Reynolds number at vehicle water radiator
Reynolds number at vehicle water radiator
(OP)
Hi
I have a question about water radiator design for vehicle. How much can increase Reynolds number? What happen if it reaches to 10000? When we use largeer Reynolds number then reduce weight of radiator and this is very important for manufacturer.
Thanks
I have a question about water radiator design for vehicle. How much can increase Reynolds number? What happen if it reaches to 10000? When we use largeer Reynolds number then reduce weight of radiator and this is very important for manufacturer.
Thanks





RE: Reynolds number at vehicle water radiator
By increasing the flow rate?
By making the passages smaller?
Wouldn't that increase the pressure drop?
Is it even possible to make a tube flatter than they do now?
Wouldn't it clog more easily?
Mike Halloran
Pembroke Pines, FL, USA
RE: Reynolds number at vehicle water radiator
-Reidh
RE: Reynolds number at vehicle water radiator
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RE: Reynolds number at vehicle water radiator
Mike Halloran
Pembroke Pines, FL, USA
RE: Reynolds number at vehicle water radiator
I try to reduce the weight by increase number of coolant pass. Something likes U or even N shape.
When the motor works at idle state the flow of coolant is about 1/3 and coolant side is limitation and Reynolds number is less than 2000. I want to change the flow from one top to bottom to U or even N shape. At this new shape the Reynolds number increase to 3800 at idle state (lowest coolant flow rate) but at highest coolant flow rate the Reynolds number reach to near 10000.
Low flow rate is 20 liters per minute and high flow rate is about 60 Lpm
RE: Reynolds number at vehicle water radiator
For the weight of even putting a baffle inside a tank, you could probably have another row of tubes.
... which might allow you to subtract a little from the overall height and width of the radiator, which would give you a weight reduction, mostly by making the frame smaller.
Mike Halloran
Pembroke Pines, FL, USA
RE: Reynolds number at vehicle water radiator
I want to add only one or two baffles at one tube row and not more, then core width will be the same.
RE: Reynolds number at vehicle water radiator
In general you are correct. The slope of the heat rejection- coolant mass flow graph is just about 0 for most reasonable coolant flows (obviously ramps up from 0 flow rate).
-Reidh
RE: Reynolds number at vehicle water radiator
The coolant generally runs a Reynolds Number greater than 2350 (transition to turbulence). The equivalent heat-transfer coefficient on the coolant side is anywhere from say 2000 to 20,000 W/m2.K, depending on the coolant flowrate & tube turbulence mechanism eg. dimples, turbulator etc.
So, speeding up coolant velocity often does very little to increase the overall radiator heat-transfer performance. Try speeding up your airside flow & see what effect it has.
Best of success.
Des Aubery...
(adTherm Technology)
(www.adthermtech.com)
Best regards,
Des Aubery...
(adTherm Technology - www.adtherm.com - info@adtherm.com)
RE: Reynolds number at vehicle water radiator
RE: Reynolds number at vehicle water radiator
I most definitely do not promote removing properly working thermostats, but removing it cannot cause overheating, and removing it TEMPORARILY may indicate a faulty thermostat.
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RE: Reynolds number at vehicle water radiator
Or, eat that ice cream cone while driving with the window open and see whether it warms up and melts quicker than in still air.
Well then, are the folks who believe they have had even good running engines overheat when running completely 'stat-less liars or fools?
Probably not. The race shops that advocate thermostat removal add a restrictor plate at the same location. This would have the effect of creating pressure drop as the coolant leaves the block, which does 2 good things. First it reduces pump flow a bit, and that improves the relative pump inlet NPSH condition making cavitation less likely. Second, it raises the pressure in the block a bit (which is already over the pressure set by the pressure cap), reducing the chance of local boiling at hot spots in the cylinder heads, which WOULD clobber the engine cooling in exactly the areas that need it the most.
RE: Reynolds number at vehicle water radiator