润滑油对基于制冷循环的喷雾冷却系统性能的影响

针对高功率固体激光器的散热需求，设计了一种基于制冷循环的喷雾冷却系统，并对其换热性能进行研究。由于制冷系统的压缩机需要润滑，冷却液中不可避免地会混有润滑油。润滑油会对冷却液的粘度、表面张力产生影响，并可能产生油膜，从而对冷却液的换热过程产生强化或抑制。因此，通过实验研究，分析了润滑油对喷雾冷却换热性能的影响。实验结果表明，冷却液中存在润滑油，会增大冷却液流经喷嘴过程中的阻力，减小流量，但根据本系统的应用情况，可以忽略；在低热流密度时，含有一定量的润滑油更有利于热源表面温度的均匀分布，高热流密度时，2%(质量分数)的含油量对温度分布不均的影响可以忽略；润滑油的存在可以提高临界热流密度，使得系统的散热能力得到提高，更有利于其在高功率固体激光器散热领域的应用。

Influence of lubricating oil on spray cooling system based on refrigerant cycle

For heat dissipation of the high power solid state laser (HPSSL), a spray cooling system based on refrigerant cycle was designed, and its heat transfer performance was studied. Because the compressor in the refrigerant system needs lubricating, it is inevitable to mix the lubricating oil in the coolant. Lubricating oil has influence on the viscosity, surface tension of the coolant, and may produce oil film, which could strengthen or inhibit the heat transfer process of the coolant. We analyzed the influence of lubricating oil on spray cooling heat transfer performance. The experimental results show that lubricating oil increases the resistance of coolant passing through the nozzle and decreases the coolant flowrate, but as to this system, this influence could be neglected. Lubricating oil enhances the heat transfer performance of coolant, and benefits uniform distribution of the heat source temperature at low heat flux. Lubricating oil also enhances the critical heat flux and heat dissipation ability of the system, making this spray cooling system more beneficial to HPSSL heat dissipation.