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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 973 records · Page 54
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Win–Win strategies to promote air pollutant control policies and non-fossil energy target regulation in China

The rapid growth of energy consumption in China has led to increased emissions of air pollutants. As a response, in its 12th Five Year Plan the Chinese government proposed mitigation targets for SO2 and NOx emissions. Herein we have investigated mitigation measures taken in different sectors and their corresponding impacts on the energy system. Additionally, as non-fossil energy development has gained traction in addressing energy and environmental challenges in China, we further investigated the impact of non-fossil energy development on air pollutant emissions, and then explored interactions and co-benefits between these two types of policies. An extended Global Change Assessment Model (GCAM) was used in this study, which includes an additional air pollutant emissions control module coupling multiple end-of-pipe (EOP) control technologies with energy technologies, as well as more detailed end-use sectors in China. We find that implementing EOP control technologies would reduce air pollution in the near future, but with little room left to implement these EOP technologies, other cleaner and more efficient technologies are also effective. These technologies would reduce final energy consumption, increase electricity’s share in final energy, and increase the share of non-fossil fuels in primary energy and electricity consumption. Increasing non-fossil energy usage at China’s proposed adoption rate would in turn also reduce SO2 and NOx emissions, however, the reductions from this policy alone still lag behind the targeted requirements of air pollutant reduction. Fortunately, a combination of air pollutant controls and non-fossil energy development could synergistically help realize the respective individual targets, and would result in lower costs than would addressing these issues separately.

Air pollution↗
DOE OSTI2019

Improving the energy efficiency of room air conditioners in China: Costs and benefits

China is the world's largest consumer of room air conditioners, and it contributes about a quarter of global space cooling CO 2 emissions. We model the costs and benefits of recently proposed new room air conditioner minimum energy performance standards (MEPS) in China. Our results suggest that newly proposed MEPS brings accumulative CO 2 emissions reductions of 12.8% between 2019 and 2050, and accumulative bill saving of 2620 billion RMB to China's consumers. The benefits of the proposed MEPS decrease with longer MEPS revision intervals and increase with shorter intervals—indicating that the intervals should be balanced to maximize benefits while accommodating constraints due to air conditioner manufacturer design cycles. We also model potential nationwide benefits from higher MEPS. Across two increasingly aggressive MEPS scenarios, China's room air conditioner electricity consumption and CO 2 emissions in 2050 are both reduced by 15–53% compared to the proposed MEPS. The highest-efficiency scenario (reaching MEPS of annual performance factor 5.4 in 2025) provides the largest long-term national benefits. These results could inform development of a Chinese regulatory regime that effectively updates room air conditioner MEPS. Because China is the world's largest manufacturer of room air conditioners, the economic, energy, and emissions benefits resulting from higher Chinese MEPS could also have a global reach.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2021

Cost-Performance Trade-off in thermoelectric air conditioning system with graded and constant material properties

Thermoelectric (TE) air cooling is a solid-state technology that has the potential to replace conventional vapor compression-based air conditioning. In this paper, we present a detailed system-level modeling for thermoelectric air conditioning system with position-dependent (graded) and constant material properties. Strategies for design optimization of the system are provided in terms of cost-performance trade-off. Realistic convection heat transfer at both sides of the system are taken into account in our modeling. Here, the effects of convection heat transfer coefficients, air flowrate, and thermoelectric material properties are investigated with varying key parameters such as TE leg thickness, module fill factor, and input current. Both constant material properties and graded properties are considered for the TE materials, and they are compared in terms of the degree of cooling, coefficient of performance (COP), and power consumption. For graded materials, we employ one-dimensional finite element methods to solve the coupled electrical and thermal current equations with arbitrary profile of material properties varying with position along the TE legs. We find that graded materials can enhance the degree of cooling, but only at the expense of COP, compared to the case of constant property materials. With constant material properties of ZT = 1 and relatively low electric current, the power consumption of TE coolers can be lower than those of conventional air conditioners at an equivalent cooling capacity. Considering additional advantages such as demand-flexible operation, low noise, and high scalability, thermoelectric cooling could be a competitive technology for future air conditioning applications.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2018

Parental stress and air pollution increase childhood asthma in China

Highlights: • Little is known about the effect of stress-pollution interaction on childhood asthma. • We examined associations of parental stress and air pollution with childhood asthma in China. • Association of air pollution with asthma is significant in children exposed to high parental stress. • Association of parental stress with asthma is significant in children exposed to high air pollution. • Interactive effect of stress and air pollution on asthma indicates a common biological pathway. Although air pollution and social stress may independently increase childhood asthma, little is known on their synergistic effect on asthma, particularly in China with high levels of stress and air pollution.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2010

