No abstract

Summary A novel cascade configuration consisting of one standing wave unit and one travelling wave unit arranged in series is studied in this paper. Theoretically, a straight‐line cascade engine provides an efficient energy conversion, reduces the difficulties of fabrication and allows no Gedeon streaming. In order to achieve such a powerful cascade thermoacoustic engine, the regenerator of the travelling wave unit must be operated in high impedance and travelling wave phasing region. Various techniques of phase adjustment by modifying the configurations and geometrical dimensions of the system are investigated both numerically and experimentally in order to adjust the position of the sweet spot as well as to promote the acoustic impedance in the regenerator. It is found that the effective tuning methods with less modification here are accomplished by changing the volume of down‐cavity and reducing the flow area of down‐resonator by inserting the pencil. The exploration also shows that the acoustic field in the system is quite sensitive to the effect of down‐resonator length. The performance of the proposed system is clearly improved after the phase‐adjustment schemes are completely implemented, in which the regenerator works within the sweep spot zone with high acoustic impedance. Copyright © 2016 John Wiley & Sons, Ltd.

Summary A travelling‐wave thermoacoustic refrigerator driven by a cascade thermoacoustic engine is evaluated experimentally in this paper. A prototype is developed under the constraint of a low‐cost and less complicated device. In order to reduce the total budget, commercial materials and standard parts are selected, and air at atmospheric pressure is used as working fluid in the system. The thermoacoustic coupled engine‐refrigerator system consists of 1 standing‐wave unit, 1 travelling‐wave unit, and 1 travelling‐wave refrigerator arranged in a linear configuration. A resonator‐tube is connected at each end of the thermoacoustic core. The effects of the length and hydraulic radius of the regenerator in the refrigerator on the cooling performance are investigated at different levels of input power. In the experimental results, the maximum temperature difference of 17.6°C was realised at the no‐load condition. The maximum coefficient of performance relative to Carnot (COPR) of 2.4% was accomplished at the cooling load of 13 W.

No abstract

No abstract

No abstract

No abstract

Summary Recent studies have revealed that the operating temperature and temperature uniformity within the battery pack significantly affected its performance. In this study, the air‐cooled thermal management system of a densely packed battery pack was numerically investigated under different cell arrangements such as inline, offset, and staggered configurations to evaluate their cooling characteristics. The effects of inlet ambient air velocity and discharge rate were also evaluated to guarantee the temperature of the battery pack operated within an optimal range. The results revealed that increased airflow enhanced the cooling performance of the system but also increased the flow resistance, resulting in large power consumption. A battery pack operating at the low discharge rate of 0.5C might not require forced air‐cooling. For fast discharge rates, especially over 2C‐rate, forced air‐cooling would not be economical for battery thermal management. A narrow cell‐to‐cell distance can decrease the cell temperature and also improve space utilization; however, it increased the power consumption for circulating air and the risk of a thermal runaway propagation. A trade‐off between thermal dissipation and energy consumption was investigated. After comparing several circumstances, the offset layout was the appropriate choice for the air‐cooled thermal management system, followed by the inline layout. It satisfied the requirements of low power consumption, high space utilization, and efficient cooling performance; in particular, the offset layout consumed about 43.1% less power than the inline layout, while losing space utilization of only 6.3%.