Daveis said:
Hi,
Not many microbes will grow in the high temperature, hostile environment inside of the typical engine.
Antifreeze, it's name implies this, increases temperature range. Both up wards and down wards. Another quality that antifreeze has is lubricant for the mechanical water pump that circulates the coolant though out the engine.
If you are worried about fungus growing in your amps cooling system, add some rubbing alcohol.
Corrosion....
If you mount the transistors on different blocks but do not isolate them from the metal (no mica insulators) then you will most definitely want some anti-corrosion additive. With the voltage difference between the collectors (assuming emitter follower output stage) there would be significant corrosive potential. Perhaps you could also investigate using mineral oil or some other non-conductive liquid as a coolant?
If you mount the transistors on different blocks but do not isolate them from the metal (no mica insulators) then you will most definitely want some anti-corrosion additive. With the voltage difference between the collectors (assuming emitter follower output stage) there would be significant corrosive potential. Perhaps you could also investigate using mineral oil or some other non-conductive liquid as a coolant?
Unless you fellas are hell-bent on re-inventing the wheel, you might take a look at my water-cooled Aleph thread from way back when.
Note that water may start as pure, deionized, etc. but that's not to say that it will stay that way.
Separating the devices will give you thermal drift. You're going to need to match them more closely than usual. There's also a (possible) hidden penalty, in that you're pushing the devices farther apart, which will mean you'll need longer leads going to and from the devices, etc.
I haven't got time to read all the posts here in detail, but scanning through them led me to the conclusion that there are a goodly number of ideas being put forth that aren't completely thought through.
Something to think about: If you take a normal heatsink and plunge it into water at the same temperature as the air, will the efficiency increase or decrease? Why?
Grey
Note that water may start as pure, deionized, etc. but that's not to say that it will stay that way.
Separating the devices will give you thermal drift. You're going to need to match them more closely than usual. There's also a (possible) hidden penalty, in that you're pushing the devices farther apart, which will mean you'll need longer leads going to and from the devices, etc.
I haven't got time to read all the posts here in detail, but scanning through them led me to the conclusion that there are a goodly number of ideas being put forth that aren't completely thought through.
Something to think about: If you take a normal heatsink and plunge it into water at the same temperature as the air, will the efficiency increase or decrease? Why?
Grey
with well or de-ionized/distilled water id suggest a biocide
http://www.petrastechshop.com/pepcobi1.html
and/or anti-microbial tubing
http://www.petrastechshop.com/1id3odtysian.html
http://www.petrastechshop.com/pepcobi1.html
and/or anti-microbial tubing
http://www.petrastechshop.com/1id3odtysian.html
Well, I suppose efficiency is what goes in vs what goes out... I guess it's all going out somehow but, where it hits the air is the output measure node? Right? And, the "in" must be the bottom of your output transistors? I guess I don't really want to be that detailed or someone will pick it apart anywayGRollins said:
Suffice it to say the mass of the water and energy (heat) it can store and or take on, is more heat than the equal volume of air by far. The molecular contact with the heatsink is many many times more for the denser water than air. Barring any flow or volume considerations in your question, you could say, an air heatsink would generrally take out more heat emersed into water than in open still air
It's really a little apples and oranges unless you just look at the die or transistor temp in either system. Provided there are no serious design errors in either application. Water can be very, very good at carrying away the unwanted heat To save some searching... the old thread was
http://www.diyaudio.com/forums/showthread.php?s=&threadid=190&perpage=25&highlight=&pagenumber=1
http://www.diyaudio.com/forums/showthread.php?s=&threadid=190&perpage=25&highlight=&pagenumber=1
70/30 water/antifreeze would work well. I've used this mixture several times for cooling my ppi art amps with a small radiator under the bumper area. Never had a problem with microbe growth or gumming up. I actually used a cheap 12v fuel pump and a small reservoir (spare radiator overflow tank) Amazingly the antifreeze kept the fuel pump from having problems.
What a vast assortment of ideas, you guys are great!
Magura, I'll have copper in the system for sure.
Grey, perhaps thermal drift will become more of a problem than I realized.
A little antifreeze for lubrication is a fine idea.
This is going to be fun. The best part: I can run the bias up without fear of running out of cooling capacity!
Magura, I'll have copper in the system for sure.
Grey, perhaps thermal drift will become more of a problem than I realized.
A little antifreeze for lubrication is a fine idea.
This is going to be fun. The best part: I can run the bias up without fear of running out of cooling capacity!
Yep, as noted in my original thread I started with aluminum, then went over to copper. Copper is, perhaps, a little more expensive, but seeing as how there's an entire world of copper plumbing parts out there, just waiting for you, I feel that it's well worth it. It conducts heat well, solders, is available in nearly every shape and size that you could ask for, and looks sexy.
What else do you want?
Anti-freeze isn't necessary. Keep in mind that the water pumps in cars are designed for external lubrication. Your average water pump will be internally lubricated and will derive no benefit from the anti-freeze. And if you were planning on running the system so hot that you need to raise the boiling point of the fluid, you've blown a gasket...that's too bloody hot for your output devices, anyway.
