Quote:
Originally Posted by JRMichler
Reference #25 in that paper, "Compact Heat Exchangers", by Kays and London, is a very good book for anybody who wants to know why automobile radiators are designed the way they are.
Counterflow works best when the flow rates are low, and temperature changes are high. When the flow rates are high, and temperature changes are low, then a cross flow radiator works almost as well as a counterflow. In an automotive application, a cross flow radiator is cheaper than a slightly smaller counterflow radiator.
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I imagine that is when excess air is considered free with cars so a high flow is no concern, but when the aero cost is factored in and airflow is reduced, then maybe we need to also consider how it is directed through the radiator to gain the highest advantage from the lower flow.
Quote:
Originally Posted by jeff88
With the cooler flow at the bottom of the radiator, does it make sense to have the grill block lower and have venting inside of the bumper force air upwards towards the higher temperaturs coolant?
I've read most people prefer to block the upper portion of the grill more than lower, but I would think that would hurt cooling and if you do the lower, you can actually block more.
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The aerodynamics are maximised by blocking upper grill and drawing air in from lower grill, this reduces the amount of air going under the vehicle, the slightly longer air path length is not a problem as this is alowing the air to reduce velocity and increase pressure at the radiator face.
Directing more air through the hotter/upper portion of radiator rather surely must lead to a more efficient outcome than just pushing it evenly through the entire core.