Operando measurement of lattice strain in internal combustion engine components by neutron diffraction.

Engineering neutron diffraction can nondestructively and noninvasively probe stress, strain, temperature, and phase evolutions deep within bulk materials. In this work, we demonstrate operando lattice strain measurement of internal combustion engine components by neutron diffraction. A modified commercial generator engine was mounted in the VULCAN diffractometer at the Spallation Neutron Source, and the lattice strains in both the cylinder block and head were measured under static nonfiring conditions as well as steady state and cyclic transient operation. The dynamic temporal response of the lattice strain change during transient operation was resolved in two locations by asynchronous stroboscopic neutron diffraction. We demonstrated that operando neutron measurements can allow for understanding of how materials behave throughout operational engineering devices. This study opens a pathway for the industrial and academic communities to better understand the complexities of material behavior during the operation of internal combustion engines and other real-scale devices and systems and to leverage techniques developed here for future investigations of numerous new platforms and alloys.

The Complex, Unique, and Powerful Imaging Instrument for Dynamics (CUPI2D) at the Spallation Neutron Source (invited).

The Oak Ridge National Laboratory is planning to build the Second Target Station (STS) at the Spallation Neutron Source (SNS). STS will host a suite of novel instruments that complement the First Target Station's beamline capabilities by offering an increased flux for cold neutrons and a broader wavelength bandwidth. A novel neutron imaging beamline, named the Complex, Unique, and Powerful Imaging Instrument for Dynamics (CUPI2D), is among the first eight instruments that will be commissioned at STS as part of the construction project. CUPI2D is designed for a broad range of neutron imaging scientific applications, such as energy storage and conversion (batteries and fuel cells), materials science and engineering (additive manufacturing, superalloys, and archaeometry), nuclear materials (novel cladding materials, nuclear fuel, and moderators), cementitious materials, biology/medical/dental applications (regenerative medicine and cancer), and life sciences (plant-soil interactions and nutrient dynamics). The innovation of this instrument lies in the utilization of a high flux of wavelength-separated cold neutrons to perform real time in situ neutron grating interferometry and Bragg edge imaging-with a wavelength resolution of δλ/λ ≈ 0.3%-simultaneously when required, across a broad range of length and time scales. This manuscript briefly describes the science enabled at CUPI2D based on its unique capabilities. The preliminary beamline performance, a design concept, and future development requirements are also presented.

Impact of a Commercially Available Low Carbon Renewable Diesel Fuel on the Light-Off and Light-Down Characteristics of a Diesel Oxidation Catalyst.

Meeting future greenhouse gas emissions targets in transportation may require transition in part to renewable low carbon fuels to power the medium- and heavy-duty sectors. At this moment, market renewable low carbon diesel fuels are available and integrated with the fueling infrastructure in select areas. Though this is encouraging, little is known about the impact these renewable diesel fuels may have on modern aftertreatment systems and their ability to convert toxic emissions. This work explores the impact of a renewable hydrotreated vegetable oil (HVO) diesel fuel on catalyst light-off and light-down of a diesel oxidation catalyst (DOC) with a production diesel engine over ramp rates reflective of real-world operation. Hydrocarbon (HC) and carbon monoxide (CO) emissions were investigated using various exhaust analyzing instruments placed before and after the model γ-Al2O3 DOC: Flame ionization detector (FID), nondispersive infrared (NDIR), and Fourier transform infrared spectroscopy (FTIR). The results of this work conclude that HC and CO conversion during catalyst light-off and light-down is significantly impacted by the fuel properties unique to the mostly paraffinic renewable HVO diesel, with light-off and light-down of the catalyst being improved for the renewable diesel fuel with respect to a certification diesel fuel for all ramp rates explored. Compared to certification diesel, HVO diesel reduced steady-state DOC-out HC and CO at idle by >50% and reduced the 50% conversion temperature (T50) during light-off by 45 °C for both HC and CO at a 20 °C/min ramp rate.

Quantification of Sub-Pixel Dynamics in High-Speed Neutron Imaging.

The high penetration depth of neutrons through many metals and other common materials makes neutron imaging an attractive method for non-destructively probing the internal structure and dynamics of objects or systems that may not be accessible by conventional means, such as X-ray or optical imaging. While neutron imaging has been demonstrated to achieve a spatial resolution below 10 µm and temporal resolution below 10 µs, the relatively low flux of neutron sources and the limitations of existing neutron detectors have, until now, dictated that these cannot be achieved simultaneously, which substantially restricts the applicability of neutron imaging to many fields of research that could otherwise benefit from its unique capabilities. In this work, we present an attenuation modeling approach to the quantification of sub-pixel dynamics in cyclic ensemble neutron image sequences of an automotive gasoline direct injector at a 5 µs time scale with a spatial noise floor in the order of 5 µm.