The demands on modern engine-cooling systems are complex. Although increased performance, reduced fuel consumption, longer durability and cleaner emissions may appear to be at odds with each other, the engine-cooling supplier must address them. No matter what kind of radiator is used, the principle is the same – to transfer heat efficiently and to keep costs low in the process. Important aspects now include the optimisation of the cooling airflow and the cooling circuit, as well as refinement of thermo-management for control and regulation.
The radiator, in particular, is one of those components that lend itself to being the focal point of a subassembly. Numerous items, such as a condenser, external oil coolers and perhaps even grilles and headlamps can be added to the radiator and fan. Future applications may need a second or even a third fan. The high cost of fuel, particularly in Europe, means that designers are seeking ways of reducing the airflow in the car, which is leading towards the use of smaller heat exchangers.
Euro 4 encourages smart cooling
Manufacturers predict future growth in smart engine cooling systems as the European auto industry moves towards meeting Euro 4 emissions regulations. Such regulations have prompted Valeo to develop a real time cooling control strategy that will optimise engine temperature to actual driving conditions. Engine cooling systems have traditionally been oversized because of the need to cope with the worst possible conditions. Valeo’s Themis – Thermal Management Intelligent System – is capable of regulating the engine temperature according to the vehicle load. A number of research cars, including a Renault Mégane, Mercedes-Benz A-class, Chrysler Voyager and Volvo S80, have been equipped with THEMIS and a control unit capable of measuring and optimising performance. Valeo intends to start the production of engines with this system by 2004.
Manufacturers also see growth for charge-air coolers driven by increased penetration of diesel engines in the light vehicle market, new emissions standards and increased module sales. A spokeswoman for Denso told us: “In addition to the charge-air coolers, we see growth for EGR (exhaust gas recirculation) coolers in Europe. Many trucks will have both charge-air coolers and EGR coolers to meet severe emission regulations. We can see a similar situation occurring in Japan with regard to charge-air coolers and EGR gas coolers. The number of light vehicles having charge-air coolers and EGR coolers will increase both in Europe and Japan.”
Developing powertrain-cooling systems for hybrid and fuel cell vehicles is another main thrust of new product development. Cooling systems are also becoming more modular, thereby lowering costs and simplifying installation.
Aluminium is being used to replace steel in many engine-cooling system components and the transfer from copper-brass to aluminium radiators seems to be almost complete. Aluminium radiators are not only lighter and cheaper than copper radiators but also demonstrate higher heat transfer performance and better durability. Aluminium alloys also have very good corrosion protection.
While aluminium radiators represent a significant portion of European production, they constitute only a small but growing proportion in North America, mainly in the aftermarket. Indeed, the total use of copper in passenger car assembly in North America is said to have fallen from around 5lb per car in 1990 to less than 1lb today. The trend in the aftermarket is the continuing shift in customer preference for complete replacement radiators at the expense of radiator cores. In Japan, almost all new passenger cars are equipped with aluminium radiators.
In the North American truck market, there is an increasing realisation by OEMs that aluminium radiators could replace those made of copper and brass. This should cause a dramatic change in the industry within the next three to five years as truck makers phase out their demand for copper manufactured radiators. In Europe almost all large trucks already have aluminium radiators.
According to the International Copper Association, aluminium has largely replaced copper in the original-equipment automotive radiator market, particularly in the US. However, it is estimated that copper still accounts for about two thirds of the global radiator market. Copper is particularly dominant in heavy-duty applications and in the aftermarket where the metal has an 80% market share.
With technological advances and design innovations, new brazed copper-brass radiators have been developed that are 35% – 40% lower in weight than traditional copper-brass radiators. These brazed radiators are produced more easily and at a lower cost than comparable aluminium radiators.
Plastic header tanks, which were first fitted to radiators in the 1970s, are now almost universally used as original equipment. Plastic components are widely used in coolant systems such as radiator end tanks, water-pump impellers, inlets, outlets and thermostat housings.
The cooling aftermarket, as a whole, is in decline. The once large independent sector has experienced a decline in the US and one in Europe has swiftly followed this. It has been estimated that the coolant package and cooling system reliability has improved by a factor of five since the mid-1980s. Much of this is due to the improvements in build quality and the introduction of plastic tanks, aluminium cores and seamless welded radiator tubes. It is reckoned that only 2.5% of radiators currently fail during their first five years. In the late 1980s this figure was almost 9%. The average life before repair (or replacement) is necessary is now said to be between eight and 12 years, but it could easily be higher. In 1995 Denso built a radiator designed to last ten years. Today the Japanese company has set its sights on offering a unit with at least a 12-year product lifespan. Aluminium cores are not only more reliable than the old copper-brass variety, but can also be repaired.
The increasing use of aluminium in radiators is also said to have environmental and cost benefits. Copper-brass radiators consist of a mixture of materials that are not so easy to recycle. For these reasons, some major radiator manufacturers forecast a significant reduction in the use of copper-brass materials in 2002-2003. Estimates suggest that approximately 70% of radiators distributed through the aftermarket today are brass-copper, the remainder being aluminium. The balance is likely to switch by 2003.
Engine cooling system manufacturers and products supplied
|Manufacturer||Engine-cooling system products|
|Behr||Radiators,Charge-air coolers,Engine-cooling modules,Oil coolers,Condensers,Visco fan clutches|
|Calsonic Kansei||Radiators,Oil coolers,Intercoolers,Motors and cooling fans|
|Delphi Harrison Thermal Systems||Radiators,Oil coolers,Engine-cooling modules|
|Denso Corp.||Radiators,Oil coolers,Intercoolers,Integrated cooling modules,Coolant temperature coolers,Radiator fan controllers|
|Modine||Radiators & radiator cores,Oil coolers,Charge-air coolers,Exhaust gas recirculation coolers,|
|Toyo Radiator||Radiators,Evaporator condensers,Coolers|
|Valeo||Radiators,Heat exchangers,Condensers,Oil coolers,Exhaust gas recirculation coolers,Charge-air coolers,Fan systems,Engine-cooling modules|
|Visteon||Radiators,Front-end cooling modules,Condensers,Compressors,Oil coolers|
|Source: Auto Research Analysts|