Bubble explosion in pool boiling around a heated wire in surfactant solution

This paper reports a new pool boiling phenomenon of bubble explosion in a surfactant solution. The working fluid was an aqueous solution of cetyltrimethyl ammonium chloride (CTAC) with addition of sodium salicylate (NaSal) at the same mass concentration. A platinum wire was horizontally placed in the fluid for heating. The boiling heat transfer performances of the tested fluid at fluid temperature (288.15 K) and different concentrations of CTAC/NaSal solution (0-400 ppm) have been presented. It's found that the tested surfactant solution significantly augmented boiling heat transfer as compared with water, and the best heat transfer performance was found at the concentration ranging from 5 to 100 ppm. With a high-speed camera and an inverted microscope, the nucleation boiling process on the heated wire was recorded. For the first time, we observed a new bubble explosion phenomenon around the heated wire in CTAC/NaSal solutions (at concentration beyond 0.1 ppm), which is apparently different from the previously reported boiling explosion due to homogeneous nucleation. Together with the observed strong jet-flow behaviors, bubble explosion strengthened the local disturbance and enhanced the boiling heat transfer. It was conjectured that the strong jet-flow phenomenon is essentially the traces of small bubbles and bubble explosion is a failed coalescence of unstable bubbles, which leads to the disturbance and boiling heat transfer enhancement. (C) 2016 Elsevier Ltd. All rights reserved.