I was thinking about the observations I had written here on this forum and put my thoughts together about water and using that to cooling the laser.
When I modified my laser it was a little haphazardly done and with little forethought on how effective water cooling is by itself. No refrigerant or Peltier chips.
The water itself… Pure deionized water would best medium for cooling and distilled is the next best. Deionized water unfortunately is a bit pricey at 22 bucks per gallon so I’m sticking with distilled at a couple of bucks.
I’ve also come to the realization that the ambient temperature of your work area is as important, if not more important than the concern for the heat generated by the laser tube. Yes, you got to get the heat out from the tube but the heat generated by the laser tube is dependent on its duty cycle (The amount of time it is on while running a job and watts used). It’s not having as big effect on your ability to cool the tube as your available water temperature to act as a heat dump. A warm room or day could have your tank temperature already warm way beyond where you want your coolant to be.
The rough calculations (very rough) that I did for the required wattage to cool the system were most likely correct for continuous use of a K40 tube at 100% but none of us would ever do that. I suggested 250 to 300 watts of Peltier for cooling.
Now after more thought I believe that with a 5 gallon tank… 120 watts may be enough if you also pre-cool the tank and system before you use your laser. Especially on warm days as I don’t want the system to be trying to cool the tank down at the same time I’m using it.
This is where, as Don is considering , using one of those small refrigerators may better because the water is always cool if you build your tank inside of it. Control your temp and turn things on for 15 minutes or so to acclimate the tube temp and away you go.
However, for me it wouldn’t fit under my stand and I don’t want to change that so it’s a Peltier system and some insulation. Haven’t thought much on it but maybe a remote to turn the pump and Peliers on from inside the house. I got one not being used but I 'd have to buy a relay.
Here I go again can’t leave well enough alone so I’m going to change my coolant system again and last night I bought a few things off the ‘Bay’ to add. God forbid my tube goes out because I’d most likely bump it up a few watts! I don’t want to go there for a time as I’m thinking the controller is next.
Here’s what I ordered.
A 180 watt Peltier cooling system to replace my air cooling one (because I don’t have the time to build my own.
They claim an effective cooling of 124 watts. We will see if that is enough this summer. If not, I guess I’ll have to a fork over a few more bucks and added a few more cooling watts.
I bought a 12v 30 amp power supply just in case and also ordered the hall effect flow meter, and a electronic programmable thermostat. The rest of stuff I have here.
I did consider building my own Peltier cooling system but I’ve got so many other projects going on that summer would have been over by the time got to it. Besides, I put all the cost together ordering everything and with shipping I wouldn’t have saved more than two or three sawbucks.
While waiting for this stuff I only have to build a insulated box for the tank I have now.
Thoughts?…