Gas phase shifting multistage displacer cryocooler

Abstract

A displacer cryocooler including a multistage heat exchanger is modified with a phase shifting device connected between stage volumes for gas phase shifting of gas pressure in the cryocooler for improving the efficiency and temperature range of expander cryocoolers.

1 . A cryocooler a first volume and a second volume, the cryocooler comprising,
 a first stage defining a first volume for containing gas at a first temperature and first pressure, and   a second stage defining a second volume for containing the gas at a second temperature and second pressure, and   a gas phase shifting device between the first volume and the second volume, the gas phase shifting device providing a pressure and temperature phase difference between the first volume and the second volume, wherein,   the cryocooler is a displacer cryocooler,   the first stage is a moving first heat exchanger, and   the second stage is a moving second heat exchanger.   
   
   
       2 . The cryocooler of  claim 1  wherein,
 the cryocooler is selected from a group consisting of coolers, heaters, and heat pumps.   
   
   
       3 . The cryocooler of  claim 1  wherein,
 gas mass flow is in phase with the gas pressure in the first volume and the second volume.   
   
   
       4 . The cryocooler of  claim 1  wherein,
 the cryocooler comprises a compressor,   the moving first heat exchanger and the second stage heat exchanger are portions of a porous piston driving gas pressure and mass flow from the compressor.   
   
   
       5 . The cryocooler of  claim 1  wherein,
 the cryocooler comprises a controller, and the gas phase shifting device is a flow impedance device.   
   
   
       6 . The cryocooler of  claim 1  wherein,
 the gas phase shifting device is a valve.   
   
   
       7 . The cryocooler of  claim 1  wherein,
 the gas phase shifting device is a flow impedance device selected from the group consisting of valves, sharp edge orifices, and porous mediums.   
   
   
       8 . The cryocooler of  claim 1  wherein,
 the gas phase shifting device is a flow impedance device, and   cooling of gas from the first volume to the second volume is controlled by flow impedance of the gas phase shifting device for controlling mass flow and pressure waves between the first volume and the second volume.   
   
   
       9 . The cryocooler of  claim 1  wherein,
 the gas phase shifting device is an inertance gap.   
   
   
       10 . The cryocooler of  claim 1  wherein,
 the gas phase shifting device is a flow inertance device selected from the group consisting of tubes and gaps.   
   
   
       11 . The cryocooler of  claim 1  wherein,
 the gas phase shifting device is a flow inertance device, and cooling of gas from the first volume to the second volume is controlled by flow inertia of the gas phase shifting device for controlling mass flow and pressure waves between the first volume and the second volume.