What liquid has ideal thermal properties for this project?

[Alexandermonk]

I want to circulate cold water through copper tubing curled in a spiral about a fan. I'll cool the water with a large block of ice that I can remove and replace like a battery. To avoid making a mess I can freeze the ice inside of a copper housing, and pump the water in copper tubes around that housing to make it removable.
I'm wondering if there's a better choice of liquid than water for this? One that would melt slower, thus, need to be replaced less often? Also, what would that quality be called?

 

[mfb]

Also, what would that quality be called?

Latent heat of fusion together with heat capacity. For a temperature around 0°C, water should be ideal. It has very high values for both. In addition, it is cheap, not toxic and easy to store and replace.

Why do you need such a system? Did you consider a heat pump?

 

[AlephZero]

To avoid making a mess I can freeze the ice inside of a copper housing, and pump the water in copper tubes around that housing to make it removable.

Remember that ice occupies about 10% more volume than water. If you burst your "copper housing" you will certainly make a mess!

The volume expansion doesn't matter much if you are freezing ice cubes in a flexible plastic tray, but freezing a large block of ice in a rigid metal container is a different situation.