Effects of dissolved air on subcooled and saturated flow boiling of water in a small diameter tube at low pressure

Experimental results on flow boiling of air saturated water flowing through a tube of inner diameter di = 4.03 mm are presented. Both subcooled and saturated flow boiling are investigated, covering pressures from 177 to 519 kPa, mass fluxes from 478 to 839 kg m−2 s−1 and heat fluxes from 210 to 736 kW m−2. By comparing the measured results with existing prediction methods derived for degassed liquids the study concludes that the presence of dissolved air in the testing fluid can be regarded as a second order effect, and no special attention to dissolved air appears required.