The problem with vortex cooling tube is that it is hottest in the middle as cold stream reflected at the hot end mixed with the hot stream there.
The cone reflector causes the cold spiral stream and hot spiral stream to mix. This shifts the hot spot down the middle of the tube.
A cone with a parabola indent with a width equal to the opening at the cold exit and a focus flush at its rim, may contain the cold spiral and stop the unwanted mixing.
May air conditioning be cheap...
