Pool boiling enhancement with environmentally friendly surfactant additives

Abstract

Boiling heat transfer is used in variety of industrial processes and applications, such as refrigeration, vapor cycle power generation, heat exchangers, petroleum refining, and chemical manufacturing. Enhancements in boiling heat transfer processes are critical for making these applications more energy efficient. The aim of this paper is to demonstrate the water pool boiling phenomena under the influence of environmentally friendly surfactant additives. The test setup used in this study has multiple benefits. First, the test setup enhances teaching in variety of classes through in-class demonstrations and student experiments. An experiment is described to allow the students to visualize and qualify different modes of boiling heat transfer. In addition, the test setup provides a platform for research in boiling enhancement. Using surfactant additives in boiling causes increased number of nucleation sites and decreased level of wall superheat. For determining surfactant effects, different concentrations of sodium lauryl sulfate (SLS), ECOSURF™ EH-14, and ECOSURF™ SA-9 are added to pure water and enhancement through surfactants is quantified. When times until boiling (liquid temperature reaches the boiling point) are measured, 17, 10.3, and 19.6 % lower times found (for SLS, EH-14, and SA-9, respectively) compared to pure water. Wall temperature reduction is measured for 50 ppm SLS 9.48 %, for 300 ppm EH-14 11.3 %, and for 200 ppm SA-9 10.43 %. It can be concluded from this study that a reduction in surface tension leads to a higher nucleation site density and more small bubbles on the boiling surface.