Analysis of parallel mini-channels’ complex flow boiling and dryout dynamics based on the pressure drop signals

Abstract

Based on a heat exchange experiment, the authors used R141b as the working medium, and analyzed the differential pressure signal of parallel mini-channels (N = 9, L = 250 mm, Wc = 2 mm, H = 2 mm). Different flow patterns (bubble flow, slug flow, annular flow, dryout, mist flow) have different pressure drops. Flow boiling characteristics were analyzed by the adaptive optimal kernel time–frequency representation (AOK-TFR), autoregression (AR) power spectrum and recurrence plot (RP). Then, the dryout kinetics of working fluids were revealed. Finally, through the combination of three recursive characteristic parameters, the dryout prediction based on the differential pressure signal was proposed, which provides the theoretical basis for the dynamic characteristics of boiling heat transfer. At the same time, it gives a solution for prevention of the second type of heat transfer deterioration in a project.