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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 919 records · Page 51

All sources NASA NTRS DOE OSTI

NASA NTRS1995

Adiabatic charging of nickel-hydrogen batteries

Battery management during prelaunch activities has always required special attention and careful planning. The transition from nickel-cadium to nickel-hydrogen batteries, with their high self discharge rate and lower charge efficiency, as well as longer prelaunch scenarios, has made this aspect of spacecraft battery management even more challenging. The AXAF-I Program requires high battery state of charge at launch. The use of active cooling, to ensure efficient charging, was considered and proved to be difficult and expensive. Alternative approaches were evaluated. Optimized charging, in the absence of cooling, appeared promising and was investigated. Initial testing was conducted to demonstrate the feasibility of the 'Adiabatic Charging' approach. Feasibility was demonstrated and additional testing performed to provide a quantitative, parametric data base. The assumption that the battery is in an adiabatic environment during prelaunch charging is a conservative approximation because the battery will transfer some heat to its surroundings by convective air cooling. The amount is small compared to the heat dissipated during battery overcharge. Because the battery has a large thermal mass, substantial overcharge can occur before the cells get too hot to charge efficiently. The testing presented here simulates a true adiabatic environment. Accordingly the data base may be slightly conservative. The adiabatic charge methodology used in this investigation begins with stabilizing the cell at a given starting temperature. The cell is then fully insulated on all sides. Battery temperature is carefully monitored and the charge terminated when the cell temperature reaches 85 F. Charging has been evaluated with starting temperatures from 55 to 75 F.

Lurie, Chuck↗

NASA NTRS1999

Response of NiMH Cells to Burp Charging

Performance cycling and calorimetric analysis of nickel metal hydride (NNH) calls have revealed that reverse pulse ("burp") charging improves performance over other charging techniques. Burp charging periodically applies a short-duration, high-rate discharge pulse followed by short rest during an otherwise galvanostatic charge as shown in Fig. 1. Results show improved charge input and output, lower heat generation during charge, lower charge overvoltage, and no loss of cycle life [I]. The burp charge method has been improved over the years purely by trial and error. Several hypotheses have been put forward (see articles cited in (1) to explain why burp charging improves performance For example, it has been suggested that the discharge pulses dislodge gas bubbles that would otherwise mask the active elect-ode surfaces. However, no evidence was found in the literature to support this or other hypotheses. Overall, a better understanding of the phenomenon is needed to help guide further improvements in the burp-charging method, and this is the objective of our investigation.

Darcy, Eric C.↗

NASA NTRS2004

An Educational Multimedia Presentation on the Introduction to Spacecraft Charging

Over the last few decades, significant knowledge has been gained in how to protect spacecraft from charging; however, the continuing technical advancement in the design and build of satellites requires on-going effort in the study of spacecraft charging. A situation that we have encountered is that not all satellite designers and builders are familiar with the problem of spacecraft charging. The design of a satellite involves many talented people with diverse backgrounds, ranging from manufacturing and assembly to engineering and program management. The complex design and build of a satellite system requires people with highly specialized skills such that cross-specialization is often not achievable. As a result, designers and builders of satellites are not usually familiar with the problems outside their specialization. This is also true for spacecraft charging. Not everyone is familiar with the definition of spacecraft charging and the damage that spacecraft charging can cause. Understanding the problem is an important first step in getting everyone involved in addressing the appropriate spacecraft charging issues during the satellite design and build phases. To address this important first step, an educational multimedia presentation has been created to inform the general engineering community about the basics of spacecraft charging. The content of this educational presentation is based on relevant published technical papers. The presentation was developed using Macromedia Flash. This software produces a more dynamic learning environment than a typical slide show , resulting in a more effective learning experience. The end result is that the viewer will have learned about the basics of spacecraft charging. This presentation is available to the public through our website, www.dplscience.com, free of charge. Viewers are encouraged to pass this presentation to colleagues within their own work environment. This paper describes the content of the multimedia presentation.

