Articles & Issues

Language: English

Conflict of Interest: In relation to this article, we declare that there is no conflict of interest.

Publication history: Received December 29, 2012
Accepted February 11, 2013

This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/bync/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

All issues

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

Kyoung-Min Koo Soowon Lee¹ Sung-Gyu Kim Young-Man Jeong Jae-Keun Lee Nae-Hyun Park¹ Byung-Chul Na¹ Yoon-Jae Hwang¹ Byung-Soon Kim¹ Joon-Hyun Hwang¹ Soo Hyung Kim^2†

School of Mechanical Engineering, Pusan National University, San 30, Jangjeon-dong, Geumjung-gu, Busan 609-735, Korea ¹Air Conditioning Energy Company, LG Electronics, 391-2, Gaeumjeong-dong, Changwon City, Gyeongnam 641-711, Korea ²Department of Nanomechatronics Engineering, Pusan National University, San 30, Jangjeon-dong, Geumjung-gu, Busan 609-735, Korea

sookim@pusan.ac.kr

Korean Journal of Chemical Engineering, May 2013, 30(5), 1029-1033(5), 10.1007/s11814-013-0024-9

Download PDF

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_x000D_ under the following conditions: the refrigerant saturation temperature, 5 oC; 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.

Keywords

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

References

Mohanty DK, Singru PM, Korean J. Chem. Eng., 29(9), 1144 (2012)
Chun BH, Kang HU, Kim SH, Korean J. Chem. Eng., 25(5), 966 (2008)
Webb RL, McQuade WF, ASHRAE Trans., 99(1), 225 (1993)
Chen JC, ASME Paper 63-HT-34 (1963)
Kim NH, Kim DY, Int. J. Heat Mass Transf., 53(9-10), 2311 (2010)
Webb RL, McQuade WF, ASHRAE Trans., 99, 1225 (1993)
Zheng J, Chyu MC, Ayub Z, Int. J. Refrig., 31, 564 (2008)
Chyu MC, Zheng J, Ayub Z, Int. J. Refrig., 32, 1876 (2009)
Kline SJ, McClintock FA, Mech. Eng., 75, 3 (1953)
Chen JC, I & EC Process Design and Development., 5(3), 322 (1966)
Browne MW, Bansal PK, Appl. Therm. Eng., 19, 595 (1999)