Charged EVs | Purdue researchers develop liquid phase change-cooled cable to enable higher charging current

The road to faster charging runs through greater cooling capacity (so to speak). Higher charging power levels mean higher current, which means that greater amounts of heat must be removed from charging cables.

Purdue University engineers have invented a new, patent-pending charging cable that uses a novel cooling method. The researchers say their wonder cable can remove up to 24.22 kilowatts of heat, and thus can deliver a current 4.6 times that of the fastest currently available chargers.

The project was funded by an R&D alliance between Purdue and Ford.

“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 Purdue Professor Issam Mudawar.

Though the prototype hasn’t been tested on EVs yet, Mudawar and his students demonstrated in the lab that their prototype accommodates a current of over 2,400 amps, more than enough to reduce charging times for large commercial EVs to five minutes. The most advanced chargers “currently” available deliver only 520 amps.

Ultimately, charge times will depend on the power output ratings of the power supply and charging cable, and the power input rating of the EV’s battery. To obtain a sub-five-minute charge, all three components will need to be rated to 2,500 amps.

Mudawar’s lab intends to work with EV or charging cable manufacturers to test the prototype on EVs within the next two years.

EV charging stations rely on liquid cooling systems, but a conventional liquid cooling system for cables would make them heavier and more difficult for drivers to handle.

For the past 37 years, Mudawar has been developing ways to more efficiently cool electronics by taking advantage of the way liquid captures heat when boiled into a vapor. A liquid-to-vapor cooling system can remove 10 times more heat than pure liquid cooling, making it possible to use a smaller wire diameter inside the charging cable while dissipating a higher current.

Research papers on the team’s experimental demonstration of the charging cable prototype and the cooling method it uses have been published in the International Journal of Heat and Mass Transfer.

Mudawar says liquid-to-vapor cooling is so effective at removing large amounts of heat that EVs could charge in far less than five minutes using this technology. “The industry doesn’t really need EVs to charge faster than five minutes, but we think we can increase the current even more by modifying both the state of the incoming liquid and the design of the cooling space around the conductor wires in the charging cable. My lab has developed solutions using liquid phase change technology for many applications, including in aerospace and defense. We knew how capable the technology is.”

Source: Purdue University

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