中文摘要：

为了探究DMLS（直接金属激光烧结）微型换热器换热通道表面粗糙度对纳米流体制冷剂流动沸腾传热的影响,运用化学抛光技术改变不同DMLS微型换热器换热管道表面的粗糙度,制备0.01%低浓度Al2O3/R141b纳米流体制冷剂为实验工质,在不同的热流密度9.4~29.4 k W/m2、质量流率184.3~432.2 kg/（m2·s）下,研究不同DMLS换热管道表面下的粗糙度对Al2O3/R141b流动沸腾传热特性。研究结果表明：粗糙度对纳米流体制冷剂在DMLS微型换热器内流动沸腾传热有显著影响,纳米流体制冷剂的换热性能随粗糙度的减小而减弱,粗糙度减小80.4%,换热性能减弱22.5%;相同的工况下,相比于表面粗糙度为8.7μm DMLS微型换热器换热管道,纳米流体制冷剂在粗糙度为5.8、3.2、1.7μm DMLS微型换热器换热管道中的平均换热系数分别减小7.1%、14.1%、22.5%;DMLS微型换热器换热通道表面粗糙度越大,表面凹凸程度越大,单位长度换热通道内,纳米流体制冷剂与通道表面有更多的接触面积,促使单位面积上有更多的纳米制冷剂核气化核心密度,同时核化起点提前、壁面过热程度越低,有利于强化传热效果;实验结果与修正后的LAZAREK传热模型结果相对偏差为9.88%,验证了数学模型的有效性及实验结果的可靠性。

英文摘要：

The roughness influence on flow boiling heat transfer characteristics of nanofluid refrigerant in direct metal laser sintering （DMLS） micro heat exchangers was analyzed through changing the roughness of different DMLS micro heat exchanger channels surface by using chemical polishing technology and preparing 0.01% A12O3/R141b as working medium under the conditions of different heat fluxes 9.4 - 29.4 kW/m2 and mass flow rates 184.3 -432.2 kg/（m·s） in order to research the roughness of DMLS micro heat exchanger channels surface impact on flow boiling heat transfer characteristics of nanofluid refrigerant. The research results showed that roughness had a significant impact on flow boiling heat transfer of A12O3/R141b in DMLS micro heat exchangers and heat transfer performance was weakened with the decrease of roughness, which was found that heat transfer coefficient was weakened by 22.5% when roughness was decreased by 80.4%. And the average heat transfer coefficient which the surface roughness of DMLS micro heat exchanger channels were 5.8 μm, 3.2 μm and 1.7 μm were weakened by 7.1% , 14. 1% and 22.5% compared with the surface roughness of DMLS micro heat exchanger channels was 8.7 μm under the same conditions, respectively. It was also found that nanofluid refrigerant had much more contact area with the channel surface per unit length channels which degree of concave and convex surface was greater on the DMLS micro heat exchanger larger roughness surface so that it made refrigerant have more nucleate gasification density in per unit area and nucleation starting point in advance and another thing was that super-heating degree was much lower, which were conducive to strengthening heat transfer effect. It verified the validity of the mathematical model and the reliability of the experimental results as the value of MAE was 9.88%, which was relative deviation between experimental results and revised LAZAREK heat transfer model.