Recent Stirling Conversion Technology Developments and Operational Measurements at NASA Glenn Research Center

Oriti, Salvatore M.; Schifer, Nicholas A.

doi:10.2514/6.2009-4556

Cited by 9 publications

(8 citation statements)

References 9 publications

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“…The first TWTEG was developed by Backhaus et al for electricity generation aboard spacecraft in 2004 [25,26]. It was capable of providing an electric power of 39 W. Similar systems were later built by Sunpower [27] and Wang et al [20]. Wu et al built several TWTEGs with various configurations recently, including a TWTEG with a resonator [17,28], a TWTEG with double-acting alternators [18], and a TWTEG with resonant tubes [29].…”

Section: Introductionmentioning

confidence: 99%

An acoustically matched traveling-wave thermoacoustic generator achieving 750 W electric power

Wang

Sun

Zhang

et al. 2016

Energy

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Traveling-wave thermoacoustic electric generator (TWTEG) is promising in efficiently converting the heat of fuel combustion, solar energy, industrial waste heat, etc. into electricity with a very scalable power output. Based on the decoupling method and theoretical analysis, the acoustic impedance requirements of the traveling-wave thermoacoustic engine (TWTE) and linear alternators (LAs) to reach an efficient and powerful operation state were studied quantitatively. A 1 kW level traveling-wave thermoacoustic electric generator was then built for experimental study. Good matching conditions of acoustic impedances were then experimentally demonstrated by modulating the working frequency, load resistance, and electric reactance of the thermoacoustic electric generator, which agreed well with the theoretical analysis. A maximum electric power output of 750.4 W and a highest thermal-to-electric efficiency of 0.163 have been achieved by the acoustically matched thermoacoustic electric generator with helium of 3.16 MPa as the working gas. This work would be instructive for the acoustic matching and designs of high-performance thermoacoustic electric generation systems.

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Section: Introductionmentioning

confidence: 99%

An acoustically matched traveling-wave thermoacoustic generator achieving 750 W electric power

Wang

Sun

Zhang

et al. 2016

Energy

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“…At its most efficient operating point, the system generated 39W electric power at a thermal-to-electric efficiency of 18% [18,19]. In 2008, Sunpower Inc. developed a coaxial traveling wave thermoacoustic electric generator, which achieved an electric power output of 50W [20]. Wu et al constructed a traveling-wave thermoacoustic electric generator that produced 481W electric power with an efficiency of 15% [21].…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of a looped-tube travelling-wave thermoacoustic engine with a bypass pipe

Al-Kayiem

2016

Energy

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A new configuration ("a looped-tube with a bypass pipe") was recently proposed for low temperature travelling wave thermoacoustic engines and a prototype using atmospheric air as the working gas achieved an onset temperature difference as low as 65 °C. However, no further research has been reported about this new configuration to reveal its advantages and disadvantages. This paper aims to analyse this type of engine through a comprehensive numerical research. An engine of this type having dimensions similar to the reported prototype was firstly modelled. The calculated results were then qualitatively compared with the reported experimental data, showing a good agreement. The working principle of the engine was demonstrated and analysed. The research results show that an engine with such a bypass configuration essentially operates on the same thermodynamic principle as other travelling wave thermoacoustic engines, differing only in the design of the acoustic resonator.Both extremely short regenerators and a near-travelling wave resonator minimise the engine's acoustic losses, and thus significantly reduce its onset temperature difference. However, such short regenerators likely cause severe heat conduction losses, especially if the engine is applied to heat sources with higher temperatures. Furthermore, the acoustic power flowing back to the engine core is relatively low, while a large stream of acoustic power has to propagate within its resonator to maintain an acoustic resonance, potentially leading to low power density. The model was then applied to design an engine with a much longer regenerator and higher mean pressure to increase its power density. A thermoacoustic cooler was also added to the engine to utilise its acoustic power, allowing the evaluation of thermal efficiency. The pros and cons of the engine configuration are then discussed.

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“…A thermoacoustic generator combines the advantages of a thermoacoustic engine and a linear alternator to generate electricity from low temperature heat sources with high efficiency and high reliability. There have been continuous research efforts to develop travelling-wave thermoacoustic electric generator in the past decade [11][12][13][14][15][16][17]. However, the linear alternators are costly, which counteracts the advantages of thermoacoustic engines such as simplicity and low cost.…”

Section: Introductionmentioning

confidence: 99%

A two-stage traveling-wave thermoacoustic electric generator with loudspeakers as alternators

Kang

Cheng

et al. 2015

Applied Energy

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This paper presents the design, construction and tests of a traveling-wave thermoacoustic electric generator. A two-stage travelling-wave thermoacoustic engine converts thermal energy to acoustic power. Two low-impedance linear alternators (i.e., audio loudspeakers) were installed to extract and convert the engine's acoustic power to electricity. The coupling mechanism between the thermoacoustic engine and alternators has been systematically studied numerically and experimentally, hence the optimal locations for installing the linear alternators were identified to maximize the electric power output and/or the thermal-to-electric conversion efficiency. A ball valve was used in the loop to partly correct the acoustic field that was altered by manufacturing errors. A prototype was built based on this new concept, which used pressurized helium at 1.8 MPa as the working gas and operated at a frequency of about 171 Hz. In the experiment, a maximum electric power of 204 W when the hot end temperature of the two regenerators reaches 512℃ and 452℃, respectively. A maximum thermal-to-electric efficiency of 3.43% was achieved when the hot end temperature of the two regenerators reaches 597℃ and 511℃, respectively. The research results presented in this paper demonstrate that multi-stage travelling-wave thermoacoustic electricity generator has a great potential for developing inexpensive electric generators.

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Recent Stirling Conversion Technology Developments and Operational Measurements at NASA Glenn Research Center

Cited by 9 publications

References 9 publications

An acoustically matched traveling-wave thermoacoustic generator achieving 750 W electric power

An acoustically matched traveling-wave thermoacoustic generator achieving 750 W electric power

Numerical investigation of a looped-tube travelling-wave thermoacoustic engine with a bypass pipe

A two-stage traveling-wave thermoacoustic electric generator with loudspeakers as alternators

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