Environment-friendly car air conditioning systems using carbon dioxide (CO2) as an alternative refrigerant could appear on volume-built cars from 2005, say manufacturers.  Eco-warriors should welcome news that the same gas that gives a bottle of pop its fizz is set to heat and cool cars, reports Matthew Beecham.

Cold comfort
Manufacturers predict future growth in sophisticated air conditioning systems as the European auto industry moves towards meeting Euro 4 emissions regulations and in new technologies, such as using carbon dioxide (CO2) in the refrigeration system. The European Union is pushing for environmentally friendly cooling systems such CO2 to replace R-134a refrigerant.  The moves follow the Kyoto protocol on climate control, which showed R-134a to be an undesirable substance.  Some Western European countries have already taken steps to either reduce or ban the use of R-134a, probably by 2005.

Given that the days of R-134a refrigerant are numbered, most manufacturers are at full tilt toward developing CO2 solutions.  They believe that carbon dioxide, compared to other refrigerating agents, such as air and propane, is the most promising alternative substance.  Although CO2 is considered a global-warming gas, R-134a causes 1,300 times more global warming and atmospheric damage.  Manufacturers believe that using CO2 as a refrigerant would not contribute to global warming.  Engineers at Modine Manufacturing Co argue that, since CO2 as a refrigerant will reduce the additional fuel consumption caused by operating the air conditioning system, the ‘equivalent’ CO2 emissions from the exhaust pipe will be reduced. Modine claims its CO2 systems, which can be used for both heating and cooling, are very efficient and environmentally friendly. Modine says it is currently exploring several commercial applications for its CO2 components and systems.

CO2 air conditioning systems use closed systems, which require smaller amounts of refrigerants compared to conventional systems.  That saves space and improves packaging.  CO2 systems also improve fuel economy by consuming less power to achieve the same level of passenger comfort as R134a systems.  A CO2 unit is capable of reducing the temperature inside the cabin from 75ºC to 22ºC in just 25 minutes compared to 36 minutes using an R-134a air conditioner.  They can also heat the passenger compartment quicker, too.  Modine engineers reckon that if a car has been parked at -20º, it normally takes about 42 minutes for the heater to raise the cabin temperature to 22ºC, compared to just 12 minutes using a CO2 system.  Because R-134a is a greenhouse gas, it must be recovered and recycled during servicing, unlike CO2 systems.

While the use of CO2 to heat and cool the cabin is promising, it requires new heat exchangers and the redesign of a number of components.  The highly pressurised systems must also have fail-safe mechanisms to protect the mechanics who subsequently repair them.  The operational pressure applied to the CO2 refrigerating agent will be up to 140 bars – around five times higher than the pressure when operated by R-134a systems.

Visteon points out that CO2 air conditioning systems can provide supplemental heat with an integrated heat pump.  This is a boon for the increasing number of vehicles with direct injection diesel and gasoline engines, which often struggle to provide adequate heating for the cabin. Visteon believes that this could eliminate the need for separate electric or fuel fired heaters.

Visteon’s new cooling method uses carbon dioxide
(CO2) in a refrigerant system
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Source: Visteon

Other manufacturers developing their own CO2 solution include Denso, Behr and Valeo.  Denso is the world’s largest supplier of automotive air conditioning systems with a 24% market share.  Its CO2 air conditioning unit differs from a conventional system in a number of novel ways.  First, a gas cooler cools CO2 refrigerant discharged from the compressor.  Because CO2 refrigerant exceeds the critical point of CO2 at the high-pressure side, CO2 refrigerant is not condensed by the gas cooler.  Instead, the expansion valve condenses a part of the CO2 refrigerant as a result of adiabaltic expansion.  The second main departure is the way in which the inner heat exchanger is located between the gas cooler and the heat exchanger in order to further cool the CO2 refrigerant, discharged from the gas cooler, by exchanging heat with refrigerant flowing at the low pressure side of the system.  Denso also claims that the unit is easier to install since the accumulator is integrated with the internal heat exchanger and the expansion valve.

Toyota is expected to introduce a carbon dioxide heating and cooling system on a fuel cell hybrid vehicle this year.  Some German vehicle makers are expected to introduce carbon dioxide systems by 2005.

