To obtain effects of geometric parameters on nucleate pool boiling heat transfer in a vertical annulus with closed bottoms, an empirical correlation is newly suggested. For the development, a total of 494 data points has been obtained for various combinations of a diameter, tube lengths, and a gap size. The developed correlation is consisted of dimensionless parameters and predicts experimental data within ±17% error bound. It has been identified that the length of the outside tube should be counted into the analyses to estimate heat transfer coefficients accurately.

pool boiling, annulus, correlation, bottom confinement, vertical tube.