Experimental investigation on the photovoltaic-thermal solar heat pump air-conditioning system on water-heating mode

An experimental study on operation performance of photovoltaic-thermal solar heat pump air-conditioning system was conducted in this paper. The experimental system of photovoltaic-thermal solar heat pump air-conditioning system was set up. The performance parameters such as the evaporation pressure, the condensation pressure and the coefficient of performance (COP) of heat pump air-conditioning system, the water temperature and receiving heat capacity in water heater, the photovoltaic (PV) module temperature and the photovoltaic efficiency were investigated. The experimental results show that the mean photovoltaic efficiency of photovoltaic-thermal (PV/T) solar heat pump air-conditioning system reaches 10.4%, and can improve 23.8% in comparison with that of the conventional photovoltaic module, the mean COP of heat pump air-conditioning system may attain 2.88 and the water temperature in water heater can increase to 42 C. These results indicate that the photovoltaic-thermal solar heat pump air-conditioning system has better performances and can stably work. (author)

14 SOLAR ENERGY↗
DOE OSTI2016

Future air pollution in the Shared Socio-economic Pathways

Emissions of air pollutants such as sulfur and nitrogen oxides and particulates have significant health impacts as well as effects on natural and anthropogenic ecosystems. These same emissions also can change atmospheric chemistry and the planetary energy balance, thereby impacting global and regional climate. Long-term scenarios for air pollutant emissions are needed as inputs to global climate and chemistry models, and for analysis linking air pollutant impacts across sectors. In this paper we present methodology and results for air pollutant emissions in Shared Socioeconomic Pathways (SSP) scenarios. We first present a set of three air pollution narratives that describe high, central, and low pollution control ambitions over the 21 st century. These narratives are then translated into quantitative guidance for use in integrated assessment models. We provide an overview of pollutant emission trajectories under the SSP scenarios. Pollutant emissions in these scenarios cover a wider range than the scenarios used in previous international climate model comparisons. Furthermore, the SSP scenarios provide the opportunity to access a more comprehensive range of future global and regional air quality outcomes.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2026

Experimental and data-driven characterization of window-induced air leakage in residential buildings

Windows contributes up to 40% of envelope heat losses and around 9% of total building energy consumption due to air leakage. In the U.S., 48 million homes still use single-pane windows. Although the U.S. has an estimated 1.4 billion windows in its building stock and about 24 million windows are installed annually, only around 29 million individual window replacements (∼2%) occur each year. To address this gap, this study generates empirical evidence by (1) evaluating the contribution of windows to whole-building air leakage in 20 residential buildings using blower door tests before and after window replacement and (2) assessing whether building and window characteristics influence the measured change. Most simulation studies assume that replacing windows not only lowers the U-factor but also reduces air leakage by 10–20%. However, this assumption lacks empirical validation, highlighting the need for experimental analysis of air leakage specifically associated with windows. Using blower door tests in accordance with ASTM E779–19, the results indicated an average reduction in air infiltration of 6.1% within the range of 0.5–19.30% across all buildings and no significant correlations were found between air leakage improvements and any building/window characteristics. This research aims to help homeowners, and energy modelers to provide empirical data on importance of upgrading to more energy-efficient windows, supporting energy-efficient building standards.

Air leakage↗
DOE OSTI2019

Membrane-based liquid desiccant air dehumidification: A comprehensive review on materials, components, systems and performances

Membrane-based liquid desiccant air dehumidification (MLDAD) is a separation process driven by the vapor pressure difference. In contrast to the conventional liquid desiccant air dehumidification, MLDAD uses semi-permeable membranes to separate the processing air and desiccant liquid so that only water vapor molecules in the air side can transfer through the membrane and be absorbed by the solution. Here, the vapor is removed from the air stream, and the carryover of solution droplets in the air is also able to be eliminated. This review addresses the characteristics of liquid desiccants and membranes, the design of MLDAD modules and systems, the performance assessment and comparison of the dehumidification and regeneration module, as well as the system-level energy analysis. State-of-the-art research results are presented, and the future needs for this promising technology are discussed.

