浸没式液冷系统氟化液冷凝散热与沸腾换热匹配研究

Balance between Condensing and Boiling Heat Exchange of the Dielectric Liquid in Immersion Liquid Cooling System

在两相浸没式液冷系统中,冷凝散热与沸腾换热匹配是高效、稳定运行的重要前提。本文通过实验研究了冷凝管类型和冷却水运行参数对系统冷凝散热与沸腾换热匹配的影响。结果表明:当冷凝管散热量不低于氟化液池沸腾传热量时,系统实现热量匹配,且热量恰好匹配时所需冷却水流量最小。相比于光滑管,三维强化管的冷凝传热性能更好,使得在相同水温下恰好达到热量匹配所需的冷却水流量更小。系统在热量恰好匹配时可获得最高的性能系数(COP)。在热负荷为210 kW/m^(2)时,系统采用光滑管、外侧强化管和双侧强化管获得的最高COP分别为4.5、6.9和7.6,但在系统达到热量匹配后,COP随冷却水流量的增加而降低,当冷却水流量增至恰好实现热量匹配流量的1.5、2.7、3.8倍时,COP分别下降39.0%、60.1%、69.2%。

A balance between condensing and boiling heat exchange is an important prerequisite for the efficient and stable operation of two-phase immersion liquid cooling systems.In this study,the effects of the condensate tube type and cooling water parameters on the balance of the condensing and boiling heat transfer of the system were studied experimentally.The results show that the system achieved heat balance when the heat exchange rate of the condensate tube was not lower than the pool boiling heat transfer rate of the dielectric liquid,and the required flow rate of the cooling water was minimized when the heat exchange in the system was exactly balanced.The performance of the 3D-enhanced tube was better than that of the smooth tube,and a lower cooling water flow rate was required for the system to achieve the same cooling water inlet temperature.The highest coefficient of performance(COP)of the system was obtained when the heat exchange in the system was perfectly balanced.At a heat load of 210 kW/m^(2),the highest COPs of the system obtained using the smooth tube,outer enhanced tube,and double-sided enhanced tube were 4.5,6.9,and 7.6,respectively.However,the COP decreased as the flow rate of the cooling water increased after the heat exchange balance in the system was achieved.When the flow rate of the cooling water increased to 1.5,2.7,and 3.8 times the flow rate that achieves heat exchange balance,the COP of systems with the smooth tube,outer enhanced tube,and double-sided enhanced tube decreased by 39.0%,60.1%,and 69.2%,respectively.