What type of turbocharger do natural gas engines need?

Semi driving on highway

Key takeaways:

  • Natural gas turbochargers are specifically designed for natural gas engines.
  • Natural gas turbochargers are optimized for high-altitude performance, crucial for markets like China.
  • Natural gas turbochargers offer lower total operational costs and better compliance with emissions regulations.

At Cummins Inc., we’re constantly looking for ways to advance sustainable transportation solutions. As the industry shifts to lower-emission fuels to reduce pollution, natural gas engines are one critical pathway to cleaner mobility. Cummins is therefore working to innovate component-level technologies supporting natural gas engines.

Understanding how natural gas engines work and the components enabling their optimal operation can help provide a better view into the future of engine technologies.  One such critical component is the turbocharger. Cummins Turbo Technologies has spent decades designing and manufacturing Holset® turbos for natural gas engines.

In this article, we’ll explain a bit more about natural gas turbos, their performance and some of the benefits and challenges these components have.

Do natural gas engines need different turbos?

Yes, natural gas engines require different turbochargers than diesel engines due to their higher operating temperatures and distinct air-to-fuel ratios. Unlike diesel engines, which operate with a lean burn and a higher air-to-fuel ratio, natural gas engines require a stoichiometric burn. This means the mixture of oxygen and fuel is balanced precisely (1:1 air-to-fuel ratio) for efficient combustion, ensuring no unburnt fuel or excess oxygen remains. Consequently, natural gas engines require smaller turbochargers since less air is needed for stoichiometric combustion compared to the leaner burn in diesel engines. For example, a diesel engine might need an HE500 turbo, but a natural gas engine could use an HE300 or HE400 due to its lower air requirements.

Natural gas engines also influence the size and core requirements of the turbocharger. In diesel engines, turbocharger efficiency is a key focus, whereas, in natural gas engines, the primary considerations are achieving the required mass flow rate and meeting exhaust gas recirculation (EGR) demands.

Cummins addresses these specific needs by reducing back pressure at the turbine stage and enhancing the bypass capability of turbochargers with our twin-entry dual wastegate turbocharger technology.

Additionally, the more intense temperatures and pressures within natural gas engines necessitate changes to the turbocharger’s components and materials. Natural gas turbos, for instance, are built with high-temperature materials at the turbine stage to resist thermal fatigue and feature water-cooled bearing housings to protect the rotor system under extreme conditions.

Things to consider with turbochargers for natural gas engines

Turbochargers for natural gas can deliver power and performance for your applications. But two main considerations remain: 

  • High-Altitude Performance: In markets like China, which is a leader in natural gas applications, engines often operate at higher altitudes. These conditions can create low-cycle fatigue due to changes in turbine inlet temperatures, adding more thermal load to the turbo.
  • Material Selection: High temperatures of the natural gas systems demand advanced materials, which can drive up costs. So, customers need to strike the right balance between performance and cost savings.

Cummins leverages its expertise in diesel and natural gas engines to deliver specifically designed turbocharger components that enhance the performance and durability of natural gas systems. While initial costs for natural gas turbochargers may be higher, the total cost of operation is often lower due to cheaper fuel and increased reliability. Additionally, natural gas engines equipped with the right turbochargers are better positioned to meet stringent emissions regulations.

At Cummins, we're not just responding to challenges; we're leading the way with proactive solutions. Natural gas will play a key role in reducing emissions across the transportation industry. As global regulations tighten, we're focused on developing engines that offer environmental and cost benefits.

Cummins Components Business Unit

Components Business Unit

Cummins Custompaks are being used for water management as Thailand struggles with its water crisis

CustomPak on site

Water crisis

Sixty Cummins Inc. CustomPaks are in service in Thailand as part of a critical water management plan aimed at easing the country’s water crisis – a crisis that has caused enormous economic and social damage and stirred conflict among communities.

Over the past several decades, Thailand has continually faced water problems caused by severe drought. Water reserves in dams and reservoirs are insufficient while water resources are often contaminated with toxins caused by urban communities and the industrial and agricultural sectors.

Severe flooding is a threat, too, at a time when the realities of climate change are hanging over the country.

As a result, the allocation of precious water resources, which must be shared among various stakeholders including new and existing industry, large and small agriculture, and cities and villages has become a flashpoint.

