Heat transfer and CHF in subcooled flow boiling of aqueous surfactant solutions

Flow boiling heat transfer characteristics of surfactant solution was studied and compared to that of pure water. The tested fluid was an aqueous solution of cetyltrimethyl ammonium chloride (CTAC) with addition of sodium salicylate (NaSal) at the same mass concentration. Tests were performed with 6.0 x 3.5 mm cross-section channel over flow rate range of 192-403 ml/min, at inlet temperature of 80 degrees C and an outlet pressure of 101.3 kPa. Liquid column method and resistance method of temperature determination were adopted to obtain accurate experimental data. The present experimental results show that, the flow boiling in CTAC/NaSal solutions at an appropriate concentration (100 ppm, ppm refers to part per million) behaved a good flow boiling performance. The heat transfer coefficient of 100 ppm CTAC/NaSal solution at the critical heat flux (CHF) was increased to 1.36 times compared to that of pure water. Besides, the CHF of 0.08 mm thick Nickel foil was increased to about 126% by surfactant addition when the concentration was beyond 100 ppm. The addition of CATC/NaSal increased the nucleation site density and inhibits bubble coalescence which were likely to be causes of enhancing the boiling heat transfer coefficient and CHF of subcooled flow boiling of CATC/NaSal aqueous solutions.