Challenges of Conditioning Oil and Coolant
As OEMs continue to develop electric vehicles, thermal management will be a key topic for years to come. Requirements for testing and physical simulation under thermal extremes are becoming more prevalent, which is driving requirements for new types of test equipment. There is a new focus pushing fluids to thermal extremes. With this new focus, safety and accuracy percolate to the top. In this blog post we will cover challenges in simulating weather extremes with oil and coolant.
Coolant
Coolant is typically a 50/50 mixture of both water and glycol (as wide as 70/30 in either direction). The ratio is determined by the desired engineering effect. Water is extremely conductive, which makes it very effective at heat transfer. We see this in how rapidly a person’s body temperature drops when submerged in ice water (Not an experiment we’d recommend). Glycol, on the other hand, increases the boiling point of coolant as well as drops the freezing point. This means the mixture can stay in the liquid phase over a much larger temperature range before turning to a solid (freezing) or a gas (boiling). The down side is that glycol has half the heat capacity of water, which means it’s half as effective at heat transfer.
With coolant, great care must be taken when approaching temperatures over 100°C. Things get a whole lot more difficult when trying to manage the pressures within the system. If not managed properly, the test fluid will not react in a way that is predictable or stable. Great care must be taken to pressurize the system appropriately for the conditions. This is because coolant can begin to boil off before reaching a high test temperature point. Pressurizing the system allows for a higher boiling point of coolant, thus enabling a safe and reliable test to be conducted.
Oil
Oil behaves differently from Coolant due to some key complicating factors. Let’s start with the purpose of oil. We typically use oil to lubricate and/or thermally manage subsystems. Oil is an effective lubricant due to its dense viscous form (compared to water) which creates a non-compressible liquid barrier between interacting metals.
Oil's viscous form also makes it a great thermal insulator, which is not great for heat transfer and thermal cycling testing. This means it takes longer to remove/conduct heat. The only way to counteract this thermal gradient effect is to incorporate a heater or heat exchanger that is appropriately sized for the thermal ramp rate conditions. This allows for an optimized distribution of heat allowing for good thermal conditioning. In this system design there are a few things to keep in mind:
The total volume of oil
The desired rate of change (typically driven by an OEM spec)
Fluid Flow rate
and more
How we can help
Test systems to benchmark performance, durability, and end-of-line production validation
Robust fluid conditioning subsystems, engineered for prolonged use between extremes.
Accurately measure key parameters for on/off and proportional multi-port control valves.
On the control side, simulate various test conditions (i.e. hot/cold fluid and air temperature) according to industry standards
Fluidify™ is a plug-and-play rapid fluid temperature control module, Ideal for performance or durability testing of oil and coolant components
We also utilize our systems, standards, and technologies to support clients with test services
Responsive support services that range from 24/7 engineering assistance to full system calibration (meets ISO 17025 standard).
