Water cooled COBs

[Uberknot]

If your chips are boiling water, something is seriously wrong with the design somewhere.

My chips and water blocks run cold to the touch. Not boiling, not hot- not even warm. COLD. No accident, I did it intentionally to improve chip efficiency.

heh run a CPU at 4.8+ ghz for awhile stress testing I've tested as high as it will go....I set mine at 4.0 ghz normally. When you start reaching like 90-95C.......it's getting hot!

Anyhow I doubt a COB would ever put out as much heat as a stressed i7 CPU unless you just wanted to blow it up.

 

[questiondj42]

If your chips are boiling water, something is seriously wrong with the design somewhere.

My chips and water blocks run cold to the touch. Not boiling, not hot- not even warm. COLD. No accident, I did it intentionally to improve chip efficiency.

It's still advisable to run coolant instead of water. Water is corrosive.

 

[Uberknot]

I really like water cooling btw and If you know what you are doing and are very careful doing the proper inspections and testing it won't leak. I just want anyone who is even thinking about trying this to please understand there is a lot that can go wrong if you just try to slap things together.

 

[loftygoals]

Am reading correctly that you're going to be using actual water, and not coolant for this? CPU cooling uses a coolant that doesn't boil at 212*F. They're designed for heat transfer and are less prone to pressure fluctuations. Water makes vapor and pressure. It will boil inside those lines.

Well it's been running for over 2 months and not had any issues...

If I had boiling water something would be seriously wrong somewhere! I have a FLIR camera and so can tell you exact temps. My hottest water lines are under 40C in a 25C room when cooling 2100w.

"Coolant" actually is worse at heat transfer than water. There's a good reason you don't run your car with 100% antifreeze... water works better at transferring heat and so keeps temps lower than a special coolant. But the coolant has anticorrosive and antifreeze properties which is why you run at least some in summer and a LOT in winter in cold countries.

The specific heat capacity of 100% ethylene glycol at 40C is 2.5J/g/C. The specific heat capacity of 100% water at the same temp is 4.1J/g/C. Yes water absorbs 50% more heat energy than ethylene glycol for the same rise in temp.

Didn't we learn this stuff in school science class when we were about 15 years old? Wasn't anyone else paying attention?

 

[loftygoals]

heh run a CPU at 4.8+ ghz for awhile stress testing I've tested as high as it will go....I set mine at 4.0 ghz normally. When you start reaching like 90-95C.......it's getting hot!

Anyhow I doubt a COB would ever put out as much heat as a stressed i7 CPU unless you just wanted to blow it up.

Well akshully... a Core i7-4790K at 4GHz has a TDP of only 88W.

At first I was temped to go with computer water cooling radiators but soon figured out they wouldn't have anywhere near the required cooling power as computer processors are only putting out 1-200w of of heat max and still getting 80C+ temps under full load.

That's why I went with a car radiator and fan. To put things in perspective a small car engine can put out 50,000w of heat (although the cooling system is pressurised and running at high temps).

 

[ttystikk]

Well it's been running for over 2 months and not had any issues...

If I had boiling water something would be seriously wrong somewhere! I have a FLIR camera and so can tell you exact temps. My hottest water lines are under 40C in a 25C room when cooling 2100w.

"Coolant" actually is worse at heat transfer than water. There's a good reason you don't run your car with 100% antifreeze... water works better at transferring heat and so keeps temps lower than a special coolant. But the coolant has anticorrosive and antifreeze properties which is why you run at least some in summer and a LOT in winter in cold countries.

The specific heat capacity of 100% ethylene glycol at 40C is 2.5J/g/C. The specific heat capacity of 100% water at the same temp is 4.1J/g/C. Yes water absorbs 50% more heat energy than ethylene glycol for the same rise in temp.

Didn't we learn this stuff in school science class when we were about 15 years old? Wasn't anyone else paying attention?

