Cryogenic distribution systems are complex engineering installations combining process piping, vacuum insulation, thermal shielding, supports, instrumentation and numerous auxiliary components that must operate reliably over a wide range of temperatures and operating conditions. KrioSystem Ltd. designs and manufactures such systems for research and industrial cryogenic applications, where thermal, mechanical and manufacturing requirements have to be addressed simultaneously.
An important component of many cryogenic insulation systems is the thermal link. Thermal links provide a conductive connection between a cooled process line and a thermal shield while usually allowing relative movement caused by manufacturing tolerances and differential thermal contraction during cool-down. They typically consist of a mechanically attached interface, such as a clamp or block, connected to the thermal shield by a flexible high-conductivity element, commonly a copper or aluminium braid. Although a single thermal link is a relatively simple component, large cryogenic installations may contain hundreds or even thousands of such connections. Their thermal performance, repeatability, manufacturability and cost can therefore have a significant impact on the overall design of the cryogenic system.
In practice, the effective thermal conductance of a thermal link is determined not only by the thermal conductivity of its constituent materials but also by thermal contact resistance at the mechanically assembled interfaces. This creates a need for reliable design methods and experimental data that can be directly applied to industrial cryogenic components.
To address this issue, KrioSystem Ltd., in cooperation with Wroc?aw University of Science and Technology, has developed a combined numerical and experimental approach for the design and characterization of flexible thermal links.
Following the development of a sequential thermo-mechanical FEM methodology, a dedicated cryogenic test facility has been designed and commissioned to experimentally characterize complete thermal-link assemblies and individual metal-to-metal interfaces.
For a cryogenic system supplier such as KrioSystem, optimization of these apparently minor components is relevant not only from a thermal-performance perspective, but also in terms of production repeatability, assembly time and cost.

Keywords
Cryogenic distribution systems|Thermal links|Heat transfer|Thermal Contact Resistance