In the frame of the proposed project, a comprehensive Modelica library for the modelling of aircraft air conditioning and thermal management will be developed, covering all relevant fluid domains as well as mechanical, electrical and control aspects. The developed library will cover:
- Vapour cycle system, including valves, heat exchangers (two phase – two phase, two phase – liquid, two phase – air), reservoirs and refrigerant compressors
- Air cycle system, including compressor, turbines, air – air heat exchangers, water extractors and sprayers, fans, jet pumps, valves and scoops
- Liquid loop systems, including piping, pumps, valves, air – liquid heat exchangers and reservoirs
- 1-D aircraft cabin model, covering 3-D effects backed by experimental validation
- Air distribution system models e.g. ducting and mixing chamber
- Electrical and mechanical models including motor drives, bearing losses and mechanical connections
- System control capabilities and linking the models to external tools
The library will be developed using the latest features of the Modelica language for more robust and efficient simulation. Object-oriented modelling and a user-oriented library structure will allow efficient future development and extension of the library.
The developed models will fully support multilevel modelling, allowing an easy switching between dynamic and steady state modelling for different design phases.
On the basis of this library, a multi-objective optimization strategy will be developed, making full use of the newly created capabilities to model the multi-domain system interdependencies. The multi-objective optimization strategy shall help to find optimum system architectures with respect to the targets of the Clean Sky JTI i.e. minimum environmental impact at minimum overall cost and maximum passenger comfort.
The objective of the TEMPO project was the development of a comprehensive model library for aircraft environmental control and cooling system simulation. The library covers multiple physical and functional domains with focus on thermo-fluid and power modelling. In the thermo-fluid domain the library covers air systems, liquid cooling systems and vapour cycle systems, allowing the simulation of comprehensive power system architectures on aircraft level. The library was implemented using the object-oriented modelling language Modelica. The library is designed to allow scalable modelling. Scalable modelling means that the model equations representing the system model can be easily exchanged to adapt a system model to the simulation requirements at a specific phase in the system design cycle. Instead of rebuilding a system model for a new simulation task as the system design cycle progresses, the system topology information already available in existing system models can be reused by automatically switching the equations underneath.
During the course of TEMPO, a library structure that supports this feature has been developed and implemented. Currently, the library contains four "layers", each designed for the application in a specific phase of the design cycle. The first layer consist of low complexity, static models. This layer is intended for use in early conceptual design, where different architectures are under investigation and component performance requirements need to be deducted from high level system performance requirements.
The second implemented layer consists of more detailed static models. Thermodynamic behaviour of the components is governed by performance maps and allow to feed data that becomes available from detailed component design into the system model. This allows early predictions and verification of system performance.
The third set of models include dynamic models. The models include one-dimensionally discretized components and first principle modelling approaches. The physical and modular approach followed in modelling these components result in highly adaptable models which can be parametrized over a broad range for fast simulation or high thermodynamic accuracy.
The fourth layer of models is suitable for fixed-step solver application and designed for fast simulation speed while capturing the system dynamics. The library is complemented with a cabin model for a single-aisle type commercial passenger aircraft. The cabin model includes three independent temperature zones including the flight deck and the air distribution system. The dynamic thermal behaviour of the fuselage structure is modelled in detail with multi-layered wall, floor panel and internal structure models. Radiation effects are modelled internally as well as externally.