肿瘤低温治疗探针强化换热特性

The Heat Transfer Enhancement Characteristics of a Novel Tumor Cryoprobe

利用快速预冷汽液分离器,改进了肿瘤低温治疗系统;考察了驱动压力对探针表面温度的影响.经过传热分析,指出在17°C生理盐水中探针内部液氮流动沸腾模式为膜态沸腾,针对流动膜态沸腾提出了螺旋细丝和螺旋丝网两种强化换热形式,并对其传热特性进行了初步研究.结果表明:使用了快速预冷汽液分离器后,探针预冷时间大大缩短,并随驱动压力增大而减小;加入螺旋丝和螺旋丝网后,在预冷阶段出现明显的热力振荡,并伴有密度波振荡,平均换热系数为原来的1.5倍,在17°C生理盐水中10 min时2.5 mm探针表面温度最低可达-160°C,大大提高了探针的冷却性能.

The cryosurgery system was developed by using a vapor-liquid separator. The effect of the driven pressure on the temperature of the probe surface was investigated. According to the heat transfer analysis, the flow boiling pattern inside the probe in 17℃ brine is considered to be the film boiling. Hence, two kinds of heat transfer enhancement techniques for the flow film boiling, the helical coiled wire and the helical mesh, were proposed, and the heat transfer characteristics were studied primarily. The results show that the precooling time of the probe is shortened significantly with the help of the vapor-liquid separator, and decreases with the driven pressure. With the helical coiled wire and the helical mesh, significant thermal oscillation corresponding the density-wave is observed in the precooling time. The average heat transfer coefficient enhances 1.5 times with the mentioned heat transfer enhancement techniques, and the temperature of the 2.5 mm cryoprobe surface can reach -160℃ in 17℃ brine within 10 min.