Why do I need Active Charge Air Cooling (ACC)?

Posted: 3rd July, 2018

Why do I need Active Charge Air Cooling (ACC)?

Car and engine designers often say to us – “Why do I need ACC when my current intercoolers do the job?”  In many situations, they may be correct.  However, passive charge cooling – using conventional intercoolers - can’t reduce the charge air temperature to ambient (or below).  On a dynamometer, the transient response might do so but that is caused by the thermal mass of the intercooler.  Repeat the cycle or operate in very hot ambient conditions and the charge air will be hot, causing all sorts of problems.

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Why is our system different?

Firstly, it uses a novel approach – the turbo expander.  This piece of equipment looks somewhat similar to a conventional turbocharger and consists of a compressor and a turbine mounted on the same shaft.  We actually use expansion through the turbine to cool the charge air – in effect, it is a refrigerator.  The thermodynamic process is ‘air standard refrigeration cooling’.

Here’s how it works:

The vehicle’s engine and its turbocharger are unchanged from a conventional installation.  The air from the turbocharger is cooled through an intercooler (radiator) as normal and then is compressed by the compressor in our machine. 

The air is then cooled in another intercooler before being expanded across the turbo-expander turbine which reduces the temperature of the exiting air to well below ambient levels if needed.  The power generated by the expander’s turbine is used to drive the turbo-expander’s compressor, so it is, in effect, self-powered.  The now nicely cold air then enters the engine to mix with the fuel and provide the combustion to generate power.

Secondly, our system is active.  This means that we can not only produce cool air for your engine, but we can control its temperature to a pre- determined value.  Currently, charge air temperature is just about the only engine parameter that is not controlled with great precision in modern engines.  Ignition timing, valve timing, fuel/air ratio, compression ratio and many other variables are closely monitored and controlled by the ECU but inlet temperature can vary significantly, with major impacts on power, economy and emissions.

Active Charge Air Cooling is a means for both reducing and controlling charge air temperatures.  Temperature control is achieved by an air mixing process driven by target air manifold temperature, all controlled by our Patented control process. Reducing intake air temperature improves the knock margin, enabling reductions in excess fuel inputs and improving both power and fuel economy.  Our system allows the designer or owner to set the required inlet temperature and that will be maintained during variations in ambient conditions and the load on the engine.

The Benefits of the Active Charge Air Cooling System

  • A reliable and simple way to maintain low charge air temperature
  • The opportunity to increase power through more mass flow and improved detonation control
  • Fuel economy improvement
  • Cleaner combustion with fewer emissions
  • Can be retrofitted to existing vehicles and incorporated in production designs.

Steve Hinton is Director and joint owner of Air Cycle Technology and responsible for guiding the growth of this exciting and innovative engineering and manufacturing business. With a First Class Honours degree in Mechanical Engineering, Steve has a wealth of experience from years in the rail industry and management consultancy and is a Fellow and past Chairman of the British American Project, a transatlantic leadership development and networking organisation.

Contact Steve direct on steve.hinton@aircycletechnology.co.uk, call 01444 410564 or arrange a free consultation here.

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