Pool boiling heat transfer characteristics of non-Newtonian Xanthan gum solutions

Polymeric solutions as a subcategory of non-Newtonian fluids are prepared by the dissolution of polymeric additives into a solvent and find applications in many areas. Their advantage over new generation fluids such as nanofluids is that they have no side effects such as agglomeration and sedimentation of particles, which is common for nanofluids. This study presents an experimental study on nucleate pool boiling of aqueous Xanthan gum solutions of different concentrations. The results revealed that heat transfer coefficients of prepared polymeric solutions were lower than those of pure water. Heat transfer coefficients decreased with concentration until the concentration reached a certain amount (500 mg/L). Beyond this value, there was no change in heat transfer performance with concentration. Nevertheless, a monotonically decreasing trend was observed for high concentrations (>= 4000 mg/L), which is associated with sharp changes in surface tension and boiling patterns beyond a certain concentration. In visualization studies, different pool boiling patterns were recorded particularly for high concentrations, which bolster the heat transfer results. RAMAN tests were also conducted to check for the stability of the solutions. (C) 2015 Elsevier Inc. All rights reserved.