Lin, E.↗

NASA NTRS2010

Electrostatic Power Generation from Negatively Charged, Simulated Lunar Regolith

Research was conducted to develop an electrostatic power generator for future lunar missions that facilitate the utilization of lunar resources. The lunar surface is known to be negatively charged from the constant bombardment of electrons and protons from the solar wind. The resulting negative electrostatic charge on the dust particles, in the lunar vacuum, causes them to repel each other minimizing the potential. The result is a layer of suspended dust about one meter above the lunar surface. This phenomenon was observed by both Clementine and Surveyor spacecrafts. During the Apollo 17 lunar landing, the charged dust was a major hindrance, as it was attracted to the astronauts' spacesuits, equipment, and the lunar buggies. The dust accumulated on the spacesuits caused reduced visibility for the astronauts, and was unavoidably transported inside the spacecraft where it caused breathing irritation [1]. In the lunar vacuum, the maximum charge on the particles can be extremely high. An article in the journal "Nature", titled "Moon too static for astronauts?" (Feb 2, 2007) estimates that the lunar surface is charged with up to several thousand volts [2]. The electrostatic power generator was devised to alleviate the hazardous effects of negatively charged lunar soil by neutralizing the charged particles through capacitive coupling and thereby simultaneously harnessing power through electric charging [3]. The amount of power generated or collected is dependent on the areal coverage of the device and hovering speed over the lunar soil surface. A thin-film array of capacitors can be continuously charged and sequentially discharged using a time-differentiated trigger discharge process to produce a pulse train of discharge for DC mode output. By controlling the pulse interval, the DC mode power can be modulated for powering devices and equipment. In conjunction with a power storage system, the electrostatic power generator can be a power source for a lunar rover or other systems. The negatively charged lunar soil would also be neutralized mitigating some of the adverse effects resulting from lunar dust.

Choi, Sang H.↗

NASA NTRS2013

Battery Charge Equalizer with Transformer Array

High-power batteries generally consist of a series connection of many cells or cell banks. In order to maintain high performance over battery life, it is desirable to keep the state of charge of all the cell banks equal. A method provides individual charging for battery cells in a large, high-voltage battery array with a minimum number of transformers while maintaining reasonable efficiency. This is designed to augment a simple highcurrent charger that supplies the main charge energy. The innovation will form part of a larger battery charge system. It consists of a transformer array connected to the battery array through rectification and filtering circuits. The transformer array is connected to a drive circuit and a timing and control circuit that allow individual battery cells or cell banks to be charged. The timing circuit and control circuit connect to a charge controller that uses battery instrumentation to determine which battery bank to charge. It is important to note that the innovation can charge an individual cell bank at the same time that the main battery charger is charging the high-voltage battery. The fact that the battery cell banks are at a non-zero voltage, and that they are all at similar voltages, can be used to allow charging of individual cell banks. A set of transformers can be connected with secondary windings in series to make weighted sums of the voltages on the primaries.

Davies, Francis↗

NASA NTRS2015

Spacecraft Charging Sensitivity to Material Properties

Evaluating spacecraft charging behavior of a vehicle in the space environment requires knowledge of the material properties relevant to the charging process. Implementing surface and internal charging models requires a user to specify a number of material electrical properties including electrical resistivity parameters (dark and radiation induced), dielectric constant, secondary electron yields, photoemission yields, and breakdown strength in order to correctly evaluate the electric discharge threat posed by the increasing electric fields generated by the accumulating charge density. In addition, bulk material mass density and/or chemical composition must be known in order to analyze radiation shielding properties when evaluating internal charging. We will first describe the physics of spacecraft charging and show how uncertainties in material properties propagate through spacecraft charging algorithms to impact the results obtained from charging models. We then provide examples using spacecraft charging codes to demonstrate their sensitivity to material properties. The goal of this presentation is to emphasize the importance in having good information on relevant material properties in order to best characterize on orbit charging threats.

Minow, Joseph I.↗

NASA NTRS2018

Simulation of Charge Collection to Spacecraft Surfaces: Freja Satellite

As spacecraft travel through plasma, spacecraft surfaces become charged by the collection of charged particles. This process is referred to as Surface Charging. These charges can be detrimental to the vehicle's electronic subsystems as they present a threat of electrostatic discharge (ESD) to onboard circuitry. The process of Surface Charging is complex and is affected by many elements. The charging of each surface is unique. The potential of an individual surface is dependent upon many variables including but not limited to the surface's geometry, material and its location. Each surface also has unique interactions with the surrounding plasma. Other factors that play large roles in the charging process is the density and temperature of plasma ions and electrons. Using Nascap-2k, a model of the Freja satellite has been constructed, and its auroral plasma environment has been imitated to simulate surface charging characteristics. The charging process of the Freja satellite has been modeled iteratively with incremental changes in both the Maxwellian electron temperature (eV) as well as the Gaussian electron energy (eV). This study provides an analysis of the sensitivity between spacecraft surface charging and these two primary variables of electron differential flux.

