Ice Bucket: AIO vs Heat Exchanger

[StoneyMahoney]

During the Jayztwocents vs Gamers Nexus OC battle, I was confused as to why the contestants used submerged radiators rather than actual liquid-to-liquid heat exchangers. So I thought I'd get one and try it.

 

 

This is a plate heat exchanger I got as a refurbished spare for a domestic hot water heater for £10 (GBP). It's rated heat transfer is 2.5k when being used to heat water in that application, so I needed to test whether it would work well enough given the much smaller temperature delta between ice water and a PC water cooling loop. If I was patient enough to do this properly I would have tapped G1/4 threads into the ports, but couldn't get access to a pillar drill to do it and fluffed it up a little trying to do it manually. So those barbs are just super-glued into place.

 

 

With some cheap-ass chinese watercooling parts and semi-decent fittings to build my test unit with, this is the result just before I fired it up. The hot and cold loops counter-flow in opposite directions through the heat exchanger for optimum efficiency, that blue thing you can see in the background is a coolbox full of ice water - as I had that available, I also tested a Cooler Master Seidon v3 240mm AIO I had laying around to see how it compared. The AIO was deployed as-is, with all the dust cleaned out of it, the radiator submerged and finally with an additional pump (borrowed from the heat exchanger) to circulate the water around the coolbox. The CPU block attached to the heat exchanger hot loop is also a cheap chinese thing, it does have some 1mm channels cut into the cold plate running between the two ports, but it's still primitive AF.

 

 

The test bench has a delidded, LM'd, Devil's Canyon i5-4690K running at 1.35v and 4.5GHz, 1.85v Vrin. Moderate LLC settings have been applied. The test load is Prime95 v29.8b6 Small FFTs FMA3, measurements are CPU Package temperature measures from HWiNFO64. Reported CPU Package Power consumption during the tests is ~180W.

 

 

AIO - Dusty: 36C Idle, 98C Load

AIO - Clean: 35C Idle, 94C Load

AIO - Ice, static: 15C Idle, 75C Load

AIO - Ice, flow: 12C Idle, 65C Load

Heat Exchanger: 10C Idle, 57C Load

 

So yeah, worked pretty well. Concept proved (like it needed it.) Would be interested to see how it stacks up against larger radiators but I don't have any lying around I can use. Never mind.

It needs some improvements. The heat exchanger itself has some kind of residue inside it that seems to be burnt into place, I've tried to clean it out chemically to no avail and a fair amount of flakey bits broke off into both loops during these tests. The connection to the heat exchanger itself leaks in a few places and the water block was crap, but my main idea is to add some temperature sensors to the two loops, along with atmospheric temperature and humidity sensors, allowing a controller to calculate the dew point and adjust the flow rate through the cold loop to maintain the hot-side of the loop condensation-free as a safety feature, not to mention self-detecting fire-and-forget smart ice-bucket cooling that runs just above the dew point sounds like a cool idea.

 

 

Condensation built up on cold loop, the heat exchanger and the hot loop reservoir very quickly, but not so quickly on the hot loop tubing and the water block - lots of wiping it off though, had to remove the fan I placed on the RAM (blood was indeed shed to bring you these results.)

 

 

Soggy CPU socket, but it survived a few hours of HWBOT runs after these tests no problem - can't waste 6Kg of ice now, can I?

 

 

Pay no attention to the thermal paste spread, thermals were fairly even across the cores in use, the lop-sided remnants here are from where I had to man-handle the block to get the suction to release. Also please ignore the rough edges, I had to dremel the AMD bits of the bracket off to get it to fit. But do pay attention to the condensation that built up on the underside of the block.

 

So yeah, hopefully you actually get to see the images here, as opposed to when I tried to post this on Reddit and it's .jpg processing immediately broke. Suck it, /r/overclocking! Hey Alex and Linux, next crazy cooling experiment, perhaps?

[Spakes]

Actually, they are planning on bringing reworked chiller with Threadripper, afaik, so...

[SolarNova]

PHEs are most certainly the way to go when looking at sub ambient and subzero cooling.

 

A future project i've had on the books for a good few years now is to scratch build a R1270 (Propene/Propylene ~ -47c boil point) refrigerant chiller with a large PHE condenser.  A large insulated res with a separate high flow rate chiller side loop that stays on all the time, and a PC side loop that turns on only when the PC is on. Use Mayhems XT-1 60% mix as the PC side liquid loop coolant.

 

Run the PC in a dry air (nitrogen) sealed case and have a more or less 24/7 capable subzero build.

 

PHE's are no more expensive than PC rads and for liquid to liquid cooling are way more efficient. That BHE u have their is a small one ..cheap in comparison to good rads.