Indirect Charge Air Cooling

Liquid Cooled Charge Air Cooling, sometimes referred to as Indirect Charge Air Cooling is a key strategy in the reduction of emissions and efficiency improvement in modern low emission diesel engines. This technology see’s the conventional “Air to Air” charge air cooler replaced by a more advanced system involving a low temperature cooling circuit, coolant circulation pump, low temperature radiator and a liquid cooled charge air cooler or LCCAC.

Product Description


The advantages of this system in a heavy duty vehicle are numerous, and offset added cost and complexity of these systems compared to the conventional air to air approach. This is becoming increasingly important looking at Euro 6 engines and beyond.

1. Improved engine transient response – the LCCAC system delivers a significant improvement in engine transient response this is due to the reduced intake volume of the system meaning that less work needs to be done by the turbo to pressurise the intake system, reducing the “Turbo Lag” effect. This means that pressurised charge air is delivered to the cylinders faster than with a conventional system improving combustion efficiency and reducing exhaust emissions.

2. Improved charge air temperature control – as coolant has a higher specific heat capacity than air the LCAC system is able to absorb rapid changes in intake air temperature more effectively than a conventional system. Thus reducing intake air temperature spikes typically seen with a conventional system under acceleration as the conventional system response time lags behind the conditions seen at the engine. The LCCAC system provides an effective thermal damper and greatly improves the consistency in the intake air temperature leading to improved combustion and reduced emissions. It is also possible through the regulation of the low temperature coolant flow rate to more accurately control the intake air temperature, also preventing over cooling of the charge air in low ambient air temperatures.

3. Improved engine bay packaging – the LCAC system allows for greatly improved engine bay packaging when compared to a conventional system, due in part to the reduced volume of the low temperature coolant radiator when compared to that required for the air to air charge air cooler and also the elimination of the intake air pipework from the turbo to the intercooler and back to the engine, this being replaced by relatively small bore coolant pipe. The LCAC system also allows for greater flexibility in the location of the low temperature radiator as it can be placed further away from the engine than an air to air intercooler, especially if used in conjunction with its own electrically powered fans rather than relying on the engine driven fan.

AVID Technology has unique IP in the field of LCAC systems relating to both the design and control of such systems for heavy duty vehicle applications. Our history in the design and supply of high performance intelligent electrically powered coolant pumps such as the WP29, high performance electric cooling fans such as the FiL-11, control systems and heat exchanger design and optimisation give us a unique skill set in this field.

LCAC systems combine well with hybrid and mild hybrid power train architectures for more information contact AVID here.