Question

Is there a way to speed up Peltier cooling?

Answer 1

My guess is your peltier are not enough to cool the whole suitcase (or not being applied current enough). Here is my reasoning:

1 - No heatsink on cold side + water: I guess this means when nothing is transfering heat from the suitcase to the peltier, the peltier gets cold enough to condense water.

2 - Heatsink on cold side + no water: since transfer of heat from the suitcase to the peltier is more effective now, the peltier doesnt get cold enough to condensate, hence no water is present in the morning.

So in conclusion, its either not powerful enough (by nature or lack of supply) and/or the suitcase is not well thermally insulated.

Answer 2

yes there a way to speed up Peltier cooling.