Pulse tube refrigerator with variable phase shift
AssigneeThe Regents of the University of California
InventorsGregory W. Swift, David L. Gardner
Life of this patent
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Abstract
An orifice pulse tube refrigerator (PTR) having a pulse tube and a reservoir with a compliance value C is provided with a variable acoustic impedance connecting the pulse tube and the reservoir. The variable acoustic impedance includes two or more variable impedances, which may be an inertance and valves forming variable resistive members, wherein the resulting acoustic impedance has a phase angle that is variable for improved cooling efficiency. The inertance may also be variable to further provide for varying the phase angle. In another improvement, an acoustic transmission line connects the pulse tube and a driver unit for recovering power from the pulse tube for return to the driver to further increase the PTR operating efficiency.
Claims9
In a pulse tube refrigerator having a pulse tube with an oscillating mass flow for energy transfer and a reservoir with a volume defining a compliance value C, an improvement comprising a variable acoustic impedance connecting said pulse tube in series with said reservoir;
- said variable acoustic impedance including a tube member having a diameter and length forming an inertance with a value L and a variable resistive member having a first series resistive member R.sub.s and a second parallel resistive member R.sub.p, said inertance, first resistive member, and said resistive member connected to form an impedance Z selected from ##EQU4## where j=.sqroot.-1 and .omega. is the radian frequency of said oscillating mass flow, wherein said acoustic impedance formed by the values C, L, R.sub.s and R.sub.p provides a phase angle between fluid pressure and mass flow that is variable to optimize cooling power of said pulse tube refrigerator.
In a pulse tube refrigerator having a hot end driver for establishing an oscillating mass flow of a fluid within said refrigerator, a regenerator for receiving said oscillating mass flow for heat transfer with said fluid, and a pulse tube, an improvement comprising an acoustic transmission line having a length greater than about .lambda./2.pi., where .lambda. is the wavelength of said oscillating mass flow and connecting said pulse tube with said driver for returning power from said pulse tube to said driver.
Dependencies are inferred from the claim text.