宝马考虑快充阶段的发热问题：充电接口和电池的瓶颈

在前几天的Green Car Congress的报道里面，有一则宝马在设计在优化快充条件下的热管理的主意的报道，是值得一读的。面向下一代热管理，核心的问题在于考虑在快充阶段的发热（面向快充的200-300kW），在车辆停置条件下，把大量的热量散出去

备注:之前的热管理主要以放电为主，没有把充电的要求作为独立的分支，因为散热量也不大

BMW is seeking alternative cooling technologies for vehicle batteries to further improve peak cooling capacity during fast charging while reducing cooling components’ vibration and noise emission.Faster charging creates more heat to be dissipated within a short period of time. 

现有方案和缺点：使用冷媒直冷的方案在快充条件下的噪声比较大

Current technologies use electric refrigerant compressors.Rising cooling capacities would generate significantly higher vibrations through fans and other moving components. The thus generated acoustic emissions during faster charging would need sophisticated damping measures to allow pleasant circumstances for people and the surrounding environment.

For example, if you are having a conversation in a charging car, noise above 25 dB(A) is considered uncomfortable. If you are standing close to a charging car, noise from the HVAC System including the radiator above 35 dB(A) is perceived as discomfort.

宝马的考虑的要求包括：

冷却技术主要针对的是把电池表面的温度导热到外部去，温度范围涉及到-20至45°

Cooling technology working with temperature gradients between battery surface and ambient temperature, operating temperature range -20 °C to +45 °C.

Scalable for future battery capacities and heat dissipation. As a starting point for the challenge, solutions should assume needing a cooling power > 20 kW during the fast charging with 200-300 kW.

Low noise production, not beyond 35 dB(A).

Power density: realizable thermal performance compared to the component volume.

Peak cooling performance is not required 24/7. Instead the proposed solution has to operate only within the limited time period of fast charging.

The vehicle will not be moving while charging, so there is no circulating air for cooling available. The heat flux to ambient air must also be implemented by the system.

也给出了一些技术的方向：

Magnetocaloric technologies

Electrochemical cooling

Schukey machine applications

Thermoacoustic cooling

Absorption cooling

The use of phase change materials (vapor cooling)

Innovative compression methods

Cooling medium is not specified

BMW will not consider passsive cooling technologies requiring high temperature gradients between battery surface and ambient temperature（这里的意思是很坚决）technologies harmful to the environment, or technologies with high service and maintenance requirements.

根据前端时间倪总他们的测试，350A的情况下，充电接口温升20摄氏度，在当前的电池温升就成了个瓶颈，在350Ah流过电池，这些热量咋办。

小结：随着充电接口的问题解决，电池的瓶颈特别是电池的散热作为一个课题会独立的出来。