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From: Klaus Vestergaard Kragelund <klauskvik@hotmail.com>
Newsgroups: sci.electronics.design
Subject: Re: dumping a lot of heat
Date: Sun, 8 Dec 2024 00:19:37 +0100
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On 04-12-2024 22:29, john larkin wrote:
> I'm thinking about building a biggish rackmount dummy load box. It
> would simulate series resistance and inductance. Part of the problem
> is that it will need to dump a lot of heat.
> 
> We are using copper CPU coolers on PC boards, which are great up to a
> couple of hundred watts, but I'd like to do a kilowatt or two.
> 
> https://highlandtechnology.com/Product/P945
> 
> It would take a heap of expensive extruded heat sinks and fans to get
> rid of a kilowatt. At 1 K/W, a pretty good heat sink, that's 1000 degC
> temp rise.
> 
> A small hair dryer can dump a kilowatt. So some sort of red-hot
> nichrome coils and a vicious fan might work.
> 
> I'd prefer to not use water.
> 
> I wonder if there is some sort of runs-red-hot power resistor.
> 
I have thought many times, but never got around to make an electronic 
load with many parallel circuits. At JLCPCB the mounting cost is low, so 
no biggie

The idea is to spread the heat out, not relying on one element, but 
many. Imagine a big PCB, like A3 size, spread out with 100 equal 
circuits electronic loads. Frequency response would be high, power 
dumping high also. Use a aluminum PCB like those used for LED lamps to 
get even lower Rth