In search of advanced vehicles with higher energy efficiency and ultra-low emissions, researchers at Oak Ridge National Laboratory are accelerating a search engine that gives scientists and engineers an unprecedented picture of the atomic operation of real-time combustion engines. .
The new capacity is a motor specially built to operate inside a neutron beam line. This neutron engine offers a unique test environment, which allows the investigation of structural changes of new alloys designed for the environment of a high temperature combustion engine and operating under realistic conditions.
ORNL first unveiled the capability in 2017, when researchers successfully evaluated a small, prototype engine with a cylinder head cast from a new aluminum-cerium at high temperatures. alloy created in the laboratory. The experiment was the first in the world in which a running engine was analyzed by neutron diffraction, using the VULCAN neutron diffractometer from the Energy Washing Neutron Source or SNS, at ORNL.
The results of the research, published in The works of the National Academy of Sciences, not only proved the strength of the unique alloy, but also demonstrated the value of using non-destructive methods, such as neutrons, to analyze new materials.
Neutrons penetrate deep even through dense metals. When neutrons scatter atoms in a material, they provide researchers with a wealth of structural information down to the atomic scale. In this case, scientists have determined how the alloys work in operating conditions, such as high heat and extreme stress or tension, to identify even the smallest defects.
The success of the experiment led ORNL to design a research engine specially designed on a scale relevant to the industry for use in VULCAN. The capacity is based on a two-liter, four-cylinder car engine, modified to run on a cylinder to save test space on the beam line. The motor platform can be rotated around the cylinder axis to provide maximum measurement flexibility. The engine is specially designed for neutron research, including the use of fluorocarbon-based coolant and oil, which improves visibility in the combustion chamber.
The capability will provide researchers with the experimental results they need to quickly and accurately examine new materials and improve the high-fidelity computational models of engine projects.
“All over the world, industry, national laboratories and academia are looking at the interface between the turbulent combustion that occurs in the engine and the heat transfer process that takes place through solid components,” said Martin Wissink, project leader at ORNL. “Understanding and optimizing this process is really essential for improving the thermal efficiency of engines.”
“Currently, most of these models have almost no in situ validation data,” he added. “The goal is to fully solve the stress, tension and temperature in the entire field on all metal parts of the combustion chamber.”
The engine was designed to ORNL specifications and is currently under final development with the Southwest Research Institute and will be commissioned at the DOE National Transportation Research Center or NTRC at ORNL prior to first use at SNS, which is expected to at the end of 2021. Both the NTRC and the SNS are scientific facilities for DOE users, providing access to the most advanced tools of modern science to researchers around the world.
The VULCAN instrument from the NHS is ideal for research because it hosts larger structures, said Ke An, the instrument’s lead scientist. VULCAN is designed for deformation, phase transformation, residual stress, texture and microstructure studies. According to An, they are preparing the platform for the neutron engine with a new exhaust system and other adaptations, including a new engine control interface.
“This is what will excite people, producing results on a larger, state-of-the-art engine,” said An. The “neutron engine” will offer even more options to users who want to validate their models to solve problems such as stress, voltage and temperature. Shows the direct value of neutrons for an important production sector. “
Measurements from the neutron engine will be introduced in high-performance calculations or HPC, models developed by scientists to accelerate progress for advanced combustion engines.
Researchers are interested in making accurate predictions about phenomena such as heat loss, flame extinguishing and evaporation of fuel injected into the cylinder, especially during cold engine operation, when emissions are often higher. Data from the neutron engine are expected to provide a new understanding of how the temperature of the metal components of the engine changes throughout the engine over the engine cycle.
The resulting high-fidelity models can be run quickly on supercomputers, such as Summit, the fastest and smartest computer in the country. The summit is hosted at ORNL as part of the Oak Ridge Leadership computing facility, also a scientific facility for DOE users.
“We tune these fundamental scientific capabilities to applications and perform measurements in real engineering devices and systems,” said Wissink. “The complete measurement of voltages and temperatures in the engine components is something that has not been possible so far. It is crucial to have this data either as a validation or as a boundary condition for HPC models that can be shared with automotive researchers. “
The neutron engine enhances existing capacity at ORNL and other national laboratories working to create more energy-efficient and ultra-clean engines, said Robert Wagner, director of ORNL’s Division of Buildings and Transportation Sciences.
“The ability to operate an engine in the neutron beam line allows us to perform unprecedented measurements under realistic engine conditions,” Wagner said. This capability adds to the unique resources that national laboratories bring to advance the efficiency and emissions of combustion engines, such as the optical engine research at Sandia National Laboratories and the Advanced Photon Source at Argonne National Laboratory.
The power of these unique resources is currently aligned to solve the most difficult problems through a consortium of six laboratories called the Partnership for the Advancement of Combustion Engines, run outside the DOE Vehicle Technology Bureau.
“What sets us apart here at ORNL is the available science portfolio,” Wagner said. “We use the world’s most powerful neutron source, the country’s fastest supercomputer and world-class materials science, in coordination with our transportation expertise, to meet the major challenges of a more sustainable energy future.”
Reference: 21 December 2020, The works of the National Academy of Sciences.
DOI: 10.1073 / pnas.2012960117
Research into neutron engines is primarily supported by the DOE’s Office of Vehicle Technology’s Office of Energy Efficiency and Renewable Energy (EERE). Access to the NHS is supported by the DOE Science Bureau. The aluminum-cerium alloy research was sponsored by the DOE Institute of Critical Materials, which is supported by the DOE’s advanced production office EERE, along with Eck Industries, which contributed to the development and testing of the alloy and licensed the material.