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Advanced ventilation techniques for modern long-range passenger aircraft to promote future energy management systems

Periodic Reporting for period 3 - ADVENT (Advanced ventilation techniques for modern long-range passenger aircraft to promote future energy management systems)

Reporting period: 2020-09-01 to 2022-08-31

In case of civil aviation, the environmental control system (ECS) consumes large amounts of energy, especially during long-range flights. Novel ventilation concepts offer the potential for energy savings by reconsidering the fresh air fraction. Besides energy saving benefits, the improvement of the thermal passenger comfort, air quality and simplified manufacturing processed are also possible using new concepts CleanSky2’s project ADVENT addressed this topic and aimed at enhanced ventilation concepts.
To evaluate alternative ventilation concepts regarding passenger’s comfort several criteria are studied focusing on enhanced heat removal efficiency, optimized local ventilation and air exchange efficiencies to improve the air quality and thus the passenger well-being. Considering the environmental aspect, alternative concepts with the possibility to save bleed air associated with reduced cooling demands promise energy savings. Several components of the ECS benefit from these new concepts resulting in smaller and lighter components. Additionally, a redesign of the ducting system promises weight savings and thus a lower fuel consumption.
The top-level objectives and the conclusions of the actions are:
1. Identification and benchmarking of novel ventilation concepts for modern long-range cabins using numerical simulations. To identify and verify new concepts, parametric studies were conducted experimentally and numerically. A simple “one-optimizing-all-challenges” ventilation concept was not found. However, single technology bricks were determined enhancing the performance of current knowledge and providing a scientific knowledge for upcoming aircraft configurations and module-integrated ventilation concepts as desired by the industry.
2. Deployment, set-up and testing of a ground-based, full-scale test facility (mock-up) for experimental simulations and studies of future long-range cabin ventilation concepts under realistic thermodynamically boundary conditions. Hereto, a test rig, representing a full-scale long-range cabin mock-up, was designed and setup. Special attention was given to the possibility to precisely define the thermal and fluid dynamical boundary conditions. The test facility is fully operational for EU research landscape and EU aviation industry and furthermore presented to the general audience, local politicians and journalists and highlighted in two films. A peer-reviewed journal publication with details on the new mock-up is gold-open access available DOI:10.1007/s13272-022-00594-2.
3. Provision of an experimental reference database of comfort-relevant parameters for different ventilation systems. Here, many results of the different ventilation concepts were summarized and evaluated in the published scientific publications, all open access available. In total, seven peer-reviewed contributions to conference proceedings and one peer-reviewed journal publication were published. Further information going beyond the published results are available upon request.
To achieve the top-level objectives, among others, the following tasks were performed.
New Mock-Up Test Facility: Planning, design and erection of the new mock-up, startup including test of the air supply, volume flow measurement and temperature-control system. Subsequently, New ventilation concepts, thermal manikins as well as the latest measurement techniques (e.g. local probes, infrared thermography, tracer-gas measurement system) were installed. Further, several control units were implemented to monitor and control the boundary conditions. Temperature-controlled sidewalls were used to simulate thermodynamically realistic boundary conditions.
Analysis of ventilation concepts: Promising novel concepts were pre-selected using numerical simulations. Here, thermal comfort and energy saving potential serve as an evaluation criterion. Following. various concepts with more than 25 different configurations were tested in the new mock-up. Herein the concepts were analyzed under cruise conditions, hot-day-on-ground conditions and a dynamic flight scenario. Evaluation parameter were temperature, velocity and CO2 distributions as well as heat removal efficiency and integral comfort quantities. The findings were evaluated and summarized.
The results can be summarized as i) an applicable CFD tool-chain for the numerical evaluation of cabin ventilation, ii) a new cabin mock-up research facility for the investigation of cabin ventilation under various boundary conditions and iii) an enhanced scientific understanding and a vast database on different ventilation approaches. The dissemination activities comprised among others scientific publications, a patent application and public lab-tours. These are summarized in the report on dissemination and communication.
The progress beyond the state of the art comprises a) a new long-range cabin mock-up providing thermodynamically realistic boundary conditions for static and dynamic investigation of different flight phases. Hereto, temperature-controlled fuselage elements were successfully installed and tested. To our best knowledge, this new mock-up is the largest dual-aisle cabin mock-up allowing the investigation of ventilation concepts regarding their energy efficiency, thermal comfort and capability of integration under precise boundary conditions. Further, novel ventilation concepts can be integrated with a high degree of flexibility due to the modular design of the test rig. b) Three new ventilation concepts revealed their potential for optimizing thermal comfort and energy efficiency in numerical simulations. Here, a CFD model including a tool chain was implanted to calculate comfort relevant indices. One new concepts was applied for a patent and a second one is in preparation for a patent application.
The results of the project comprised the identification and experimental validation of a ventilation concepts with benefits in terms of passenger comfort and energy efficiency. In specific, single technology bricks were determined enhancing the performance of current knowledge and providing a scientific knowledge for upcoming aircraft configurations and module-integrated ventilation concepts as desired by the industry.
Further, the deployment of a ground-based test rig for experimental simulations of modern long-range cabins will be highly relevant for the European aircraft industry. The flexible integration of novel ventilation concepts and simultaneously providing thermodynamically realistic boundary conditions are the main features. Finally, an experimental and numerical database was compiled comprising velocity, temperature and CO2 distributions as well as ventilation efficiencies for different ventilation concepts.
Impacts of the project were the identification of ventilation concepts with heat removal efficiencies more than 50% higher than provided by state-of-the-art mixing ventilation while at the same time improving thermal passenger comfort. It should be noted that a concomitant weight reduction of the supporting systems was not estimated. Other concepts reduce the demand of long and complex air supply ducts by highly module-based integration. Further, the measurements revealed, that novel concepts can maintain acceptable CO2 distributions in the cabin at reduced fresh air supply. These results clearly highlight the potential of energy reduction associated with fuel savings and thus with decreased amounts of CO2 exhaust.
thermal manikins seated in new cabin mock-up