太阳能相变蓄热炕的实验及数值模拟研究

Experimental and Numerical Simulation Research on Solar Phase Change Heat Storage Kang

为实现太阳能相变蓄热炕的快速升温,采用毛细管网及配置高导热复合相变材料来提高炕体的热响应时间,通过数值模拟与实验研究相结合的方法对炕体的热工性能进行研究。本文首先对比不同熔点石蜡的差示扫描量热(differential scanning calorimetry,DSC)曲线,选取35#石蜡作为研究对象,采用熔融混合法制备不同配比的石蜡-膨胀石墨复合定形相变材料;并通过渗漏测试确定最佳配比。实验表明:当膨胀石墨质量分数为8%时,复合定形相变材料渗漏率较低,为兼顾储热、导热性能的最佳配比。将石蜡复合相变材料应用于太阳能相变蓄热炕,通过计算流体动力学(computational fluid dynamics,CFD)建立三维非稳态传热模型,对炕体进行24 h供热模拟设计;模拟表明:太阳能相变蓄热炕在昼间垫面温度达到24.2℃,夜间垫面温度达到30.2℃。通过Trnsys(transient system simulation program)软件对组合式系统进行运行模拟发现:组合系统均可达到设计的45℃及以上;另外,组合式系统全年节电量为2974.7 kW·h,或节省标准煤469.9 kg,或减少二氧化碳1240.5 kg、一氧化碳70.9 kg、PM_(10)6.8 kg等,节能减排量显著。

In order to realize the rapid temperature rise of solar energy phase change heat storage Kang,capillary network and high thermal conductivity composite phase change material are used to improve the thermal response time of the Kang,and the thermal performance of the Kang is studied by combining numerical simulation with experimental research.In this paper,the DSC curves of paraffin with different melting points are compared,and 35#paraffin is selected as the research object.The paraffin-expanded graphite composite shape-stabilized phase change materials with different proportions are prepared by melt mixing method,and the best proportion is determined by leakage test.The experimental results show that when the mass fraction of expanded graphite is 8%,the leakage rate of the composite shape-fixing phase change material is low,which is the best ratio for both heat storage and thermal conductivity.The paraffin composite phase change material is applied to the solar energy phase change heat storage Kang,and a three-dimensional unsteady heat transfer model is established by CFD,and the 24-hour heating simulation design of the Kang body is carried out.The simulation results show that the temperature of the solar energy phase change heat storage Kang reaches 24.2℃in the daytime and 30.2℃at night.Through the operation simulation of the combined system by Trnsys(transient system simulation program)software,it is found that the combined system can reach the designed 45℃and above;In addition,the combined system saves 2974.7 kW·h of electricity,or saves 469.9 kg of standard coal,or reduces 1240.5 kg of carbon dioxide,70.9 kg of carbon monoxide,106.8 kg of PM,etc.,with remarkable energy saving and emission reduction.