中文摘要：

对非能动余热排出系统的换热器管外对流换热进行数值分析,比较组织流道和不组织流道时换热器管束外部的流动分布的差异和换热能力的大小,数值计算结果表明,组织流道可优化换热器管外的流动,提高换热器的换热能力。比较分析无流道、有流道和流道出现缝隙对换热能力、阻力和出口温度等的影响。分析结果表明,组织流道会使换热能力增加约20%,阻力增加约1倍;当流道出现缝隙时,单缝隙对换热器的换热能力影响不大,多缝隙会损失一部分换热量。

英文摘要：

The convective heat transfer was studied around the heat exchanger tube in the passive residual heat removal system.The flow difference and heat exchange capability were compared around the tubes with and without baffle.The numerical results show that the baffle can optimize the flow inside the heat exchanger tube and improve heat exchange capability.The heat exchange capability,flow resistance and outlet temperature were investigated for the cases without baffle,with baffle and when the baffle has gaps respectively.The results show that the baffle can increase the heat exchange capability by 20% and double the flow resistance.The single gap has little effect on the heat exchange capability,while multi-gap will result in losing some amount of heat transfer rate in heat exchange.