ETT has developed air conditioning units fitted with inverter compressors known as the ACU-SRV (air-conditioning unit - variable refrigeration system). The company won a contract for mobile air conditioning units in response to a call for tenders by the aircraft manufacturer Airbus in the late 2000s. Flexibility, energy savings and precise temperature control during the manufacture and maintenance of aircraft were the determining factors - now more than ever before - when selecting equipment.

    Flexibility: the internal volumes of the aircraft manufactured by Airbus vary according to the model concerned (A350, A320 etc.). Also, when Airbus tendered out the new air conditioning units in 2009, ETT proposed first a system using multiple cooling circuits and compressors fitted in tandem.

    Precise temperatures and energy savings: the second step in the partnership between Airbus and ETT was to move to units with compressors in tandem with the units that equipped with inverter compressors. "For these units, we selected the Danfoss Maneurop VTZ inverter compressors. They work with the refrigerant required by the aircraft manufacturer, namely R407C, and they are highly reliable. We have been using them for many years in other applications and we have even been among the pioneers for variable speed systems in commercial applications with Danfoss. Thanks to inverter technology, the airflow blown into the cabin is kept at a constant temperature of 8°C. This helps guarantee the reliability of installation, welding, cleaning, control and electronics work as well as the comfort of the installation or maintenance teams. This benefit could only be obtained so accurately and efficiently with variable speed. The system consumes far less energy than fixed-speed compressors because it is constantly adapting to external and internal temperatures," says Christophe Marziou, Special Projects manager at ETT. 

    Operation of the unit: The solution for Airbus consists of an ACU-SRV unit connected to the plane by means of a flexible duct 40cm in diameter, blowing in air at a constant temperature of 8°C. This unit has a refrigeration capacity of 40kW. Several patents have been filed for the ACU-SRV. Installation and commissioning are easily handled by a qualified installer.