The longer I keep at this, the more respect I develop for the side effects of thermal drift. It's pretty good at kicking over the apple cart. It's not that you can't make separate modules and try to keep things under control, but it's just a whole lot easier to do it all at once with a row of devices mounted side-by-side on a single copper bar. For the Alephs, I put the gain devices on one rack and the Aleph current source devices on the other. The front end nestles between the two.
And, yes Virginia, I can dissipate a truly terrifying amount of heat. I have never, and I mean never found the limits of what this thing can do. I was running four channels of Aleph 2 on it and it was barely warm. That's 1200W of heat. Think about it.
Not to mention a few other projects, here and there.
The thing's a beast.
I'm glad I built it.
(If only it were portable...)
Grey
What else do you want?
Anti-freeze isn't necessary. Keep in mind that the water pumps in cars are designed for external lubrication. Your average water pump will be internally lubricated and will derive no benefit from the anti-freeze. And if you were planning on running the system so hot that you need to raise the boiling point of the fluid, you've blown a gasket...that's too bloody hot for your output devices, anyway.
The longer I keep at this, the more respect I develop for the side effects of thermal drift. It's pretty good at kicking over the apple cart. It's not that you can't make separate modules and try to keep things under control, but it's just a whole lot easier to do it all at once with a row of devices mounted side-by-side on a single copper bar. For the Alephs, I put the gain devices on one rack and the Aleph current source devices on the other. The front end nestles between the two.
And, yes Virginia, I can dissipate a truly terrifying amount of heat. I have never, and I mean never found the limits of what this thing can do. I was running four channels of Aleph 2 on it and it was barely warm. That's 1200W of heat. Think about it.
Not to mention a few other projects, here and there.
The thing's a beast.
I'm glad I built it.
(If only it were portable...)
Grey
I guess I'll go scrounging around the local scrap-metal yard. Grey, you and the boys have convinced me to go with a one piece plate cooler.
With the F4s and Peter's pcbs, the copper plates can be rather small--I'm guessing a five by six inch rectangle an inch thick, or so; I'll know more when the boards arrive.
I can bore and tap the plates, solder in a copper manifold (inlet/outlet)... yeah. Or, I could use a 1/4" thick plate with copper tubing snaked back and forth and soldered beneath...much faster to fabricate! Come to think of it, a couple of copper plates bolted together could sandwich a flat wound coil of copper tubing (resembling an electric stove-top burner)--one inlet, one outlet. This way there's no heat warping to deal with.
I rarely listen to music for more than an hour, so a 5 gallon pale could be the reservoir. If the coolant requires additional cooling, I can run it through a radiator. Ooooh, there's going to be four stereo pairs. Eight amplifiers may heat that water up sooner than I anticipated.....definitely going to need that radiator!
It seems I build amplifiers more for the challenge than the listening pleasure...my hearing's not all that good. Of course, when the house is empty, I crank it up a bit and the meaning of music comes home to roost.
Here's a thought: the radiator could be placed in a chimney tower and use convection to move the air.
Fun stuff to sleep on. BTW: Thanks everyone for the participation.
With the F4s and Peter's pcbs, the copper plates can be rather small--I'm guessing a five by six inch rectangle an inch thick, or so; I'll know more when the boards arrive.
I can bore and tap the plates, solder in a copper manifold (inlet/outlet)... yeah. Or, I could use a 1/4" thick plate with copper tubing snaked back and forth and soldered beneath...much faster to fabricate! Come to think of it, a couple of copper plates bolted together could sandwich a flat wound coil of copper tubing (resembling an electric stove-top burner)--one inlet, one outlet. This way there's no heat warping to deal with.
I rarely listen to music for more than an hour, so a 5 gallon pale could be the reservoir. If the coolant requires additional cooling, I can run it through a radiator. Ooooh, there's going to be four stereo pairs. Eight amplifiers may heat that water up sooner than I anticipated.....definitely going to need that radiator!
It seems I build amplifiers more for the challenge than the listening pleasure...my hearing's not all that good. Of course, when the house is empty, I crank it up a bit and the meaning of music comes home to roost.
Here's a thought: the radiator could be placed in a chimney tower and use convection to move the air.
Fun stuff to sleep on.
BTW: Thanks everyone for the participation. 
So, doing this has been on my mind for some time. I've built several water cooling rigs for large frame ion lasers, and for a couple thermoelectric air conditioners that never panned out. (Terrible efficiency) I also have a water cooled test load about half built up.
So my question: I had a problem with some sort of buildup on all metal surfaces inside the cooling loop of my last system. It was a white powdery substance (when dry). The system included copper, brass, and stainless fittings and ran using just distilled water. So, did I have electrolysis between metals going on or what?
So my question: I had a problem with some sort of buildup on all metal surfaces inside the cooling loop of my last system. It was a white powdery substance (when dry). The system included copper, brass, and stainless fittings and ran using just distilled water. So, did I have electrolysis between metals going on or what?
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