Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “air conditioning”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,207 records · Page 67
All sourcesNASA NTRSDOE OSTI
NASA NTRS2011

Bench-Scale Trace Contaminant Testing of SA9T at Ambient and Reduced Pressure Conditions

A principal concern for air revitalization technology in a closed loop system is the capability to control carbon dioxide (CO2) and humidity (H2O). An amine based sorbent technology, SA9T, has been evaluated for use in this application and several programs are evaluating it for use in both cabin and space suit applications. While the CO2 and H2O performance of the sorbent has been tested extensively, the question of how trace contaminants impact performance requires further evaluation. This paper presents experimental results of bench-scale SA9T testing that was performed under a variety of test conditions and with several different trace contaminants. Tests were conducted to determine if the capacity of the SA9T media to sufficiently remove CO2 and H2O is compromised after exposure to a fully saturated trace contaminant at ambient conditions. Tests also were conducted to evaluate the performance of SA9T at ambient conditions in a continuous 30-day test with a mixed trace contaminant stream. In addition, testing also evaluated the impact of CO2 and H2O removal performance at suit loop pressures (29.6 KPa/4.3 psia) during cyclic operation with a constant inlet contaminant load.

Broerman, Craig↗
NASA NTRS2011

Small Scale Trace Contaminant Testing of SA9T at Ambient and Reduced Pressure Conditions

A principle concern for air revitalization technology in a closed loop system is the capability to control carbon dioxide (CO2) and humidity (H2O). An amine based sorbent technology, SA9T, has long been evaluated for use in this application and several programs are evaluating it for use in both a cabin as well as space suit applications. While the CO2 and H2O performance of the sorbent has been tested extensively, the question of how trace contaminants impact performance requires further evaluation. This paper presents experimental results of small scale SA9T testing that was performed over a variety of test conditions and with a variety of trace contaminants. Testing evaluated the ability of SA9T media to sufficiently remove CO2 and H2O after exposure to a fully saturated trace contaminant at ambient conditions. Testing also evaluated the impact of CO2 and H2O removal performance at suit loop pressures during cyclic operation with a constant inlet contaminant load. In addition, testing evaluated the performance of SA9T at ambient conditions in a continuous 30-day test with a mixed trace contaminant stream.

Broerman, Craig↗
DOE OSTI2022

Synthesis of Nitro Compounds from Nitrogen Dioxide Captured in a Metal-Organic Framework

Increasing levels of air pollution are driving the need for the development of new processes that take “waste-to-chemicals”. Herein, we report the capture and conversion under ambient conditions of a major air pollutant, NO 2 , using a robust metal-organic framework (MOF) material, Zr-bptc (H 4 bptc = 3,3',5,5'-biphenyltetracarboxylic acid), comprising {Zr 6 (μ 3 -O) 4 (μ 3 -OH) 4 (COO) 12 } clusters linked by 4-connected bptc 4– ligands in an ftw topology. At 298 K, Zr-bptc shows exceptional stability and adsorption of NO 2 at both low (4.9 mmol g –1 at 10 mbar) and high pressures (13.8 mmol g –1 at 1.0 bar), as measured by isotherm experiments. Dynamic breakthrough experiments have confirmed the selective retention of NO 2 by Zr-bptc at low concentrations under both dry and wet conditions. The immobilized NO 2 can be readily transformed into valuable nitro compounds relevant to construction, agrochemical, and pharmaceutical industries. In situ crystallographic and spectroscopic studies reveal strong binding interactions of NO 2 to the {Zr 6 (μ 3 -O) 4 (μ 3 -OH) 4 (COO) 12 } cluster node. This study paves a circular pathway to enable the integration of nitrogen-based air pollutants into the production of fine chemicals.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Direct Air Capture Using Trapped Small Amines in Hierarchical Nanoporous Capsules on Porous Electrospun Fibers (Final Technical Report)

