e
)
130,17 kJ/kg
4. Coeffisient Of Performance(COP)
a. COP
aktual
= 3,28
b. COP
carnot
= 3.79
5. Refrigeration Efficiency (η)
86,47%
6. Pressure Ratio:
6,22,
b. Length of capillary pipe 200 cm, diameter 0.031
inch.
The test results in the table 2 above, it appears that
at 120 minutes with a refrigerant mass of 40 g, the
evaporator temperature reaches a temperature of -
16.5 at a low pressure of 10 Psi.
The data from this test, plotted in the coolpack
application, obtained a graph as shown in the figure
below:
Figure 4: Graph of p-h diagram for Length of capillary pipe
200 cm, diameter 0.031 inch.
The graph in this figure shows the enthalpy values as
follows:
h
1
= 386,87 kJ/kg h
3
= 261,43 kJ/kg
h
2
= 424,64 kJ/kg h
4
= 261,43 kJ/kg
The performance of the refrigerator based on the
enthalpy values is as follows:
1. Specific work by the Compressor (Q
w
).
37,77 kJ/kg
2. The heat is released by the condenser (q
k
)
163,21 kJ/kg
3. Refrigeration Effect (q
e
)
128,66 kJ/kg
4. Coeffisient Of Performance(COP)
a. COP
aktual
= 3,41
b. COP
carnot
= 4.28
5. Refrigeration Efficiency (η)
79,68%
6. Pressure Ratio:
6,33
c. Length of capillary pipe 250 cm, diameter 0.031
inch.
In the table above, it appears that at minute 120 with
a refrigerant mass of 40 g, the evaporator temperature
reaches a temperature of -19 at a low pressure of 8
Psi.
The data from this test, plotted in the coolpack
application, obtained a graph as shown in the image
below:
iCAST-ES 2022 - International Conference on Applied Science and Technology on Engineering Science
156

Figure 5: Graph of p-h diagram for Length of capillary pipe
250 cm, diameter 0.031 inch.
The graph in this figure shows the enthalpy values as
follows:
h
1
= 385,28 kJ/kg h
3
= 258,26 kJ/kg
h
2
= 424,37 kJ/kg h
4
= 258,26 kJ/kg
Refrigerator performance based on enthalpy values
are as follows:
1. Specific work by the Compressor (Q
w
).
39,09 kJ/kg
2. The heat is released by the condenser (q
k
)
166,38 kJ/kg
3. Refrigeration Effect (q
e
)
127,02 kJ/kg
4. Coeffisient Of Performance(COP)
a. COP
aktual
= 3.25
b. COP
carnot
= 4.21
5. Refrigeration Efficiency (η)
77,27%
6. Pressure Ratio :
6,77.
4 CONCLUSION
Based on the results of the study in table above, it can
be concluded as follows:
1. The results showed that the performance of the
length of capillary pipe 150 cm, diameter 0.031
inch, Coeficient of Performance (COP) was 3.28,
Refrigeration Efficiency 86.47%,, and
refrigeration effect 130.17 kJ/kg.
2. For length of capillary pipe 200 cm, diameter
0.031 inch, Coeficient of Performance (COP) was
3.41, Refrigeration Efficiency 79.68%,, and
refrigeration effect 128.66 kJ/kg.
3. In length of capillary pipe 250 cm, diameter 0.031
inch, the Coeficient of Performance (COP) is
3.25, Refrigeration Efficiency 77,27%, and
refrigeration effect 127,02 kJ/kg.
ACKNOWLEDGEMENTS
The authors would like to thank State Politeknik of
Kupang for the financial support through the RUTIN
Research Programme. A thank you also goes to
Wilmar Sagala for their help to record the values of
performance of refrigerator system based on variation
of length of capillary pipe using manifold gauge and
electrical equipments.
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