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.

An apparatus for exchanging heat with a fluid includes a heat exchanger having first and second opposing surfaces and a plurality of flow passages permitting axial fluid flow between the surfaces. A manifold having an interface surface is in thermal contact with the first surface and includes a thermally conductive body for conducting heat in an axial direction between the interface surface and a heat transmitting surface. A plurality of feed passages extend through the thermally conductive body in a transverse direction, the passages having an inlet for receiving or discharging fluid. A plurality of distribution passages have ends in fluid communication with at least one of the feed passages and openings distributed over the interface surface. The distribution passages are configured to cause a change in fluid flow direction between a transversely directed flow in the feed passages and an axially directed flow at the openings.

In a conveying device, a belt conveyer is equipped with a conveying portion that conveys an object from an upstream region to a downstream region. A heat source heats the conveyed object. A cooling portion is located downstream of a terminal end of the belt conveyor and cools the object. A first thermoacoustic cooling device cools the cooling portion. A first prime mover generates acoustic waves from heat transmitted from the first heat source. A first receiver generates, from the acoustic waves, cooling heat corresponding to a cooling temperature that is lower than a temperature of the heat source.

A thermoacoustic cooling device includes a tube in which a working fluid is enclosed; a first stack that generates acoustic waves in the working fluid with use of a temperature gradient; a first high-temperature heat exchanger provided at a first side of the first stack to heat the first side of the first stack; a first low-temperature heat exchanger provided at a second side of the first stack; a second stack in which a temperature gradient is generated by the acoustic waves; a second high-temperature heat exchanger provided at a first side of the second stack, which has a high temperature; a second low-temperature heat exchanger provided at a second side of the second stack, which has a low temperature; and a heat transfer portion configured to connect the second low-temperature heat exchanger to the first low-temperature heat exchanger so as to transfer heat therebetween.

An apparatus includes an exhaust system, a cooling system, and two or more thermoacoustic devices. A first thermoacoustic device is configured to convert heat energy from the exhaust system to amplify an acoustic wave. A second thermoacoustic device configured to convert energy in the amplified acoustic wave to an input for the cooling system. The apparatus may be incorporated or in communication with an engine or a generator.

A thermoacoustic transducer includes a mechanical converter providing power conversion between acoustic and mechanical power and includes a diaphragm defining a compression and an expansion chamber. A thermal converter including a flow passage having a regenerator portion is thermally coupled for conversion between acoustic and thermal power. The mechanical converter is in fluid communication with the flow passage through transmission ducts completing an acoustic power loop having a volume containing a working gas. A transmission duct cross-sectional area is less than a regenerator flow area, which is less than a diaphragm surface area. The diaphragm undergoes resilient displacement causing pressure oscillations within the volume. The power loop is configured to cause one location along the loop to have anti-phase pressure oscillations to pressure oscillations in the mechanical converter.

A thermoacoustic machine including a device for measuring at least one parameter representative of a temperature of a first external source and/or of a second external source, and a control device configured to modulate the acoustic power generated by one or more acoustic sources such that the temperature of one said external source connected to one or more thermoacoustic cells of the machine reaches or remains substantially identical to a setpoint temperature is disclosed.