An experimental investigation of oscillatory heat transfer in helical coiled tube with steam water two-phase density wave oscillation flow

Some results of experimental research on the oscillatory heat transfer characteristics including transient and time-average heat transfer coefficients for vapour-water two phase flow during the processes of density-wave oscillation occurring in helical coiled tube boiling channel system were presented. The experiment was performed at a closed-circulation test loop under the following parameters ranges: system pressure p = 0.5-3.5 MPa; Mass flow rate G = 200-2100 kg/(m2·s); Intel subcooling of working fluid ΔTsub = 20-90 degree C; Heat flux of wall of test section qw = 0-540 kW/m2. The range of oscillatory periods of density-wave oscillations T was 1.25-14 s and mainly concentrated in the range of 4-10 s. The features of transient and time-averaged heat transfer coefficients were described and analyzed. New mechanisms and non-dimensional parameters to characterize the features of heat transfer process were proposed, and a correlation for the prediction of oscillatory heat transfer coefficients was obtained on the basis of experimental data and mechanism analysis