Advertisement

Comparative Study of the Straight Capillary Tube for CO2 and R22 Refrigerants

  • Pravin Jadhav
  • Neeraj Agrawal
  • Ajit Mane
Chapter
  • 44 Downloads
Part of the Smart Innovation, Systems and Technologies book series (SIST, volume 174)

Abstract

This paper indicates a comparative study of a straight capillary tube, by considering an adiabatic, homogenous, and unchoked flow model. The model is developed for a CO2 and R22 refrigerants by employing the basic principles of fluid and thermodynamics. Thermodynamic properties of R22 and CO2 are obtained from property code REFPROP and CO2PROP, respectively. The result of the model is validated with earlier published results. The variation in mass flow rate at different geometric factors of the tube has been evaluated. The change in tube length is calculated at the given mass flow rate, tube diameter, and surface roughness. The major change in the performance of the capillary tube is observed for the tube diameter, while less variation is observed with surface roughness. The mass flow rate of CO2 is nearly 8–9 times of R22 refrigerant at different geometric configurations. The capillary tube length of CO2 is about 1.4 times of R22 refrigerant. This study is useful to the design of the straight capillary tube with CO2 and R22 refrigerants.

Keywords

Capillary tube CO2 Mass flow rate R22 

.

Nomenclature

A

Cross-sectional area of capillary tube (m2)

Cp

Specific heat (kJ kg−1 K−1)

d

Capillary tube diameter (mm)

f

Friction factor (–)

G

Mass flux (kg m−2 s−1)

h

Specific enthalpy (kJ kg−1)

L

Capillary tube length (m)

m

Mass flow rate (kg s−1)

P

Pressure (bar)

Re

Reynolds number, \({\text{Re}} = \rho Vd/\mu\) (–)

T

Temperature (K)

V

Velocity (m s−1)

x

Dryness fraction (–)

Greek Symbol

ε

Internal surface roughness (mm)

\(\Delta T_{\text{sub}}\)

Degree of subcooling (K)

μ

Dynamic viscosity (Pa s)

v

Specific volume (m3 kg−1)

ρ

Density (kg m−3)

Subscripts

1–4

Capillary tube state points

C

Capillary

evpt

Evaporator

g

Saturated vapor

gc

Gas cooler

i

Element

k

Condenser

l

Saturated liquid

tp

Two phase

cr

Critical

sat

Saturation

max

Maximum

min

Minimum

References

  1. 1.
    Lorentzen, G.: Revival of carbon dioxide as a refrigerant. Int. J. Refrig. 17(5), 292–300 (1994)CrossRefGoogle Scholar
  2. 2.
    Jabaraj, D.B., Kathirvel, A.V., Lal, D.M.: Flow characteristics of HFC407C/HC600a/HC290 refrigerant mixture in adiabatic capillary tubes. Appl. Therm. Eng. 26(14–15), 1621–1628 (2006)CrossRefGoogle Scholar
  3. 3.
    Agrawal, N., Bhattacharyya, S.: Experimental investigations on adiabatic capillary tube in a transcritical CO2 heat pump system for simultaneous water cooling and heating. Int. J. Refrig. 34, 476–483 (2008)CrossRefGoogle Scholar
  4. 4.
    Zhou, G., Zhang, Y.: Numerical and experimental investigations on the performance of coiled adiabatic capillary tubes. Appl. Thermal Eng. 26, 1106–1114 (2006)CrossRefGoogle Scholar
  5. 5.
    Jadhav, P., Agrawal, N.: A comparative study in the straight and a spiral adiabatic capillary tube. Int. J. Ambient Energy (2018).  https://doi.org/10.1080/01430750.2017.1422146CrossRefGoogle Scholar
  6. 6.
    Agrawal, N., Bhattacharyya, S.: Adiabatic capillary tube flow of carbon dioxide in a transcritical heat pump cycle. Int. J. Energy Res. 31, 1016–1030 (2007)CrossRefGoogle Scholar
  7. 7.
    Jadhav, P., Agrawal, N., Patil, O.: Flow characteristics of helical capillary tube for transcritical CO2 refrigerant flow. Energy Procedia 109C, 431–438 (2017)CrossRefGoogle Scholar
  8. 8.
    Jadhav, P., Agrawal, N.: Numerical study on choked flow of CO2 refrigerant in helical capillary tube. Int. J. Air-Conditioning Refrig. 26(03), 1850027 (2018).  https://doi.org/10.1142/S201013251850027XCrossRefGoogle Scholar
  9. 9.
    Jadhav, P., Agrawal, N.: Study of homogenous two phase flow through helically coiled capillary tube. Adv. Sci. Eng. Med. 10, 1–5 (2018)CrossRefGoogle Scholar
  10. 10.
    Bansal, P., Wang, G.: Numerical analysis of choked refrigerant flow in adiabatic capillary tubes. Appl. Therm. Eng. 24, 851–863 (2004)CrossRefGoogle Scholar
  11. 11.
    Churchill, S.W.: Friction factor equations spans all fluid-flow regimes. Chem. Eng. 84(24), 91 (1977)Google Scholar
  12. 12.
    Lin, S.: Local frictional pressure drop during vaporization of R-12 through capillary tubes. Int. J. Multiph. Flow 17(1), 95–102 (1991)CrossRefGoogle Scholar
  13. 13.
    Sarkar, J., Bhattacharyya, S., Ramgopal, M.: Optimization of transcritical CO2 heat pump cycle for simultaneous cooling and heating applications. Int. J. Refrig. 27(8), 830–838 (2004)CrossRefGoogle Scholar

Copyright information

© Springer Nature Singapore Pte Ltd. 2020

Authors and Affiliations

  • Pravin Jadhav
    • 1
  • Neeraj Agrawal
    • 1
  • Ajit Mane
    • 2
  1. 1.Dr. B. A. Technological UniversityLonere, RaigadIndia
  2. 2.Annasaheb Dange College of Engineering & TechnologyAshta, SangliIndia

Personalised recommendations