Experimental and numerical analysis of saturation boiling is carried out on a vertical confined tube with a high aspect ratio of 75. Heat transfer coupled with the solid heat conduction which provides a more realistic description of nucleate pool boiling. This study conducts visual observation of vapor phase behavior and investigates the distribution of the vapor phase along the height of a vertical tube. Meanwhile, a corresponding numerical simulation is conducted, according to the VOF method. The computed heat transfer coefficient agrees well with the experimental result, demonstrating the capability of the described numerical model to predict the boiling heat transfer for the flow regimes along the height. Comparison of bubble shapes between experiment and computation also shows a good agreement. The local characteristics of vapor bubbles as well as flow and heat transfer in the saturation boiling regime are present. In addition, a variety of statistical data, such as the heat flux partitioning and the ratio of vapor-to-liquid area over the heat transfer surface, which cannot be measured in the experiments, can also be derived from the results of the simulation. (C) 2018 Elsevier Ltd. All rights reserved.