Engineering topics

Neubauer, J.

Publications and source records attributed to Neubauer, J..

9 records

DOE OSTI2021

Relating phase transitions to pore size distributions and mechanical mortar properties in CSA-OPC-C$ based systems – The potential impact of delayed straetlingite formation

The scope of this research is to investigate the performance evolution of five ternary CSA-OPC-Cs systems. Time resolved thermodynamic modeling was employed to gain insight into changes in the volume fractions of the hydrating pastes and link these changes to trends in the pore size distributions of the mortars. Pore solution analyses were performed to investigate which hydrates have the potential to exert high crystallization pressures. In three out of five blends the resulting tensile stress exceeded the tensile strength of the materials, resulting in the occurrence of coarse pores, which could be linked to the measured compressive strengths. Two damaging crystallization processes were identified in the investigated blends. One is the continuous precipitation of ettringite at high supersaturation in a system with high anhydrite addition. The other is the delayed crystallization of straetlingite at high supersaturation and crystallization pressure in the confined environment of mature pastes.

36 MATERIALS SCIENCE↗

DOE OSTI2018

Impact of initial CA dissolution on the hydration mechanism of CAC

Usually, for basic investigations on the hydration behaviour of CA (monocalcium aluminate, CaAl{sub 2}O{sub 4}) preferably pure samples without the presence of other hydraulic phases are used. In the presented study we apply an alternative approach investigating mixes that contain tiny to low amounts of CA (0.5–20 wt%) besides CA{sub 2} (CaAl{sub 4}O{sub 7}) or C{sub 6}AF{sub 2} (Ca{sub 6}Al{sub 2}Fe{sub 4}O{sub 15}). The hydration of the mixes is investigated by isothermal heat flow calorimetry, in-situ XRD and pore solution analysis at 23 °C. A modified thermodynamic database enables the calculation of saturation indices for relevant hydrate phases in the investigated systems. CA similarly influences the hydration of both CA{sub 2} and C{sub 6}AF{sub 2} although the exact impact strongly depends on the initial CA/water ratio in the mixes. Up to a certain amount CA is completely consumed during the first minutes after mixing. Beyond this amount the presence of undissolved CA causes an induction period and retards the hydration of CA{sub 2} or C{sub 6}AF{sub 2}.

36 MATERIALS SCIENCE↗

DOE OSTI2018

The early hydration of OPC investigated by in-situ XRD, heat flow calorimetry, pore water analysis and 1H NMR: Learning about adsorbed ions from a complete mass balance approach

In-situ XRD, heat flow calorimetry, pore water analysis and {sup 1}H NMR were used in order to gain more detailed understanding for cement hydration within the first hours of hydration. All methods used show very satisfying accordance. All information gained from the different methods were used in order to calculate absolute mass balance for several ions in order to get an idea about ionic reservoirs adsorbed on surfaces during cement hydration. Sulfate and aluminum adsorption show impact on sulfate depletion, calcium does not.

36 MATERIALS SCIENCE↗

DOE OSTI2018

Acceleration of OPC by CAC in binary and ternary systems: The role of pore solution chemistry

In dry-mortar-formulations calcium aluminate cement (CAC) is often used as a set accelerator for ordinary Portland cement (OPC). However, a critical amount of CAC is able to delay not only the silicate reaction but also the renewed C{sub 3}A dissolution of an OPC. This delay can be counteracted by adding an appropriate amount of calcium sulfate (C$) to the mix OPC/CAC. The initial hydration period is dominated by fast ettringite formation from CA (CAC) and CaSO{sub 4} from OPC generating early strength. High aluminum and low calcium concentrations in the pore solution probably hinder C-S-H seeding and precipitation, thus preventing alite dissolution. Aluminum has to be initially removed by precipitating hydrate phases to change the pore solution chemistry. The start of the silicate reaction is then induced by increasing the calcium concentration in the pore solution.

36 MATERIALS SCIENCE↗

DOE OSTI2015

USABC Development of 12 Volt Battery for Start-Stop Application: Preprint

Global automakers are accelerating the development of fuel efficient vehicles, as a part of meeting regional regulatory CO2 emissions requirements. The micro hybrid vehicles with auto start-stop functionality are considered economical solutions for the stringent European regulations. Flooded lead acid batteries were initially considered the most economical solution for idle-stop systems. However, the dynamic charge acceptance (DCA) at lower state-of-charge (SOC) was limiting the life of the batteries. While improved lead-acid batteries with AGM and VRLA features have improved battery longevity, they do not last the life of the vehicle. The United States Advanced Battery Consortium (or USABC, a consortium of GM, Ford, and Chrysler) analyzed energy storage needs for a micro hybrid automobile with start-stop capability, and with a single power source. USABC has analyzed the start-stop behaviors of many drivers and has developed the requirements for the start-stop batteries (Table 3). The testing procedures to validate the performance and longevity were standardized and published. The guideline for the cost estimates calculations have also been provided, in order to determine the value of the newly developed modules. The analysis effort resulted in a set of requirements which will help the battery manufacturers to develop a module to meet the automotive Original Equipment Manufacturers (OEM) micro hybrid vehicle requirements. Battery developers were invited to submit development proposals and two proposals were selected for 50% cost share with USABC/DOE.

