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Your search keyword '"Chang, H.‐A."' showing total 562 results
Start Over Author "Chang, H.‐A." Publisher elsevier b.v.
562 results on '"Chang, H.‐A."'

16. Numerical study on storage performance of metal hydride reactors with multiple spiral fins.

Author

Chang, H., Tao, Y.B., and Wang, W.Y.

Subjects
*HYDRIDES, *FINS (Engineering), *HYDROGEN storage, *HEAT transfer, *PERFORMANCE theory, *NANOFLUIDS
Abstract

Metal hydride (MH) is an efficient hydrogen storage method with high density and moderate operating conditions. Thermal management is required for hydrogen storage and release to cope with the strong thermal effects generated by the reaction. The MH reactor with spiral fins is proposed to improve the hydrogen storage efficiency by increasing the heat transfer characteristics of the reactor. The hydrogen absorption and desorption performances of the MH reactors with different spiral fin structures have been discussed. The results show that the MH reactor with spiral fins present better reaction performance compared to that of the MH reactor with longitudinal fins. And the larger the fin spiral cycle (SC), the faster the reaction rate. The hydrogenation time and dehydrogenation time could be maximally reduced 29.8% and 29.2% with fin spiral cycle increasing from 1/4 to 1, where the hydrogen storage density kept constant. The hydrogenation time and dehydrogenation time could be reduced 53.1% and 34.7% with fin number (FN) increasing from 4 to 16, while the hydrogen storage density is reduced 24.1%. Keep the volume of fins consistent, the fin number and fin thickness (FT) are optimized, and the results are FN = 8, SC = 1, FT = 1 mm, the corresponding hydrogen storage density is 0.087 g mm−1. The performance of the reactor with the optimal fin parameters under different operation conditions was also analyzed. The recommended operation parameters are concluded as the hydrogen pressure of 1.0 MPa for absorption and 0.1 MPa for desorption, heat transfer wall temperature of 293.15 K for absorption and 353.15 K for desorption. • A MH reactor with spiral fins is proposed to enhance reaction performance. • Large spiral cycle or fin number accelerates absorption and desorption rates. • Optimized fin parameters with 8 fins, 1 mm thickness and 1 spiral cycle are derived. • Spiral fin exhibits better performance than straight and tree-shaped fins. [ABSTRACT FROM AUTHOR]

Published
2023
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31. Numerical study on hydrogen and thermal storage performance of a sandwich reaction bed filled with metal hydride and thermochemical material.

Author

Chang, H., Tao, Y.B., and Ye, H.

Subjects
*HEAT storage, *HYDROGEN storage, *HYDRIDES, *HEAT of reaction, *HEAT transfer, *THERMAL resistance, *THERMAL conductivity
Abstract

Hydrogen storage and release process of metal hydride (MH) accompany with large amount of reaction heat. The thermal management is very important to improve the comprehensive performance of hydrogen storage unit. In present paper, thermochemical material (TCM) is used to storage and release the reaction heat, and a new sandwich configuration reaction bed of MH-TCM system was proposed and its superior hydrogen and thermal storage performance were numerically validated. Firstly, the optimum TCM distribution with a volume ratio (TCM in inner layer to total) of 0.4 was derived for the sandwich bed. Then, comparisons between the sandwich reaction bed and the traditional reaction bed were performed. The results show that the sandwich MH-TCM system has faster heat transfer and reaction rate due to its larger heat transfer area and smaller thermal resistance, which results in the hydrogen storage time is shortened by 61.1%. The heat transfer in the reaction beds have significant effects on performance of MH-TCM systems. Increasing the thermal conductivity of the reaction beds can further reduce the hydrogen storage time. Moreover, improving the hydrogen inflation pressure can result in higher equilibrium temperature, which is beneficial for the enhancing heat transfer and hydrogen absorption rates. •Integrating TCM in MH hydrogen storage reactor can recycle the reaction heat. •A new sandwich configuration reaction bed of MH-TCM system was proposed. •The new reaction bed can shorten hydrogen storage time by 61.1%. •Improving TCM thermal conductivity or H 2 pressure are efficient ways to accelerate hydrogen storage rate. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
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