An experimental study of gas-liquid flow in a narrow conduit

This paper reports an experimental study of non-boiling air-water flows in a narrow conduit (diameter 1.95 mm). Results are presented for pressure dro p characteristics and for local heat transfer coefficients over a wide rang e of gas superficial velocity (0.1-50 m s(-1)), liquid superficial velocity (0.08-0.5 m s(-1)) and wall heat flux (3-58 kW m(-2)). For a given liquid flow rate, the data exhibit sudden changes in pressure drop and, to a lesse r extent, in heat transfer characteristics as the gas flow is increased. Th ese events are believed to correspond to flow transitions, from bubbly, to intermittent slug, to annular flow. Overall, the pressure drops in these di abatic non-boiling two-phase hows can be estimated with good accuracy using correlations developed for adiabatic conditions. The heat transfer results are, on average, reasonably well described by the two-phase convective hea t transfer components of flow-boiling correlations but there is considerabl e scatter in some cases. (C) 2000 Elsevier Science Ltd. All rights reserved .