This article also appears in
Subscribe now »
Tenneco's Cold Start Thermal Unit provides active heat management for rapid catalyst light-off in cold conditions. (Ryan Gehm)

Tenneco talks ‘clean air’ tech, trends

In October 2018, Tenneco Inc. completed its “transformational” acquisition of Federal-Mogul LLC, and now is working to realign the businesses and establish two independent companies by late 2019. The Aftermarket and Ride Performance company will focus on global-OE ride performance and braking as well as multi-line, multi-brand aftermarket solutions; the Powertrain Technology company will continue to address fuel economy, power output, and criteria pollution requirements for gasoline, diesel and hybrid-electric powertrains across the various regions of the world. The Tenneco name will remain with the Powertrain, or Clean Air, side of the business, according to John Wehrenberg, the leader of the Commercial Truck Off-Highway (CTOH) business for Clean Air.

“The most exciting space in truck and off-highway, at the moment, is in the Asian markets, driven by the regulatory changes that are coming less than 18 months from now” with Bharat VI in India and China VI, he said during an interview with Truck & Off-Highway Engineering last fall. Wehrenberg and Bernd Scherer, Tenneco’s Executive Director of Engineering, offered their viewpoints on these markets and other topics.


What approach is Tenneco taking to the upcoming emissions standards in India and China?

John: That’s been one of the biggest focus areas for our newly formed CTOH group, to get out there and win the awards. A good example of that is in India, where the engineering and product management team put together a modular structure that we’ve offered to all the different customers, and we’ve won nearly two-thirds of the market. We’ll triple our sales in the next two years as the market becomes not only more sophisticated in the content level, but now it’s covering all the different units in the market.


Bernd: We were already in China and India, quite actively with China IV and Bharat IV. But those systems were [basically] SCR-only aftertreatment systems…The real difference now with Bharat VI and China VI is these will be for the whole of India and China [not just certain areas]. It has an impact on fuel delivery, certainly, so those aftertreatment systems require very low sulfur fuel. In India, instead of a typical North American and European approach, where you have at least 24 months to do engineering work and then go in to production, [several] OEMs need a lot of support from their suppliers to go from Bharat IV to Bharat VI [in a relatively short amount of time]. So we took a modular approach where we pre-develop aftertreatment systems; we decided what kind of different substrate sizes is a good fit to that displacement, for example. And we can build an in-line system or switchback or U-shape. That gives the customer a cost-advantage and also a time-to-market advantage. This is what a lot of customers like Mahindra and Tata are really interested in.


Does this approach carry over to the off-highway segments?

Bernd: For off-highway it’s been more stringent from a timing perspective, because in China, January 2020 the regulation will kick in. Some customers are already pre-developing systems, but there are others that really don’t know today what they’re going to do, so they have to rely on their supply base to get that solved [largely with] existing models. The advantage is the regulation in China and in India is equal to Tier 4 Interim or Stage III B in Europe, so we can go back to architectural solutions we have in production and customize that to India and China, because certainly from a cost perspective we need to rework that a little bit.


How is Tenneco working to address the trade-off between CO2 and NOx reduction?

Bernd: Hitting both is certainly difficult—there’s always kind of a balance. Whatever you change when you go to combustion temperatures, for example, you influence the NOx. And whatever you do there, you might solve with aftertreatment…I am not in a position to say there’s a present solution that fixes your CO2 and NOx problem with the same device. We wish we did, but it’s certainly a good point. When we look into what’s coming next, we don’t see a clear pathway identified other than from a regulatory perspective. In Europe, now we are discussing CO2. Do we cut that by 15% or 30%? It might be 30% if you go electric. And at 15%, you might have to bring in solutions like Rankine waste heat recovery. This is something we really have to watch carefully and see what we have developed in our advanced-engineering community and determine how and when that fits with the different requirements for the markets.


John: We are working with a couple of different partnerships around the world to try to address the front side of the engine—what can be done say with temperature on the combustion side that has an immediate impact on the aftertreatment side. That’s not something that Tenneco or many others have necessarily done in the past. So we’ve put together a series of relationships, and they differ by OEM, to take more of a full-system approach to it.


Where does waste heat recovery stand in terms of a practical solution?

Bernd: The systems are ready to go from advanced engineering into application engineering. But the market is hesitant to see where the CO2 regulation is going, and if they need it. I think everybody likes to avoid an additional system on their truck that brings a little bit more complexity and weight when you have to integrate that into the powertrain. We are still working with customers on building up demonstration trucks and continue working on getting that solution production ready. But there’s not really a pull from the industry today to have that in 2020 on the trucks.


John: But there’s a lot of interest. Our customer projects are in three different continents.


What are the main challenges to overcome for your next generation of products?

John: It’s a temperature challenge, and then the other biggest thing is a mixing challenge. Those are the two things that everybody will be wrestling with in the next few years—keep the temp up and get the DEF [diesel exhaust fluid] properly dispersed into the gas stream.


Bernd: The one challenge is the low-temperature NOx conversion and therefore we would have active or passive systems to help with that. And the other thing is that everybody’s looking to higher engine out NOx, so they will require a higher DEF dosing rate, which is certainly a challenge. And what that means is that we have to further develop and improve our decomposition reactors, and it’s something that we’re doing right now. It’s not pulling it up by 5%—it’s really 40%, 50% or 60% more. Some others are overcoming that with a dual-injection, so they have two separate SCRs and two different injection points in the exhaust system. We would have a kind of close-coupled SCR with the first injection point, and then we have your main aftertreatment system for the main DEF dosing point. Those are the kind of things that we are looking into for the next-generation aftertreatment systems.

And it's probably worth mentioning the background, why the NOx level will go up is that most of the OEMs are trying to take out the EGR loop of the engines that will increase engine out NOx but will help them because there are reliability issues with EGR coolers and stuff like that. So, that’s the main reason that the NOx level will go up and the requirement for higher DEF dosing rates.

Continue reading »