Latent heat storage has higher energy density, but most phase change materials (PCMs) have low thermal conductivity. Current research focuses on conduction dominated heat transfer mechanism to increase the heat transfer performance. However, convection also has important effects on promoting PCM melting and solidification processes. Therefore, an active stirring method with conduction dominated heat transfer mechanism was studied. A shell storage with stirrer inside was constructed and tested. Paraffin was selected as the PCM; the heat transfer fluid (HTF) was water. The results show that average charging rate increased by 32.23 J/s than that without stirring, and the average discharging rate increased by 47.39 J/s. Completion time for charging/discharging with stirring was shortened by 9.61% and 48.61% than that without stirring. In the charging process, the average power of motor was 16.08 W, and the average discharging rate was greater than 500 J/s, accounting for less than 3.2%. In the discharging process, the average power consumption of the motor accounted for less than 5.2% of the discharging rate. It may be considered that convection dominated heat transfer mechanism can effectively improve phase-change heat transfer performance with lower active power consumption
Waiting halls of railway stations are typically structured as large-spaced buildings and consume a large amount of energy. This study aimed to explore the effect of the law of thermal properties of waiting hall enveloped in railway stations on building energy consumption and to disclose the energy-saving potential of waiting hall of railway stations. A waiting hall model based on the waiting hall of the Chengdu Railway Station was established using the Quick Energy Simulation Tool (eQUEST). Numerical simulation on energy consumption of waiting hall was conducted by changing the performance parameters of building envelope and area ratio of skylight and sun-shading mode. The influences of thermal properties of building envelope on energy consumption were discussed. Results demonstrate that, when the waiting hall of the railway station applies a glass curtain wall as the envelope, the coated insulting glasses used contribute to the low building energy consumption with an energy saving rate of 5.3%. With the increase in area ratio of skylight, building energy consumption decreases first and then increases. The rate reaches the valley at 20% area ratio of skylight. Sunshading measures on the glass curtain wall and skylight, especially external sun-shading measure, can significantly reduce building energy consumption. The findings provide theoretical basis for building energy efficiency design for the waiting halls of railway stations in regions with hot summer and cold winter, and have important theoretical significance and engineering application value in promoting building energy efficiency design in the said regions.
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