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Biphasic Heat Transport integration for efficient heat exchange within Composite materials Nacelle

Periodic Reporting for period 1 - BISANCE (Biphasic Heat Transport integration for efficient heat exchange within Composite materials Nacelle)

Reporting period: 2019-10-01 to 2020-12-31

The project intends to test in icing wind tunnel (IWT) one demonstrator of engine air intake integrated in a nacelle and equipped with an innovative biphasic heat transport system for regenerating the energy from the oil of the engine. The objective, by testing the technology in a representative environment, is to reach TRL5. At the end of the project the technology will be able to be further developed towards TRL6 to 9 with the final aim to be transferred to the aeronautic value chain.

The ambition of the project is to demonstrate the possibility to use the energy from the engine oil for protecting the engine air intake against the ice accretion. To make sure that the oil is sufficiently cooled down in all the environmental conditions, even the warmest ones, aircraft on the ground for example, a significant area of the nacelle will be used as a heat exchange surface additionally to the ice protected surface.
The perspective of this heat exchange concept is to optimize the existing system architecture by removing the active cooling system for the oil, removing the active ice protection system, and to harvest the energy from the oil to regenerate it for the ice protection purpose.

Modifying an aluminium structure into a composite nacelle would decrease the weight by 50% for a similar structural resistance.
Replacing the classical Air Cooling Oil Cooled System and the active ice protection system will lead to another weight saving.
Substituting the active systems (oil cooling and ice protection systems) by the biphasic passive system will permit to save around 100kW of power per A/C.
Globally, combining all the above effects, the objective is to save 25kg and 889 000kg of CO2 emissions per A/C along its life.

The promising environmental benefits listed above will directly enhance the competitiveness of the European companies proposing and operating these new technologies. The fuel saving will decrease the operational costs by 200 000$ for each A/C compared to a similar A/C with a metallic nacelle and active systems.
At this stage of the project, alignment of the system requirements is completed, the conceptual phase is finished as well. The preliminary design of the system and of the structure is at an advanced level while the manufacturing of the coupons has just started.

A very detailed specification was received, discussed and adjusted between Airbus D&S, Calyos and Sonaca. The scope of this specification goes far beyond the scope of the project and is at a level above TRL5. This detailed specification is a good news since it provides excellent guidelines to develop and to design the biphasic system.

Along the first phase of the project, various system integration concepts into the structure were proposed.
The constraints are different depending on the investigated area, so structural integration concepts were independently proposed for the three following areas:

✓ Panels of the nacelle (integrating the biphasic system for oil cooling purpose)
✓ Front lip of the air intake (integrating the biphasic system for ice protection purpose)
✓ Rear parts of the air intake (integrating the biphasic system for ice protection purpose)

Finally, after the conceptual design review was completed, it was decided to perform the following selection:
✓ For the nacelle panels: fully metallic concept
✓ For the front lip area: additive manufacturing concept
✓ For the rear part of the air intake: tubes embedded in a carbon structure

The performance requirements were provided, in the specification described, and were used to propose several biphasic system architectures. The needed heat transfer to comply with both functions of the biphasic system was widely investigated (oil cooling and ice protection). All the flight phases, including the situation where the aircraft is on ground, were considered and the most critical conditions for both functions were highlighted.
One of the main conclusions on the power analysis is that the current active oil cooling system cannot be fully removed because the amount of heat to be extracted is too significant.
For power optimization reasons, the relative locations of the ice protection system (PAIS) and of the oil cooling systems (POCS) within the overall system architecture were discussed and compared together.

For validating the conceptual design, it is planned to manufacture several coupons and to have them tested. As of 31/12/20, the manufacturing tooling for the composite coupons is designed and built.

The conceptual design of the prototype has been performed with the concepts for front and rear sides of the air intake and for the side metallic panels as well. The concept for the system architecture has been done also.
The biphasic system will be developed and will propose a unique passive solution in terms of ice protection of the air intake.
Since the initial phases of the project, the amount of energy available for the passive heat transport and the technology foreseen for the system provide good hope that the ice protection will be efficient.
Also, the first investigation showed goood results for the thermal efficiency of the system and it is reasonnable to think that the current active oil cooler system will be downsized using a biphasic system resulting in significant power savings.

On top of the activities linked to the system itself, a huge effort is brought to the integration of the system into the structure of the nacelle. Three concepts of integration are investigated:

- An additive manufacturing process for the air inlet, allowing a full integration of the system tubing within the inlet structure. Such a technology enables the optimisation of the system integration design leading to the realization of complex architecture and the optimization of the overall weight. This technology will first be investigated through the manufacturing of coupons before implementing it on the full scale specimen.

- An advanced metallic structure for the side panels of the nacelle, featuring channels for the fluid circulation. The metallic sheets will be chemically machined to create the channels, covering the entire surface of the panels. To ensure the airtightness of the channels, the metallic sheets will be welded together using an advanced electron beam welding process.

- A composite structure for the rear side of the air intake. Aluminium tubes will be cured together with carbons fiber plies. Also, a metallic mesh will be located inside the laminate for improving the heat conductivity through the material and to enhance the thermal performance of the system.


Once all the coupons and reduced scale specimens are tested and analysed, the risks associated to the innovative system and structure will be cleared such as the activities for the full scale specimen can start, leading to the final test in icing wind tunnel.
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