纳米流体流动传热性能的实验与模拟研究

为了研究高温冷却条件下,γ-Al2O3-PG90纳米流体作为冷却介质在一车用机油冷却器内的流动传热性能,采用三维k-ε湍流模型,应用块结构网格生成技巧,融合流固耦合研究方法和薄壳导热模型数值模拟了纳米流体的性能,进行了基液与纳米流体的性能对比计算,分析了纳米粒子体积分数对性能的影响,考察了纳米流体物性预测模型的普适性,并研究了将纳米流体视为单相流体进行性能分析的可行性,通过实验测试得到了性能数据.研究发现:与基液相比,纳米流体强化换热效果明显,流动阻力有所增加,随着纳米粒子体积分数的增加,传热性能提高,流动阻力增加,说明该物性预测模型不能普适,当纳米粒子体积分数大于3%时,将纳米流体视为单相流体的性能研究结果与实验数据偏差较大,可能原因是单相流体流动无法反映较多的粒子之间的相互作用.

Experimental and numerical study of nanofluid flow and heat transfer performance

Three dimensional k-ε turbulence model, block-structured grid system, and fluid-solid coupling study method combined with shell conduction model were adopted to simulate the nanofluid flow and heat transfer performance under high temperature cooling condition. The nanofluid γ Al2O3 PG90 was used as cooling medium in a vehicular oil cooler. Performance comparative analysis between baseliquid and nanofluid was carried out and the effect of nanoparticle volume fraction on the performance was investigated. Simultaneously, the universal applicability of the nanofluid property prediction model and the feasibility of regarding nanofluid as single phase fluid to study the performance were analyzed. Performance test rig was set up to obtain test data. Nanofluid can improve the heat transfer, contrasted with baseliquid, and the flow resistance increases slightly. Heat transfer is improved and the flow resistance increases with the increasing nanoparticle volume fraction. The property prediction model is not universal applicability and it is not feasible to regard nanofluid as single phase fluid  to study the performance when the nanoparticle volume fraction is higher than 3%. The possible reason maybe that the single fluid flow cannot reflect the interaction of more nanoparticles.