This report summarizes the carbon capture research and development conducted by The State University of New York at Buffalo (UB) and GTI Energy (GTI) for award “DE-FE0031969: Direct Air Capture Using Trapped Small Amines in Hierarchical Nanoporous Capsules on Porous Electrospun Fibers” sponsored by the U.S. Department of Energy (DOE). The objective of this project is to develop an innovative sorbent structure of trapped small amines in HNC embedded in PEF for DAC. This involves tailoring both sorbent and PEF materials to achieve a compact system for DAC with high capacity for CO 2 at concentrations typically available in air and at near ambient conditions. An innovative sorbent structure of trapped small amines in hierarchical nanoporous capsules (HNC) embedded in porous electrospun fibers (PEF) was developed for direct air capture (DAC). This involves tailoring both sorbent and PEF materials to achieve a compact system for DAC with high capacity for CO 2 at concentrations typically available in air and at near ambient conditions. An interfacial polymerization process was developed, which utilized loaded amines inside mesoporous silica and trimesoyl chloride (TMC) dissolved in organic solvents as the precursors, to generate a polyamide (PA) coating layer on mesoporous silica and thus trap amines. Reaction conditions, including TMC concentration, organic solvents, reaction time, etc., for interfacial polymerization were optimized to effectively trap loaded amines, and cyclic heating-cooling operation was conducted to evaluate the coating quality. Larger pore volume mesoporous silica was also synthesized to increase amine loading and thus increase CO 2 capacity. The optimized sorbent material exhibited CO 2 capacity as high as 4.88 mmol/g under humid DAC conditions and negligible loss (<1%) during 10 cyclic heating-cooling operations. The optimized PA-coated sorbent also showed fast adsorption and desorption kinetics, with <20% t1/2 increase compared to uncoated sorbent. PEF fabrication conditions, including organic solvents for dissolving core and shell polymers, voltage, distance from the nozzle to the collection panel, etc. were adjusted to better incorporate HNC. After incorporating the optimized sorbent material into PEF, the structured sorbent had a CO 2 capacity of approximately 4.0 mmol/g under humid DAC conditions, with capacity loss of 0.17% per cycle and t1/2 increase less than 10%. A techno-economic analysis (TEA) for the process design for a DAC system based on our developed sorbent structure of trapped small amines in HNC embedded in PEF was conducted. The process design included process description and major equipment sizing and energy and mass balances in addition to scale-up research results and estimated capture cost. Aspen Adsorption Simulator was used to fit the experimentally measured breakthrough curves and extract equilibrium and kinetic data of the optimized sorbent. Our results indicated that for a DAC plant with CO 2 productivity of 3,000 tonne/year, the levelized cost of CO 2 capture was $\$$612/tonne, with the largest contribution of 44.33% from the fixed operation cost. Increasing CO 2 productivity, while maintaining similar fixed operation cost, is expected to significantly reduce the CO 2 capture cost. A sensitivity study was also conducted to understand the influence of total plant cost, sorbent cost, CO 2 concentration in the feed, sorbent mat lifetime, sorbent regeneration electricity, and adsorption blower pressure drop on the levelized cost of CO 2 capture, revealing a capture cost range of $\$$520-870/tonne.

36 MATERIALS SCIENCE↗
NASA NTRS1977

Optimum space shuttle launch times relative to natural environment

Three sets of meteorological criteria were analyzed to determine the probabilities of favorable launch and landing conditions. Probabilities were computed for every 3 hours on a yearly basis using 14 years of weather data. These temporal probability distributions, applicable to the three sets of weather criteria encompassing benign, moderate and severe weather conditions, were computed for both Kennedy Space Center (KSC) and Edwards Air Force Base. In addition, conditional probabilities were computed for unfavorable weather conditions occurring after a delay which may or may not be due to weather conditions. Also, for KSC, the probabilities of favorable landing conditions at various times after favorable launch conditions have prevailed have been computed so that mission probabilities may be more accurately computed for those time periods when persistence strongly correlates weather conditions. Moreover, the probabilities and conditional probabilities of the occurrence of both favorable and unfavorable events for each individual criterion were computed to indicate the significance of each weather element to the overall result.

King, R. L.↗
NASA NTRS2019

Evaporation from the Southern Ocean Estimated on the Basis of AIRS Satellite Data

Evaporation plays an important role in the global water and energy cycles and, hence, in climate change. Evaporation over the Southern Ocean, where the Antarctic sea ice coverage has a large annual cycle, is poorly quantified. In this study, daily evaporation is estimated for the Southern Ocean with a sea‐ice‐specific algorithm, using surface temperature and air humidity from National Aeronautics and Space Administration's Atmospheric Infrared Sounder (AIRS), and wind speeds from Modern‐Era Retrospective Analysis for Research and Applications, Version 2 (MERRA‐2), reanalysis during 2003–2016. An uncertainty of 34% was found in the evaporation product. The results indicate that annual evaporation has considerable interannual and regional variability, but with a decreasing trend during the study period over most of the Southern Ocean. There are, however, areas where evaporation has increased, specifically in the Ross Sea in winter and summer, with smaller positive trends in spring and fall. Overall, the changes in the difference between the surface specific humidity and the air specific humidity, and to a much lesser extent in the wind speed, are the main drivers for the changes in evaporation throughout the year. During spring and fall months, changes to the sea ice cover, which alter the surface specific humidity, are the main drivers for the change, but in summer and winter the main driver is the air‐specific humidity. Air masses originating from the Antarctic continent (south) are associated with cold and dry conditions, which increase evaporation, whereas air masses from lower latitudes in the Southern Ocean (north) are associated with warm and moist conditions, decreasing evaporation. Comparisons with other reanalysis evaporation products produce similar trends, although annual averages differ.

