Coolants

Engine coolants disperse 30% of the energy generated in a commercial vehicle's engine. This heat is generated by the combustion of fuel and the friction of moving engine parts. As engines become more powerful the role of the coolant becomes even more important, and this is the focus of much new research.

Why are coolants important?

Prolonged heat has a damaging effect upon the structural integrity and function of engine components. Effective cooling maintains their integrity and gives components a longer life. Engine parts, such as radiators, are increasingly manufactured from engineered polymers with a high thermal resistance because plastic weighs less than the traditional metal. The more effective the coolant technology available the wider the range of materials manufacturers will have to choose from. Emissions technology, such as exhaust gas recirculation, is raising engine combustion temperatures.

What types of coolant are there?

• Water/glycol mix: Typical coolant mixes 3% water – which on its own has limited heat transfer properties – with a dash (5%) of anti-corrosion additive, to the remaining 92% which is made up of a glycol base fluid. It is the glycol which does most of the heat transfer work.
• Carboxylates: these have improved heat transfer characteristics and better corrosion protection than conventional glycol-based fluids.

What are the challenges of coolant technology?

Cooling takes place in two ways. One is to the air through the large surface area of radiators etc (think elephants’ ears); this has already been exploited almost to the full in truck design, and giving greater surface area also means larger components and more weight. The second way is through the thermal transfer properties of the coolant which literally carries the heat away. Solids transfer heat better than liquids – but you cannot circulate a solid. Therefore one of the areas of research is to increase the density of liquid by adding nano-particles.

Getting the blend right is also a challenge. Manufacturers want higher levels of anti-corrosion agent, but this lowers the heat transfer potential of the coolant at a time when engines are getting hotter. Coolant has a useful lifespan – a gycol/water mix will need replacing regularly according to manufacturer’s instructions as it loses its heat transfer properties. Coolants must also be recovered at the end of a vehicle’s life.

How do coolants prevent engine failure?

Coolant and fuel specialist ChevronTexaco reckons 20% of all engine failures are caused by coolant neglect, including hose failures, radiator blockage, corrosion in the cavities of the engine block, and scaling and deposit formation around key components. Coolants include effective anti-corrosion agents which target vulnerable areas. Chevron says its latest Havoline coolant product, for example “is a carboxylate-type coolant, which uses a new chemical process to target the places where corrosion takes place".

How does a using a new generation coolant benefit me?

• Improved performance
• Longer coolant drain intervals – not just cheaper but greener
• Longer component life
• Less chance of engine failure

As an example Chevron claims its Havoline Extended Life Coolant can offer typical drain intervals of four years, with the possibiliy of drain intervals up to 750,000 miles or eight years. Chevron believes this means that over an eight-year life cycle the new product will be 57% cheaper to use than a standard 1:1 mix of water and conventional coolant. An academic paper on the performance of carboxylate coolants is summarised here.

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Learn how new carboxylate technology could save your fleet money - take the Coolants Challenge and receive a cool gift:

The Coolant Challenge is open to UK residents aged 18 or over.

Promoter: Chevron Limited, 1 Westferry Circus, Canary Wharf, London E14 4HA.