42 ENGINEERING↗
DOE OSTI2010

Energy and economic performance analysis of an open cycle solar desiccant dehumidification air-conditioning system for application in Hong Kong

In this article, a transient simulation model and the EnergyPlus were used to study the energy performance and economical feasibility for integrating a solar liquid desiccant dehumidification system with a conventional vapor compression air-conditioning system for the weather condition of Hong Kong. The vapor compression system capacity in the solar assisted air-conditioning system can be reduced to 19 kW from original 28 kW of a conventional air-conditioning system as a case study due to the solar desiccant cooling. The economical performance of the solar desiccant dehumidification system is compared with that of the conventional air-conditioning system. The results show that the energy saving potentials due to incorporation of the solar desiccant dehumidification system in a traditional air-conditioning system is significant for the hot wet weather in Hong Kong due to higher COP resulted from higher supply chilled water temperature from chiller plants. The annual operation energy savings for the hybrid system is 6760 kWh and the payback period of the hybrid system is around 7 years. The study shows that the solar assisted air-conditioning is a viable technology for utilizations in subtropical areas. (author)

14 SOLAR ENERGY↗
DOE OSTI2024

Air separation and N 2 purification with Ba 0.15 Sr 0.85 FeO 3-$δ$ via a two-step thermochemical process

Thermochemical air separation to produce high-purity N 2 was demonstrated in a vertical tube reactor via a two-step reduction–oxidation cycle with an A-site substituted perovskite Ba 0.15 Sr 0.85 FeO 3–δ (BSF1585). BSF1585 particles were synthesized and characterized in terms of their chemical, morphological, and thermophysical properties. A thermodynamic cycle model and sensitivity analysis using computational heat and mass transfer models of the reactor were used to select the system operating parameters for a concentrating solar thermal-driven process. Thermal reduction up to 800 °C in air and temperature-swing air separation from 800 °C to minimum temperatures between 400 and 600 °C were performed in the reactor containing a 35 g packed bed of BSF1585. The reactor was characterized for dispersion, and air separation was characterized via mass spectrometry. Gas measurements indicated that the reactor produced N 2 with O 2 impurity concentrations as low as 0.02 % for > 30 min of operation. Additionally, a parametric study of air flow rates suggested that differences in observed and thermodynamically predicted O 2 impurities were due to imperfect gas transport in the bed. Temperature swing reduction/oxidation cycling experiments between 800 and 400 °C in air were conducted with no statistically significant degradation in N 2 purity over 50 cycles.

14 SOLAR ENERGY↗
DOE OSTI2018

Aqueous Polysulfide–Air Battery with a Mediator-Ion Solid Electrolyte and a Copper Sulfide Catalyst for Polysulfide Redox

Aqueous sodium polysulfide–air batteries are a promising system for enabling low-cost, high energy density, environmentally benign batteries for grid-scale deployment. However, the sluggish redox kinetics of aqueous polysulfide requires the use of a catalyst. Cobalt sulfide is a traditional catalyst with good activity and stability, but it uses expensive and toxic cobalt. This study demonstrates for the first time the long-term cycling performance of a sodium polysulfide–air battery with a low-cost copper sulfide catalyst for polysulfide redox. Alkaline sodium polysulfide anolyte is paired with an acidic sodium phosphate buffered air catholyte by means of a Na+-ion solid-state electrolyte, which eliminates chemical crossover between the two electrodes while serving as a mediator-ion solid electrolyte. Long-term cycling is achieved by means of a decoupled charge and discharge air electrode. Furthermore, the effect of CuS redox activity in the polysulfide–air voltage window is tested by pre-discharging CuS in LiOH and in NaOH. It was found that the sodium polysulfide–air batteries with CuS catalyst exhibit good cycling performance, with the overpotential only showing a modest increase of 0.09 V after 100 cycles. Batteries assembled with CuS pre-discharged in LiOH exhibit a small boost in performance, while batteries assembled with CuS pre-discharged in NaOH show a small performance decline.

25 ENERGY STORAGE↗
DOE OSTI2010

The behavior of NaOH at the air-water interface, a computational study

Molecular dynamics simulations with a polarizable multi-state empirical valence bond model were carried out to investigate NaOH dissociation and pairing in water bulk and at the air-water interface. It was found that NaOH readily dissociates in the bulk, and the effect of the air-water interface on NaOH dissociation is fairly minor. Also, NaOH complexes were found to be strongly repelled from the air-water interface, which is consistent with surface tension measurements. At the same time, a very strong preference for the hydroxide anion to be oriented towards the air was found that persisted a few angstroms towards the liquid from the Gibbs dividing surface of the air-water interface. This was due to a preference for the hydroxide anion to have its hydrogen pointing towards the air, and the fact that the sodium ion was more likely to be found near the hydroxide oxygen than hydrogen. As a consequence, the simulation results show that surfaces of NaOH solutions should be negatively charged, in agreement with experimental observations, but also that the hydroxide has little surface affinity. This provides the possibility that the surface of water can be devoid of hydroxide anions, but still have a strong negative charge. This work was supported by the US Department of Energy Basic Energy Sciences' Chemical Sciences, Geosciences & Biosciences Division. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