Boisvert, Linette↗
NASA NTRS1938

Engine Performance and Knock Rating of Fuels for High-output Aircraft Engines

Data are presented to show the effects of inlet-air pressure, inlet-air temperature, and compression ratio on the maximum permissible performance obtained on a single-cylinder test engine with aircraft-engine fuels varying from a fuel of 87 octane number to one 100 octane number plus 1 ml of tetraethyl lead per gallon. The data were obtained on a 5-inch by 5.75-inch liquid-cooled engine operating at 2,500 r.p.m. The compression ratio was varied from 6.50 to 8.75. The inlet-air temperature was varied from 120 to 280 F. and the inlet-air pressure from 30 inches of mercury absolute to the highest permissible. The limiting factors for the increase in compression ratio and in inlet-air pressure was the occurrence of either audible or incipient knock. The data are correlated to show that, for any one fuel,there is a definite relationship between the limiting conditions of inlet-air temperature and density at any compression ratio. This relationship is dependent on the combustion-gas temperature and density relationship that causes knock. The report presents a suggested method of rating aircraft-engine fuels based on this relationship. It is concluded that aircraft-engine fuels cannot be satisfactorily rated by any single factor, such as octane number, highest useful compression ratio, or allowable boost pressure. The fuels should be rated by a curve that expresses the limitations of the fuel over a variety of engine conditions.

Rothbrock, A M↗
DOE OSTI2023

Aging studies of Dual functional materials for CO 2 direct air capture with in situ methanation under simulated ambient conditions: Ru thrifting for cost reduction

Dual function materials (DFMs) comprised of 0.25 %Ru, 6.1 %Na 2 O/γ-Al 2 O 3 //monolith were evaluated for about 250 hours time-on-stream (TOS) at various simulated ambient climate capture conditions followed by temperature swing methanation to 280 °C. Herein this paper focuses on the impact of thrifting Ru to low levels and the impact on performance. Results showed both stable CO 2 capture capacity and CH 4 production with 0.25 % Ru DFM deposited on a ceramic monolith. The CO 2 conversion to CH 4 production was decreased slightly by the Ru decrease from 1 % to 0.25 %. The capture capacity decreased since a lower Ru content reduces the complete decomposition of the Na 2 CO 3 precursor producing fewer active adsorption sites (“Na 2 O”). The deployment of a low Ru DFM monolith would significantly decrease the overall capital cost and give more potential for a large-scale direct air capture and methanation (DACM) application.

03 NATURAL GAS↗
NASA NTRS1987

Downdrafts within High Plains cumulonimbi. I - General kinematic structure

Results from a comprehensive investigation in which observations from several case studies are integrated with three-dimensional cloud model results to examine the general kinematic structure of downdrafts associated with High Plains precipitating convection are presented. One particular downdraft type, the low-level precipitation-associated downdraft, is the focus of this paper. General airflow and trajectory patterns within low-level downdrafts are convergent from 0.8 km upwards to downdraft top, typically less than 5 km AGL. Observed mass flux profiles often increase rapidly with height as a result of strong buoyancy forcing below the melting level. Inflow to the low-level downdraft, although vertically continuous can be separated into two branches. The up-down branch originating within the planetary boundary layer initially rises up to 4 km and then descends within the main precipitation-associated downdraft. The midlevel branch, usually more pronounced during early downdraft stages, originates from above the PBL and transports low-valued theta sub e air to low levels. The depth of the low-level downdraft can be approximated by the environmental sounding transition level, defined as the vertical height interval separating conditionally unstable to neutral air below from roughly stable air above. The low-level downdraft is most frequently located along the upshear storm flank relative to the updraft, although a downshear downdraft may become common under higher environmental wind shear.

