Доступ предоставлен для: Guest

ISSN Online: 2377-424X

ISBN Print: 0-85295-345-3

International Heat Transfer Conference 10
August, 14-18, 1994, Brighton, UK

SOME ASPECTS OF EXPERIMENTAL IN-TUBE EVAPORATION

Get access (open in a dialog) DOI: 10.1615/IHTC10.5490
pages 187-192

Аннотация

The heat transfer characteristics for refrigerant-oil mixture of horizontal in-tube evaporator have been investigated experimentally. A smooth copper tube and a micro-fin tube with norminal 9.5 mm o.d. and 1500 mm length were tested.
For the pure refrigerant flow, the dependence of the axial heat transfer coefficient on quality was weak for the smooth tube, but for the micro-fin tube, the coefficients were 3 to 10 times increased with increases in quality. 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 coefficients of the mixture for low and medium qualities were increased at low mass fluxes. For 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, and, finally, the micro-fin tube 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 pure vapor quality.