What you’ll learn:
- A new cooling technology has been proposed for EV high-current charging cables.
- The system relies on the use of subcooled flow boiling to remove the heat from the cable.
- 进行实验以使用HFE-7100作为冷却剂在Annuli中获取亚冷沸腾的数据。
减少电动汽车（EV）的充电时间时，许多挑战仍然存在。其中包括充电站的电源量，充电站的电源转换电子设备，将电源从充电站载到车辆的电缆以及车辆本身内的充电子系统(Fig. 1).
Each of these barriers requires new approaches and solutions, likely to be addressed by different industry specialists. Of course, when it’s about charging currents of several hundred amperes and up, every solution requires thorough analysis, testing, and vetting to make sure it works well, works reliably, and works safely.
Clearly, the amount of current delivered to the EV is an important factor in determining required charge time. A team at Purdue University is focused on that charging cable and has analyzed, devised, and tested a way to increase the current-carrying capacity from its present maximum of 520 A to over 2400 A. They note that the 520-A figure is the highest by far, as many chargers fall well below that(Fig. 2).
The cooling benefits make it possible to use a smaller wire diameter inside the charging cable and dissipate a higher current, while removing a little over 24 kW of heat. “My lab specializes in coming up with solutions for situations where the amounts of heat that are produced are way beyond the capabilities of today’s technologies to remove,” said Issam Mudawar, Purdue’s Betty Ruth and Milton B. Hollander Family Professor of Mechanical Engineering.
Fluid-Based Cooling
为了实现这一大幅度增加，团队采用了基于流体的电缆冷却，因为电缆中的不可避免的电阻很少，其连接器也会产生大量I2R heating. The team accomplished this via rigorous fluid and thermal modeling, detailed equations, and additional insight into the dynamics of cooling,
该项目始于电缆的基本热模型(Fig. 3)，但这并没有开始揭示随着流体动力学建模的进行，它们所考虑的微妙和现实考虑因素。他们添加了从多个角度来表征系统动力学的复杂方程式到高级建模和随后的仿真工具包。
Their objective was to develop a consolidated theoretical/empirical method for predicting the heat transfer and pressure drop characteristics of both laminar and turbulent flows though concentric circular annuli with a uniformly heated inner wall and adiabatic outer wall. By capturing heat in both liquid and vapor forms, a liquid-to-vapor cooling system can remove at least 10X more heat than pure liquid cooling.
尽管沿整个电缆保持子冷沸腾是一个关键的实践目标，但这种合并方法被证明能够应对多个流动状态（单相液体，亚冷沸腾，饱和沸腾和单相蒸气）。他们的模型在预测局部表面和流体温度方面非常有效。
Building and Testing the Model
While it’s one thing to model and simulate regardless of sophistication, it’s another to build and test what these indicate. The team’s arrangement involved pumping highly subcooled dielectric liquid HFE-7100 though a concentric circular annulus mimicking a segment of an actual cable. A uniformly heated 6.35-mm-diameter inner surface represented the electrical conductor and adiabatic 23.62-mm-diameter outer surface for the external conduit.
在这样水平的功率，热和流体流动下，基本管道本身也很复杂，控制和测量所需的各种传感器以及感兴趣的参数也很复杂。（图4和5）.
尽管原型尚未在电动汽车上进行测试，但Mudawar教授和他的学生在实验室中证明了他们的原型可容纳2.4 ka的电流。（请注意，他已经通过利用液体煮沸时捕获热量的方式来更有效地冷却电子设备的方法已经工作了37年；通过在液体和蒸气形式中捕获热量，液体之间的蒸气冷却系统可以去除大约与单独液体冷却相比，热量的数量级高。）
它们的原型模仿了现实世界充电站的所有特征：它包括泵，与实际充电线相同直径的管，相同的控件和仪器，并保持相同的流速和温度（图6）.
For More Details…
The work is described in extreme detail in two somewhat overlapping papers, each of which is among the longest ones I have ever seen in any academic journal. The papers include copious analysis, modeling data, detailed tables, insight, and results. They also thoughtfully include a full page defining all the nomenclature, Greek symbols, subscripts, acronyms, and abbreviations used.
两篇具有长长标题的论文，但只有三个作者是”Experimental investigation of subcooled flow boiling in annuli with reference to thermal management of ultra-fast electric vehicle charging cables” (20 pages) and “巩固Annuli中沸腾的理论/经验预测方法，参考超快速电动汽车充电电缆的热管理”（22页）。两者都落后于付费墙，但可访问的副本已发布在Gwangju科学技术学院（韩国）的两相流量和热管理实验室（TPFTML）网页上这里.
该项目由研究与开发福特汽车公司与普渡大学之间的联盟. The researchers have filed a patent application for their charging cable invention.
