Batteries used in hybrid and electric cars work hard and run hot. Traditional cooling systems use an array of pumps, heat exchangers, cooling fans and hoses to manage that heat. Florida’s Embry-Riddle Aeronautical University needed something lighter and simpler for its entry in the Department of Energy’s EcoCAR 3 competition.
The solution: an aluminum cooling plate filled with biobased phase change material.
A team of mechanical engineering students at the school designed and built the plate under the direction of Sandra Boetcher, associate professor of mechanical engineering.
The school’s EcoCAR entry required that the plate use a PCM with a peak melting point of 45 degrees Celsius (113 degrees F). To achieve that temperature, the team selected two commercially available PCMs – PureTemp 37 and PureTemp 48 – and mixed them together.
Boetcher explains the photo at right:
“That’s the inside of the plate before we sealed the aluminum lid on it. On the inside is a copper tube. At the time we put this in the car, we were under a strict deadline and did not have time to redo the bending of the copper tube. The copper tube feeds a cold ethylene-glycol/water mixture as backup for when the PCM has completely melted and needs to resolidify while the car is driving.
“I was concerned that the copper tube didn’t provide enough coverage of the area, but that cold plate has been in the car for the past 2.5 years and it works great. Actually, the back-up pump that runs the ethylene-glycol/water through the copper tube rarely even turns on which means that under our test-driving conditions, the cold plate is acting 100 percent passive. The terrible part of the PCM is that it loves to leak. We feel that there has been some leaking.”
The plate is lighter and simpler than a water-cooled system. “It doesn’t take any energy to run,” said Patrick Currier, an associate professor who advises the EcoCAR team. “We’re not wasting power cooling things. This is a totally passive system, so unless it leaks, it can’t fail.”
Embry-Riddle filed for a U.S. patent on the device in 2015.
“The diagrams in the patent are similar to what we have in the EcoCAR right now, although the geometry is a little different,” Boetcher said. “The research we are conducting is still on-going. The applications we envision could be anything that requires PCM – battery cooling, building technologies, etc.”
Embry-Riddle is one of 16 North American universities challenged to redesign a 2016 Chevrolet Camaro into a hybrid-electric car to reduce environmental impact, while maintaining the “muscle and performance” the car is known for.
The teams have had four years to develop their entries. The cars will be put to the test in a variety of events in Arizona and California in May. Winners will be chosen in 40-plus categories at an awards ceremony in Hollywood on May 22, with more than $100,000 in prize money at stake.