L. Curt Maxey

Non-destructive evaluation of slot-die-coated lithium secondary battery electrodes by in-line laser caliper and IR thermography methods

Non-destructive, in-line quality control methods were adopted for evaluating the thickness and homogeneity of wet and dry lithium secondary battery electrodes. Laser caliper and infrared (IR) thermography methods were implemented in a systematic fashion for the first time to evaluate the quality of electrodes during the coating process on a slot-die coater. Laser caliper sensors were mounted, aligned, and subsequently calibrated at the oven inlet of the coating line in order to examine the thicknesses of different cathodes and anodes. The effect of various factors such as substrate vibration, temperature, surface reflectivity and laser positions on the thickness measurement during slot-die coating were evaluated. The setup was used to monitor the wet thickness of the cathode and anode, and the precision of the in-line laser thickness measurement was determined to be less than ±2%. Thickness deviation for cathodes was typically ±2.0–2.3%, and for anodes it was typically ±2.2–2.6%, which confirms excellent precision of the measurement. The homogeneity of the dried electrodes was also evaluated by IR thermography at the oven outlet of the coating line. Temperature profiles from thermography images of dry electrodes were carefully examined to detect any flaws and inhomogeneity present in the electrodes. An increase or decrease in the temperature profiles indicated defects/flaws in the electrodes that could not be observed in optical images. The techniques applied in this work will be helpful for detection of electrode flaws and contamination during large-scale manufacturing and to identify flawed product prior to lithium-ion cell assembly.

PERFORMANCE OF NEW HYBRID SOLAR LIGHTING LUMINAIRE DESIGN

We report on the performance of a new hybrid luminaire designed to blend light from a fiber optic solar source with electric fluorescent lamps. The luminaire design studied involves a commercially-available fluorescent luminaire that had been modified to include optical elements for efficiently dispersing a fiber optic solar light source. Quantitative measurements of the hybrid luminaire’s optical efficiency and spatial intensity distribution/deviations are discussed. The effects of static differences and dynamic fluctuations in spatial intensity distribution are qualitatively discussed and potential design improvements examined.Copyright

Hybrid Solar Lighting Provides Energy Savings and Reduces Waste Heat

ABSTRACT Artificial lighting is the largest component of electricity use in commercial U.S. buildings. Hybrid solar lighting (HSL) provides an exciting new means of reducing energy consumption while also delivering significant ancillary benefits associated with natural lighting in buildings. As more than half of all federal facilities are in the Sunbelt region (defined as having an average direct solar radiation of greater than 4 kWh/m2/day) and as more than half of all square footage available in federal buildings is also in the Sunbelt, HSL is an excellent technology fit for federal facilities. The HSL technology uses a rooftop, 4-ft-wide dish and secondary mirror that track the sun throughout the day (Figure 1). The collector system focuses the sunlight onto 127 optical fibers. The fibers serve as flexible light pipes and are connected to hybrid light fixtures that have special diffusion rods that spread out the light in all directions. One collector powers about eight hybrid light fixtures—which can i...

Automated alignment system for aspheric mirrors

This paper describes measurement algorithms and control procedures that can be effectively applied to the automation of an alignment procedure for paraboloidal optical mirrors. Interferometric alignment of an off-axis paraboloidal optical mirror can be a tedious and labor- intensive process. We review a previous solution to the alignment problem that employs a corner-cube retroreflector and present a method of automating this process using an imaging interferometer coupled to a processing system that controls a set of actuators. The relevant image-processing algorithms are described, and the actuator-control system is discussed. Methods of extending this solution to the automatic alignment of other aspheric optics are explored.

Luminaire development for hybrid solar lighting applications

Efficient hybrid luminaire development is an integral part of the Hybrid Solar Lighting Program at Oak Ridge National Laboratory. Hybrid luminaires are necessary to blend light from a fiber optic solar source with electric fluorescent lamps. The luminaire designs studied involve a commercially available fluorescent luminaire that has been modified to include optical elements for efficiently dispersing fiber optic solar light sources. Quantitative measurements of optical efficiency and spatial intensity distribution for two luminaire designs are compared.

Novel technique for aligning paraboloids

A technique is described for aligning an autocollimating test of an off-axis paraboloidal segment. A corner reflector (corner-cube retroreflector) is incorporated as an alignment aid to interferometrically align a paraboloidal segment to a spherical wavefront. This alignment task is typically quite challenging and time consuming because the interferograms obtained from a partially aligned autocollimating test cannot be easily interpreted for alignment correction. The normal alignment process requires iterative cycles of adjustment, realignment, and evaluation to achieve results. The use of a corner reflector significantly reduces the time required for the alignment of a n autocollimating test because it provides images and interferograms that can easily be interpreted for alignment correction. The wide dynamic range of this alignment technique makes it applicable to a variety of alignment tasks involving paraboloidal mirrors.