Wolfley, Olivia H.↗

NASA NTRS2018

Simulation of Charge Collection to Spacecraft Surfaces: Freja Satellite

As spacecraft travel through space plasma, spacecraft surfaces become charged by the collection of charged particles. This process is referred to as Surface Charging. These charges can be detrimental to the vehicle's electronic subsystems as they present a threat of electrostatic discharge (ESD) to onboard circuitry. The process of Surface Charging is complex and is affected by many elements. The charging of each surface is unique. The potential of an individual surface is dependent upon many variables including but not limited to the surface's geometry, material and its location. Each surface also has unique interactions with the surrounding plasma. Other factors that play large roles in the charging process is the density and temperature of plasma ions and electrons. Using Nascap-2k, a model of the Freja satellite has been constructed, and its auroral plasma environment has been imitated to simulate surface charging characteristics. The charging process of the Freja satellite has been modeled iteratively with incremental changes in both the Maxwellian electron temperature (eV) as well as the Gaussian electron energy (eV). This study provides an analysis of the sensitivity between spacecraft surface charging and these two primary variables of electron differential flux.

Wolfley, Olivia Hope↗

DOE OSTI2014

Impact of Charge Degradation on the Life Cycle Climate Performance of a Residential Air-Conditioning System

Vapor compression systems continuously leak a small fraction of their refrigerant charge to the environment, whether during operation or servicing. As a result of the slow leak rate occurring during operation, the refrigerant charge decreases until the system is serviced and recharged. This charge degradation, after a certain limit, begins to have a detrimental effect on system capacity, energy consumption, and coefficient of performance (COP). This paper presents a literature review and a summary of previous experimental work on the effect of undercharging or charge degradation of different vapor compression systems, especially those without a receiver. These systems include residential air conditioning and heat pump systems utilizing different components and refrigerants, and water chiller systems. Most of these studies show similar trends for the effect of charge degradation on system performance. However, it is found that although much experimental work exists on the effect of charge degradation on system performance, no correlation or comparison between charge degradation and system performance yet exists. Thus, based on the literature review, three different correlations that characterize the effect of charge on system capacity and energy consumption are developed for different systems as follows: one for air-conditioning systems, one for vapor compression water-to-water chiller systems, and one for heat pumps. These correlations can be implemented in vapor compression cycle simulation tools to obtain a better prediction of the system performance throughout its lifetime. In this paper, these correlations are implemented in an open source tool for life cycle climate performance (LCCP) based design of vapor compression systems. The LCCP of a residential air-source heat pump is evaluated using the tool and the effect of charge degradation on the results is studied. The heat pump is simulated using a validated component-based vapor compression system model and the LCCP results obtained using the three charge degradation correlations are compared.

Air Conditioning↗

DOE OSTI2023

Electrostatic charge buildup and electrostatic discharge monitoring system and method

A system for monitoring electrostatic charge buildup and electrostatic discharge (ESD) remotely comprises a plurality of electrostatic charge measurement units and a data acquisition device. Each electrostatic charge measurement unit includes a primary charge plate, a static sensor device, a secondary charge plate, and a shielded cable. The primary charge plate is positioned proximal to an object. The static sensor device includes an input sensor at which an electric voltage is measured and outputs an electronic signal whose level varies according to the measured electric voltage. The secondary charge plate is positioned in proximity to the input sensor of the static sensor device. The shielded cable includes an inner conductor electrically connected to the primary charge plate and the secondary charge plate and an outer conductor electrically connected to electrical ground. The data acquisition device receives the electronic signal from the static sensor device of each electrostatic charge measurement unit.

