Recent advances and applications of solar photovoltaics and thermal technologies

Clean, efficient and affordable energy for a sustainable future

Modeling and experimental investigation of a free-piston Stirling engine-based micro-combined heat and power system

Thermoacoustic engines convert heat energy into high amplitude acoustic waves and subsequently into electric power. This article provides a review of the four main methods to convert the (thermo)acoustic power into electricity. First, loudspeakers and linear alternators are discussed in a section on electromagnetic devices. This is followed by sections on piezoelectric transducers, magnetohydrodynamic generators, and bidirectional turbines. Each segment provides a literature review of the given technology for the field of thermoacoustics, focusing on possible configurations, operating characteristics, output performance, and analytical and numerical methods to study the devices. This information is used as an input to discuss the performance and feasibility of each method, and to identify challenges that should be overcome for a more successful implementation in thermoacoustic engines. The work is concluded by a comparison of the four technologies, concentrating on the possible areas of application, the conversion efficiency, maximum electrical power output and more generally the suggested focus for future work in the field.

Review on the conversion of thermoacoustic power into electricity

Latest developments in thermoacoustic devices have demonstrated comparable power output and efficiency, but higher reliability and lower cost when compared to conventional low-grade heat recovery technologies. A good coupling between multiple physical fields plays a pivotal role in realizing these potentials. This article provides a comprehensive review of the multi-physics coupling effects, namely, thermal-acoustic coupling, acoustic-mechanical coupling and mechanical-electric coupling, inside thermoacoustic devices including thermoacoustic engines, thermoacoustic electric generators, thermoacoustically-driven refrigerators, etc. The basic principles, operating characteristics, design strategies and future prospects are discussed individually for each coupling effect. System-level design techniques and synthetic optimization methodologies in consideration of the multi-physics coupling effects are presented. This review work gives insights into the underlying mechanisms of various coupling effects in thermoacoustic devices and provides guidelines for improvements of modern thermoacoustic technologies for low-grade thermal energy recovery, refrigeration and electric power generation purposes.

Multi-physics coupling in thermoacoustic devices: A review

Development of a 5 kW traveling-wave thermoacoustic electric generator

This article introduces a multi-stage heat-driven thermoacoustic cryocooler capable of reaching cooling capacity about 1 kW at liquefied natural gas temperature range without any moving mechanical parts. The cooling system consists of an acoustically resonant double-acing traveling wave thermoacoustic heat engine and three identical pulse tube coolers. Unlike other traditional traveling wave thermoacoustic heat engines, the acoustically resonant double-acting thermoacoustic heat engine is a closed-loop configuration consists of three identical thermoacoustic conversion units. Each pulse tube cooler is bypass driven by one thermoacoustic heat engine unit. The device is acoustically completely symmetric and therefore “self-matching” for efficient traveling-wave thermoacoustic conversion. In the experiments, with 7 MPa helium gas as working gas, when the heating temperature reaches 918 K, total cooling capacity of 0.88 kW at 110 K is obtained with a resonant frequency of about 55 Hz. When the heating tempera...

A 1 kW-class multi-stage heat-driven thermoacoustic cryocooler system operating at liquefied natural gas temperature range

An efficient looped multiple-stage thermoacoustically-driven cryocooler for liquefaction and recondensation of natural gas

The invention relates to a travelling wave thermo-acoustic combined cooling heating and power system which is composed of at least three travelling wave thermo-acoustic engines, at least one travelling wave thermo-acoustic refrigerating machine, a linear generator and resonance units. The travelling wave thermo-acoustic engines are connected in an end-to-end mode through the resonance units to form a loop. One end of the travelling wave thermo-acoustic refrigerating machine is laterally connected to the resonance units, and the other end of the travelling wave thermo-acoustic refrigerating machine is connected with the linear generator. The travelling wave thermo-acoustic combined cooling heating and power system converts heat energy into acoustic power through the travelling wave thermo-acoustic engines, the travelling wave thermo-acoustic refrigerating machine achieves refrigeration through a part of acoustic power, the linear generator converts the acoustic power at an outlet of the travelling wave thermo-acoustic refrigerating machine into electric energy and provides a suitable phase position for the travelling wave thermo-acoustic refrigerating machine, and the performance of the travelling wave thermo-acoustic refrigerating machine is improved. The temperature of cooling water of each cooling machine is increased to be used for life heat supply. Compared with the prior art, the travelling wave thermo-acoustic combined cooling heating and power system can achieve output of cold energy and electric energy at the same time in one device, the systematic complexity is reduced, the reliability is improved, and the travelling wave thermo-acoustic combined cooling heating and power system has the advantages of being high in efficiency, flexible in power and the like, and can be applied to the field of utilization of energy such as solar energy, industrial waste heat and biomass energy.

Tianjiao Bi

Papers

Development of a 5 kW traveling-wave thermoacoustic electric generator

A 1 kW-class multi-stage heat-driven thermoacoustic cryocooler system operating at liquefied natural gas temperature range

An efficient looped multiple-stage thermoacoustically-driven cryocooler for liquefaction and recondensation of natural gas

Travelling wave thermo-acoustic combined cooling heating and power system

Time-domain acoustic-electrical analogy investigation on a high-power traveling-wave thermoacoustic electric generator