Knupp, Kevin R.↗
NASA NTRS2014

A Thermal Analysis of a Hot-Wire Probe for Icing Applications

This paper presents a steady-state thermal model of a hot-wire instrument applicable to atmospheric measurement of water content in clouds. In this application, the power required to maintain the wire at a given temperature is used to deduce the water content of the cloud. The model considers electrical resistive heating, axial conduction, convection to the flow, radiation to the surroundings, as well as energy loss due to the heating, melting, and evaporation of impinging liquid and or ice. All of these parameters can be varied axially along the wire. The model further introduces a parameter called the evaporation potential which locally gauges the maximum fraction of incoming water that evaporates. The primary outputs of the model are the steady-state power required to maintain a spatially-average constant temperature as well as the variation of that temperature and other parameters along the wire. The model is used to understand the sensitivity of the hot-wire performance to various flow and boundary conditions including a detailed comparison of dry air and wet (i.e. cloud-on) conditions. The steady-state power values are compared to experimental results from a Science Engineering Associates (SEA) Multi-Element probe, a commonly used water-content measurement instrument. The model results show good agreement with experiment for both dry and cloud-on conditions with liquid water content. For ice, the experimental measurements under read the actual water content due to incomplete evaporation and splashing. Model results, which account for incomplete evaporation, are still higher than experimental results where the discrepancy is attributed to splashing mass-loss which is not accounted in the model.

Thermal Analysis↗
NASA NTRS2018

Extreme Air Pollution Events in Hokkaido, Japan Traced Back to Early Snowmelt and Large-Scale Wildfires Over East Eurasia: Case Studies

To identify the unusual climate conditions and their connections to air pollutions in a remote area due to wildfires, we examine three anomalous large-scale wildfires in May 2003, April 2008, and July 2014 over East Eurasia, as well as how products of those wildfires reached an urban city, Sapporo, in the northern part of Japan (Hokkaido), significantly affecting the air quality. NASA's MERRA-2 (the Modern-Era Retrospective analysis for Research and Applications, Version 2) aerosol re-analysis data closely reproduced the PM2.5 variations in Sapporo for the case of smoke arrival inJuly 2014. Results show that all three cases featured unusually early snowmelt in East Eurasia, accompanied by warmer and drier surface conditions in the months leading to the fires, inducing long-lasting soil dryness and producing environmental conditions conductive to active wildfires. Due to prevailing anomalous synoptic-scale atmospheric motions, smoke from those fires eventually reached a remote area, Hokkaido, and worsened the air quality in Sapporo. In futurestudies, continuous monitoring of the timing of Eurasian snowmelt and the air quality from the source regions to remote regions, coupled with the analysis of atmospheric and surface conditions, may be essential in more accurately predicting the effects of wildfires on air quality.

MERRA-2↗
DOE OSTI2021

An Efficient Bifunctional Air Electrode for Reversible Protonic Ceramic Electrochemical Cells

One of the main bottlenecks that limits the performance of reversible protonic ceramic electrochemical cells (R-PCECs) is the sluggish kinetics of the oxygen reduction and evolution reactions (ORR and OER). Here, the significantly enhanced ORR and OER kinetics and stability of a conventional La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF) air electrode by an efficient catalyst coating of barium cobaltite (BCO) is reported. The polarization resistance of a BCO-coated LSCF air electrode at 600 oC is 0.16 Ω cm 2 , about 30% of that of the bare LSCF air electrode under the same conditions. Further, a R-PCEC with the BCO-coated LSCF air electrode shows exceptional performance in both fuel cell (maximum power density of 1.16 W cm -2 at 600 ºC) and electrolysis (current density of 1.80 A cm -2 at 600 ºC at 1.3 V) modes. Finally, the performance enhancement is attributed mainly to the facilitated rate of oxygen surface exchange.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS1981

Terrestrial photovoltaic performance reference conditions

The rationale behind the selection of key photovoltaic performance reference (reporting) conditions, including the standard Air Mass 1.5 solar spectrum and reference irradiance and cell temperature levels, is investigated. Besides providing a repeatable reference for performance comparisons, it is shown that the choice of reference conditions directly controls the accuracy of array energy output prediction calculations. Conclusions are drawn on the accuracy associated with present reference conditions, and recommendations are made concerning alternative reference conditions with improved accuracy.

