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KSME International Journal

, Volume 14, Issue 5, pp 537–546 | Cite as

Some aspects of experimental in-tube evaporation

  • Samchul Ha
Thermal Engineering · Fluid Engineering · Energy and Power Engineering

Abstract

The heat transfer characteristics of refrigerant-oil mixture for horizontal in-tube evaporator have been investigated experimentally. A smooth copper tube and a micro-fin tube with nominal 9.5 mm outer diameter and 1500 mm length were tested. For the pure refrigerant flow, the dependence of the axial heat transfer coefficient on quality was weak in the smooth tube, but in the micro-fin tube, the coefficients were 3 to 10 times greater as quality increases. Oil addition to pure refrigerant in the smooth tube altered the flow pattern dramatically at low mass fluxes, with a resultant enhancement of the wetting area by vigorous foaming. The heat transfer coefficients of the mixture for low and medium qualities were increased at low mass fluxes. In the micro-fin tube, however, the addition of oil deteriorates the local heat transfer performance for most of the quality range, except for low quality. The micro-fin tube consequently loses its advantage of high heat transfer performance for an oil fraction of 5%. Results are presented as plots of local heat transfer coefficient versus quality.

Key Words

Refrigerant-Oil Mixture In-Tube Evaporator Smooth Tube Micro-Fin Tube Heat Transfer Coefficient Mass Flux 

Nomenclature

De

Envelope diameter (mm)

Do

Outside diameter

f

Fin height (mm)

G

Mass flux (kg/(m2s))

q

Heat flux (kW/m2)

t

Tube thickness

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Copyright information

© The Korean Society of Mechanical Engineers (KSME) 2000

Authors and Affiliations

  1. 1.LG Electronics Inc.KyungnamKorea

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