## 3 IPTMS Architecture Design
### IPTMS with Advanced EPS and TMS  
As discussed in Section 2.2, the heat loads of EPA are different from conventional aircraft, and because of the additive electric components, the TMS design for EPA faces more challenges, such as increased weight, induced drag, and TMS power use [39; 67]. Therefore, the IPTMS architecture design for EPA should consider the interactions between the EPS and TMS architectures. [PERSON] et al. [68] proposed a sensitivity study of IPTMS for a Megawatt-class (MW-class) turboelectric aircraft. They investigated the impacts of advancements in power distribution systems and TMSs on the aircraft's performance and proposed three potential TMS architectures. They found that a 150-passenger MW-class turboelectric aircraft is infeasible at the current technological level due to the TMS challenges. In addition, they state that the advancements in TMSs are more urgently needed for the aircraft. [PERSON] et al. [69; 70] proposed IPTMS architectures for different aircraft implementing advanced AC power systems. They developed a high-efficiency megawatt motor and a high-efficiency AC converter for the AC transmission of the aircraft EPS. Compared with the conventional DC transmission approach, the EPS with AC transmission reduces the conversion steps and the electric component weights. As a result, the TMS is redesigned to reduce the cooling loops. It was found that their IPTMS architecture design can significantly reduce overall system weight, drag, and power use. In [71], the IPTMS of a long-endurance unmanned HEA integrates the TMS with the propulsion system through a fuel loop. The fuel is reheated before burning in the combustor, rejecting the heat from the powertrain in order to increase the engine's thermal efficiency. Compared with the conventional propulsion system, the IPTMS can save 750 lb of fuel despite a 708 lb increase in the overall weight due to the electrification. Furthermore, [PERSON] et al. [44] presented an IPTMS design which implements an advanced EPS architecture with AC distribution system and a conventional TMS. It was found that this IPTMS design can achieve 2.5% reduction in fuel consumption. They also presented an Outer Mould Line (OML) cooling for the same advanced EPS architecture. Compared with the conventional TMS design, the IPTMS design with passive TMS can provide an additional 0.8% reduction in fuel burn. However, it results in an increase in TMS weight. [PERSON] et al. [42] presented a trade-off study to investigate the impact of the efficiencies of the electrical components on the OML-based passive TMS performance. It was found that, under the low-efficiency condition, the TMS weight is over twice as heavy as the weight at the normal-efficiency condition, and the required area for the installation of the passive TMS exceeds the area available. In [72], [PERSON] et al. designed different TMS architectures for a hybrid-electric aircraft that implements either a ram air heat exchanger or a skin heat exchanger for liquid cooling and phase-change cooling. Through the comparison of different TMS architectures, it was found that for more significant improvements in minimising the negative impact of the TMS, the TMS design should be integrated with the EPS, considering different power and design needs. Additionally, the IPTMS design could further reduce fuel consumption when combined with other multidisciplinary analyses, such as those involving aerodynamics and aircraft structures. The aim of the IPTMS design with advanced EPS and TMS is to minimise the challenges due to the electrical propulsion system, such as the additional weight, the required power for cooling, and the drag due to the use of ram air. The EPS design can affect the requirements of the TMS, while TMS design can similarly contribute to the power requirements. Therefore, trade-off studies are needed between the advancements in thermal and power domains, as the requirements for propulsion and TMSs, operating conditions, and architectures vary for different scales of aircraft.