A multi-stage traveling wave thermoacoustic engine is disclosed. A plurality of heat engine stages are formed as a toroidal spiral cascade of N stages inside a pressure vessel. Each stage feeds into the next stage such that all of the thermoacoustic power cycles past a common set of thermal interfaces multiple times with the single domed pressure vessel. The inventive thermoacoustic engine is simpler and cheaper to manufacture and more reliable due to the minimization of hot joints.

A multi-stage traveling wave thermoacoustic engine is disclosed. A plurality of heat engine stages are formed as a toroidal spiral cascade of N stages inside a pressure vessel. Each stage feeds into the next stage such that all of the thermoacoustic power cycles past a common set of thermal interfaces multiple times with the single domed pressure vessel. The inventive thermoacoustic engine is simpler and cheaper to manufacture and more reliable due to the minimization of hot joints.

Disclosed are a thermoacoustic engine with high conversion efficiency from heat energy to acoustic energy and a designing method for the thermoacoustic engine. A stack of the thermoacoustic engine has a plurality of flow passages extending through a thermoacoustic piping section. A hot heat exchanger is coupled to one end in a longitudinal direction of the stack. A cold heat exchanger is coupled to the other end in the longitudinal direction of the stack. And a length in the longitudinal direction of the hot heat exchanger is greater than a length in the longitudinal direction of the stack, and is greater than a length in the longitudinal direction of the cold heat exchanger.

The efficiency of solar power collection is increased by adding a thermal energy storage stage to a sunlight concentrator and thermodynamic power generator system. The thermal energy storage includes tubes or capsules made of a phase change material that stores thermal energy in different temperature stages through a working fluid. The stored thermal energy is directed to the thermodynamic generator during off-sun periods.

Examples of a modular compression chamber for use in a compression system are disclosed. The modular compression chamber comprises a plurality of individual modules and a plurality of fasteners to attach the plurality of modules in an interlocking fashion to form the chamber. The modules have a pre-determined geometry and size to form a compression chamber with a desired geometry and size. The plurality of fasteners keeps each of the individual modules in compression with neighboring modules so that the formed chamber maintains its integrity during operation. The modules can comprise a plurality of pressure wave generators to generate a pressure wave within the chamber. In one embodiment, the pressure wave generators have a pre-determined geometry and size and are configured to interlock with the neighboring generators forming the individual modules. The fasteners are configured to maintain intimate contact between side walls of the adjacent pressure wave generators.

A thermoacoustic electric generator system includes: a thermoacoustic engine provided in an annular tube; a turbine provided in a branched tube and rotating when receiving acoustic energy, which is generated by thermoacoustic oscillation of working gas in the thermoacoustic engine; and a generator for converting kinetic energy, which is generated by rotation of the turbine, to electric energy. The turbine is provided at a specified position that belongs to a region between a first position and a second position in each region of the branched tube, the first position being an intermediate position between one end and the other end, and the second position being an intermediate position between the first position and the other end.

An acoustically resonating medium has one or more nodes and anti-nodes. Insulating a first side of a resonating medium at a node from ambient air and exposing the opposite second side of the resonating medium at the node to ambient air results in thrust in the direction of the first side. Insulating the second side of a resonating medium at an anti-node from ambient air and exposing the first side of the medium at the anti-node to ambient air also results in thrust in the direction of the first side.

Ultrasonic actuator device (100) includes actuator arm arrangement (10) including first and second actuator sections (11,12), wherein the first section is arranged for coupling with support structure (50) and the second section is movable relative to the first section, and ultrasonic driver device (20) including at least one ultrasonic driver unit (21-28) coupled with at least one of first and second sections for driving actuator arm arrangement (10) and for providing movement of the second section relative to the first section, and wherein actuator arm arrangement (10) is movable with at least two degrees of freedom and the at least one ultrasonic driver unit includes an array of oscillating elements being arranged for creating an acoustic stream in an adjacent medium in response to application of ultrasound. Furthermore, an operational instrument including at least one ultrasonic actuator device (100) and a method of using the device are described.

An apparatus for generating a pressure wave in a liquid medium is disclosed. The apparatus includes a plurality of pressure wave generators having respective moveable pistons, the pistons having respective control rods connected thereto. The apparatus also includes a plurality of transducers coupled to the liquid medium and means for causing the pistons of respective ones of the plurality of the pressure wave generators to be accelerated toward respective ones of the plurality of transducers. The apparatus further includes means for causing restraining forces to be applied to respective control rods to cause respective pistons to impact respective transducers at respective desired times and with respective desired amounts of kinetic energy such that the respective desired amounts of kinetic energy are converted into a pressure wave in the liquid medium.

A device and method for treating a wound of a patient with negative pressure is provided. The device comprises a heat-assisted pump system. The pump system can be powered in part by heat derived from the patient. The pump system may be configured to be highly planar, light weight, and portable. The pump system may comprise a Stirling engine or a thermal acoustic engine.