University of California

David L Gardner

Gregory W Swift

Scott N Backhaus

A thermoacoustic device is formed with a resonator system defining at least one region of high specific acoustic impedance in an acoustic wave within the resonator system. A plurality of thermoacoustic units are cascaded together within the region of high specific acoustic impedance, where at least one of the thermoacoustic units is a regenerator unit.

Cascaded thermoacoustic devices

A thermoacoustic engine-driven system with a hot heat exchanger, a regenerator or stack, and an ambient heat exchanger includes a side branch load for rapid stopping and starting, the side branch load being attached to a location in the thermoacoustic system having a nonzero oscillating pressure and comprising a valve, a flow resistor, and a tank connected in series. The system is rapidly stopped simply by opening the valve and rapidly started by closing the valve.

Method and apparatus for rapid stopping and starting of a thermoacoustic engine

A traveling-wave device is provided with the conventional moving pistons eliminated. Acoustic energy circulates in a direction through a fluid within a torus. A side branch may be connected to the torus for transferring acoustic energy into or out of the torus. A regenerator is located in the torus with a first heat exchanger located on a first side of the regenerator downstream of the regenerator relative to the direction of the circulating acoustic energy; and a second heat exchanger located on an upstream side of the regenerator. The improvement is a mass flux suppressor located in the torus to minimize time-averaged mass flux of the fluid. In one embodiment, the device further includes a thermal buffer column in the torus to thermally isolate the heat exchanger that is at the operating temperature of the device.

Traveling-wave device with mass flux suppression

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.

Growing community of inventors

Los Alamos, NM, United States of America

David L Gardner