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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 1,711 records · Page 95
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Combined Techno-Economic Analysis and Life Cycle Assessment of an Integrated Direct Air Capture System with Advanced Algal Biofuel Production

The continuous increase in carbon dioxide (CO2) concentration in the atmosphere since the First Industrial Revolution correlates convincingly with the ongoing rise of the Earth's global average temperature contributing to climate change. As a response, carbon capture and sequestration (CCS) technologies are being implemented to mitigate anthropogenic CO2 emissions by capturing CO2 from high emitting point sources, such as power plants, refineries, and cement factories, and subsequently buried in geological formations underground for long term storage. Recently direct air capture (DAC) has emerged as a promising alternative technology that captures CO2 directly from the atmosphere for use or sequestration. This study investigates the potential synergistic benefits of integrating a solid amine-based DAC system with advanced algal biofuel production in photobioreactors (PBRs). DAC utilization allows the removal of atmospheric CO2 while also decoupling algae production facilities from anthropogenic point CO2 sources and avoiding the cost and logistics challenges of transporting CO2 long distances to remote facilities. Techno-economic analysis and life cycle assessment are performed to assess the economic and environmental benefits of heat and mass integration between the DAC and the PBR for biofuel production. The DAC-PBR system integration also considers on-site flue gas handling options, DAC capital utilization, the tradeoff between centralization or decentralization of key unit operations, and the PBR array. This presentation will discuss how optimizing DAC-PBR process integration can enhance the algal biofuel's economic and environmental sustainability and the prospect of DAC enabling the circular carbon economy.

algal biofuel production↗
DOE OSTI2012

Transmutation abilities of the SFR low void effect core concept 'CFV' 3600 MWth

This paper presents an evaluation of the potential of minor actinide transmutation in a 3600 MWth SFR core designed with the low void effect core concept (namely 'CFV concept'). This concept is based upon an axially heterogeneous design with an internal fertile zone, and two radial fuel zones with different heights. Two modes of minor actinide transmutation are considered. The homogeneous mode where the minor actinides (MA) are diluted in the fuel is studied considering different options: - MA diluted in the whole core, - MA diluted in the internal and external fuel zone, - MA diluted in the internal fertile zone, for which different isotopic vectors and contents in fuel are analyzed. The heterogeneous mode is also studied with MA placed in external blanket bearings, with contents of 20%. The results are compared to those obtained with a traditional homogenous core concept (SFRV2B type) in terms of transmutation performances. Impacts of the transmutation assumptions on transmutation performances, on fuel cycle and safety parameters (void effect, Doppler) are also presented. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2024

Off-Design Load Analysis of sCO2 Bottoming Cycle for a Natural Gas Combined Cycle Power Plant with Carbon Capture

As an alternative to a steam cycle, a supercritical carbon dioxide (sCO2) power cycle can be considered. Able et. al performed an analysis of an sCO2 cycle in a 2x2-1 configuration; however, this study did not include carbon capture. Previous studies assumed an H-Frame turbine and added a solvent based 95% carbon capture system and performed a levelized cost of electricity (LCOE) optimization for the plant. Their results suggest a LCOE slightly better than when using a steam cycle. In the study, steam is still generated in the heat recovery sections for the solvent regeneration in the carbon capture stripper reboiler. H-Frame gas turbines are also assumed. This work starts with the optimal design from the mentioned work to analyze the off-design performance of the power plant from 100% down to 50% load. The main operational findings and plant-efficiency for off-load conditions while maintaining the target CO2 capture rate are presented. H-Frame gas turbine off-design performance and exhaust conditions to the heat recovery section are obtained from commercial software, Thermoflow®. The CO2 turbomachinery, heat exchangers and other unit operations are sized and implemented in an Aspen Plus® model. Using the gas turbine exhaust conditions as input, the sCO2 cycle is optimized by adjusting stream split ratios, sCO2 circulation flowrate and compressor speed for maximum efficiency. This is done while keeping the target 95% CO2 capture.

Chinen, Anderson Soares↗
NASA NTRS2002

Reliability Testing of NASA Piezocomposite Actuators

NASA Langley Research Center has developed a low-cost piezocomposite actuator which has application for controlling vibrations in large inflatable smart space structures, space telescopes, and high performance aircraft. Tests show the NASA piezocomposite device is capable of producing large, directional, in-plane strains on the order of 2000 parts-per-million peak-to-peak, with no reduction in free-strain performance to 100 million electrical cycles. This paper describes methods, measurements, and preliminary results from our reliability evaluation of the device under externally applied mechanical loads and at various operational temperatures. Tests performed to date show no net reductions in actuation amplitude while the device was moderately loaded through 10 million electrical cycles. Tests were performed at both room temperature and at the maximum operational temperature of the epoxy resin system used in manufacture of the device. Initial indications are that actuator reliability is excellent, with no actuator failures or large net reduction in actuator performance.

