Efficient Energy Management for Greener Aviation

Project Information

ENERGIZE

Grant agreement ID: 737792

DOI

10.3030/737792

Project closed

EC signature date 23 January 2017

Start date 1 February 2017

End date 31 July 2022

Funded under

• SOCIETAL CHALLENGES - Smart, Green And Integrated Transport

Total cost

€ 940 645,00

EU contribution

€ 940 645,00

Coordinated by

DEUTSCHES ZENTRUM FUR LUFT - UND RAUMFAHRT EV
Germany

Periodic Reporting for period 4 - ENERGIZE (Efficient Energy Management for Greener Aviation)

Reporting period: 2021-02-01 to 2022-07-31

Summary of the context and overall objectives of the project

The trend towards More Electric Aircraft with higher integration of different sub-systems into a common energy network requires innovative approaches for the energy management. First, a well-designed energy management saves energy by optimizing power split. Second, it allows by its improved handling of loads to reduce the conservatism of the architectural design and hence weight and emissions. Therefore, energy management functions are a key enabling technology that needs to be available in early architectural design. They need to be of limited complexity in order to be quickly developed and potentially certifiable for on-board implementation.

Energy Management is hence a vital component for the future electrification of aircraft. Although this project focusses on the electrification of on-board systems some of its findings may be transferred to electric propulsion concepts as well. The electrification is important to society because it is one of the key-enablers towards a more sustainable aviation. The reduction of power consumption goes along with the reduction of CO2 and other polluting exhaust gases. The reduction of power consumption and the electric integration may also provide cost benefits that help to maintain flying affordable. In addition, electric environmental control systems may remove the health concerns that surround the current use of bleed-air.

The main objectives of ENERGIZE is to enable the design of energy management already in the early design stages of an aircraft. This can be broken down into the following sub-objectives:
- Create a model-base sufficiently detailed to show all relevant impacts of energy management actions for both the thermal and electric side.
- Make both the energy algorithm and the model-base versatile and flexible in their use so that many variants can be tried out.
- Demonstrate the certifiability and real-time capability of the energy management algorithm
- Assess the impact of the energy management on both operation and sizing.

In terms of maturity, DLR and NLR reached TRL4 by their own effort and supported industry to reach TRL5.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The project Energize created model-based algorithms tailored to meet the demands of a combined electrical thermal management system. To this purpose both DLR and NLR built up a near comprehensive model of the on-board system matching a future more-electric short-to-medium range aircraft. The model includes a thermal and an electric part and also enables to study the interaction between these domains which is essentially taken the waste heat of the electronic devices properly into account.

The concept of discomfort level was introduced to have a market-oriented arbiter logic that handles potential energy savings across multiple consumers. The effect on going to higher level for discomfort can be studied using the model for all phases of a mission and even for complete missions. The resulting combined electric and thermal energy management can be implemented as a discrete algorithm and easily runs in real-time on simple standard micro-controllers.

Reflecting on the main objectives, we have reached to following end-result:
- We have successfully created a very suitable modeling base of sufficient detail without sacrificing performance.
- The model base is very versatile as major sub-systems (such as cabin or ECS pack) can be easily replaced with different variants.
The main remaining difficulty is the control of the ECS packs especially in a fully integrated system.
- Real-time capability has been successfully demonstrated.
- We can show the impact on operation and potential energy savings for certain flight phases. There remain however certain open questions on how to optimally realize the dehumidification of outside fresh air.
We could not achieve an impact assessment on the final sizing of the overall system. This proved to go beyond our current capabilities.
Regarding the maturity, the model-base and algorithm have passed gate reviews for TRL3 and TRL4. For TRL5 on a functional level further work would be needed. The control of electric packs remains an issue for quick analysis and the topic of dehumidification has to be clarified.
During the project we have published 4 conference publications and 1 journal publication.
The model-base of ENERGIZE gained attention within the European aviation community and hence further exploitation is planned in Clean Aviation projects. Also internally we plan to further contribute to solving the challenging control tasks that involve electric environmental control systems.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Impact

Regarding the final impact on the overall aircraft performance, we initially estimated that enabling a more-electric aircraft can lead to savings of up to 1.7% of mission block fuel. During ENERGIZE we reached no findings that contradicted this assessment but also we could not further validate it.

However, electric propulsion concepts offers far greater savings potential. Such concepts will make the electrification of on-board systems then inevitable. We hence see our main contribution as a better enabler for electric on-board systems and hope to contribute to quick entry into the market. We expect this to happen at smaller aircraft first though.

During the project execution, we have also learned that vapour cycles (as there also used in the electric ECS of energize) contribute to 16%(!) of the overall electricity consumption in Germany. The optimal design and control of electric driven environmental control system may offer more to gain than the aviation sector as a whole.

Our work shows that the potential improvement on electric ECS performance from the point of a thermodynamic cycle analysis can be major but the most critical point is the requirement and control options for humidity. Here we speak about double percentage figures of energy savings for these sub-systems.

The wider socio-economic impact of this project is that we aim to reduce the cost for the modeling and control of electric and thermal system development. This will hopefully speed up the development of energy management solution in the aviation sector and also in other sectors. This happens in two different paths:
- The modeling knowledge gained in ENERGIZE indirectly also contributes to the free software solutions that DLR is offering to the broad public (not specific for aviation).
- We are building a digital twin that shall find its use in Clean Aviation projects and is to be shared among OEMS and system suppliers in the aviation sector.

Progress

Regarding the effort in Modeling and Simulation ENERGIZE pushed beyond the state of the art significantly.
- We introduced the concept of discomfort levels to harmonize the intervention of energy management algorithms across domains.
- We developed new prototypical control strategies for electric ECS packs.
- We improved the cabin models by many details so that we can extrapolate unforeseen conditions.
- We improved the robustness of thermofluid models by a new computational approach and worked on the robustness of countless component models.
- We built a comprehensive on-board system model of a More-Electric single-aisle aircraft. The model has more than 18’000 equations and 200 states in total and is able to perform full mission simulations from take-off to cruise to landing.
We are able to perform these complex simulations on a common laptop with a real-time micro-controller in the loop.

Model-base and real-time Hardware