Something to de-light motorists
In just a few weeks, the first stage of some long-awaited European legislation will swing into force, allowing manufacturers to introduce their dynamic bending front lighting systems.  Initially, this will allow swiveling of the low beam function.  These increase the range of dipped beam in curves by almost 50%.  But within a few years, car headlights will play a more active role in vehicle safety.  For those with good memories, these systems are reminiscent of the swiveling headlamps once used in Citroen’s DS saloon car models during the 1960s, which used a mechanical linkage between steering and headlamps to swivel the beam.  Although seen as a great idea at the time, legislation soon put the dampers on it, requiring that vehicle headlights be fixed in the straight-ahead position.

Expert Analysis

Global market for automotive heating, ventilation and air conditioning

This report will provide you with a clear and concise insight into the sector with essential coverage of the sector across Europe, North America, South America and Japan. Coverage includes, Market share data, Penetration levels by vehicle segment 2000-2010, Forecast OE sales to 2005, Review of the latest technology and trends, Merger, acquisition and joint venture activity plus brief profiles of the major companies: Behr, Calsonic Kansei, Delphi Automotive Systems, Denso, Sanden, Valeo, Visteon, Zexel. Find out more here.

From March, however, new legislation will remove the shackles from manufacturers enabling them to offer the first phase of adaptive lighting in Europe. Motorised units within each headlamp assembly linked to an ECU will perform the trick here.  Sensors to monitor vehicle speed and steering angle ensure the correct distribution and control of the beam.  Valeo’s bending light system features a motorized bi-xenon projector that rotates by up to 20 degrees from the normal position in order to shed more light into an oncoming bend in the road.  The French group’s system made its debut on the new Porsche Cayenne SUV launched at the Paris motor show last year.

Later generations will adapt the beam and its intensity and direction to help drivers see the road better. These systems will use electronics and simulation technologies to programme the headlights to react to the different actions of the driver. The computer-controlled headlight system can be programmed to react to a wide range of driving situations.  The full advanced front lighting (AFS) version, with additional features such as motorway beam operation or special light distribution for bad weather conditions, is forecast for approval by 2005.  For example, a long, slim beam of light adapted for motorway driving and an extremely broad, but shorter beam of light, when driving in cities. In addition, the angle of the beam can be reduced automatically, thus reducing glare.  Looking further ahead, such adaptive lighting technology could be integrated with a vehicle’s navigation system to generate anticipatory information, thereby illuminating a bend in good time.

Although these moves mark a major step forward in vehicle lighting, the technology has been under development for some time.  In 1997, lighting manufacturers in the US, Europe and Japan worked together on the Eureka AFS project.  The group set out to develop the case for a new EC regulation that could trigger a move towards adaptive lighting.

All the major lighting manufacturers are now advancing systems that can optimize light distribution to fit certain driving situations.  But they are all doing it slightly differently.

AFS technology is available with either halogen or xenon reflectors.  Visteon believes that by introducing halogen-based AFS, it can help vehicle makers achieve rapid and extensive market penetration with its dynamic bending light technology.  Given that halogen AFS headlamps are cheaper than xenon, they are more suitable for compact and mid-sized cars in Europe.

How do I look?
If you drive a VW Golf, Opel Astra or Ford Focus and are looking to personalise your car but curious about how it might look before going ahead, Hella has the solution.  The German lighting specialist has developed software to enable drivers to retrofit their car virtually with its products via www.hella.com.  Using Hella’s ‘E-motion factory’, drivers can try out different colour and product combinations in a virtual world, from xenon retrofit headlamps to snazzy combination rear lamps. They can even see their revamped car in 3-dimensions and watch the optical effect during driving by means of a ‘test drive’ on the monitor.

Accessorise you car, virtually
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Source: Hella

Back a bit …
Reversing into a tight spot is never easy.  For some time, Valeo has been one of the world’s leading suppliers of parking assist systems, a sensor-based system that detects obstacles and gives a audible warning if the car is about to hit something.  It currently supplies more than 1 million of its Ultrasonic Part Assist systems to vehicle makers worldwide.  The French group’s aftermarket arm, Valeo Service, is now marketing the same product for retrofitting suitable for 80% of the European car park.