You are here : Home > The DSBT > Next step towards the miniaturisation of space cryocoolers

Arkadii Sochinskii

Next step towards the miniaturisation of space cryocoolers

Published on 26 October 2018
Thesis presented October 26, 2018

Abstract:
This research is done in the framework of miniaturisation of pulse tube cryocoolers studies and especially to gain a better understanding of the mass flow and heat transfert in the regenerator, which is a crucial component of these type of cryocoolers.
In this work we present a numerical and experimental study of the Darcy-Weisbach friction factor and Nusselt number for a continuous and steady flow at moderate Reynolds number O(1−100) in a micro-machined regenerators. The influence of porosity from 40 to 80 % and of the geometry parameters are studied. Well-controlled microstructures represent convoluted channels of 10, 20 or 40 μm width and 100 or 300 μm depth generated by rhombic- or sinusoidal-shaped columns. The channels are etched in Silicon wafers using DRIE MEMS technology. The thermometers are integrated inside the regenerator’s micro-structure to measure the temperature evolution. The efficiency of the regenerators is estimated using two different approaches: the first, as a ratio of pressure drop losses and heat transfer efficiency (NPH/NTU); the second, as a volumetric heat transfer density coefficient proposed by Bejan. The numerical study of the efficiency shows the interest of proposed micro-structures.

Keywords:
Regenerator, MEMS, Friction factor, Nusselt number, DRIE, Pulse tube

On-line thesis.