Numerical analysis of a novel coaxial annular tube convective heat switch

• Published in: Cryogenics (Guildford) 2024-01, Vol.137, p.103772, Article 103772
• Main Authors: Zhang, Yu, Liao, Yi, Zha, Kuifan, Liu, Xuming, Pan, Changzhao
• Format: Article
• Language: English
• Subjects: CFD; Coaxial annular tube; Cryogenics; Heat switch; Natural convection
• ISSN: 0011-2275; 1879-2235
• DOI: 10.1016/j.cryogenics.2023.103772

•A novel coaxial annular tube convective heat switch has been developed..•An CFD analysis of the operational mechanism of this convective heat switch is conducted.•The influence of geometric parameters on its performance is studied and optimized.•The results obtained offer valuable guidance for the design of this novel heat switches. Heat switches are commonly used in cryogenic instruments to provide thermal contact or isolation between the hot and cold masses over a temperature range from millikelvin to room temperature. This study presents a new type of convective thermal switch that implements an annular tube design replacing the twin-tube structure. To study the effects of geometry and operating parameters on thermal performance, a computational fluid dynamics (CFD) model is developed. The results show that the designed heat switch provides a thermal conductance of 33.79 mW/K when the end temperatures are 4.2 K and 40 K. In addition, it can automatically change to thermal isolation mode with a residual thermal conductance of 0.19 mW/K. The thermal conductance is increased from 33.79 mW/K to 38.90 mW/K by extending the length of the inner tube. This novel heat switch holds promise for precooling the modern cryogen-free dilution refrigerator (DR) and adiabatic demagnetization refrigerator (ADR).