# Designing a Conceptual Digital Twin Architecture for High-Temperature Heat Upgrade Systems
## 5 Discussion
### Digital Twin Benefits  
As seen in the literature [52], most digital twin development starts after having a physical entity. This is not always the case, as digital twins can also exist during the creation phase of a product life cycle [49], which includes four main phases: create, build, operate, and dispose. Developing a digital twin early in the creation phase offers key advantages, such as enabling virtual testing, identifying design inefficiencies, and accelerating development by simulating components before they are physically available. Our digital twin use case of high-temperature heat upgrade systems for industrial processes currently covers both the create and build lifecycles. While the physical system is still under development [46], with only some of the components available as physical prototypes (TES [40; 41; 42] and HT-HP [43; 44; 45]), and the other components are physically simulated (electric heaters and heat sinks for the waste heat and heat demand respectively), the digital twin development can continue unrestricted. As the physical and the digital counterpart are not tightly coupled, modeling and simulating components do not require to have the physical entity present. This allows for greater flexibility in terms of development approaches. By having flexible twin prototypes for each component of the heat upgrade system, the digital twin can optimize the design by taking into account environmental data, waste heat availability, and heat demand throughout a large period of time. This process provides system design parameters, such as the optimal TES PCM, TES volume, HT-HP power consumption, and whether additional green energy sources such as Fresnel collectors should be included. By building the digital system before the physical counterpart, we can easily create different settings for each desirable physical implementation of the hightemperature heat upgrade system, regardless of the industries involved or geographical environment characteristics. An advantage of this approach is integrating physical devices with virtual simulated devices. This enables continuous testing during the build phase, finding errors faster. While usually prototypes are tested in stand-alone settings, with the help of digital twins the entire heat upgrade system can be tested as a whole. This approach, of model and simulation first, also improves costs by not having to physically build every iteration of the prototype. Once the digital twin is linked to the physical counterpart, the benefits are realized through the Service layer of the proposed digital twin architecture. Using the already available historical and real-time data, the digital twin system provides a real-time, virtual representation of the entire waste heat recovery system. With the help of visual interfaces, operators can monitor key parameters such as waste heat availability, heat pump performance, heat delivery efficiency, and system temperatures, and quickly identify any deviations from expected performance. By simulating the thermal dynamics of the system, the digital twin can optimize the capture and upgrading of waste heat based on real-world data. The system can continuously adjust parameters such as pressure and flow rates to maximize the efficiency of the heat pump. This optimization reduces energy losses, ensures maximum recovery of waste heat, and enhances the overall system's energy efficiency. Operators can simulate various \"what-if\" scenarios to explore different operational strategies and process improvements. For instance, operators can test the impact of adjusting heat pump settings, varying heat load demands, or implementing different control algorithms without interrupting the real-world operation. This provides valuable insights into how the system would perform under different conditions, leading to continuous process improvement and innovation. Using the AI predictive capabilities, the digital twin system will forecast equipment wear and potential failures.