基于热舒适性纳米喷泉的流动与传热特性

发布时间：2018-12-15 17:28

【摘要】：目前关于纳米喷泉流动与传热特性及微区域热舒适度方面的研究较少,为了研究其流动与传热机理,本文基于气-液两相流模型和金刚石-乙二醇/水纳米流体高沸点、低冰点等优良特性,在有限柱体空间内建立了一种基于热舒适性的新型高效换热喷泉-"纳米喷泉",对比研究了金刚石-乙二醇/水纳米流体、水射流工质分别对喷泉流动与传热的影响,同时讨论了纳米颗粒体积分数v和表征流体流动情况的雷诺数(Reynolds,Re)对喷泉流动与传热的影响,分析了局部温度分布、流线分布、平均温度和流体换热量在空间内的变化,并依据ASHRAE55—1992标准和ISO7730标准对微区域的热舒适度进行了评价。结果表明:随着Re数和v增大,换热强度均得以不同程度地提升,热舒适程度也逐渐增加。Re=1.0×105和Re=1.2×105时,纳米颗粒体积分数从0增加至1%的换热强度提升较为明显,前后两种Re数可分别强化1.5%和2.8%;Re=1.4×105时,体积分数从3%增至5%的换热强度可提升11.5%,强化效果最为明显。故较小Re数下,较低组分的纳米流体强化换热效果较好;而在较大Re数下,较高组分纳米流体的强化换热效果更好。
[Abstract]:There are few studies on the flow and heat transfer characteristics of nano-fountains and the thermal comfort of micro-region. In order to study the mechanism of flow and heat transfer, this paper is based on the gas-liquid two-phase flow model and the high boiling point of diamond-glycol / water nano-fluid. In this paper, a new high efficiency heat transfer fountain, "nanometer fountain", based on thermal comfort, was established in the finite cylindrical space with low freezing point, and the diamond glycol / water nano-fluid was comparatively studied. The effects of working fluids of water jet on the flow and heat transfer of fountains are discussed respectively. The effects of volume fraction v of nanoparticles and Reynolds number (Reynolds,Re), which characterizes the flow of fluid, on the flow and heat transfer of fountains are discussed, and the local temperature distribution is analyzed. The variation of streamline distribution, mean temperature and fluid heat transfer in space was evaluated according to ASHRAE55-1992 and ISO7730 standards. The results show that with the increase of Re number and v, the heat transfer intensity increases in varying degrees, and the thermal comfort increases gradually. When the volume fraction of Re=1.0 脳 10 ~ 5 and Re=1.2 脳 10 ~ 5 increases from 0 to 1%, the heat transfer strength increases obviously. The two kinds of Re numbers were enhanced by 1.5% and 2.8%, respectively. When the volume fraction of Re=1.4 脳 10 ~ 5 is increased from 3% to 5%, the heat transfer intensity can be increased by 11.55.The strengthening effect is the most obvious. Therefore, the heat transfer enhancement effect of nano-fluid with lower component is better than that with higher Re number with smaller Re number, but with higher Re number, the enhanced heat transfer effect of nano-fluid with lower component is better than that of nano-fluid with higher Re number.
【作者单位】：中国矿业大学电力工程学院;
【基金】：中国博士后科学基金项目(2014M551694)
【分类号】：TK124

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