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Re: [Amps] more - oil bath GS-35b

Subject: Re: [Amps] more - oil bath GS-35b
From: Steve Wright <>
Date: Thu, 02 Apr 2015 08:13:41 +1300
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Thanks greatly Chris for your additions there. It would have been a lot of work for me to make clear examples like that, but you see them regularly so can comment concisely. Most of my lessons learned about cooling have been from the automotive world, in particular, pushing the coolant through the radiator so fast, that the radiator cannot extract the heat from it. I've added a few comments to your words - if one of them is glaringly wrong, do feel free to put your big boot on top of the offending section! Best regards mate! ;)

On 02/04/15 05:00, wrote:
There are optimum flow rates based on heat exchanger coolant medium [...]

[...] depends on the surface area of the inside and outside elements of the exchanger and the device being cooled.

Different areas of the engine run at different temperatures, and flow rate is varied to optimize heat extraction.

Flow rates can easily be managed in parallel circuits by using restrictors and valving. Flows depend on the type of exchanger, cooling or heating. In serial circuits, flow (coolant time) is managed by tube size or length.

For sure faster flow is *NOT* necessarily better. In automotive racing water (or water mix) coolant is NOT flowed as fast as possible through the engine, but very careful design has water flow going at different rates in different parts of the engine.
Race cars must not undercool some part, but may not throw loads of energy at the problem when that loss of power may cost them the race. Correspondlingly, in the shack we won't run fans and pumps at full speed because they are noisy, and may be counterproductive.

thermostats have restrictor plates to control water flow rates. Current cooling systems use electronic water pump drives and electronic thermostats to optimize flow according to load, blah blah. Air flow through heat exchangers is similarly regulated for optimum heat exchange speeds.
The thermostat must not open and blow hot coolant through the radiator at high velocity, or there will not be enough time for the heat to be removed.

I am sure in an oil to air heat exchanger with a submerged valve there will be an optimal flow rate for the oil and the air, that is far away from the fastest flow rate [...]
Slower is better. Monitor the output temperature of the radiator and throttle coolant flow, but then there must be adequate coolant flow for the tubeset. Size of radiator is adjusted to get "coolant time in the radiator".


Yes, a oil-cooled tubeset is a parallel path. It may be that one tube runs hotter and measures must be taken. I hope not. Maybe a piece of pipework may be pinched slightly to compensate.

I think I have most of the "cooling stuff" in the ballpark. I won't be spending much more time on it unless I find a show-stopper or someone else does, so if anyone has a well thought out show-stopper I'd be keen hear it!

Note for readers just joining this discussion - the project is about using an alternative cooling paradigm, for the purpose of getting noisy blowers out of the shack.


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