Schantz, Eric T.↗

DOE OSTI2016

Charging of Proteins in Native Mass Spectrometry

Factors that influence the charging of protein ions formed by electrospray ionization from aqueous solutions in which proteins have native structures and function were investigated. Protein ions ranging in molecular weight from 12.3 to 79.7 kDa and pI values from 5.4 to 9.6 were formed from different solutions and reacted with volatile bases of gas-phase basicities higher than that of ammonia in the cell of a Fourier-transform ion cyclotron resonance mass spectrometer. The charge-state distribution of cytochrome c ions formed from aqueous ammonium or potassium acetate is the same. Moreover, ions formed from these two solutions do not undergo proton transfer to 2-fluoropyridine, which is 8 kcal/mol more basic than ammonia. These results provide compelling evidence that proton transfer between ammonia and protein ions does not limit protein ion charge in native electrospray ionization. Both circular dichroism and ion mobility measurements indicate that there are differences in conformations of proteins in pure water and aqueous ammonium acetate, and these differences can account for the difference in the extent of charging and proton-transfer reactivities of protein ions formed from these solutions. The extent of proton transfer of the protein ions with higher gas-phase basicity bases trends with how closely the protein ions are charged to the value predicted by the Rayleigh limit for spherical water droplets approximately the same size as the proteins. These results indicate that droplet charge limits protein ion charge in native mass spectrometry and are consistent with these ions being formed by the charged residue mechanism.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2013

The effect of a direct current field on the microparticle charge in the plasma afterglow

Residual charges of individual microparticles forming dense clouds were measured in a RF discharge afterglow. Experiments were performed under microgravity conditions on board the International Space Station, which ensured particle levitation inside the gas volume after the plasma switch-off. The distribution of residual charges as well as the spatial distribution of charged particles across the cloud were analyzed by applying a low-frequency voltage to the electrodes and measuring amplitudes of the resulting particle oscillations. Upon “free decharging” conditions, the charge distribution had a sharp peak at zero and was rather symmetric (with charges concentrated between −10e and +10e), yet positively and negatively charged particles were homogeneously distributed over the cloud. However, when decharging evolved in the presence of an external DC field (applied shortly before the plasma switch-off) practically all residual charges were positive. In this case, the overall charge distribution had a sharp peak at about +15e and was highly asymmetric, while the spatial distribution exhibited a significant charge gradient along the direction of the applied DC field.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2014

Charge density stabilised local electron spin pair states in insulating polymers

A model is presented that addresses the energy stability of localized electron states in insulating polymers with respect to delocalized free electron-like states at variable charge densities. The model was derived using an effective Hamiltonian for the total energy of electrons trapped in large polarons and spin-paired bipolarons, which includes the electrostatic interaction between charges that occurs when the charge density exceeds the infinite dilution limit. The phase diagram of the various electronic states with respect to the charge density is derived using parameters determined from experimental data for polyethylene, and it is found that a phase transition from excess charge in the form of stable polarons to a stable state of bipolarons with charge = 2 and spin number S = 0 is predicted for a charge density between 0.2 C/m{sup 3} and ∼2 C/m{sup 3}. This transition is consistent with a change from low mobility charge transport to charge transport in the form of pulses with a mobility orders of magnitude higher that has been observed in several insulating polymers.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2026

Strategies for Enhancing Battery Life Under Fast Charging: Insights from NMC-Based Cell Cycling

Fast charging improves the usability of consumer electronics and electric vehicles (EVs) by reducing range anxiety and downtime but accelerates battery degradation and raises safety concerns. Optimizing operational conditions during fast-charging is critical to mitigating aging and ensuring safety. This study evaluated multilayer Gr/NMC811 cells under various conditions, including depths of discharge (DODs of 68%, 84%, and 100%), upper charge cutoff voltages (4.1–4.2 V), and post-charge rest periods (2–30 min), using a 20 min fast charging protocol for up to 500 cycles (up to 150,000 miles of EV use assuming 3.3 mi/kWh vehicle level energy efficiency). Surprisingly, higher DODs under fast charging improved battery life and performance compared to lower DODs. Reducing the upper charge cut-off voltage helped mitigate degradation. A brief 2 min rest period after charging further reduced aging effects. The primary aging modes were loss of lithium inventory and cathode active material. Although minor lithium plating was observed within 500 cycles, it did not affect performance significantly. These findings suggest that, with optimized conditions, cells can sustain hundreds of fast charge cycles—equivalent to over 100,000 miles of EV use—without significant adverse effects on performance or longevity.

