Experimental study on pressure drop of flow boiling in the vertical narrow annuli

Experimental study associated with two-phase flow of boiling in the vertical narrow annuli with the gap width of 1.0 and 1.5 mm has been conducted. The test section can be simultaneously heated from inner and outer tubes by electricity. The system pressure range examined is from 1.5 to 6.0 MPa. Based on the experimental data, a new correlation of two-phase multiplier, which is based on single liquid phase flow in the ducts, has been developed. The new correlation can predict the experimental data well and the mean deviation is 11.6%.