Boiling on a Tube Bundle: Part II-Heat Transfer and Pressure Drop

An extensive experimental study was undertaken to measure nucleate pool boiling heat transfer coefficients, local bundle boiling heat transfer coefficients, and two-phase bundle pressure drops for R134a and R236fa on one plain tube bundle configuration. The experimental database allowed the refinement of frictional pressure drop models previously developed at the Laboratory of Heat and Mass Transfer. Together with the new onset of dryout prediction method presented in part I (preceding article in this issue), this constitutes a significant improvement in such prediction methods. The local bundle boiling heat transfer data highlighted the dependency of the heat transfer coefficient on the heat flux as expected for the present conditions. The new method was proposed and worked well versus the present database and was also validated against additional refrigerants from independent studies. It was proven to also work reasonably well for falling film evaporation data, proving the new prediction method is applicable for a wide range of operating conditions.