Cooler (radiator) core data scaling / extrapolation

[murpia]

We have data from a supplier for the performance of a cooler core of the thickness we plan to use. It is a dual-pass configuration with inlet and outlet on the same side of the core and a transfer tank on the other end, and has been tested as such.

However, the dimensions of the tested core are different to our application, and more importantly it has been tested at a lower coolant flow rate than our engine.

I plan to scale the data according to tube count and length, treating the dual-pass configuration as one long, thin core of half the height and twice the width. So, I can calculate the performance of one tube, then assume if it's e.g. 20% shorter the deltaT is 20% less. Sound sensible?

But, is it sensible to extrapolate for a larger coolant flow rate? I can fit a curve to the current set of points, but we need data for over double the flow rate per tube, which seems a bit of a stretch...

Any help or references appreciated,
Regards, Ian

 

[reidh]

Ian,

There comes a point where increasing coolant flow rate will not increase the heat rejection of the radiator. It is hard to say if extrapolating will work or not in your situation: it depends on where your test data stops (if it stops while you are still on the sloped section of the flow rate vs. heat rejection curve, then you will not know where it will level off) and how far you plan to extrapolate.

-Reidh

 

[murpia]

We have four points of flow rate data, and they do show the trend you indicate of diminishing cooling with increasing flow. The points allow a curve fit, rather than a linear extrapolation, so we should be able to find the cut-off point.

Any opinion as to the scaling method for cooler core size?

Thanks, Ian

 

[Fabrico]

Stewart Components, who has been manufacturing racing water pumps for many years, claims double pass radiators require 16x more pressure to flow the same volume of coolant through them, as compared to a single pass radiator.

One thing is for sure, the entire system is really a package and you may or may not get the flow you expect.