Thermal-Fluid Behavior and Design of Heat Transfer Ehancement for Mg2Ni Hydride Storage Canisters

• Main Authors: Ci-Siang Lin, 林琪翔
• Other Authors: Chih-Ang Chung
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/55048379603103422955

碩士 === 國立中央大學 === 能源工程研究所 === 97 === A study of the hydrogen absorption and desorption processes using Mg2Ni hydrogen storage alloy is presented for investigation on the thermal-fluid behavior in canister and influences of canister geometry. Absorption and desorption reaction rates and equilibrium pressures are calculated by fitting experimental data in literature using least-squares regression. Then, the fitted parameters are used in the simulations for the thermal-fluid behavior of hydrogen storage canisters. Since the alloy powders will expand in absorption, and shrink in desorption, the canisters in question comprise a metal bed and expansion volume. To enhance heat transfer, we consider the canisters to be equipped with a air pipe at the centre line and/or with internal fins. Simulation results show the bare cylindrical canister can not carry out during two hours absorption or desorption reactions, but the canister with the addition of a concentric heat exchanger pipe with fins can complete absorption or desorption reactions during about 6000 s. Results also show the reaction rates can be further increased by adjusting working parameters For absorption processes, it benefit by reducing surrounding temperature, increasing inlet pressure or increasing flowing air velocity. For desorption processes, the reaction rate can be increased by increasing surrounding temperature, reducing outlet pressure or increasing flowing air velocity. Finally, adjusting the internal fin volume shows that it is the fin volume that principally affects the heat transfer enhancement of the hydride canister.