An electric race car with 3D printed components. [Slow whistle.]
This story began when SHINING 3D provided its state-of-the-art SLM 3D printing technology to students at a leading research university in China — the Harbin Institute of Technology. SHINING 3D has developed a growing expertise in automotive 3D printing, so their staff worked closely with a student team to produce an electric race car for the 2018 Student’s Formula Electric China. It won third place.
One of the 3D printed components designed specifically for this race car was the radiator.
Defining the Challenge
The smooth functioning of the radiator is critical to the operation of the engine and affects vehicle longevity.
Even an electric engine generates a lot of heat – heat that if unchecked can cause premature wear or cause components to seize, crack or melt. In modern vehicles, the radiator is made of aluminum and located at the front of the engine compartment right behind the grill. This affords it the greatest access to air flow and enables it to disperse heat efficiently.
But traditional radiator design creates many little problems even as it attempts to solve the larger problem. The radiator core is fabricated by welding hundreds of thin aluminum fins to flattened aluminum tubes. A typical radiator actually has 10 to 15 fins per square inch! The coolant flows from the radiator inlet, through the aluminum tubes, to the outlet at the lower point of the radiator. During this process, the fins conduct the heat through the tubes to the air flowing through the radiator.
So a radiator is comprised of many individual parts fashioned together — hundreds of fins, many tubes and MANY soldered or welded intersections among them. With so many joints, it is not surprising that a common reason for radiator failure is corrosion of these joints. When the joints begin to fail, radiator fluid leaks and the radiator no longer functions as intended. If not quickly replaced, engine failure is the result.
Back to the race car.
The demands on a race car’s engine mean the integrity and efficiency of its cooling system are absolutely vital to its performance. Radiator redesign was therefore a strategic target as the original had been produced by conventional methods and had many welded components.
SHINING 3D recommended the student team consider 3D printing a metal radiator. This would allow for an integrated design to eliminate leakage concerns. The students agreed and together they and the SHINING 3D engineers spent many hours working on and optimizing the prototype. Many factors came into play.
The team decided that in order to protect the engine, the new radiators must not permit the coolant to exceed 48°C. With that as a starting point, it was calculated that the radiators must have the capacity to vent 12 kW.
Among the variables considered in the redesign were,
the reserved heat dissipation coefficient
the logarithmic mean temperature difference between the hot and cold feeds
water scale and oil pollution
allowance for ambient heat dissipation
a requirement that the dissipation area remain tight at 2.5 meters
With these variables and requirements in mind, the students and engineers set themselves to redesign the radiator. It was an exciting process. Additive manufacturing technology allowed the designers great latitude and offered a tight turnaround.
When the design was complete, the new radiator prototypes were printed out of aluminum alloy. The SHINING 3D EP-M250 SLM printer was chosen because of its large 200 mm x 250 mm x 300 mm build volume.
After post-treatment (heat treatment and sand blasting), the radiator prototype was installed and testing began.
Success! Test results demonstrated that the new design reduced coolant temperature by about 10°C compared to the original used in previous races. A very significant improvement in heat dissipation.
Of course a cooling system involves more than the radiator. Additional improvements were made to the car’s cooling system when SHINING 3D successfully created motor cooling water jackets and condenser parts.
This story was about a new cooling system for a pretty sweet race car. But the real story is that metal 3D printing opens up new frontiers for auto design, and its advantages are not restricted to high end or specialty vehicles. More conventional auto manufacturers also stand to benefit from the low cost, high efficiency and high quality improvements possible with metal 3D printing.
So while we cannot all anticipate a waving checkered flag in our future, quite likely one of your next vehicles will sport high-tech 3D printed auto parts. Maybe even a new radiator design!
Don’t get too revved up though. Quite likely the local police department’s fleet will also.