12 V START-STOP↗

DOE OSTI2015

Identifying and Overcoming Critical Barriers to Widespread Second Use of PEV Batteries

Both the market penetration of plug-in electric vehicles (PEVs) and deployment of grid-connected energy storage systems are presently restricted by the high cost of batteries. Battery second use (B2U) strategies--in which a single battery first serves an automotive application, then is redeployed into a secondary market--could help address both issues by reducing battery costs to the primary (automotive) and secondary (electricity grid) users. This study investigates the feasibility of and major barriers to the second use of lithium-ion PEV batteries by posing and answering the following critical B2U questions: 1. When will used automotive batteries become available, and how healthy will they be? 2. What is required to repurpose used automotive batteries, and how much will it cost? 3. How will repurposed automotive batteries be used, how long will they last, and what is their value? Advanced analysis techniques are employed that consider the electrical, thermal, and degradation response of batteries in both the primary (automotive) and secondary service periods. Second use applications are treated in detail, addressing operational requirements, economic value, and market potential. The study concludes that B2U is viable and could provide considerable societal benefits due to the large possible supply of repurposed automotive batteries and substantial remaining battery life following automotive service. However, the only identified secondary market large enough to consume the supply of these batteries (utility peaker plant replacement) is expected to be a low margin market, and thus B2U is not expected to affect the upfront cost of PEVs.

25 ENERGY STORAGE↗

DOE OSTI2015

Quantifying the Effect of Fast Charger Deployments on Electric Vehicle Utility and Travel Patterns via Advanced Simulation: Preprint

The disparate characteristics between conventional (CVs) and battery electric vehicles (BEVs) in terms of driving range, refill/recharge time, and availability of refuel/recharge infrastructure inherently limit the relative utility of BEVs when benchmarked against traditional driver travel patterns. However, given a high penetration of high-power public charging combined with driver tolerance for rerouting travel to facilitate charging on long-distance trips, the difference in utility between CVs and BEVs could be marginalized. We quantify the relationships between BEV utility, the deployment of fast chargers, and driver tolerance for rerouting travel and extending travel durations by simulating BEVs operated over real-world travel patterns using the National Renewable Energy Laboratory's Battery Lifetime Analysis and Simulation Tool for Vehicles (BLAST-V). With support from the U.S. Department of Energy's Vehicle Technologies Office, BLAST-V has been developed to include algorithms for estimating the available range of BEVs prior to the start of trips, for rerouting baseline travel to utilize public charging infrastructure when necessary, and for making driver travel decisions for those trips in the presence of available public charging infrastructure, all while conducting advanced vehicle simulations that account for battery electrical, thermal, and degradation response. Results from BLAST-V simulations on vehicle utility, frequency of inserted stops, duration of charging events, and additional time and distance necessary for rerouting travel are presented to illustrate how BEV utility and travel patterns can be affected by various fast charge deployments.

25 ENERGY STORAGE↗

DOE OSTI2015

Deployment of Behind-The-Meter Energy Storage for Demand Charge Reduction

This study investigates how economically motivated customers will use energy storage for demand charge reduction, as well as how this changes in the presence of on-site photovoltaic power generation, to investigate the possible effects of incentivizing increased quantities of behind-the-meter storage. It finds that small, short-duration batteries are most cost effective regardless of solar power levels, serving to reduce short load spikes on the order of 2.5% of peak demand. While profitable to the customer, such action is unlikely to adequately benefit the utility as may be desired, thus highlighting the need for modified utility rate structures or properly structured incentives.

25 ENERGY STORAGE↗

DOE OSTI2014

Battery Lifetime Analysis and Simulation Tool (BLAST) Documentation

The deployment and use of lithium-ion (Li-ion) batteries in automotive and stationary energy storage applications must be optimized to justify their high up-front costs. Given that batteries degrade with use and storage, such optimizations must evaluate many years of operation. As the degradation mechanisms are sensitive to temperature, state-of-charge (SOC) histories, current levels, and cycle depth and frequency, it is important to model both the battery and the application to a high level of detail to ensure battery response is accurately predicted. To address these issues, the National Renewable Energy Laboratory (NREL) has developed the Battery Lifetime Analysis and Simulation Tool (BLAST) suite. This suite of tools pairs NREL’s high-fidelity battery degradation model with a battery electrical and thermal performance model, application-specific electrical and thermal performance models of the larger system (e.g., an electric vehicle), application-specific system use data (e.g., vehicle travel patterns and driving data), and historic climate data from cities across the United States. This provides highly realistic long-term predictions of battery response and thereby enables quantitative comparisons of varied battery use strategies.

25 ENERGY STORAGE↗