This paper details a research study that was undertaken by Babcock ME&S behalf of the UK Defence Science and Technology Laboratory (DSTL) to improve the understanding of cooling performance of Phase Change Materials (PCMs). The Chilled Water Plants (CWP) on naval platforms are often not optimised to cope with high peak thermal demands whilst operating in challenging climates. The cooling demands on future platforms are set to increase with the introduction of high energy systems such as Laser Directed Energy Weapons (LDEWs), driving the exploration of alternative cooling technologies that have the potential to improve system efficiency and size. Latent Heat Thermal Energy Storage (LHTES) systems utilise PCMs and have the ability to supplement the Chilled Water (CW) system and smooth cooling loads at peak demand. Phase Change Materials are substances which absorb and release large amounts of latent heat when undergoing a change in physical state. A LHTES tank representative of scaled down naval system was modelled using 3D computational fluid dynamics (CFD) in ANSYS Fluent. Hydrated salts were chosen as the PCM due to the favourable thermal properties. The thermal characteristics of the tank and the viability as a cooling system were assessed by simulating a variety of thermal load profiles. The computational model acts as a digital twin of an experimental setup, which will later be used for validation. This paper is primarily focussed on the approach to modelling the tank, model parameters and findings.