CO2 Laser Cooling Method Comparison

[@familiekruit6068]

I have two simple suggestions. 1. One of the reasons the temperature is rising is that every 5 to 7 minutes the icemaker compressor will reverse it cycle and heat up the coil to release the ice cubes. Since that manifold is spraying cooling water on it, it will add that heat to the cooling circuit. I suggest adding some antifreeze like glycol to your cooling water. That way you'll don't have to use that manifold as the ice maker simply won't be able to make ice cubes. Therefore the return line can discharge directly into the tank and thus not picking up any heat from the reverse cycle. 2. Go for 2 stage cooling by adding a 240mm radiator with a pair of high pressure 120mm fans to the return line. This will probably take off just enough heat to let the icemaker maintain a constant temperature. The reason behind this is that a radiator cools more effectively with a higher temperature difference while a compressor cools more efficiently with a lower temperature difference.

[@SarbarMultimedia]

Thanks for your investment of time and money to demonstrate how unsuitable and inefficient Peltier devices are for this application. I think the fixation with keeping the temperature in the 18 to 20 C region is a myth created by the chiller manufacturers. Go look at the tube manufacturer's specifications and most will tell you that water temperatures up to 40 C are permitted. I have carried out my own tests for 3 hours continuously with a 70 watt tube running at between 40 and 47C. I recorded a 5% loss of power , which at the time I did not understand but there were no ill effects to the tube which still runs today (6 years later). I have encountered many correspondents with refrigerated chillers (CW5000/5200) that experience serious "banding" problems when doing photo engraving. It has long been known that this banding coincides with the refrigeration switching on and off. In the absence of a REAL explanation as to why the power was changing, the simple fix was to create a coil from annealed microbore tube (from any hardware superstore) and connect the chiller to this coil rather than the laser tube. The copper coil then sits in a seperate water reservoir and the water from that reservoir is pumped through the tube with a cheap submersible pond pump. This system removes the shock cooling to the tube by buffering it with this seperate reservoir that changes temperature slowly.. Problem solved. But why? You have to understand the physics of how the tube works but briefly there are two reflecting mirrors at the ends the tube. These are vital for the amplification of the photon population that results in the watts power output. These mirror MUST be perfectly flat and aligned to each other and heat up when the tube is on. Look carefully at a tube and you will usually see a full water jacket at the HV end mirror and a partial water jacket at the output end mirror The rapid cooling shock as the refrigerated water turns on/off cools the back face of the mirror causing distortion. This impairs the perfect reflections and in turn reduces the power output. Slow temperature changes have virtually no distorting effect on those mirrors . That is why buffering the refigerated water solves the power change issue. Also, ther bigger the reservoir the slower the temperature change.

[@peterlandin457]

Nice video. If you like to have a more constant cooling and dropping the temp lower, just let the icing machine do its work and generate ice in to the water at the pump and it will cool alot better

[@chrisl4999]

Thank you for putting this together. I've got a smaller omtech (k40) and I was considering a different method than just putting a frozen bottle of water into my "cooling" bucket to keep it chilled. Lots to think about.

[@raycap]

Thank you for showing all your testing, very helpful

[@johnsmith-000]

Nice study. Obviously the Peltiers are not a solution, which is in fact consistent with TEC coolers for computer processors, where they didn't do a good job either. I have an idea, which I haven't tried, but maybe you can since you have an ice maker already installed. You are trickling water down the ice making elements, which may not utilize them to their full potential. The idea is simple enough and costs next to nothing - find the food/ice rectangular plastic container which fits the compartment under the cooler tubes, with inlet and outlet tube attachments at the opposing sdes, and put it under the ice making "fingers", fil with water so that the elements are fully submerged and circulate that water only, using the bottom compartment as an overflow drain only. I don't know what the minimum quantity of water is needed, biu it's probably wise to choose the container with as big a volume as fits up there. I think that should improve the cooling efficiency, how much is a question. But I have a feeling you might get to a point where the tube will not overheat regardless of the workload. And I would also use the thermostat to actually switch the cooler on and off if it's temperature range allows this.

[@ixamraxi]

You could improve the efficacy of the chiller by removing all of the internal electronics and connecting power directly to the compressor, so that anytime its plugged it, it just runs constantly (just leave the diverter valve unplugged, its designed to change the freon flow to allow the cooling element to heat up in order to release the ice). Then just use the external inkbird ITC308 controller to cut power if the chiller bottoms out in temp. This will prevent you from having to deal with 'cycles' at all. For peltiers, I had the same experience, there just isn't enough surface area. I had slightly better results changing to HDD heatsinks rather than CPU/GPU heatsinks, but still not enough surface area to cool efficiently.

[@familiekruit6068]

Depends on the kind of compressor. Modern refrigerators and icemakers (at least in Europe due to regulatory standards) come with a DC powered inverter driven compressor making it much harder to make modifications like that.

[@ixamraxi]

@@familiekruit6068 Good to know, thank you. I figured he was in America because of the style of plug, so that recommendation should work in this case. For European, do you know if the invertor circuit is a separate board/module, or included on the main control board? If its separate, the procedure would be basically the same as the US, except one would keep the invertor. If its on the main control board, there might be some signal tracing needed in order to skip the control circuitry, but it should be possible to use the invertor portion of the circuit, and essentially ignore the rest. I'd have to see the board to know.

[@familiekruit6068]

@@ixamraxi Took a refrigerator apart last year to take out the compressor as I wanted to build a silent airbrush compressor. There was a mainboard inside with lots of SMD components and some SSR’s on it that appeared to drive te compressor. There was also what looked like a data line between the compressor which if I remember correctly had a 7 pin connector. Did some research with an oscilloscope, the power to the compressor looked like a PWM signal. Also, the compressor wouldn’t run with the data line connected. I couldn’t find a dry contact anywhere that would start the compressor without the mainboard connected. Also, the mainboard wouldn’t start the compressor without the temperature sensor and the display in the door connected. Its nothing like the old ones so it ended up to be rather useless.

[@ixamraxi]

@@familiekruit6068 Sounds frustrating. At that point, it might actually be worthwhile to build a small invertor circuit that can drive the compressor independently without needing the mainboard. You can probably buy them, as I am sure others have run into the same problem over there, but it would could a fun project if not.

[@thebosun181]

Interesting! I've been thinking of using a plate wort chiller that I have for cooling

[@Qwerty_c]

Doesn't the fact that the temperature has increased to 25 degrees have to do with the flow rate of the pump? Perhaps if your pump moved a higher flow rate, it would help. Another thing that I think can be done is to insulate the hoses so that the cold water does not dissipate. I see that the journey to the laser is long. Perhaps the water does not reach your laser so cold because it travels a very long stretch.

[@bestyoutubernonegraternumber1]

Wow man, people really go to great lengths to avoid getting a real active chiller lol.

[@jj8482]

How does the inkbird work with the icemarker ? Beacuse when it turns it off and on don't you have to still put it on manually?

[@ryanpatrick9635]

I only use the Ink Bird to monitor temperature and send an alarm to the phone app if it drops below a setpoint temperature. That lets me know if something happened to the heater and it stopped working.