The Clean Aviation Sustainable Water-Injecting Turbofan Comprising Hybrid-Electrics (SWITCH) project aims to answer the challenge of climate-neutral Small to Medium Range (SMR) transport by developing a revolutionarily sustainable gas turbine propulsion system and further boosting it with hybridization to improve energy efficiency by 25% and reduce non-CO2 related climate impact by more than 60%. The core of SWITCH is the revolutionary Water-Enhanced Turbofan (WET) concept, which offers unmatched potential to enable climate-neutral aviation based on existing and future infrastructure, while also retaining the key benefits of gas turbine propulsion to meet the full range of thrust, speed, and all other mission requirements. Wet combustion allows NOx emission reduction of more than 80% and water recovery traps particles resulting in cleaner exhaust. One of the technologies being developed by Collins Aerospace is a condenser for the WET engine. To have a high efficiency and compact condenser, a range of plate-fin geometries are being explored to provide high surface area to volume ratios and low hydrodynamic resistance. This will ensure the design targets of size, weight, overall heat transfer and pressure drop are met. High fidelity and multi-physics models coupling of fluid dynamic, heat transfer and phase change will be included in condenser design tool with consideration of condensation effects on heat transfer performance. The developed models are validated against measurements from testing, such as measured heat transfer coefficient and pressure loss. This paper will present an overview of the condenser design tool and latest results.