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MELTING WITHIN HORIZONTAL H-SHAPED ENCLOSURE WITH ADIABATIC CURVED BOUNDARY AFFECTED BY INCLINATION, MONO/HYBRID NANOFLUIDS AND FINS
Journal of Enhanced Heat Transfer ( IF 2.3 ) Pub Date : 2020-01-01 , DOI: 10.1615/jenhheattransf.2020033806
Mahmoud Jourabian , Shouqi Yuan , Jinfeng Zhang , Yalin Li , Ahmad Ali Rabienataj Darzi , Ali Bayat

From an energy saving viewpoint, full melting of phase change material in thermal storage systems should be achieved. Constrained ice melting with natural convection inside a horizontal H-shaped capsule with adiabatic curved sidewalls is not completed because energy input from hot surfaces overheats the liquid phase on top while stable thermal stratification on bottom persists. Although 90° inclination of capsule engenders full melting of pure ice, the melting process is still sluggish due to low thermal conductivity of ice/water. Hence, heat transfer enhancement techniques using mono Cu, hybrid Ag/MgO nanoparticles, and 310 stainless steel fins are incorporated into system. Existing enthalpy-based lattice Boltzmann method with double distribution function model in single-phase framework is implemented. Insertion of Ag-MgO hybrid nanoparticles within horizontal H-shaped enclosure does not eradicate persistent thermal stratification. Full melting time inside 90° inclined capsule is diminished 13.6 and 24.5%, respectively, when the volume fraction of hybrid nanoparticles is increased from 0.0 to 0.01 and 0.02. While mono Cu nanoparticles give a better thermal performance in contrast to Ag-MgO hybrid nanoparticles, their price is double. Lower volume fraction (0.01) of mono Cu nanoparticles is prescribed since storage capacity is less decreased. Compared to pure PCM melting, partial internal fins mounted on bottom hot surface diminish full melting time 28.0%. However, magnitude of maximum velocity in molten PCM demonstrates that existence of fins considerably limits growth of natural convection flow.

中文翻译:

受倾斜,单/混合纳米流体和细孔影响的绝热弯曲边界在水平H形外壳内融化

从节能的角度来看,应实现热存储系统中相变材料的完全熔化。水平H内自然对流约束的冰融化具有绝热弯曲侧壁的异形胶囊未完成,因为从热表面输入的能量使顶部的液相过热,而底部的稳定热分层持续存在。尽管胶囊倾斜90°可以使纯冰完全融化,但由于冰/水的导热系数低,融化过程仍然很缓慢。因此,将使用单铜,混合Ag / MgO纳米颗粒和310个不锈钢散热片的传热增强技术整合到系统中。在单相框架下,实现了现有的基于焓的具有双重分布函数模型的格子Boltzmann方法。Ag-MgO杂化纳米粒子在水平H中的插入形的外壳不会消除持久的热分层。当杂化纳米颗粒的体积分数从0.0增加到0.01和0.02时,在90°倾斜胶囊内的完全熔化时间分别减少了13.6和24.5%。尽管单铜纳米颗粒与Ag-MgO杂化纳米颗粒相比具有更好的热性能,但其价格却翻了一番。由于存储容量的减少较少,规定了较低的单铜纳米颗粒的体积分数(0.01)。与纯PCM熔化相比,安装在底部热表面上的部分内部散热片减少了28.0%的完全熔化时间。但是,熔融PCM中最大速度的大小表明,翅片的存在大大限制了自然对流的增长。
更新日期:2020-01-01
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