物性参数对纳米流体强化换热的影响

Influence of Thermophysical Properties on Heat Transfer Enhancement of Nanofluids

对铜-氩纳米流体在矩形槽通道内流动和换热情况进行了数值模拟,对基础流体和不同体积分数的纳米流体在不同Re下的换热情况进行研究,分析了纳米流体热物性的改变对强化换热的影响.研究表明:相对于基础流体而言纳米流体由于具有较好的导热性能而强化换热,并且纳米流体体积分数越大,其导热性能越好,从而换热能力也越大.对于相同体积分数的纳米流体,其换热系数提高的程度与流体的速度有关系,流速越小,换热系数提高得越大,而随着流速的逐渐增大换热系数提高的程度逐渐下降.

Compared to base fluid, nanofluids significantly increase thermal conductivity and therefore have potential applications in many heat transfer areas. The effects of thermophysical properties and thermal dispersion on the convective heat transfer coefficients of nanofluids were investigated. The simulation results show that the thermal conductivity of nanofluids is enhanced with the addition of nanopaticles into the base fluid. The collisions between nanoparticles, fluid molecules, and the wall of flow-wall are intensified, leading to enhanced mixing agitation and turbulence. Improved thermophysical properties and thermal dispersion result in the convective heat transfer coefficient enhancement of nanofluids. The calculation results also reveal that the effect of the heat transfer enhancement of the nanofluids is related to the volume fraction and Reynolds number.