Kittithanapat Engineering Co. (KTP), has been involved in the water management system since 1996, working closely with authorities such as the Royal Irrigation Department, Department of Water Resources, Bangkok Metropolitan Authority and others.

CustomPaks on site

600 hp CustomPaks

To help KTP meet its often urgent requirements, Cummins DKSH (Thailand) has recently supplied 60 Australian-built CustomPaks – 45 powered by Cummins’ X15 engine rated at 600 hp, and 15 powered by the QSL9 rated at 325 hp. These fully self-contained powerpacks are emissions certified to Tier 3.

The CustomPaks are coupled to hydraulically-driven, large-volume submersible water pumps sourced by KTP from US company Moving Water Industries (MWI); KTP is the exclusive distributor in Thailand for these MWI Hydroflo pumps.

Prior to Cummins’ involvement, KTP was using another diesel engine brand but service support wasn’t up to the standard required.

Long-serving KTP engineer Kittisak Thanasoot says Cummins DKSH’s reputation for technical and aftersales support along with the reliability of the Cummins product were a key reason behind KTP’s decision to specify the CustomPaks for the Royal Irrigation Department.

The ability of Cummins DKSH to respond to short delivery times was also important.

“Supplying large quantities of high horsepower diesel engines for emergency situations such as flash flooding can be a challenge for KTP,” says Kittisak Thanasoot.

“Responding to the needs of the government agencies to manage such problems in a timely manner and with least impact on communities, KTP has found the answer in our partnership with Cummins DKSH.”

Power, pride and passion

Parked semi truck

The switch back to Cummins power has been beneficial for iconic New Zealand company Uhlenberg Haulage. It's all about whole-of-life costs.

Uhlenberg Haulage is closing in on 60 years in business, having been founded in 1966 by Mike and Carol Uhlenberg.

Based in Eltham, Taranaki, in New Zealand’s North Island, the operation is today owned and operated by their sons Chris, Daryl and Tony Uhlenberg.

Describing the Uhlenbergs as “old school family truckies”, Daryl talks about the company’s time-honored journey with a definite tone of pride, especially the work of his parents in laying the foundations for what is today an iconic fleet in its own right.

Cummins Inc. made its debut in the Uhlenberg fleet in 1971 with an NH250 powering a second-hand Kenworth K923 used in logging. A second Kenworth, a new W924 with a Cummins NTC335, followed soon after hauling an LPG tanker.

The Uhlenberg operation today comprises 40 prime movers and a variety of trailing gear to cater for the myriad of a jobs the fleet is involved in.

A number of Peterbilts feature in the fleet although Kenworth is now the brand of choice with six new units to be delivered over the next 12 months to cater for business growth.

Cummins’ X15 Euro 5 engine rated at 550 or 600 hp is the preferred power specification, with 18 red engines currently in the fleet.

Uhlenberg family in front of truck

Whole-of-life support

“The switch to Cummins has been a very good experience for us. We have nothing but praise for the Cummins organization,” says Daryl.

“The whole-of-life picture is the key thing for us and we’ve got that nailed with the support we get from Cummins – parts availability, scheduled maintenance, life expectancy and in-frame rebuilds.

“So the red engines turn up, we run them to life, which is 900,000 to 1.2 million kilometers, and then Cummins does an in-frame overhaul in a timely manner. If there’s an issue, parts and support are close by.

“The support we get from Cummins Palmerston North is fantastic, second to none.”

Daryl recently looked under a Kenworth that was in the workshop for a service and was surprised to see no oil leaking from the one-million-kilometer X15. “I remember when I was a fitter we had to wear a raincoat when working under a truck,” he jokes.

Fuel agnostic

Acknowledging that the push to decarbonize is now “very real”, Daryl likes the idea of Cummins’ fuel agnostic concept where one base internal combustion engine, optimized to run on diesel, can also be customized to run on ultra-low and zero-carbon fuels like renewable natural gas and hydrogen.

“My father was a pioneer of linehaul trucking in New Zealand and he always embraced new technology. He was never scared of it,” he says.

“I tend to be a little more cautious but I can see where a 500 hp natural gas or hydrogen engine would work for us in short haul applications,” he admits. “We’re certainly willing to look closely at these alternative fuel technologies when suitable infrastructure is in place.”

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