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Korean Journal of Chemical Engineering

, Volume 30, Issue 5, pp 1029–1033 | Cite as

Heat transfer property of refrigerant-oil mixture in a flooded evaporator: The role of bubble formation and oil retention

  • Kyoung-Min Koo
  • Soowon Lee
  • Sung-Gyu Kim
  • Young-Man Jeong
  • Jae-Keun Lee
  • Nae-Hyun Park
  • Byung-Chul Na
  • Yoon-Jae Hwang
  • Byung-Soon Kim
  • Joon-Hyun Hwang
  • Soo Hyung KimEmail author
Transport Phenomena

Abstract

We examined the effect of oil retention on the heat transfer performance of a shell-and-tube-type evaporator which had 26 inner tubes and was filled with the refrigerant R-134a. The refrigerant was boiled on the surface of the inner tubes in the evaporator, while chilled water circulated through these tubes. An experimental apparatus was designed to measure both the pressure and temperature profiles at the inlet and outlet of the flooded evaporator. Four windows were installed for observing the operation of the flooded evaporator. A series of experiments were carried out under the following conditions: the refrigerant saturation temperature, 5 °C; refrigerant inlet quality, 0.1; heat fluxes from water to the refrigerant, 5–7 kW/m2. The concentration of the oil retained in the refrigerant was then varied up to approximately 10% to observe the effect on the heat transfer performance of the flooded evaporator. Increasing the oil content (i.e., increasing the concentration up to a maximum of approximately 10%) in the refrigerant R134a did not lead to any appreciable reduction in the overall heat transfer coefficient of a flooded evaporator with multiple-innertubes. When the oil concentration in the refrigerant was approximately 10%, the heat transfer degradation in the case of the flooded evaporator with multiple-inner-tubes was approximately 11%, which was found to be much smaller than the heat transfer degradation in the case of a flooded evaporator with a single-tube (26–49%). This observation suggested that the oil retained in the refrigerant did not significantly deteriorate the heat transfer performance of the flooded evaporator, presumably because the presence of tube bundles promoted forced convection by agitating bubbles.

Key words

Flooded Evaporator Shell-and-tube-type Heat Exchanger R-134a/Oil Mixture Enhanced Tube Heat Transfer Degradation 

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Copyright information

© Korean Institute of Chemical Engineers, Seoul, Korea 2013

Authors and Affiliations

  • Kyoung-Min Koo
    • 1
  • Soowon Lee
    • 2
  • Sung-Gyu Kim
    • 1
  • Young-Man Jeong
    • 1
  • Jae-Keun Lee
    • 1
  • Nae-Hyun Park
    • 2
  • Byung-Chul Na
    • 2
  • Yoon-Jae Hwang
    • 2
  • Byung-Soon Kim
    • 2
  • Joon-Hyun Hwang
    • 2
  • Soo Hyung Kim
    • 3
    Email author
  1. 1.School of Mechanical EngineeringPusan National UniversityBusanKorea
  2. 2.Air Conditioning Energy CompanyLG ElectronicsChangwon City, GyeongnamKorea
  3. 3.Department of Nanomechatronics EngineeringPusan National UniversityBusanKorea

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