含肋柱微通道换热器内纳米氧化铝流体流动传热特性研究

Heat Transfer Characteristics of Alumina Nanofluid Flow in Microchannel Heat Exchanger with Ribbed Columns

陶瓷工业的节能降碳对于环境保护和可持续发展具有重要意义,而余热回收是实现节能降碳的有效途径,为了提升陶瓷窑炉中烟气余热的回收效率,研究将纳米陶瓷氧化铝粉和水组成的Al_(2)O_(3)-水纳米陶瓷流体与肋柱结合来协同强化微通道换热器换热性能。采用了非正交多松弛(MRT)格子玻尔兹曼方法(LBM)研究了含肋柱的微通道内Al_(2)O_(3)-水纳米陶瓷流体的流动传热特性,并通过与前人相关工作结果进行对比验证了该模型的准确性与可靠性。具体研究了在肋柱换热总面积不变的情况下,不同肋柱高度hi以及纳米颗粒体积分数φ对微通道流动传热特性的影响。研究结果表明,与平直流道相比,肋柱的加入显著增强了微通道的换热性能。此外,随着φ增大,微通道换热性能增强。在肋柱换热总面积不变的情况下,随着hi的增大,微通道换热性能逐渐减弱,当hi为0.3125时热性能因数TPF最大,综合传热性能与压力损失的表现最好。虽然添加肋柱使得微通道传热性能得到提升,但综合压力损失与传热性能却小于平直表面。研究结果能对微通道换热器内的结构设计与优化提供一定参考。

Energy saving and carbon reduction in the ceramic industry are of great significance for environmental protection and sustainable development,while waste heat recovery is an effective way to realize energy saving and carbon reduction.In order to enhance the utilization rate of flue gas waste heat recovery in ceramic furnaces,Al_(2)O_(3)-water nanoceramic fluids composed of nanoceramic alumina powder and water with ribbed columns were combined to synergistically strengthen the heat transfer performance of microchannel heat exchangers.The non-orthogonal multiple relaxation(MRT)lattice Boltzmann method(LBM)was used to investigate the flow heat transfer characteristics of the Al_(2)O_(3)-water nanoceramic fluid in the microchannel with ribbed columns,while the accuracy and reliability of the model were verified by comparing with the results of previous work.Specifically,the effects of rib heights hi and nanoparticle volume fractionsφon flow heat transfer characteristics of the microchannels were examined with constant total heat transfer area of the ribbed columns.The incorporation of rib columns significantly enhanced the heat transfer performance of the microchannel as compared with a flat straight runner.In addition,the microchannel heat transfer performance was enhanced asφincreases.With the same total heat transfer area of the ribbed columns,the microchannel heat transfer performance decreased with increasing hi,but the thermal performance factor TPF was the largest at hi=0.3125 and the combined heat transfer performance with pressure loss was optimized.Although the addition of ribs improved the microchannel heat transfer performance,the combined pressure loss and heat transfer performance were less than those of flat surface.The results could be used as reference for structural design and optimization within the microchannel heat exchangers.