Experimental study on pulse tube refrigeration with helium and nitrogen mixtures Original Research Article

An experimental investigation on two-component multi-phase helium and nitrogen mixtures in a single-stage pulse tube refrigerator was carried out. The experimental results show that both coefficient of performance (COP) and cooling power can be improved to some extent at above 70 K when the nitrogen fraction in the mixture is less than 25%. An approximate stable temperature platform at the triple point 63.15 K of nitrogen, which is independent of nitrogen’s fraction, is obtained when the cooling power is below 7 W.