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Direct absorption solar thermal collectors utilizing liquid-nanoparticle suspensions.

机译：利用液体纳米颗粒悬浮液的直接吸收式太阳能集热器。

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摘要

As energy consumption continues to rise while conventional energy supplies become ever more depleted there is an increasing demand for renewable energy technologies, especially solar energy in the resource rich southwestern United States. In the 1970s, researchers proposed utilizing particle suspensions in liquids to enhance the solar absorption. More recently, nanoparticle-liquid suspensions have been proposed as a means to enhance solar collector efficiency through direct absorption of the incoming solar energy. For direct absorption systems, the base fluid plays an important role in the absorption of the effective medium therefore a method for experimentally determining the extinction coefficient of four fluids commonly used in solar thermal energy applications was developed. These fluids do not absorb solar energy well and the use of nanoparticle enhancement is necessary. Through the use of a micro-solar collector, the efficiency improvement predicted by earlier models was tested for varying nanoparticle materials, volume fractions and particle shapes. Earlier studies as well as the current work show that the size and shape of the nanoparticles as well as the scattering mode all impact the amount of energy absorbed and emitted by the nanofluid. In order to optimize the efficiency of a direct absorption solar system the optimum nanoparticle-liquid combination needs to be developed. The optimum nanofluid for a direct absorption solar thermal collector is investigated numerically through the variation of particle size, collector geometry, and scattering mode. With a demonstrated efficiency improvement due to a direct absorption solar collector utilizing nanofluids, a comparative analysis was performed comparing the environmental and economic impacts for domestic hot water systems. Results show that for current nanoparticle cost and a 3 percent improvement in efficiency the nanofluid-based solar collector at the end of its life has the same economic savings as a conventional solar collector while having a lower embodied energy and higher levels of pollution offsets than a conventional collector. In addition, if 50 percent penetration of residential nanofluid-based solar collector systems for hot water heating could be achieved in Phoenix, Arizona, it is projected that over 1 million metric tons of carbon dioxide would be offset per year.
机译：随着能源消耗的持续增长，而常规能源的供应越来越枯竭，对可再生能源技术的需求不断增加，特别是在资源丰富的美国西南部的太阳能。在1970年代，研究人员提出利用液体中的颗粒悬浮液来增强太阳吸收。最近，已经提出了纳米颗粒-液体悬浮液作为通过直接吸收入射的太阳能来提高太阳能收集器效率的手段。对于直接吸收系统，基础流体在有效介质的吸收中起着重要作用，因此开发了一种实验确定太阳能热应用中常用的四种流体的消光系数的方法。这些流体不能很好地吸收太阳能，因此必须使用纳米颗粒增强剂。通过使用微太阳能收集器，针对不同的纳米颗粒材料，体积分数和颗粒形状，测试了较早模型预测的效率提高。早期的研究以及当前的研究表明，纳米颗粒的大小和形状以及散射模式都会影响纳米流体吸收和释放的能量。为了优化直接吸收太阳能系统的效率，需要开发最佳的纳米颗粒-液体组合。通过改变粒径，收集器的几何形状和散射模式，对直接吸收式太阳能集热器的最佳纳米流体进行了数值研究。由于利用纳米流体的直接吸收式太阳能集热器，效率得到了提高，因此进行了比较分析，比较了家用热水系统对环境和经济的影响。结果表明，就目前的纳米颗粒成本和效率提高3％而言，基于纳米流体的太阳能集热器在使用寿命结束时具有与传统太阳能集热器相同的经济节省，同时具有比传统太阳能集热器更低的内在能量和更高的污染补偿水平。传统的收藏家。此外，如果在亚利桑那州的凤凰城可以实现以住宅纳米流体为基础的太阳能集热器系统用于热水加热的渗透率达到50％，则预计每年将抵消超过100万吨的二氧化碳。

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  • 作者

    Otanicar, Todd Phillip.;

  • 作者单位

    Arizona State University.;

  • 授予单位 Arizona State University.;
  • 学科 Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 90 p.
  • 总页数 90
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 机械、仪表工业;
  • 关键词

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