08 HYDROGEN↗
DOE OSTI2012

Optical breakdown threshold investigation of 1064 nm laser induced air plasmas

We present the theoretical and experimental measurements and analysis of the optical breakdown threshold for dry air by 1064 nm infrared laser radiation and the significance of the multiphoton and collisional cascade ionization process on the breakdown threshold measurements over pressures range from 10 to 2000 Torr. Theoretical estimates of the breakdown threshold laser intensities and electric fields are obtained using two distinct theories namely multiphoton and collisional cascade ionization theories. The theoretical estimates are validated by experimental measurements and analysis of laser induced breakdown processes in dry air at a wavelength of 1064 nm by focusing 450 mJ max, 6 ns, 75 MW max high-power 1064 nm IR laser radiation onto a 20 {mu}m radius spot size that produces laser intensities up to 3 - 6 TW/cm{sup 2}, sufficient for air ionization over the pressures of interest ranging from 10 to 2000 Torr. Analysis of the measured breakdown threshold laser intensities and electric fields are carried out in relation with classical and quantum theoretical ionization processes, operating pressures. Comparative analysis of the laser air breakdown results at 1064 nm with corresponding results of a shorter laser wavelength (193 nm) [M. Thiyagarajan and J. E. Scharer, IEEE Trans. Plasma Sci. 36, 2512 (2008)] and a longer microwave wavelength (10{sup 8} nm) [A. D. MacDonald, Microwave Breakdown in Gases (Wiley, New York, 1966)]. A universal scaling analysis of the breakdown threshold measurements provided a direct comparison of breakdown threshold values over a wide range of frequencies ranging from microwave to ultraviolet frequencies. Comparison of 1064 nm laser induced effective field intensities for air breakdown measurements with data calculated based on the collisional cascade and multiphoton breakdown theories is used successfully to determine the scaled collisional microwave portion. The measured breakdown threshold of 1064 nm laser intensities are then scaled to classical microwave breakdown theory after correcting for the multiphoton ionization process for different pressures and good agreement, regarding both pressure dependence and breakdown threshold electric fields, is obtained. The effect of the presence of submicron particles on the 1064 nm breakdown threshold was also investigated. The measurements show that higher breakdown field is required, especially at lower pressures, and in close agreement with classical microwave breakdown theory and measurements in air.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2015

A handheld low temperature atmospheric pressure air plasma gun for nanomaterial synthesis in liquid phase

A handheld low temperature atmospheric pressure air plasma gun based on a dielectric barrier structure with hollow electrodes was proposed. The portable plasma gun with an embedded mini air pump was driven by a 12 V direct voltage battery. The air plasma jet generated from the gun could be touched without a common shock hazard. Besides working in air, the plasma gun can also work in water. The diagnostic result of optical emission spectroscopy showed the difference in reactive species of air plasma jet between in air and in water. The plasma gun was excited in 20 ml chloroauric acid aqueous solution with a concentration of 1.214 mM. A significant amount of gold nanoparticles were synthesized after 2 min continuous discharge. The plasma gun with these unique features is applicable in plasma medicine, etching, and s-nthesis of nanomaterials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Influence of air exposure duration and a-Si capping layer thickness on the performance of p-BaSi{sub 2}/n-Si heterojunction solar cells

Fabrication of p-BaSi{sub 2}(20 nm)/n-Si heterojunction solar cells was performed with different a-Si capping layer thicknesses (d{sub a-Si}) and varying air exposure durations (t{sub air}) prior to the formation of a 70-nm-thick indium-tin-oxide electrode. The conversion efficiencies (η) reached approximately 4.7% regardless of t{sub air} (varying from 12–150 h) for solar cells with d{sub a-Si} = 5 nm. In contrast, η increased from 5.3 to 6.6% with increasing t{sub air} for those with d{sub a-Si} = 2 nm, in contrast to our prediction. For this sample, the reverse saturation current density (J{sub 0}) and diode ideality factor decreased with t{sub air}, resulting in the enhancement of η. The effects of the variation of d{sub a-Si} (0.7, 2, 3, and 5 nm) upon the solar cell performance were examined while keeping t{sub air} = 150 h. The η reached a maximum of 9.0% when d{sub a-Si} was 3 nm, wherein the open-circuit voltage and fill factor also reached a maximum. The series resistance, shunt resistance, and J{sub 0} exhibited a tendency to decrease as d{sub a-Si} increased. These results demonstrate that a moderate oxidation of BaSi{sub 2} is a very effective means to enhance the η of BaSi{sub 2} solar cells.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