25 - ENERGY STORAGE↗

DOE OSTI2025

Understanding EV Charging Pain Points Through Deep Learning Analysis

Current and potential electric vehicle (EV) owners express concerns about the charging infrastructure, mentioning non-functional chargers, prolonged charging times, inconvenient charger locations, long wait times, and high costs as major barriers. Addressing these issues often requires analyzing actual vehicle charging data, which is typically proprietary and inconsistent due to diverse standards and protocols. To understand and improve the EV charging experience, customer reviews are typically used to identify common customer pain points (CPPs). However, there is not a comprehensive method to map customer reviews to a standardized set of CPPs. In collaboration with the National Charging Experience (ChargeX) Consortium, this study bridges these gaps by proposing a Systematic Categorization and Analysis of Large-scale EV-charging Reviews (SCALER) framework. SCALER is an integrated, deep learning framework that segments, actively labels, analyzes, and classifies EV charging customer reviews into six CPP categories. To test its effectiveness, we used SCALER to analyze over 72,000 reviews from customers charging various EV models on different networks across the United States. SCALER achieves a classification accuracy of 92.5%, with an F1 score exceeding 85.7%. By demonstrating real-world applications of SCALER, we enhance the industry’s ability to understand and address CPPs to improve the EV charging experience.

29 - ENERGY PLANNING, POLICY AND ECONOMY↗

DOE OSTI2023

Fast Charging Infrastructure for Electrifying Road Trips to and from National Parks in the Western United States

National parks in the Western United States draw over 80 million visitors every year, and most visitors rely on personal cars for their road trips (or long-distance travels). Travel to national parks represents distinct travel demand, as they are typically located in remote areas necessitating long-distance trips. This study investigates the quantity and locations of on-route fast charging infrastructure needed by 2030 to enable seamless travel to/from national parks using electric vehicles in seven target states in the region, employing unprecedented high-resolution spatial and temporal analysis. We find that the required number of fast charging ports for on-route charging infrastructure ranges from 1,200 to 22,000, depending on different assumptions of key input parameters - vehicle electrification rate, charging behavior, average gap between charging stations, port utilization rate, and towing trailers. Our analysis also indicates that electrical load for on-route fast charging infrastructure would peak in the afternoon, in the range of 70-400 MW, varying with the key input parameters. This study illustrates how different input parameters result in different degrees of impact on various aspects of charging infrastructure. We also examine the characteristics of projected charging infrastructure in terms of land use type, relationship with traffic volume, size of stations, and other variables.

24 POWER TRANSMISSION AND DISTRIBUTION↗

DOE OSTI2017

Capacitive Deionization Using Alternating Polarization: Effect of Surface Charge on Salt Removal

Alternating polarization (AP) at ±1.2/0 V is performed on a capacitive deionization stack assembled with carbon xerogel (CX) electrodes. Long-term testing shows enhanced cycling stability without the formation of inversion peaks. AP also leads to an arch-shaped plot of salt adsorption capacity (SAC) versus cycling time, with the highest SAC of approximately 3 mg (NaCl) g −1 (CX) during this long-term test. Characterization of both the freshly prepared and cycled electrodes depict that AP results in surface charge of all the electrodes being modified from positive to negative character. Here by leveraging balances of electronic, surface, and ionic charges in carbon micropores, it is found that a portion of the electronic charge contributes to the ionic charge for salt adsorption, and another portion is parasitically consumed to balance the surface charge during the charge reconciliation process. When the consumption of electronic charge for charge reconciliation becomes minimal, both the positive and negative surface charges are nearly equivalent on the CX electrode. Under such a condition, the highest SAC values can be achieved for AP testing.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2023

The need for ion-exchange membranes with high charge densities

Ion-exchange membranes (IEMs) are essential for controlling ion transport in electrochemical membrane-based technologies for water purification, energy generation, and energy storage. In general, IEMs must exhibit high ionic conductivity and selectivity, both of which are significantly influenced by the charge and water content of the hydrated membrane. In this perspective, we compiled the charge and water contents of approximately 1,000 IEMs reported over the past several decades to assess their range and variability, as well as to reveal gaps and set clear targets for future membrane design. We compared the charge and water content of negatively and positively charged membranes, as well as membranes developed for desalination and energy applications. The majority of IEMs, regardless of structure or intended application, have volumetric charge densities below 3 mol/L[membrane]. This narrow range of charge densities limits the performance of IEMs and contributes to the observed tradeoff between ion throughput and selectivity. It is critical to develop IEMs with higher charge densities to overcome this performance limitation. Further, we highlighted several design strategies that yielded IEMs with fixed charge densities higher than 3 mol/L[membrane]. These strategies provide valuable insights and can guide the design of next-generation IEMs with high charge densities.

36 MATERIALS SCIENCE↗