Experimental Results of Pulse Tube Cooler with Inertance Tube as Phase Shifter

Interest in miniaturization of pulse tube coolers necessitated its operation at higher frequencies where fluid inertia effects start to show significant influence on the performance of the cooler. Commonly used means to achieve optimum performance of the cooler are orifice or capillary tube and double inlet. Fluid inertia at higher frequencies provide another means to achieve optimum performance. This type of phase shifter is referred in literature as “neck-tube” or “inertance tube”. Ravikumar and Matsubara [Adv. Cryogenic Eng., Vol. 43] presented experimental results of the cooler using fluid inertia as phase shifter. Their results showed that as frequency increased the “inertance tube” phase shifter enhanced the cooler performance in a region where orifice or double-inlet deteriorated the performance. For similar operating conditions inertance tube phase shifter resulted in higher pressure ratios inside the pulse tube. The fluid inertia is a strong function of inertance tube cross sectional area and length. Further experimental results exploring the dependence of no-load refrigeration temperature and refrigeration load vs refrigeration temperature on frequency of operation, inertance tube diameter and length are presented here.