Adaptable power density coating for energy efficient heating of cockpit and cabin

Final Report Summary - HELI-COMFORT (Adaptable power density coating for energy efficient heating of cockpit and cabin)

Executive Summary:

The EU FP7/CleanSky Joint Undertaking project Heli-Comfort with a duration of 18 months focused on the adaptation of heatable coating technology for use in aircraft cabin and cockpit heating. The objective of the project was to demonstrate a technology readiness level (TRL) of 4 or higher for the developed prototypical heating system and to provide insight as to whether it can provide improved thermal comfort for passengers, as well as a more energy-efficient means of heating than convective systems based on the extraction of bleed air from the rotor. The core technology is based on an electrically conductive polymer that is applied as a film on selected substrates and emits radiant infrared heat when powered. The coating has already been successfully demonstrated in previous projects for applications such as motor vehicle interior heating, as well as de-icing of aircraft wings and rotors.

In order to achieve the project goals, a lightweight, damage-tolerant aircraft cabin heating system was designed and implemented in a 1:1 scale mock-up of a helicopter. The mock-up was subjected to tests in a climate and wind tunnel, and the thermal comfort of occupants was determined based on predicted mean vote (PMV) and percentage of people dissatisfied (PPD) computations, based on the actual measurement data acquired. Along with these results another crucial source of feedback were the test persons that sat inside the mock-up cabin during different test runs (0°C to -40°C, with wind speeds up to 100km/h) and rate the thermal comfort inside the cabin. The feedback obtained from these persons with different thermal sensitivities was an additional, valuable and essential feedback about the system performance. Computational fluid dynamic (CFD) simulations of different scenarios served as a comparison to the wind tunnel tests, as well as to evaluate further scenarios that were not tested in the wind tunnel. From a materials perspective, coupon samples of the heating elements were subjected to an array of accelerated environmental conditions in order to determine the performance of the system after exposure to (party extreme) conditions such as may prevail during flight but also from prolonged exposure on the ground.

The envisaged system holds potential to provide a more energy-efficient, lighter weight and more comfortable heating solution for aircraft than today’s systems, which rely on the extraction of hot engine bleed air and often provide a non-homogeneous interior heating distribution and comfort, and decrease the propulsion efficiency of the engine.

The project was able to achieve its stated goal of demonstrating a TRL of 4 for the cockpit/cabin heating system. A higher TRL was considered technically achievable, however the management, supply chain, organizational support and related issues to achieve it were outside the scope of the project. The heatable coating was also explored as an application for pipe heating for an aircraft cargo bay water drainage system. Conclusions and recommendations for achieving a higher TRL in subsequent research/development were further outcomes.

Heli-Comfort was coordinated by AIT Austrian Institute of Technology and was developed together with the partners Villinger Research & Development, CEST Kompetenzzentrum für elektrochemische Oberflächentechnologie, Rail Tec Arsenal, and H4Aerospace.