Control strategies for electric vehicle (EV) charging using renewables and local storage

The increase of electric vehicle (EV) and plug-in hybrid-electric vehicle (PHEV) adoption creates a need for more EV supply equipment (EVSE) infrastructure (i.e., EV chargers). The impact of EVSE installations could be significant due to limitations in the electric grid and potential demand charges for residential and commercial customers. The use of renewables (e.g., solar) and local storage (e.g., battery bank) can mitigate loads caused by EVSE on the electric grid. This would eliminate costly upgrades needed by utilities and decrease demand charges for consumers. This paper aims to explore control systems that mitigate the impact of EVSE on the electric grid using solar energy and battery banks. Three control systems are investigated and compared in this study. The first control system discharges the battery bank at a constant rate during specific times of the day based on historical data. The second discharges the battery bank based on the number of EVs charging (linear) and the amount of solar energy being generated. The third discharges the battery bank based on a sigmoid function (non-linear) in response to the number of EVs charging, and also takes into consideration the amount of renewables being generated. The first and second control systems recharge the battery bank at night when demand is lowest. The third recharges the battery bank at night and during times of the day when there is an excess of solar. Experiments are conducted using data from a private site that has 25 solar-assisted charging stations at Oak Ridge National Laboratory (ORNL) in Oak Ridge, TN and 4 at a public site in Nashville, TN. Results indicate the third control system having better performance, negating up to 71% of EVSE load, compared with the second control system (up to 61%) and the first control system (up to 58%).

Hybrid optics for the visible produced by bulk casting of sol-gel glass using diamond-turned molds

Recent combinations of diffractive and refractive functions in the same optical component allow designers additional opportunities to make systems more compact and enhance performance. This paper describes a research program for fabricating hybrid refractive/diffractive components from diamond-turned molds using the bulk casting of sol-gel silica glass. We use the complementary dispersive nature of refractive and diffractive optics to render two-color correction in a single hybrid optical element. Since diamond turning has matured as a deterministic manufacturing technology, techniques previoulsy suitable only in the infrared are now being applied to components used at visible wavelengths. Thus, the marriage of diamond turning and sol-gel processes offers a cost-effective method for producing highly customized and specialized optical components in high quality silica glass. With the sol-gel casting method of replication, diamond-turned mold costs can be shared over many pieces. Diamond turning takes advantage of all of the available degrees of freedom in a single hybrid optical element: aspheric surface to elimiate spherical aberration, kinoform surface for control of primary chromatic aberration, and the flexibility to place the kinoform on nonplanar surfaces for maximum design flexibility. We will discuss the critical issues involved in designing the hybrid element, single point diamond-turning the mold, and fabrication in glass using the sol-gel process.

Flexible Sunlight—The History and Progress of Hybrid Solar Lighting

Over the past 150 years lighting has evolved significantly, enabling great spatial, temporal, and intellectual extension of the human domain. With the ability to safely generate light on demand, complex living and working spaces have evolved. The length of a useful day is no longer limited to sunlit hours. Intellectual pursuits continue around the clock, allowing the productivity that was once associated with “burning the midnight oil” to occur in well-lighted homes, businesses, and universities. With this progress has come an enormous energy burden. Lighting now accounts for one-third of the non-residential electricity usage and is the largest single use of electricity in non-residential buildings. The majority of the activity in non-residential buildings still occurs during hours when the sun is shining, making it possible to offset at least part of the electrical lighting load through daylighting. Introducing daylighting into existing buildings requires cultural and technical development. As a culture we must comprehend the value of daylighting, in terms of societal and environmental benefits. However, to introduce daylighting into existing buildings, the technology must be available in a form that is compatible with existing infrastructure. The technology must also be presented in a way that enables it to be embraced by the architects and lighting designers that will be responsible for implementing it. Hybrid solar lighting is a daylighting solution that is specifically designed to be flexibly integrated into modern building systems.

Solar Energy, Collected, Concentrated, Transported, and Distributed as Light With No Energy Conversion Via a Hybrid Solar Lighting System

Hybrid solar lighting (HSL) is a technology in which sunlight is collected and distributed via optical fibers into the interior of buildings. Analogous to hybrid electric vehicles that use both batteries and internal combustion engines to power cars, hybrid lighting employs roof-mounted collectors to concentrate sunlight into flexible optical fibers and carry it inside buildings to “hybrid” light fixtures that also contain electric lamps. As the two light sources work in tandem, control systems keep lighting levels constant by dimming the electric lights when sunlight is bright, and turning them up as the sky darkens with weather conditions or nightfall. Data indicate that on a bright, sunny day the power consumption for lighting can be reduced by 50% or more. Today, lighting in U.S. residential and commercial buildings consumes close to 5 quadrillion BTUs of primary energy and one-fifth of all electricity. In commercial buildings, one-quarter of all energy demand is for lighting. With a forecasted doubling of commercial floor space by the year 2020 comes an urgent and growing need to find more efficient ways of lighting our nation’s buildings. Typically, less than 25 percent of the electrical energy consumed for lighting actually produces light; the rest generates heat, which increases the need for air-conditioning. Unlike conventional electric lamps, the sunlight from HSL systems produces virtually no waste heat. A nationwide field trial program is under way to provide system performance data and user-feedback essential for the successful commercialization of HSL. Field trial installations include San Diego State University, San Diego, CA; Pacific Northwest National Laboratory, Richland, WA; Sacramento Municipal Utility District, Sacramento, CA; Wal-Mart, McKinney, TX; Aveda Corp., Minneapolis, MN; Staples, Long Island, NY; Braden’s Furniture, Knoxville, TN; Multipurpose Research Facility, Oak Ridge National Laboratory (ORNL), Oak Ridge, TN; University of Nevada-Las Vegas, Las Vegas, NV; Hybrid Lighting Laboratory, ORNL, Oak Ridge, TN. This paper describes the field trial program and summarizes the results to date from the field trial installations.