Investigating the evolution of the fire plume centerline temperature has both fundamental and practical importance to process safety, risk analysis and disaster control. In practice, ullage height (distance between the fuel surface and the container upper rim) is a common boundary condition that affects the burning intensity and the flaming characteristics. In this study, a series of experiments were conducted to reveal the effects of ullage height on the evolution of the heptane fire plume centerline temperature. The tested ullage height was systematically changed from zero to the value at which the flame self-extinguished. Results showed that, as ullage height increased, the fire plume centerline temperature first decreased and then slightly increased. By comparing the model predictions of previous classic models with the tested results, this study proved that previous classic models are not capable in predicting temperature profiles under high ullage height conditions. Based on physical and dimensionless analysis, a new virtual origin model was established to quantify the effects of ullage height on the virtual origin. A more universal plume centerline temperature model, which is capable to predict the centerline temperature profiles with any ullage height conditions, was proposed and validated by literature experimental data. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.