In this article, we are investigating aircraft thermal management system (TMS) architecture design problems. Here we present initial work on a conceptual-level tool that enables the generation of novel system architecture concepts through graph-based methods. Architectures are represented by a particular class of directed graphs which are generated through an enumerative procedure from a component catalog and set of network structure constraints that define the architecture feasibility. While directed labeled graphs can be used to represent the TMS architectures, evaluating their performance requires a nontrivial physics-based model derived from the graph representation. Such software tools are limited, so a custom interface between the chosen graph representation and Modelica was developed to construct the models and perform the required simulations. A case study based on an unmanned aerial vehicle (UAV) equipped with air cycle machine (ACM) based thermal management system (TMS) is shown and demonstrates that both novel and common architectures can be generated, modeled, and evaluated in this framework. The results from this work can be applied across a range of aircraft sub-systems and platforms, including manned and unmanned air vehicles.