中低温脉动热管传热性能的模拟研究

NUMERICAL SIMULATION STUDY OF THE HEAT-TRANSFER PREFORMANCE OF PULSATING HEAT PIPE AT MEDIUM AND LOW TEMPERATURE

脉动热管是一种新型传热元件,具有结构简单,传热性能突出的优点。针对可用于低温冰箱的脉动热管,采用R508B为工质,运用多相流VOF方法建立闭式环路中低温脉动热管三维数值模型进行了数值模拟分析。模拟过程中,环路脉动热管的充液率分别为30%、50%、70%,热端加热功率分别为20 W、40 W、60 W、80 W、100 W、120 W,模拟了初始充液后管内气态和液态的相间分布,获得了不同时间点管内温度分布,探讨了中低温脉动热管充液率和加热功率对热管换热性能的影响。结果表明,中低温热管与常温热管在启动和稳定运行阶段具有相似的特征,当中低温脉动热管稳定运行时,温度的波动具有周期性。脉动热管的传热性能随着加热功率增大而变化。充液率较低时,在低加热功率下的冷热两端温差和等效热阻都比较小,当加热功率较大时热阻会出现上升。当充液率较高时,在低加热功率下脉动热管的冷热两端温差和等效热阻都比较大,随着加热功率的增加,温差和热阻都减小。

Pulsating heat pipe（PHP）is a high-efficiency heat transfer device with simple structure and excellent heattransfer performance. In order to study the pulsating heat pipe which can be used in cryogenic refrigerator at the liquid R508 B zone,a three-dimensional numerical model was established and numerically analyzed based on the VOF method in the paper. The filling ratio（30%,50%,and 70%）and input power（20 W,40 W,60 W,80 W,100 W and 120 W）were applied in present numerical investigation. The distributions of vapor-liquid in PHP after the initial of working fluid and the temperature distribution were simulated. The influence of filling ratio and input power effect on the performance of heat transfer was discussed. The simulation results show that the characteristics of the flow in the R508 B zone are similar with the room temperature PHP,when the heat pipe working at the stabilization stage,the fluctuation of temperature is periodic.The heat transfer performance of pulsating heat pipe is changed with the increase of heating power,when the filling ratio is low,the temperature difference and the equivalent thermal resistance of cold and hot part are relatively small in the low heating power,the equivalent thermal resistance will increase in the high heating power. When the filling ratio is high,the temperature difference and the equivalent thermal resistance of cold and hot part are relatively big in the low heating power,and the equivalent thermal resistance will decrease with the increasing of heating power.