EFI has tested the material with customers, but the test data is proprietary. “There’s not a real good thirdparty test for it today, so it’s very much a one-on-one relationship with customers.” Testing involves initiating a thermal runaway in a representative battery pack and then measuring how long it takes to propagate throughout the pack. “In most packs in which we’ve tested our potting, it’s been somewhere around 20 minutes, where the standard before was nearer 5 minutes.” The LD material also provides structural strength and helps damp down vibrations. Diabatix showcased its ColdStream thermal analysis and design software, which can create efficient cooling systems that more closely resemble a circulation system you might find in a plant or an animal than in anything human-made, one example being a very organic-looking cold plate. “ColdStream specialises in thermotopology optimisation,” said Adrian Kramer. “You could also call it thermogenerative design. We’re not limited to battery cold plates; the idea is you can optimise any type of cooling or heat transfer application to maximise performance.” In principle, ColdStream starts working when a user uploads a highlevel CAD file to the software along with a basic set of guidelines. “You have to delimit the maximum allowable design space,” Kramer said. “So it usually starts with an empty design with basically 100% fluid flow, and gradually it generates the structures and then performs a full CFD simulation to take its first look at the performance. “After the first CFD simulation is complete, it will tweak the structures in the hope that the next iteration performs better. This is all automated, and it runs through hundreds of different design iterations and CFD simulations. With ColdStream’s thermal generative design, we help engineers run through more design iterations in less time, reaching mature thermal designs earlier.” In practice, users prime the software with a few more parameters, which can be thermal boundary conditions and the positions of key components such as battery modules and power electronics in the system. “It will always optimise the fluid flow such that it gets to those hotspots, but there are a lot of key performance criteria that can be satisfied at the same time,” Kramer added. “Users have the flexibility to choose between single and multi-objective optimisation: you might want the lowest maximum temperature, a good temperature uniformity or minimal pressure drop.” One particularly important input criterion is the method by which the part is to be manufactured. The ‘organic’ cold plate was designed for 3D printing to give the software most freedom. “We appreciate that makes the component itself very costly, and not all our customers have the budget to 3D-print cooling components,” Kramer said. “That’s why we’ve incorporated manufacturing techniques such as CNC milling, die casting, sheet metal forming, stamping and forging. The optimisation respects those constraints. “On average, we see that about 20% improved cooling efficiency is possible. We have even seen use cases with experimental validation where it’s as high as 50 or 60%. Context is always very important.” Diabatix has case studies on its website. TLX Technologies highlighted its new modular coolant valve (MCV) to illustrate a range of flow control options for emerging dynamic thermal management strategies. “Automakers know that with fast charging they’re going to need to flow the right amount of cooling fluid at the right temperature in the right volume to the right spot at the right time,” said Dennis Jensen. “So you’ve got to have the ECU, the BMS – the whole vehicle – understand what’s hot, what’s cold and what needs support from thermal management, and they’re going to need the control and the valving to get the fluid there.” Many EV start-ups want something road-ready but can’t afford custom designs and need something better than the plentiful cheap off-theshelf valves that are not made for vehicle use. To help define the MCV, TLX looked at the range of features EV developers want, and included options for various port sizes, Report | Battery Show North America 2023 46 November/December 2023 | E-Mobility Engineering Inverter cooling system designed using ColdStream software from Diabatix
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