A numerical model of a rapid response phase change heat exchange module has been developed and challenged with experimental data taken on a flow bench with multiple temperatures and flow rates for two different phase change thermal storage devices (PTSDs). The model requires an a priori knowledge of an effective overall heat transfer coefficient. A single test was used to establish a value for an effective overall heat transfer coefficient. With this information the model will predict the power removed from a fluid being cooled to closer than 15% of the peak power and the temperature of the fluid exiting the device to within 2 °C over the entire fluid discharge temperature range. This model, developed for potential use in feedback control algorithms, requires a real-time execution speed, and this goal has been achieved with a desktop quad-core computer (four times faster than real time). While 3D models with millions of cells can provide greater resolution, the large computational resources and run times required for these simulations precludes their use as a part of feedback control algorithms.