I was thinking of a setup like this:
The operation is that the pump presses one time, forcing air to fill the tubing, which forces the water out, then as the pump is refilling with air from the outside water drains into the tubing and the air that was in the tubing exits from the exhaust tube. Then this repeats. This gradually cools the water.
The reason it cools the water is the pump has 1 liter of air and the tubing also holds 1 liter of air. But there is much more surface area over the tubing so the pressure of the air drops as it fills the tube. This is because pressure is a force per area and the force doesn't change and the area increases so the pressure drops.
by the ideal gas law:
I think maybe an even better design would be with a motorized pump that's fast enough to keep the tubing from filling with water, and have the exhaust pipe connected back to entry of the pump so the same air is cooled over and over, the pump would be built so it could radiate heat well to the outside air when it pressurizes the air coming into it.