HEAT-TRANSFER AND PRESSURE-DROP FOR AIR-WATER MIXTURES IN AN ISOFLUX VERTICAL ANNULUS

Heat transfer and pressure drop in flows of air-water mixtures have be en investigated experimentally in an isoflux vertical annulus The supe rficial liquid Reynolds number, as a reference parameter, varied from 4500 to 30000, at different values of gas-to-liquid superficial veloci ty ratios zip to 20 and surface heat fluxes from 50 to 240 kW/m(2). En hancement of the two-phase heat transfer coefficient is pronounced par ticular ly at low liquid superficial velocities. The results are corre lated and compared with some models of two-phase, two-component flows for air-water mixtures within their range of validity. Satisfactory ag reement is obtained from the trend of the experimental data.