Numerical investigation of a condensation-driven dilution refrigerator

Abstract

The dilution refrigerator is the most popular subkelvin refrigerator and important for research fields such as condensed matter physics, astronomical observation, and quantum computing. For applications requiring small cooling powers as well as small footprints, the cold-cycle dilution refrigerators without ambient mechanical pumps and complex connecting gas circuits have become a new research frontier. In this paper, a condensation-driven dilution refrigerator, as a kind of cold-cycle dilution refrigerator, is studied numerically. A comprehensive model covering the thermodynamics, heat transfer and fluid dynamics is established and systematical simulations are carried out to analyze the system performance and the influence of key operating parameters. Through simulations, the T-S and P-T figures of the cold cycle at typical operating conditions are given, and the thermodynamic processes and irreversibility are analyzed. Typically, a COP of 0.025 with the corresponding thermodynamic second-law efficiency of 7.5% can be obtained at 100 mK with the still temperature being 450 mK and the condensation pump temperature being 400 mK. The results reveal the mechanism of the condensation-driven dilution refrigerators and provide useful guidance to the design and operation of experimental setup.