钠硝石熔融盐储热材料的制备与研究

发布时间：2018-02-06 07:45

  本文关键词： 太阳能储热材料 硝酸熔融盐 膨胀石墨 锡粉　出处：《西安工程大学》2015年硕士论文　论文类型：学位论文

【摘要】：化石能源的短缺及其使用带来的环境污染问题,严重制约着世界经济的发展,太阳能作为一种接近无限的清洁型能源引发世界性关注,其中太阳能热发电是太阳能开发利用中最主要的一部分。但是太阳能的使用受到昼夜交替、季节交替、天气情况的变化存在不连续性、间歇性。为了在太阳能辐射较强时将丰足的太阳能存储,在太阳辐射能较低的情况下释放热量,因此储热材料应用而生。而且储热技术以及储热材料成为了太阳能热发电技术的关键因素。储热材料中熔融盐储热材料被广泛研究,其缺点熔融盐的凝固点高,易造成管道堵塞,它腐蚀性和高温下的化学稳定性也是限制其应用于主要因素。本文在研究了硝酸钾、硝酸钠为原料,以混合熔融法工艺制备样品,通过添加膨胀石墨(Expanded Graphite,简称EG)、金属锡(Sn)和硝酸锂来观察复合熔盐的热性能变化,从而有效解决凝固性问题、高温化学稳定性及其腐蚀性问题。实验结果表明:膨胀石墨能有效提高熔融盐的导热性,添加量为质量的5%为宜;金属锡的加入对导热系数、比热容有较大的改善,但相容性差,不宜多添加;硝酸锂能有效降低复合熔盐的凝固点,但其潮解严重,且价格昂贵,可以适量添加;硝酸钠、硝酸钾、硝酸锂、膨胀石墨四者之间有良好的化学相容性,600℃以下相互之间不发生反应,无新的物相生成,满足储热材料的要求。
[Abstract]:The shortage of fossil energy and the environmental pollution caused by its use seriously restrict the development of the world economy. Solar energy, as a kind of clean energy, has aroused worldwide concern. Solar thermal power generation is the most important part of solar energy development and utilization, but the solar energy is used by day and night alternates, seasons alternates, weather condition changes exist discontinuity. Intermittence. In order to store abundant solar energy when solar radiation is strong, heat is released when solar radiation energy is low. Therefore, the application of heat storage materials. And heat storage technology and heat storage materials have become the key factor of solar thermal power generation technology. The molten salt heat storage materials in heat storage materials have been widely studied, but its shortcomings are high solidification point of molten salt. It is easy to cause pipeline blockage, its corrosion and chemical stability at high temperature are also the main factors limiting its application. In this paper, potassium nitrate, sodium nitrate as raw materials, the mixed melting process to prepare samples. The thermal properties of the composite molten salt were observed by adding expanded graphite expanded graphite (EGN) and lithium nitrate to solve the solidification problem effectively. The experimental results show that expanded graphite can effectively improve the thermal conductivity of molten salt, and the appropriate addition amount is 5%; The addition of tin improves the specific heat capacity and the coefficient of thermal conductivity, but the compatibility is poor, so it is not suitable to add more. Lithium nitrate can effectively reduce the solidification point of the compound molten salt, but its moisture is serious, and the price is expensive, so it can be added in appropriate amount. There is no reaction between sodium nitrate, potassium nitrate, lithium nitrate and expanded graphite with good chemical compatibility below 600 鈩，

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