| As Al-Cu-Si alloy has high phase change latent heat,it is a kind of phase change heat storage material with great potential of application.In order to explore its performance in service,it is necessary to measure and analyze its high temperature oxidation resistance and compatibility with the container,and to study its phase change heat transfer characteristics by numerical simulation.In this paper,Al-30Cu-5Si samples were oxidized at different temperatures for different periods of time.The mass,phase and microstructure of Al-30Cu-5Si samples were analyzed by metallographic microscope and EDS,XRD,and the oxidation law and oxidation mechanism were obtained.The container material,304 stainless steel,was immersed in the aluminum alloy liquid of Al-Cu-Si and corroded at constant temperature for different time.The quality change of 304 stainless steel under different conditions was analyzed.The corrosion characteristics of 304 stainless steel in liquid Al-Cu-Si alloy were studied by metallographic microscope,EDS and XRD.The microstructure,interface composition and liquid aluminum composition of stainless steel samples were analyzed under the same conditions.The results show that during96h oxidation,the oxidation rate of Al-30Cu-5Si alloy keeps decreasingand the oxidation rate keeps increasing.Specifically,the oxidation rate increases from 0.046%to 0.075%,and the oxidation rate decreased from 1.54×10-5g·cm-2·h-1to 0.60×10-5g·cm-2·h-1.The high temperature oxidation process of Al-30Cu-5Si alloy will be accompanied by the formation of Al2O3 and CuO,in which Al oxidation rate on the matrix surface is faster whileCu oxidation rate is slowerand little oxidation occurs for Si.During 168h corrosion,the corrosion rate of stainless steel in liquid Al-4Si alloy decreased from 7.926×10-5g·cm-2·h-11 to 2.262×10-5g·cm-2·h-1.The corrosion rate of stainless steel in Al-30Cu-5Si alloy solution decreased from 4.894×10-5g·cm-2·h-1to1.406×10-5g·cm-2·h-1.The corrosion rate of stainless steel in liquid Al-30Cu-10Si alloy decreased from 3.353×10-5g·cm-2·h-1to 1.212×10-5g·cm-2·h-1.With the increase of Si content in liquid Al-Cu-Si alloy,the corrosion amount and corrosion rate of304stainless steel decreased at the same time.Si and Cu did not affect the diffusion of Al in Fe matrix.The change of Al content of alloy affects the corrosion of molten aluminum.The melting and solidification process of Al-30Cu-5Si alloy in square and circular phase change heat storage units with heat transfer pipes in the center was simulated and analyzed.The corresponding temperature field distribution map and velocity flow field distribution map were analyzed.The melting process and solidification process of Al-30Cu-5Si alloy in phase change heat storage unit were obtained by phase interface distribution diagram and liquid phase rate curve,and the difference of heat transfer characteristics between melting and solidification of Al-30Cu-5Si alloy in phase change heat storage unit was analyzed.The effects of heat transfer temperature difference and pipe diameter on the melting process in the heat storage unit of square and cylindrical phase change are also studied.The results show that for the melting process of Al-30Cu-5Si alloy in square and cylindrical phase change heat storage unit,the melting rate in the initial stage of melting is relatively slow,the melting rate in the middle stage of melting increases at first and then keeps stable,and the melting rate in the later stage of melting decreases.The solidification rate decreases gradually during solidification.The main heat transfer mode in the early stage and the later stage of melting is heat conduction,and the main heat transfer mode in the middle stage of melting is natural convection.With the increase of heat transfer temperature difference from 155K to 205K,the melting time of Al-30Cu-5Si alloy in square heat storage unit is shortened from 374s to 326s,and the melting time in cylindrical heat storage unit is shortened from 403s to 352s.As the diameter of heat exchanger pipe increases from20mm to 40mm,the melting time of Al-30Cu-5Si alloy in square heat storage unit is shortened from 374s to 225s,and the melting time in cylindrical heat storage unit is shortened from 403s to 151s.The diameter of heat transfer pipe has great influence on the melting process of alloy in cylindrical phase change heat storage unit,and the influence of heat transfer temperature difference on the two heat storage units is not different. |
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