Abstract

A comparative study has been carried out on the adiabatic straight and helical capillary tube, using a CO2 and R22 refrigerant. The numerical model for CO2 and R22 is developed using the basic principles of conservation of mass, momentum, and energy. The effect of coiling in the helical capillary tube is compared with a straight capillary tube for CO2 and R22 refrigerant. Compared with the straight capillary tube, the percentage reduction in mass flowrate in the helical capillary tube is calculated with a change in coil diameter, tube diameter, and length. As the coil diameter increases from 30 mm to 150 mm, the percentage reduction in mass is from 5.8% to 2.2% in CO2, and 5% to 1.6% in R22. For helical capillary tube with 50 mm coil diameter, as the tube diameter increases from 1 to 1.5 mm, the percentage reduction in mass flowrate with CO2 refrigerant is from 2.65% to 4.96%, however, for R22 it is from 2.43% to 4.24%. Similarly, as the capillary tube length increases from 1.3 m to 1.8 m, the percentage reduction in mass with CO2, with 50 mm coil diameter is 4.44–4.55%. However, the percentage reduction in mass with R22 is 3.71–3.85%. Moreover, compared with the straight capillary tube, the percentage reduction in length in a helical capillary tube with coil diameter 50 mm is 16% for CO2 and 9% for R22 refrigerant.

References

References
1.
Lorentzen
,
G.
,
1994
, “
Revival of Carbon Dioxide as a Refrigerant
,”
Int. J. Refrig.
,
17
(
5
), pp.
292
300
. 10.1016/0140-7007(94)90059-0
2.
Wang
,
J.
,
Cao
,
F.
,
Wang
,
Z.
,
Zhao
,
Y.
, and
Li
,
L.
,
2012
, “
Numerical Simulation of Coiled Adiabatic Capillary Tubes in CO2 Transcritical Systems With Separated Flow Model Including Metastable Flow
,”
Int. J. Refrig.
,
35
(
8
), pp.
2188
2198
. 10.1016/j.ijrefrig.2012.07.012
3.
Zhou
,
G.
, and
Zhang
,
Y.
,
2006
, “
Numerical and Experimental Investigations on the Performance of Coiled Adiabatic Capillary Tubes
,”
Appl. Therm. Eng.
,
26
(
11–12
), pp.
1106
1114
. 10.1016/j.applthermaleng.2005.11.003
4.
Agrawal
,
N.
, and
Bhattacharyya
,
S.
,
2007
, “
Adiabatic Capillary Tube Flow of Carbon Dioxide in a Transcritical Heat Pump Cycle
,”
Int. J. Energy Res.
,
31
(
11
), pp.
1016
1030
. 10.1002/er.1294
5.
Jadhav
,
P.
,
Agrawal
,
N.
, and
Patil
,
O.
,
2017
, “
Flow Characteristics of Helical Capillary Tube for Transcritical CO2 Refrigerant Flow
,”
Energy Procedia
,
109
, pp.
431
438
. https://doi.org/10.1016/j.egypro.2017.03.055
6.
Jadhav
,
P.
, and
Agrawal
,
N.
,
2018
, “
Numerical Study on Choked Flow of CO2 Refrigerant in Helical Capillary Tube
,”
Int. J. Air-Cond. Refrig.
,
26
(
3
), p.
1850027
. 10.1142/S201013251850027X
7.
Jadhav
,
P.
, and
Agrawal
,
N.
,
2019
, “
A Comparative Study in the Straight and a Spiral Adiabatic Capillary Tube
,”
Int. J. Ambient Energy
,
40
(
7
), pp.
693
698
. 10.1080/01430750.2017.1422146
8.
Jadhav
,
P.
, and
Agrawal
,
N.
,
2020
, “
Flow Behavior of Spiral Capillary Tube for CO2 Transcritical Cycle
,”
J. Therm. Anal. Calorim
. https://doi.org/10.1007/s10973-020-09536-8
9.
Bansal
,
P. K.
, and
Wang
,
G.
,
2004
, “
Numerical Simulation of Coiled Adiabatic Capillary Tubes in CO2 Transcritical Systems With Separated Flow Model Including Metastable Flow
,”
Appl. Therm. Eng.
,
24
(
5–6
), pp.
851
863
. 10.1016/j.applthermaleng.2003.10.010
10.
Agrawal
,
N.
, and
Bhattacharyya
,
S.
,
2008
, “
Experimental Investigations on Adiabatic Capillary Tube in a Transcritical CO2 Heat Pump System for Simultaneous Water Cooling and Heating
,”
Int. J. Refrig.
,
34
(
2
), pp.
476
483
. 10.1016/j.ijrefrig.2010.09.014
11.
Jabaraj
,
D. B.
,
Vettri Kathirvel
,
A.
, and
Mohan Lal
,
D.
,
2006
, “
Flow Characteristics of HFC407C/HC600a/HC290 Refrigerant Mixture in Adiabatic Capillary Tubes
,”
Appl. Therm. Eng.
,
26
(
14–15
), pp.
1621
1628
. 10.1016/j.applthermaleng.2005.11.017
12.
Churchill
,
S.
,
1977
, “
Frictional Equation Spans all Fluid Flow Regions
,”
Chem. Chem. Eng.
,
84
(
24
), p.
91
.
13.
Mori
,
Y.
, and
Nakayama
,
W.
,
1967
, “
Study on Forced Convection Heat Transfer in Curved Pipes (2nd Report Turbulent Region)
,”
Int. J. Heat Mass Transfer
,
10
(
1
), pp.
37
59
. 10.1016/0017-9310(67)90182-2
14.
Lin
,
S.
,
Kwok
,
C. C. K.
,
Li
,
R.-Y.
,
Chen
,
Z.-H.
, and
Chen
,
Z.-Y.
,
1991
, “
Local Friction Pressure Drop During Vaporization of R-12 Through Capillary Tubes
,”
Int. J. Multiphase Flow
,
17
(
1
), pp.
95
102
. 10.1016/0301-9322(91)90072-B
15.
Sarkar
,
J.
,
Bhattacharyya
,
S.
, and
Ramgopal
,
M.
,
2004
, “
Optimization of Transcritical CO2 Heat Pump Cycle for Simultaneous Cooling and Heating Applications
,”
Int. J. Refrig.
,
27
(
8
), pp.
830
838
. 10.1016/j.ijrefrig.2004.03.006
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