非稳态人口温度下相变材料蓄热性能研究

太阳能辐射强度随时间发生变化,造成蓄热单元入口处传热流体温度呈现非稳态变化。为了分析非稳态的入口温度对相变材料蓄热特性的影响,假设传热流体入口温度1 h内随时间呈线性变化,并且1 h内的平均温度恒定在60℃。讨论了入口温度随时间线性增加及线性降低两种变化形式,对相变材料的熔化速率、熔化分数、蓄热量、固液界面位置等参数的影响。结果表明,当1 h内平均入口温度不变,而初始入口温度在30～90℃的范围内变化时,随初始入口温度增加,尽管熔化速率增加,熔化时间从42.75 min减小到20.58 min;但1 h内的总蓄热量却从72.6 kW减小到45.3 kW。

Numerical Study on Thermal Energy Storage Performance of PCM Under Non-Steady State Inlet Temperature Condition

The temperature of heat transfer fluid(HTF) at the inlet of thermal storage unit presents non-steady state characteristics due to the solar intensity changing with time.In order to analyze the effects of non-steady state inlet temperature on the performance of phase change thermal energy storage unit,the inlet temperature is assumed as linear variation with time and the average temperature in an hour is set to 60℃.Then the effects of inlet temperature linear increase or linear decrease over time on the melting rate,melting fraction,thermal storage capacity,solid-liquid interface location were numerically studied.The results show that both the melting time and thermal energy storage capacity in an hour decrease with the increase of initial HTF inlet temperature. The initial inlet temperature increasing from 30℃to 90℃will lead to the melting time decreasing from 42.75 min to 20.58 min and the total TES capacity in an hour reducing from 72.6 kJ to 45.3 kJ.