The COCOON project (for in-seat ventilation and supply for personalised COmfort COntrol ON board an aircraft) developed and demonstrated a Heating, Ventilation and Air Conditioning (HVAC) system integrated into an aircraft seat to achieve personalised comfort control. The technology bricks, designed, manufactured and prototyped by Collins Aerospace, were matured to TRL 5 for a standard economy 3-seat row, with validation tests performed in a relevant environment in the Airbus cabin air ventilation mock-up, in Hamburg test facility. COCOON project meets Clean Sky 2 objectives with a system directly contributing to environmental targets by improving the cabin thermal management, resulting in reductions of energy use by the environmental control system, fuel consumption and CO2 emissions.
Two designs of in-seat HVAC systems were developed involving different technologies, and integrated into two seat prototypes. The first prototype is based on thermoelectric technology to condition (heat/cool) the air supplied to the bottom and back seat cushion, while a fan embedded in the headrest provides ventilation to the back of the head. The second prototype involves a resistive heating under the perforated leather seat cover and fans embedded in the upholstery of the bottom and back seat cushions as well as the headrest to provide ventilation only. The in-seat HVAC system includes a human machine interface to set the thermal preferences of the passenger from an app installed on a phone or tablet. A demonstrator consisting of a 3-seat row outfitted with the new technology was delivered to the topic manager Airbus.
Multiple validation tests were carried out on the two seat prototypes, in varying environments, to assess of the performance of the systems and of the achieved thermal comfort. Different measurements were performed in a lab environment to characterize the performance of the in-seat HVAC system, in different environmental conditions.
Several validation tests were also performed with volunteers, focusing on assessing the thermal comfort and sensation levels of the volunteers on the two prototype seats compared to a “normal” seat without any in-seat HVAC system installed. The feedback from the volunteers on their comfort and sensation levels was gathered through questionnaires in different environmental conditions varying from cold (20C) to hot (28C), and different test environment from an office room to a single aisle cabin mock-up with operational cabin air ventilation system. The tests in the cabin mock-up were funded by "Konjunkturpaket 33" of the German government and carried out by Airbus with the support of Collins Aerospace. An improved thermal comfort was measured for both prototype seats in hot and cold conditions, compared to the standard seat. The volunteers reported consistently higher comfort score on the seat equipped with thermoelectric devices compared to the second design.
Finally, the thermal comfort and sensation of passengers was also evaluated with thermal manikins. Two types of thermal manikins were used to capture the thermal behaviour of the seat and of the surroundings impacted by the cabin air ventilation system, respectively the Seat Test Automotive Manikin and Automotive HVAC manikins. The validation tests were performed in the cabin air ventilation mock-up in Airbus test facility with the support of Airbus test engineers and of the subcontractor ThermoAnalytics for the test procedures and thermal comfort assessment through modelling. The validations tests with thermal manikins covered different environmental conditions from cold (20C) to hot (28C), for different seat prototypes in different seat locations (aisle and window). The measurements from the manikins in the different conditions were then processed by ThermoAnalytics to extract the thermal characteristics of the seats and fed into a thermo-regulated human model that estimates local and overall thermal sensation and comfort. The validation tests with thermal manikins presented consistent results with the ones performed on volunteers. The tests revealed an improvement in thermal comfort and sensation from a “normal” seat, without in-seat HVAC system installed, to the seat prototypes with heating, ventilation and/or air conditioning capabilities, in both hot and cold scenarios. Overall, a higher level of comfort is achieved with the first design based on thermoelectric technology, with significantly higher impact on the thermal sensation of the body parts in direct contact with the seat, compared to the second design.
