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# Water cooling a laser, calculations

## Water cooling a laser, calculations

(OP)
I have 120mm x 120mm x 27mm aluminum radiator, pump can push 106l/h, fan on radiator can push 126.55 m³/h. Liquid in system is water. I need to cool 30W laser with it. How much power can be removed. Laser tube is 700mm long, made out of glass and water flows around 15mm wide inner glass tube with thickness of 2mm. What will be the exit water temperature and what will be exit water temperature from radiator.
Need answer as fast as possible pls.
Replies continue below

### RE: Water cooling a laser, calculations

(OP)
I dont know. It is 120mm radiator for PC. Mabey they have a standard

### RE: Water cooling a laser, calculations

The math is pretty simple

Temp = Heat/(htc * area)

htc = heat transfer coefficient
area = total surface area of all the fins

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### RE: Water cooling a laser, calculations

(OP)
There is about 1540 fins. Every one of them is 4mm long and 20mm high so that should be 1/12500m2. Total surface is then 0.1232m2.
Temp=30W/(0.1232m2 x 235W/mk)=1.036K
Is that right?

### RE: Water cooling a laser, calculations

No, that's the equation for thermal conduction, and you didn't use it correctly, and it will only tell you the temperature drop across the fin itself.

Look up the equation for forced convection.

This site is for work-related questions by working engineers

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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