How hot is the water leaving the laser tube?

A friend and I were setting up a cooling bucket(5 gal) and he mentioned needing to keep the tubes coming from the laser away from things which are sensitive to heat because the water leaving the laser tube was really hot. I disagreed claiming if it was the case the little 5g of water would heat up quite quickly but he persisted with the claim.

Does anyone know what the temperature differential is between inlet and outlet when the inlet is ~20C?

If it’s hot the laser is going to die quickly.

Temperature delta will depend on current (volume per time) for but 40 W laser / 20% efficiency means max heating the water at a measly 200W.

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The water coming out of the tube is typically less than 2°C warmer.

E.g. 2 liters per minute and 200W:

> 200 * 60 / 2 / 4168

The water coming out of the tube would be less than 1.5°C warmer.

The reason why we still need chillers is because we continuously cycle the same water, which gradually heats it up.

E.g. we have 10 liters at 20°C in our reservoir and we continuously dump 200W of heat into it:

> 10 * (30 - 20) * 4168 / 200 / 60

It would only take 35 minutes to go from 20°C to 30°C.