Efficiency of a double helix vs dimroth condenser

[rubelstrudel]

I have been droolign over shiny copper and trying to make my own double helix copper pipe condenser to put in my still. But after contemplating the design for a while, I started wondering why none of the professional lab equipment used such a design. That again lead to having a good think about what we want to achieve with these contraptions.

What we really want from a counterflow condenser is that the warmest coolant should come in to contact with the warmest gas, then as the gas is cooled it comes into contact with colder and colder coolant. When the coolant is at its warmest, the whole point is to take that coolant with all the heat out of the system as fast as possible.

dimroth_copper.jpg

A double helix works counter to this. When the hot coolant goes through a new spiral, maximising the contact between the hot and the cold coolant we will get heat transfer directly from the hot coolant to the cold coolant without drawing more heat out of the gas.

custom-wound-14-solid-copper-condenser-coil-helix.jpg

So I postulate that a "double helix condenser" looks nice, but is a really inferior design to the classic dimroth design. Even better would be to have the hot coolant exit the condenser at the hottest point, but let us now keep to the slot in design criteria.