Engines, transmissions and hydraulic systems. What do they all have in common? They can all be sources of heat in a vehicle that are often neglected, or at least poorly managed.

Everyone knows that these components require cooling. They provide heat exchangers for them and assume that the thermal effects are negligible, as the cooling provision is deemed adequate. But what is often neglected are the effects of local heat fluxes on ancillary components, and the degradation that can occur due to them.

As components are often designed as sub-assemblies the interaction of either their thermal performance of the performance of equipment around them and its effects can be overlooked.

However thermal analysis is not just about removing heat, it can be about adding it as well. Integrating waste heat flow into other process is common practice in the chemical industries to improve efficiency, and should often be considered for vehicle applications, such as waste heat storage for hot start up to reduce emissions, or engine air bleed for defrosting applications.

The figures below are of the velocity and temperature contours of a simplified model of a small hatchback car. The heat exchanger of the car (the radiator) is mounted at the front and is fed by air entering the engine bay of the car via the grille.

At part throttle/low load, most of the heat of the engine is passed through the block in to the coolant, thus the radiator has to reject the majority of the excess heat. It can be seen in this example that the heat from the radiator is being passed back over the engine block, which quite obviously does not have a cooling effect. This heat will eventually escape underneath the car, but could potentially affect ancillary components of the engine such as rubber hoses, spark plug etc. leads causing premature failure, or could cause problems for other coolers.

Good thermal analysis and the elimination of hot spots and areas of recirculation can improve component life, and increase reliability of your systems. This is passed on to your customers, who will come to realise that your products are superior because they last longer, and do not suffer from thermal problems.

Mcilwain & Associates can help you examine your heat flows and determine optimum spacing of components, and/or develop solutions to mange them, to prevent heat related problems occurring. We can assist you in devising measurement programs that can be used to develop and validate mathematical models, so that problems can be identified and rectified before any production commitments are made.

We are also interested to assist in aero-thermal analysis of electronic equipment and power supplies.

 

For enquiries about vehicle or general thermal analysis please email information@mcilwainandassociates.com

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