No, we were counting on you to take notes while we were sleeping off the previous night's excesses, lol

 

[ttystikk]

Well akshully... a Core i7-4790K at 4GHz has a TDP of only 88W.

At first I was temped to go with computer water cooling radiators but soon figured out they wouldn't have anywhere near the required cooling power as computer processors are only putting out 1-200w of of heat max and still getting 80C+ temps under full load.

That's why I went with a car radiator and fan. To put things in perspective a small car engine can put out 50,000w of heat (although the cooling system is pressurised and running at high temps).

In this case delta T is similar but the operating temperatures are lower. A chiller stone kills it in this application, actually boosting chip performance while removing the heat.

 

[Uberknot]

Well akshully... a Core i7-4790K at 4GHz has a TDP of only 88W.

At first I was temped to go with computer water cooling radiators but soon figured out they wouldn't have anywhere near the required cooling power as computer processors are only putting out 1-200w of of heat max and still getting 80C+ temps under full load.

That's why I went with a car radiator and fan. To put things in perspective a small car engine can put out 50,000w of heat (although the cooling system is pressurised and running at high temps).

Oh yeah that's why I set it back to 4.0, running at 4.8+ and stress testing memory jacks it much higher and it gets really hot fast..The Radiator I use is like 200 mm x 460 mm ( entire top of the Corsair case I have ) and that will give you some slack esp with a larger res.

 

[Bubblin]

Well it's been running for over 2 months and not had any issues...

If I had boiling water something would be seriously wrong somewhere! I have a FLIR camera and so can tell you exact temps. My hottest water lines are under 40C in a 25C room when cooling 2100w.

"Coolant" actually is worse at heat transfer than water. There's a good reason you don't run your car with 100% antifreeze... water works better at transferring heat and so keeps temps lower than a special coolant. But the coolant has anticorrosive and antifreeze properties which is why you run at least some in summer and a LOT in winter in cold countries.

The specific heat capacity of 100% ethylene glycol at 40C is 2.5J/g/C. The specific heat capacity of 100% water at the same temp is 4.1J/g/C. Yes water absorbs 50% more heat energy than ethylene glycol for the same rise in temp.

Didn't we learn this stuff in school science class when we were about 15 years old? Wasn't anyone else paying attention?

Most water loops pc or otherwise run a small amount of antifreeze or similar in them, it's far easier than replacing or cleaning the system due to build up. And in actual use the temp differences aren't that huge.

I used to keep my oc'ing rigs in a sealed room that was kept at outdoor temps during the winter. So anything in the room was running between -20f to +30f and the water loop required 100% antifreeze to keep from freezing solid.

When I brought it in for the summer months the temp difference between 100% antifreeze and steam distilled water were at most 4c. After seeing that I said fuck flushing it and left antifreeze in it year round.

With that rad you're running I'd be surprised if a few table spoons of antifreeze changed the temps at all.

 

[wietefras]

In this case delta T is similar but the operating temperatures are lower. A chiller stone kills it in this application, actually boosting chip performance while removing the heat.

Doesn't a chiller use a lot of electricity to remove the heat from the water though? Then you still need to get rid of the heat that comes out of the chiller.

Seems to me like the chiller only moves the heat a few yards and you get a few percent extra efficiency in return for all the power it uses. What if you use the electricity that the chiller takes and use it to power more COBs instead. Wouldn't you get more light overall? Then simply remove the heat with a regular radiator as the hot end of the chiller does.

 

[churchhaze]

80C under full load? Why even run water cooling on your CPU if you can't keep it near room temperature? I used to have a dual core AMD chip I could take to 6ghz (seriously) on air. Temps never got above 50C.

 

[Uberknot]

80C under full load? Why even run water cooling on your CPU if you can't keep it near room temperature? I used to have a dual core AMD chip I could take to 6ghz (seriously) on air. Temps never got above 50C.

