Enhancement of nucleate pool boiling heat transfer coefficient by reentrant cavity surfaces

The pool boiling of acetone, isopropanol, ethanol and water at atmospheric pressure has been carried out on a plain tube, and five different reentrant cavity (REC) heating tubes. The heat flux has remained in a range of 11–42 kW/m² for all the heating tubes. The enhancement factor, E, has been found to increase with the rise in heat flux, irrespective of the boiling liquid and the test-section tube combinations. For the pool boiling of acetone and isopropanol, the maximum enhancement factor has been attained for REC-2 tube with mouth size of 0.3 mm and for ethanol and water the mouth size could not be optimized, however, the maximum enhancement factor has been attained for REC-4 tube with mouth size of 0.2 mm. A correlation has also been developed to predict the enhancement factor, E, for the pool boiling of the test-liquids on REC heating tubes. This correlation has predicted the enhancement factor, E, in an error band of +12.5 to –7.5%.