• 热力学 •

### 真空探针冷冻和复温性能实验测试及数值模拟

1. 1. 重庆大学能源与动力工程学院，, 重庆 400044, China
2.低品位能源利用技术及系统教育部重点实验室（重庆大学）, 重庆 400044
• 收稿日期:2019-07-09 修回日期:2019-10-12 出版日期:2020-04-05 发布日期:2019-11-02
• 通讯作者: 刘玉东 E-mail:1548962812@qq.com;ydliu2000@163.com
• 作者简介:谭畯坤（1993—），男，硕士研究生，1548962812@qq.com
• 基金资助:
国家自然科学基金项目(51276204)

### Test and numerical simulation of freezing and rewarming performance of vacuum probe

Junkun TAN1,2(),Yudong LIU1,2(),Shichao GENG1,2,Bing CHEN1,2,Mingwei TONG1,2

1. 1.School of Energy and Power Engineering, Chongqing University, Chongqing 400044
2.Key Laboratory of Low-Grade Energy Utilization Technologies and Systems of Ministry of Education (Chongqing University), Chongqing 400044, China
• Received:2019-07-09 Revised:2019-10-12 Online:2020-04-05 Published:2019-11-02
• Contact: Yudong LIU E-mail:1548962812@qq.com;ydliu2000@163.com

Abstract:

A 3-mm-diameter vacuum cryoprobe was designed. Low temperature problem in non-working section of probe was solved by resistance heating and vacuum layer. The freezing and rewarming process of the vacuum cryoprobe was realized through liquid nitrogen and resistance heating, and the freezing and rewarming properties of the vacuum cryoprobe were studied in air, distilled water and isolated porcine liver. According to the temperature variation data of the vacuum probe s working section in the isolated pig liver, set the corresponding boundary conditions in the numerical simulation, and use the classical bio-heat transfer equation to calculate the temperature distribution of the vacuum probe during freezing and rewarming process in human tissues, which can better understand the performance of the designed vacuum probe. In air, firstly, the vacuum probe has same temperature that working section is -190℃ and non-working section is -100℃ at 0.2 MPa,0.25 MPa,0.3 MPa, but the cooling rate will increase with increasing pressure. Secondly, the vacuum layer outside the probe s non- working section can prevent heat transfer. Thirdly, the resistance heating method can increase the temperature of the vacuum cryoprobe. Resistance heating can make the temperature of the probe s non-working section within the acceptable range of the human body, and without damaging the human normal tissues. In distilled water, the probe s working section can form ice hockey with an axial length of 3.6 cm and a radial length of 1.8 cm at 600 s, and volume of ice hockey is 6.11 cm3. In vitro porcine liver, the freezing phenomenon can be clearly seen. The freezing temperature reaches -192.9℃ and rewarming temperature reaches -55℃ in working section, and average cooling rate is 128℃/min. At the end of the experiment, the axial frozen diameter and axial thawed diameter are 3.6 cm and 1.2 cm, respectively. In simulation, the influence heat sources on the temperature field of human tissues was analyzed. From the nephogram, the tissues form ice hockey and melt gradually. Without heat source, freezing effective area is ellipse which long axis is 12.4 mm at 600 s, while rewarming effective area is ellipse which long axis is 10.4 mm at 1400 s. If heat source is considered, whole tissue s temperature will increase during the freezing and rewarming process, and it has a great influence on rewarming process. From the overall effect, the probe has good freezing and rewarming properties, which promotes the further development of cold-heat compound therapy.

• TH 775