Plane gain

The growing concern about Heathrow Airport's environmental impact has caused one carrier to use new drive technology to reduce emissions there.

recently claimed to have cut energy use by up to 95 per cent on air handling and environmental-control systems installed in flight-simulator cells at its Heathrow Airport Flight Training centre.

The company said this was done with variable-speed drive technology developed by Parker Hannifin, a manufacturer of motion and control technologies.

The drives were installed as part of an upgrade on British Airways' 18 simulator cells. It is claimed the drives not only cut energy costs but also maintenance time. Both aspects were key because each flight simulator must be available 24 hours a day, seven days a week.

The British Airways Flight Training (BAFT) centre at Heathrow offers Civil Aviation Authority (CAA) and Joint Aviation Authorities (JAA) approved training and familiarisation courses on a wide range of aircraft. The facility is the largest civil-aviation training centre in the UK and trains British Airways' flight crews and those of other major passenger airlines and cargo carriers.

The site on which BAFT is located is managed by British Airways Properties, which has set up an Energy Saving Working Group tasked with energy-saving initiatives throughout Heathrow.

'The flight simulators make BAFT one of the heavier users of power, so investment in energy-saving initiatives in this area can give large reductions in emissions and improve our carbon footprint, in line with our corporate strategy on sustainability,' said Alan Glenister, property manager at British Airways.

Brian Woodgate, senior simulator-development engineer, explained that it is important the simulators are always available. 'Our 14 full flight and four fixed-base simulators are in constant demand, with training courses being fitted around the operational rotas of flight and cabin crews,' he said. 'It is therefore crucial that each simulator is available around the clock and functions efficiently and reliably. We are currently undertaking a scheduled programme of upgrades that are designed to improve the overall energy efficiency of the training centre by reducing energy consumption and costs.'

Each simulator is in a self-contained cell that incorporates specialised computer and hydraulics rooms for driving the flight simulator, plus dedicated environmental-control systems. These maintain the ambient temperature within set limits, cooling the complete cell area, including the computer and hydraulics plant, and the enclosed flight deck within the simulator.

Dennis Doody, senior engineering technician, said the performance of each environmental control system is critical.

'This is both for the comfort of trainers and crews and to ensure that all equipment operates efficiently,' he said. 'For example, each simulator uses three image projectors to create the high-definition 3D images seen through the cockpit windows. The image is projected onto a curved mirror, mounted within the body of the simulator, with a thin Mylar outer layer that is held in place by vacuum. Changes in ambient temperature can affect the operation of the vacuum pump, which in turn can adversely affect the magnification, clarity and realism of the projected image.'

Previously, the air-handling units in each simulator cell used an arrangement of motor-driven fans that were continuously driven at maximum speed, regardless of actual demand.

'This was extremely inefficient, in terms of both energy consumption and wear and tear on components such as motor bearings, drive shafts and belts, and made it difficult to achieve precise control of the environmental conditions in each cell,' added Doody. 'The air-handling systems were accounting for a significant proportion of all energy used in each cell.'

As part of a long-term programme to upgrade all its existing simulator cells, British Airways took the decision to redesign each air-handling system. The carrier worked with Parker, Trend, which supplied the building service control, and Emcor, which carried out the engineering work.

Each of the air-handling systems uses a large fan, typically driven by a single 11kW motor to draw air into the air ducts, from where it is passed through a pre-heater and then either a cooling or heating battery, depending on ambient temperatures.

An extraction fan sized between 4 and 16kWs, with recirculation ductwork, maintains atmospheric pressure in the cell. A series of dampers controls the air flow and draws in outside air if the external temperature is lower, to benefit from a free cooling effect.

In this upgrade, the original fan motors are retained and are now controlled by the Parker 650V AC variable-speed drives, interconnected through the Trend management unit. This enables the fans to be driven slowly or at idling speeds for most of the year, saving power, but also gives them the ability to run at maximum output during especially warm weather.

The drives are designed to be easy to configure, even in complex open-loop applications, and to provide a wide range of power outputs and options.

Doody said the drives' modular design is important if the control panels later need changing.

'Just as importantly, given our requirement to keep our simulators available 24/7, is the fact that Parker manufactures in the UK and offers excellent local technical support and immediate access to replacement parts,' he added.

The modified air-handling systems with the new Parker 650V drives have already been fitted to two of the simulator cells.

Woodgate claims there are already noticeable energy savings.

'The combined Parker and Trend system is enabling us to reduce our energy consumption in each cell by a massive 95 per cent, while at the same time cutting costs in other areas,' he added.

For example, Woodgate said, the engineering team previously needed to change filter elements every three months. Now they only fit new elements once a year and he claimed wear on moving parts such as bearings has been considerably reduced, meaning the motors last longer and require less routine maintenance.

'Also, as the air-handling units now run for most of the time at low speeds, the overall noise level in each simulator cell has decreased, improving working conditions,' he added. 'Finally, and most importantly, these upgrades using Parker variable-speed drives and Trend control technologies are extremely cost effective, giving us a payback period of less than two years and the ability to immediately reduce our carbon footprint.'