要約

Both a flow visualization experiment and measurements of heat transfer and pressure drop were conducted for water undergoing complete condensation in a family of horizontal tubes with diameters from 1.7 to 4 mm. The flow visualization experiment reveals a skewed annular liquid film over nearly the entire condensation length. Average heat transfer coefficients were calculated for tubes of 1.7, 2.5, 3.2, and 4.0 mm diameter, over a range of mass fluxes from 10 to 25 kg/m²s, at saturation temperatures of 60, 70, 80, and 90 °C. At a fixed mass flux, results for complete condensation show the average heat transfer coefficient decreases and pressure drop increases with increasing condensation length. For the same mass flux and at comparable condensation lengths, the average heat transfer coefficient and pressure drop increase with decreasing tube diameter. The effects of saturation temperature and mass flux are shown for each of the four tube diameters tested.