One of the main objectives of HugYourEngine is to shine a spotlight on individuals who are helping make internal combustion engines cleaner and more efficient. This spotlight is on Chloé Lerin.
Chloé Lerin is a post masters research fellow in the Fuels and Engines Research Group at Oak Ridge National Laboratory (ORNL). She received her master’s degree in Mechanical Engineering from the University of Wisconsin – Madison’s Engine Research Center (ERC) and her Engineering Diploma from University of Technology of Troyes in France. Her broad experimental research background involves optical spray characterization and combustion research on platforms ranging from small-displacement gasoline direct-injection engines to heavy-duty pre-chamber spark ignition engines. Her favorite research topics involve exploring sustainable and highly efficient powertrain and energy storage systems. Chloé has worked on experimental research and development of internal combustion engines since 2012, starting as a Noise Vibration and Harshness (NVH) test engineer at John Deere (2012-2015), then taking a role as a combustion and performance engineer at Cummins (2018) and more recently as a post-grad research fellow at ORNL.
Chloé is a STEM advocate and has participated in tours and outreach activities with students and women in engineering. She is also an avid motorsport enthusiast, spending a number of weekends either taking her motorcycle to the track or working on it.
Kelly Senecal (KS): When and why did you get started in combustion research? Chloé Lerin (CL): I started working on engines before doing research and although I have always been on the R&D side, I see my path to combustion research as being like a funnel. Back in France my engineering school required us to do a 1-month internship in a manufacturing plant. I was fascinated by aeronautics and went to an aircraft engine maintenance plant. There I started to learn about the engineering that goes into making an engine, going from controls and material science to mechanical engineering and found thermodynamics to be the most interesting part. Fast forward a couple years and thermodynamics classes, I decided to continue my engineering studies in an apprenticeship format and started working for John Deere Power Systems part time. This is where I was first introduced to working with engine dynamometers. I would conduct noise and vibration testing with microphones and accelerometers placed on and around the engine to assess material stress and failure. Accelerometers can capture combustion data like knock or mechanical data like valve movement, and this is what drove me to seek further understanding of the combustion fundamentals. An internship at the John Deere Product Engineering Center allowed me to take a trip to Madison to tour the ERC with Prof. Jaal Ghandhi. For every engine lover, the ERC is an obvious choice, and I was drawn by the mix of fundamental research and hands-on experience that the thesis work presented. At the ERC I was able to merge my passion for motorsports and my interest in engines by working for the Wisconsin Small-Engine Consortium where I built and studied a gasoline direct-injected V-twin engine.
KS: What are you working on now? CL: I am working on several experimental projects at ORNL. Currently, my research focuses on understanding the barriers to achieving diesel-like efficiencies with alternative fuels in medium-duty and heavy-duty applications. My two major projects focus on: (1) studying the potential for high-efficiency in heavy-duty natural gas engines using a turbulent jet ignition system and characterizing the in-cylinder thermodynamic balances to evaluate additional opportunities for improved efficiencies, and (2) investigating advanced combustion strategies in a medium-duty single-cylinder research engine to determine a pathway to enable operation without NOx after-treatment for future emission targets. Additionally, I am also supporting research activities for the SuperTruck II program.
KS: Describe your lab facilities. CL: The Department of Energy’s National Transportation Research Center at ORNL is host to a wide range of experimental research capabilities ranging from single- and multi-cylinder engines, hybrid powertrain and system integration dynamometer cells, full vehicle dynamometers and more recently a flexible chassis dynamometer that allows for vehicle steering. My research effort is primarily centered around the heavy-duty research laboratory in which we have a double-ended dynamometer and two recent 6-cylinder 13L engines, one of which I am retrofitting to operate with a fueled pre-chamber in each cylinder. This engine is also modified for port-fuel injection and allows for spark ignition operation, with or without exhaust recirculation and will allow for experimenting with a variety of fuels. The engine laboratory’s infrastructure can deliver both liquid and gaseous fuels and has direct piping for diesel and compressed natural gas. Emission characterization is performed using a 5-gas analyzer and/or an FTIR, as well as a smoke meter for particulate matter measurements.
KS: What’s your favorite type of flame? CL: My favorite type of flame is one that we have yet to study in greater details, it is the turbulent “flame” that can be observed at the nozzle of a pre-chamber. It is understood to be a hot jet of combustion radicals and unburned fuel that evolves into a propagating flame by igniting the premixed charge in the main cylinder. There is still a lot of combustion optimization work to be done on the topic of pre-chamber spark ignition because we cannot yet quantitatively assess the air/fuel ratio in the pre-chamber. I am lucky that this is one of my main areas of research and hope to participate in furthering the fundamental understanding of this mode of combustion.
KS: What’s your favorite fuel? CL: My favorite fuel type would have to a) be liquid for ease of storage and transportation, b) have an appropriate lower heating value and, c) be sustainable which means that it can be synthetically produced. There are several candidates fitting this profile, and we are still working on identifying them with programs like Co-optima for example. I think that a fuel like methanol has a lot of potential, it is the simplest hydrocarbon to synthetically produce (i.e. with renewably powered electrolysis and carbon capture), is liquid at ambient conditions, and has a high octane number which allow its use in high compression ratio engines…and it’s used in racing. Methanol still has its challenges but that’s why we do research!
KS: What advice would you give students thinking about going into combustion research? CL: I would tell them to go for it. Combustion is a field that encompasses a wide range of specialties such as chemistry, mechanical engineering, and numerical modeling and we need experts to help further our fundamental understanding as the technology and tools keep improving. Our work is exciting, research especially, since we are in charge of setting up and conducting our experiments, analyzing our data, and publishing our findings. A combustion engineer develops a lot of transferrable skills throughout his/her career, like instrumentation, wiring, coding, controls, modeling, even sometimes machining and welding.
KS: Is the IC Engine dead? CL: I think the IC engine is alive and will remain for decades to come. However, its usage is about to be targeted to specific applications where full electrification does not make sense. We are in an exciting time where all power systems and vehicles are undergoing efforts to be fully optimized. In the case of heavy-duty vehicles such as a class 8 trucks or marine equipment, the IC engine is the logical solution, and all hands are on deck to make them as clean and efficient as possible. The IC engine also represents a lot of environmental benefits as technology becomes more mature. Synthetic fuels will participate in making the engine carbon neutral or even carbon negative by emitting less CO2 than what was captured to be produced. This is considerable given that transportation is responsible for almost 1/3 of the total CO2 emitted each year in the US.
KS: How is your work helping improve fuel efficiency or reduce emissions?
CL: Most of my work is looking at alternatives to diesel in heavy- and medium- duty applications. By employing fuels with a lower reactivity, we can promote charge mixing which in turn favors lower soot emissions. However, a diesel engine that can operate at a leaner equivalence ratio will in most cases present efficiency benefits. My research studies the dilution tolerance and lean limit of low reactivity fuels, as well as cycle-to-cycle variability under a range of advanced combustion strategies to further expand the operating map of the engine past what is achievable with stoichiometric spark ignition engines.