Case No.2: Dual-diameter heat pipe

Lead into an idea of the tail expansion heat pipe for heat pipe applications.
On the evaporator area, an expanded diameter design benefits the conducting area with powdered wick structure inside of the heat-pipe, carrying more energy through phase changed vapor.

The other side of the tube is considered as condenser side. A smaller diameter tube allows smaller bending radius and brings in a better space arrangement of heat-pipes line-up.

Below is the performance comparison chart

A dual diameter heat-pipe is expanded from 6mm to 8mm. Its performance line is marked with a green triangle.  

The 6-8mm dual-diameter expansion heat pipe gives a close performance as 8mm diameter heat pipe. And its advantage is shown in price, performance, and bending space capabilities to fit into any form factor.