Best known for pistons and other reciprocating components inside internal combustion engines (ICE), Stuttgart-based Tier 1 Mahle claims it’s keeping the R&D throttle wide open to cement its role in propulsion’s electrified future. Laying out its near-term development vision via a virtual event in October, CEO Jörg Stratmann and engineering lead Martin Berger reiterated the continuing role ICE will play, augmented via hybrid and fuel-cell technologies in larger commercial applications.
According to Stratmann, Mahle’s technology group is maintaining its extensive R&D investments despite the COVID crisis, and that it is expanding its global footprint in key development areas including battery systems and hydrogen applications. These include a hydrogen infrastructure testing installation begun at its headquarters in Stuttgart, and an expanding battery R&D facility scheduled to open in December 2020 in Suzhou, China, which will focus on solutions specifically for the Chinese market.
Stratmann stressed that achieving climate and regulatory targets will require a wide breadth of tech. “We must tackle the climate targets using effective technologies and all the solutions currently available to us,” he said. “At the moment, the change in powertrain technologies is driven primarily by political objectives. The current one-dimensional debate focused on a single drive is not productive. We want a dialog that has a basis in technology.”
Based on Mahle’s projections, full electric vehicles (EVs) will gain their largest market-share footholds in personal transportation. Larger commercial applications will feature longer adoption timelines requiring bridge technologies, including hydrogen as a low-emission combustion fuel and infrastructure primer before fuel cells see wider adoption. According to its projections, full electrification is not viable in the near term for larger vehicles, with total global adoption rates by 2030 for hybrid/EVs for personal and commercial vehicles projected at 36% and 18% respectively.
According to Stratmann, the debate on future propulsion technologies is currently skewed toward a focus on fully electric vehicles. “There will not – and cannot – be one single powertrain of the future,” he stressed. “Market conditions, vehicle classes and driving profiles are too diverse for this to be the outcome.”
“Road traffic accounts for a considerable share of greenhouse-gas emissions due to the use of fossil fuels. But that doesn’t mean we should restrict ourselves to battery-electric mobility,” he added. “That’s why Mahle is continuing to follow its dual strategy: electrification, development of the fuel cell; and the use of hydrogen and alternative fuels in an intelligently electrified combustion engine.”
New hydrogen storage
A key aspect of hydrogen adoption will be on-vehicle storage of the fuel, and during the presentation, Mahle revealed a project involving a new hydrogen fuel tank. The type-IV design consists of a liner made of plastic and an outer casing made of carbon fiber. Mahle is creating a new production process for this tank that will increase its hydrogen storage density and make it less expensive to produce at the same time.
“This construction gives the pressure vessel a weight advantage over other designs,” explained Martin Berger, Mahle’s head of corporate research and advanced engineering. “We want to optimize and speed up the carbon fiber winding process. This is where we can apply our expertise in the field of plastics and our broad experience with complex production technologies. We are aiming for a 10-15% increase in storage density, [and] we want to reduce costs by 10% [as] we need fewer materials and can thus reduce machining expenses.”
Battery immersion cooling
“Fuel” storage is also an issue for EVs, particularly when it comes to fast charging, which the Mahle execs pointed to as a key roadblock to swifter adoption. “Instead of relying on ever larger batteries, we need to improve the fast-charging capability,” Berger said. “This is the only way we can offer vehicles that meet market requirements. A smaller, fast-charging battery makes the vehicle cheaper and lighter, reduces its carbon footprint and conserves finite resources.”
To accelerate fast charging capabilities, Mahle announced that it is working on immersive battery cooling. The setup permits a dielectric coolant to flow directly around the cells. Since the fluid is not electrically conductive but is thermally, maximum battery temperatures are decreased, and the fluid improves battery pack temperature homogeneity. According to Berger, immersion cooling will pave the way for a whole new generation of battery systems.
“The key challenge when it comes to fast charging is thermal management, because the charging power is limited by the maximum temperature of the battery and by the temperature differences in and between the cells,” Berger said. With immersion cooling, he noted: “Charging can take place in just a few minutes – and thus makes batteries cheaper, lighter and much more durable. This is because of the lower maximum temperature at high battery loads, and the higher temperature homogeneity significantly improves the durability of the cells.”Continue reading »