An alternative observation on the orifice pulse tube cryocooler and analysis through the unified model of cryocoolers

A new observation of the orifice pulse tube (OPT) cryocooler is proposed and analyzed on the ground of the unified model of cryocoolers. The elementary temperature reduction mechanism is modeled and verified through the measurements of Mikulin and others. This analysis refers to the upper limit performance for zero phase shift between the pulses of pressure and flow rate at the cold end. The lowest attainable temperature is formulated and pointed out as central characteristics of an OPT cooler. It dominates the closed form expressions for cooler's cooling capacity, COP and FOM as function of the compression ratio, the size of regenerator, the species of coolant and average flow rate. The so obtained upper limit of COP and FOM is about half of that in literature. Performance is also compared with Solvay and Gifford-MaMahon cryocoolers.