Analysis of the feasibility of using Invar process pipes in multichannel cryogenic helium transfer lines based on the second law of thermodynamics

This work describes examples of the use of cryogenic lines and their designs, referring in detail to typical structural nodes found in cryogenic transfer lines. As a special case, multichannel cryogenic transfer lines are described, in which the process pipes are made of Invar. This has a significant impact on the number of internal supports and the method of thermal shrinkage compensation, which directly impact into reduced heat input during the transfer of cryogenic media. The second law of thermodynamics and the Gouy-Stodola theorem are discussed from the perspective of their application in optimizing and evaluating heat and mass transfer devices. The next part of the work presents the internal structure of the selected 250 m multichannel cryogenic transfer line. Several variants of the method of supporting process pipes have been presented and compared with the solution using Invar. For each solution, an entropy analysis was carried out in order to select the best design in terms of the entropy generated in the process pipes. From the examples presented, it is proven that entropy minimization method can be used for complex optimization of entire cryogenic distribution systems, as well as their indi-vidual components.