Increase the surface area and time for heat extraction to occur with extra loops in the water part (do they make metal silly straws?)
Get really fancy and use a counterflow chiller: create a two layer straw, where tea goes through one layer while cold water goes through the other layer in the opposite direction (obviously with an outlet somewhere besides your teacup)
While metal is a better conductor of heat, when looking at the effective rate of cooling you need to take the wall thickness into account. I think a plastic straw with it’s micrometer thin walls is unbeatable.
Edit: I have trouble finding information on wall thickness of drinking straws, it one source says they are 130-250 μm thick. That is thicker than I expected.
Leave a block of wood and a brick of steel in a freezer for 24 hours and see which one feels cooler - they’ll be the same actual temperature (at least negligibly close the longer they’re left) but the metal will feel immensely cooler to the touch due to its higher capacity for heat transference.
heat capacity: any short term experiment will measure heat capacity first, conduction second
locality of contact: contact along the whole length of the straw eliminates heat conduction along the length of the straw. A single point of contact (holding the straw with fingers instead of the whole hand) behaves differently.
I thought plastic straws were thinner than 0.2 mm, so maybe the metal is actually better.
It’s fun arguing about these technicalities though!
But the goal here isn’t to maximize cooling, you still want the tea to be hot, just drinkably hot rather than dangerously.
You need to calibrate your coolant water temperature to provide the ideal amount of cooling for you.
Time to design a radiator.
While metal is a better conductor of heat, when looking at the effective rate of cooling you need to take the wall thickness into account. I think a plastic straw with it’s micrometer thin walls is unbeatable.
Edit: I have trouble finding information on wall thickness of drinking straws, it one source says they are 130-250 μm thick. That is thicker than I expected.
Counterpoint: drink a cold drink through a plastic straw and a metal straw, with your fingers on the straw. See which one feels cooler.
Leave a block of wood and a brick of steel in a freezer for 24 hours and see which one feels cooler - they’ll be the same actual temperature (at least negligibly close the longer they’re left) but the metal will feel immensely cooler to the touch due to its higher capacity for heat transference.
Doesn’t that just agree with what I’m saying? The metal is going to transfer heat more easily than the plastic
There are two compounding factors
heat capacity: any short term experiment will measure heat capacity first, conduction second
locality of contact: contact along the whole length of the straw eliminates heat conduction along the length of the straw. A single point of contact (holding the straw with fingers instead of the whole hand) behaves differently.
I thought plastic straws were thinner than 0.2 mm, so maybe the metal is actually better.
It’s fun arguing about these technicalities though!
This man HVACs