Abstract:

With the rapid development of the electronics industry, traditional heat exchange working fluids can no longer meet the increasingly high heat exchange requirements due to their low thermal conductivity. On the other hand, the relatively narrow liquid range of traditionally used working fluids makes the infeasibility towards the complicated temperature conditions along with specific working situation. Deep eutectic solvents (DESs) possess the similar properties with ionic liquids, such as low saturated vapor pressure, high boiling point and promising stability, which make them to be the promising candidates for energy transfer. In this paper, nanofluids filled with graphene, Al₂O₃ and TiO₂ nanoparticles respectively were prepared using urea /choline chloride DESs as the base fluid, and their viscosity, thermal conductivity and stability were experimentally studied. The results show that the viscosity of graphene nanofluids is greater than that of Al₂O₃ and TiO₂ nanofluids. Compared with Al₂O₃ and TiO₂, graphene displays a clearly superior thermal conductivity enhancement and 6%(mass) graphene nanofluids are able to afford a 29.0% thermal conductivity enhancement over the pristine base fluid.

Key words: deep eutectic solvent, nanoparticles, heat transfer, nanofluids, granular flow

摘要：

随着电子工业的快速发展，传统换热工质由于其较低的热导率已无法满足越来越高的换热需求。另一方面，传统的换热工质受限其相对较窄的液程范围而无法使用于复杂的温况或特殊的工作条件。低共熔溶剂（DESs）具有与离子液体相似的低饱和蒸气压、高沸点及强稳定性等优势，在传热领域具有巨大的潜力。制备了以尿素/氯化胆碱低共熔溶剂体系为基液，石墨烯、Al₂O₃、TiO₂三种纳米粒子填充的纳米流体，研究了黏度、热导率等热物性与纳米粒子和基液组成之间的关系，并系统地研究了纳米粒子结构对其稳定性的影响。实验结果表明，纳米粒子的填充会在一定程度上增加基液的黏度，其中石墨烯填充的纳米流体的黏度增加最大。此外，石墨烯能显著提高DESs的导热性能，其中6%（质量）石墨烯纳米流体热导率相比基液可增加29.0%。

关键词: 低共熔溶剂, 纳米粒子, 传热, 纳米流体, 颗粒流