Papers by Author: Ren Yuan Zhang

Abstract: The change of thermal properties of Al-17 wt.% Si alloys in different heating-cooling cycles was studied by differential scanning calorimetry (DSC). The influence of heating-cooling cycles on the latent heat of melting was discussed in the view of microstructure of Al-Si alloy. The results showed the latent heat of as-cast Al–13 wt%Si alloy is 548.6 J/g, which Al-Si alloy possesses good thermal energy storage property. The onset of melting point of Al-Si alloy increases indistinctively and is about 577 °C. When the heating-cooling cycle was 1200 times, the latent heat increased to 526.0 J/g. With heating-cooling times increase, the grain size and shape of the primary Si decrease. The shape of eutectic Si is changed into stripe

Abstract: Phase change thermal storage used metal as phase change material (PCM) is an important mode of solar thermal energy storage. In this paper, the heat charging processes of solar heating units were simulated under three kinds of heating flux 100,150 and 200kW/m2 at the bottom face respectively, while the thickness of heat receiving layer at the bottom was in 5, 10 and 15mm. Al-Si alloy was selected as PCM used in the cylindrical body of the units which were in the size of φ1000×1000mm. The change of temperature and solid-liquid phase change interface of Al-Si alloy were analyzed to find out the suitable absorber thickness of thermal energy storage units which can run safety under the condition of temperature 700~900K and heat flux 100~200kW/m2, such as the application of solar thermal energy storage unit in high temperature solar thermal power stations. In the last a test system was built up and the experimental result was close to the simulation value of a unit in the size of φ300×1000×10mm.