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.
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!
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.
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!