Chip model and where was it made? Just for research

 

[dandyrandy]

At work we use deionized water to cool laser cavities as well as large tack welders etc.

 

[ttystikk]

Doesn't a chiller use a lot of electricity to remove the heat from the water though? Then you still need to get rid of the heat that comes out of the chiller.

Seems to me like the chiller only moves the heat a few yards and you get a few percent extra efficiency in return for all the power it uses. What if you use the electricity that the chiller takes and use it to power more COBs instead. Wouldn't you get more light overall? Then simply remove the heat with a regular radiator as the hot end of the chiller does.

My chiller is removing all the excess heat from the room, just like the AC system it replaces. It's just doing it more directly... AND efficiently, which is the reason for doing it, as it reduces operating costs.

...and then it does something you may not have considered; once it's pushed that 'waste' heat up the temperature gradient, that heat has now become useful for all sorts of things like heating the facility, dehumidification, domestic hot water and more- all jobs that ordinarily cost money.

In this way, my chiller is saving far more than it's costing to operate.

 

[wietefras]

Water cooling takes the heat from the lights. Water cooling also allows you to use that heat elsewhere. Both examples don't need a chiller.

How much power does that chiller use and how much power would a simple radiator use?

 

[ttystikk]

Water cooling takes the heat from the lights. Water cooling also allows you to use that heat elsewhere. Both examples don't need a chiller.

How much power does that chiller use and how much power would a simple radiator use?

You're forgetting the pushing heat up the temperature gradient part, which DOES require a compressor.

A radiator can absolutely be effective, as long as the air temperature is always at least ten degrees F/5C below your target temperature.

In a small tent a radiator is very likely the better, nevermind more cost effective solution. However, it won't scale up to handling the needs of a commercial facility. Water chilling is scalable, more efficient and more flexible than water cooling.

I don't think we disagree anywhere, do you?

 

[wietefras]

I'm not forgetting anything. I just don't think your numbers add up.

 

[ttystikk]

I'm not forgetting anything. I just don't think your numbers add up.

The heat has to go somewhere. It doesn't vanish.

Tell me how plugging in a heater is cheaper than reusing heat you've already had to pay to remove in the first place.

 

[ttystikk]

I really like water cooling btw and If you know what you are doing and are very careful doing the proper inspections and testing it won't leak. I just want anyone who is even thinking about trying this to please understand there is a lot that can go wrong if you just try to slap things together.

Important safety message! Agreed on all counts!

Playing with water and high voltage can KILL YOU, take all necessary safety precautions including checking your connectivity with instruments. I've had some weird faults and they're no joke. No weed is worth dying for, rather it's all worth living for. The extra time and expense of ensuring safety is cheap insurance compared to the alternative.

 

[wietefras]

The heat has to go somewhere. It doesn't vanish.

Tell me how plugging in a heater is cheaper than reusing heat you've already had to pay to remove in the first place.

Well I wanted to leave it alone, but since you keep trying the same thing I guess I better explain.

A chiller doesn't make the heat vanish. It only moves the heat from the water into the air. You still need to get rid of it the heat or reuse it. Just like with a radiator. All tests I've seen with cooling have shown that putting in effort to cool the COBs more to gain efficiency costs more enrgy for the cooling. A chiller is just about the most expensive way of moving heat around. For what? 5% extra light for cooling the COBs by 25 degrees C. How about adding 5% more light to begin with and letting the COBs run at a more normal temperature?

If you have some actual numbers how much power chiller is using and that it's actually cheaper than adding 5% to the lights I'd love to hear. Based on just the marketing talk, I'm really not seeing it being more efficient.

You can name a whole list of applications where you might be able to use some excess heat, but lets be serious, you use none of those right? You'd need a load more tech to use it for any of those. Apart from heating the room and a radiator will do just fine for that.

I reuse the heat from the lights for the plants. There is very little left after using that for heating up the whole grow room to the same temperature instead of just the canopy. So no, I don't plug in a heater.