Abstract
Experimental measurements of pressure drop have been made for forced convection evaporation of refrigerant(R12)-oil(SUNISO 5GS) mixtures inside a horizontal tube. Parameters were changed in mass velocity range(110-290 kg/(m2·s))and wall heat flux(5-30 kW/m2), oil weight concentration(0-11 %), quality(0.1-1.2).
In general, at low oil concentration region up to 3%, the average pressure drop was, increased sharply with increasing oil concentration, and beyond 3% increment rate of pressure drop was gradually decreased. Average pressure drop at 10% was almost twice as this of oil free case.
The experimental data were compared with the various existing frictional pressure drop expressions.
Gronnerud's correlation and Chisholm's correlation presenting the best representations for oil free data were modified to ensure the more accurate prediction and to extend the application for oil mixture case.
The local pressure drop was predicted within ±30% by modified correlations.