Simulation of radiation energy release in air showers

A simulation study of the energy released by extensive air showers in the form of MHz radiation is performed using the CoREAS simulation code. We develop an efficient method to extract this radiation energy from air-shower simulations. We determine the longitudinal profile of the radiation energy release and compare it to the longitudinal profile of the energy deposit by the electromagnetic component of the air shower. We find that the radiation energy corrected for the geometric dependence of the geomagnetic emission scales quadratically with the energy in the electromagnetic component of the air shower with a second-order dependence on the atmospheric density at the position of the maximum shower development X {sub max}. In a measurement where X {sub max} is not accessible, this second order dependence can be approximated using the zenith angle of the incoming direction of the air shower with only a minor loss in accuracy. Our method results in an intrinsic uncertainty of 4% in the determination of the energy in the electromagnetic air-shower component, which is well below current experimental uncertainties.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Air quality and health impacts of the 2020 wildfires in California

Abstract Background Wildfires in 2020 ravaged California to set the annual record of area burned to date. Clusters of wildfires in Northern California surrounded the Bay Area covering the skies with smoke and raising the air pollutant concentrations to hazardous levels. This study uses the Fire Inventory from the National Center for Atmospheric Research database and the Community Multiscale Air Quality model to estimate the effects of wildfire emissions on air quality during the period from August 16 to October 28 of 2020. In addition, low-cost sensor data for fine particulate matter (PM 2.5 ) from the PurpleAir network is used to enhance modeled PM 2.5 concentrations. The resulting impacts on ozone and PM 2.5 are used to quantify the health impacts caused by wildfires using the Benefits Mapping and Analysis Program – Community Edition. Results Wildfire activity significantly increased direct PM 2.5 emissions and emissions of PM 2.5 and ozone precursors. Direct PM 2.5 emissions surged up to 38 times compared to an average day. Modeling results indicated that wildfires alone led to a rise in ozone daily maximum 8-h average by up to 10 ppb and exceeded PM 2.5 air quality standards in numerous locations by up to 10 times. While modeled PM 2.5 concentrations were lower than measurements, correcting these with PurpleAir data improved the accuracy. The correction using PurpleAir data increased estimates of wildfire-induced mortality due to PM 2.5 exposure by up to 16%. Conclusions The increased hospital admissions and premature mortality attributed to wildfires were found to be comparable to the health impacts avoided by strategies aimed at meeting ozone and PM2.5 air quality standards. This suggests that widespread wildfire emissions can negate years of efforts dedicated to controlling air pollution. The integration of low-cost sensor data proved invaluable in refining the estimates of health impacts from PM2.5 resulting from wildfires.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2013

High Performance Cathodes for Li-Air Batteries

The overall objective of this project was to develop and fabricate a multifunctional cathode with high activities in acidic electrolytes for the oxygen reduction and evolution reactions for Li-air batteries. It should enable the development of Li-air batteries that operate on hybrid electrolytes, with acidic catholytes in particular. The use of hybrid electrolytes eliminates the problems of lithium reaction with water and of lithium oxide deposition in the cathode with sole organic electrolytes. The use of acid electrolytes can eliminate carbonate formation inside the cathode, making air breathing Li-air batteries viable. The tasks of the project were focused on developing hierarchical cathode structures and bifunctional catalysts. Development and testing of a prototype hybrid Li-air battery were also conducted. We succeeded in developing a hierarchical cathode structure and an effective bifunctional catalyst. We accomplished integrating the cathode with existing anode technologies and made a pouch prototype Li-air battery using sulfuric acid as catholyte. The battery cathodes contain a nanoscale multilayer structure made with carbon nanotubes and nanofibers. The structure was demonstrated to improve battery performance substantially. The bifunctional catalyst developed contains a conductive oxide support with ultra-low loading of platinum and iridium oxides. The work performed in this project has been documented in seven peer reviewed journal publications, five conference presentations, and filing of two U.S. patents. Technical details have been documented in the quarterly reports to DOE during the course of the project.

25 ENERGY STORAGE↗