More and more people are switching to electric vehicles to lessen their carbon dioxide footprint. However, a problem with electric vehicles is battery overheating. This problem can be solved with CryoSolplus, a new coolant, developed by researchers at the Fraunhofer Institute in German, that is reported to be three times more efficient than water. With CryoSolplus, battery overheating in the future will be a thing of the past.
Electric vehicle batteries operate best at the ideal temperature range from 20 t0 350C. However, most electric vehicle owners can tell you that driving in midday heat during summer can push the battery temperature well beyond this range.
Operating electric vehicle batteries at 450C rather than 350C can reduce its service life by as much as 50 percent, a serious problem since a new battery can cost half as much as a new vehicle.
Conventional cooling systems are not just efficient enough to prevent battery overheating. Batteries can either be air-cooled or water-cooled.
Air-cooling systems have the advantage of limitless air entering the battery compartment. However, air is a poor heat conductor, has a low heat capacity, and requires large spaces between battery cells.
Water-cooling systems are more efficient since water is a better heat conductor and has a greater heat capacity. However, only a limited amount of water can be stored under the hood.
CryoSolplus is a dispersion made up of water, paraffin, stabilizing tensides and the antifreeze agent glycol. Three times more efficient than water in absorbing heat. It requires smaller storage space since a lesser amount will be needed to cool the battery; hence, it saves more space and weight under the hood. The downside is that it will be more expensive that water, but only by around 50 to 100 Euros.
The amazing ability of CryoSolplus is due to the solid paraffin droplets suspended in the dispersion. These droplets melt when the coolant absorbs heat, effectively storing the heat inside. When the coolant cools, the paraffin droplets solidify again. These droplets are called phase change materials.
According to Tobias Kappels, a scientist at UMSICHT, the biggest challenge in developing CryoSolplus was making the dispersion stable. The paraffin droplets are lighter that water, hence, they tend to collect and agglomerate on the surface of the dispersion. This problem was solved by adding tensides that form a protective covering around the droplets to distribute them uniformly in the water.
In order to find out which tensides are best suited to their purpose, the researchers tested the dispersion under three different stress conditions.
The first stress looked into the shelf life of the dispersion. “How long can it be stored without deterioration?” The second stress looked into the mechanical stability of the dispersion. “How well can it withstand mechanical stress from pumping through pipes?” The third stress looked into the thermal stability of the dispersion. “How well can the paraffin droplets melt and solidify repeatedly?” said Kappels.
Other parameters that the researchers are trying to optimize are the heat capacity of CryoSolplus, its ability to transfer heat and its flow capability. The next stage of the research will be testing the coolant in experimental vehicles.
[via phys.org]