Ross, R. G., Jr.↗
DOE OSTI2026

Concept of Dynamic Heat Insulation for Rotating Detonation Engines

This work introduces a new class of materials concept to dynamically reduce instantaneous heat fluxes in Rotating Detonation Engine (RDE) combustor chamber walls. The high-frequency and high-amplitude surface heat fluxes observed in RDEs arise from large instantaneous temperature differences between the detonation shockwave and chamber wall surface. These temperature gradients drive substantial energy loss and reduce the chamber gas pressure, ultimately limiting the cycle’s thermodynamic efficiency. This work introduces a concept for dynamically insulating the combustion chamber surfaces using surface layers or coatings with low thermal time scale. With such coatings, the surface temperature may follow the fluctuations of the cyclic detonation wave temperature, thus reducing the instantaneous heat flux therefore cycle-mean heat flux. To analyze these cyclic thermal phenomena, a one-dimensional analytical conduction solver was utilized with the capability to handle multilayered structures. Parametric modeling was performed using transient heat flux boundary conditions representative of a hydrogen–air RDE across a broad range of coating thermal properties and engine conditions. The coating effectiveness scaled with the product of thermal time constant and detonation wave frequency and the results were non-dimensionalized to guide future materials development. This strategy may offer benefits in increasing material survivability, reducing cooling requirements, and enhancing pressure gain.

heat transfer↗
DOE OSTI2020

Regional difference and related cooling electricity savings of air pollutant affected natural ventilation in commercial buildings across the US

Maintaining indoor air pollutants under acceptable levels is significant to protect occupants from exposure to excessive air pollutants in natural ventilation. In this paper, using the representative air pollutant concentration data, we present the natural ventilation usability with associated cooling energy saving potentials in different location settings (urban and city center, suburban and rural) of the US under the influence of local weather conditions and major outdoor air pollutants, i.e. PM2.5, PM10 and ozone. It is found that the impacts of air pollutants on natural ventilation are usually higher in urban/suburban areas than rural areas (up to 25% difference) with the PM2.5 being the most significant outdoor air pollutant affecting natural ventilation usage. Furthermore, ozone could become increasingly influential on natural ventilation as moving from urban to suburban/rural areas. As to the cooling energy saving considering the impacts of outdoor air pollutants, natural ventilation is estimated to save approximately 10%–40% cooling energy (800–2600 kWh per small commercial building) annually in different location settings of investigated areas across the US. The following economic analysis demonstrates that these electricity savings lead to approximately 80–540 dollars annual savings of building operation cost per building. If the time of use rate is adopted, these cost savings could further increase by approximately 20% (Los Angeles) to more than 50% (Albuquerque) depending on different rate structures, which further demonstrates the potential of adopting natural ventilation as a sustainability measurement with benefits for building owners without compromising occupants health.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS1977

Optimum space shuttle launch times relative to natural environment

The probabilities of favorable and unfavorable weather conditions for launch and landing of the STS under different criteria were computed for every three hours on a yearly basis using 14 years of weather data. These temporal probability distributions were considered for three sets of weather criteria encompassing benign, moderate and severe weather conditions for both Kennedy Space Center and for Edwards Air Force Base. In addition, the conditional probabilities were computed for unfavorable weather conditions occurring after a delay which may or may not be due to weather conditions. Also for KSC, the probabilities of favorable landing conditions at various times after favorable launch conditions have prevailed. The probabilities were computed to indicate the significance of each weather element to the overall result.

King, R. L.↗
NASA NTRS1986

A study of the relationship among wind speed, sea state, and the drag coefficient for a developing wave field

Controlled laboratory experiments are reported which demonstrate directly and quantitatively the influence of wave conditions in determining the drag law at the air-sea interface under neutral stability conditions. It is concluded that the analytic form first proposed by Kitaigorodskii (1970) models the roughness scale very well when the sea is dominated by the locally generated waves. It is demonstrated that, by using a unified two-parameter wave spectral model by Huang et al. (1981), Kitaigorodskii's result can be shown to contain the formulas of Charnock (1955) and Hsu (1974) as special cases. The results also identify two wind and wave-related parameters as important in determining the drag coefficient for developing wave fields.

Huang, N. E.↗
NASA NTRS2008

Non-Boltzmann Modeling for Air Shock-Layer Radiation at Lunar-Return Conditions

This paper investigates the non-Boltzmann modeling of the radiating atomic and molecular electronic states present in lunar-return shock-layers. The Master Equation is derived for a general atom or molecule while accounting for a variety of excitation and de-excitation mechanisms. A new set of electronic-impact excitation rates is compiled for N, O, and N2+, which are the main radiating species for most lunar-return shock-layers. Based on these new rates, a novel approach of curve-fitting the non-Boltzmann populations of the radiating atomic and molecular states is developed. This new approach provides a simple and accurate method for calculating the atomic and molecular non-Boltzmann populations while avoiding the matrix inversion procedure required for the detailed solution of the Master Equation. The radiative flux values predicted by the present detailed non-Boltzmann model and the approximate curve-fitting approach are shown to agree within 5% for the Fire 1634 s case.

Johnston, Christopher O.↗