Wilkie, W.↗
DOE OSTI2012

A 48-month extended fuel cycle for the B and W mPower{sup TM} small modular nuclear reactor

The B and W mPower{sup TM} reactor is a small, rail-shippable pressurized water reactor (PWR) with an integral once-through steam generator and an electric power output of 150 MW, which is intended to replace aging fossil power plants of similar output. The core is composed of 69 reduced-height, but otherwise standard, PWR assemblies with the familiar 17 x 17 fuel rod array on a 21.5 cm inter-assembly pitch. The B and W mPower core design and cycle management plan, which were performed using the Studsvik core design code suite, follow the pattern of a typical nuclear reactor fuel cycle design and analysis performed by most nuclear fuel management organizations, such as fuel vendors and utilities. However, B and W is offering a core loading and cycle management plan for four years of continuous power operations without refueling and without the hurdles of chemical shim. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
NASA NTRS1976

Cycle life test. Evaluation program for secondary spacecraft cells

Considerable research is being done to find more efficient and reliable means of starting electrical energy for orbiting satellites. Rechargeable cells offer one such means. A test program is described which has been established in order to further the evaluation of certain types of cells and to obtain performance and failure data as an aid to their continued improvement. The purpose of the program is to determine the cycling performance capabilities of packs of cells under different load and temperature conditions. The various kinds of cells tested were nickel-cadmium, silver-cadmium, and silver-zinc sealed cells. A summary of the results of the life cycling program is given in this report.

Harkness, J. D.↗
NASA NTRS1994

Lunar base heat pump, phase 1

This report describes the Phase 1 process and analysis used to select a refrigerant and thermodynamic cycle as the basis of a vapor compression heat pump requiring a high temperature lift, then to perform a preliminary design to implement the selected concept, including major component selection. Use of a vapor compression heat pump versus other types was based on prior work performed for the Electric Power Research Institute. A high lift heat pump is needed to enable a thermal control system to remove heat down to 275 K from a habitable volume when the external thermal environment is severe. For example, a long-term lunar base habitat will reject heat from a space radiator to a 325 K environment. The first step in the selection process was to perform an optimization trade study, quantifying the effect of radiator operating temperature and heat pump efficiency on total system mass; then, select the radiator operating temperature corresponding to the lowest system mass. Total system mass included radiators, all heat pump components, and the power supply system. The study showed that lunar night operation, with no temperature lift, dictated the radiator size. To operate otherwise would require a high mass penalty to store power. With the defined radiation surface, and heat pump performances assumed to be from 40 percent to 60 percent of the Carnot ideal, the optimum heat rejection temperature ranged from 387 K to 377 K, as a function of heat pump performance. Refrigerant and thermodynamic cycles were then selected to best meet the previously determined design conditions. The system was then adapted as a ground-based prototype lifting temperature to 360 K (versus 385 K for flight unit) and using readily available commercial-grade components. Over 40 refrigerants, separated into wet and dry compression behavioral types, were considered in the selection process. Refrigerants were initially screened for acceptable critical temperature. The acceptable refrigerants were analyzed in ideal single and two-stage thermodynamic cycles. Top candidates were analyzed assuming realistic component limits and system pressure drops, and were evaluated for other considerations such as safety, environmental impact, and commercial availability. A maximum coefficient of performance (COP) of 56 percent of the Carnot ideal was achievable for a three-stage CFC-11 cycle operating under the flight conditions above. The program was completed by defining a control scheme and by researching and selecting the major components, compressor and heat exchangers, that could be used to implement the thermodynamic cycle selected. Special attention was paid to using similar technologies for the SIRF and flight heat pumps resulting in the commercially available equivalent of the flight unit. A package concept was generated for the components selected and mass and volume estimated.

Goldman, Jeffrey H.↗
NASA NTRS1973

A simple performance calculation method for LH2/LOX engines with different power cycles

A simple method for the calculation of the specific impulse of an engine with a gas generator cycle is presented. The solution is obtained by a power balance between turbine and pump. Approximate equations for the performance of the combustion products of LH2/LOX are derived. Performance results are compared with solutions of different engine types.

Schmucker, R. H.↗
NASA NTRS1977

Computer modeling of a regenerative solar-assisted Rankine power cycle

A detailed interpretation of the computer program that describes the performance of one of these cycles; namely, a regenerative Rankine power cycle is presented. Water is used as the working medium throughout the cycle. The solar energy collected at relatively low temperature level presents 75 to 80% of the total heat demand and provides mainly the latent heat of vaporization. Another energy source at high temperature level superheats the steam and supplements the solar energy share. A program summary and a numerical example showing the sequency of computations are included. The outcome from the model comprises line temperatures, component heat rates, specific steam consumption, percentage of solar energy contribution, and the overall thermal efficiency.

Lansing, F. L.↗
NASA NTRS1983

Computer program for analysis of split-Stirling-cycle cryogenic coolers

A computer program for predicting the detailed thermodynamic performance of split-Stirling-cycle refrigerators has been developed. The mathematical model includes the refrigerator cold head, free-displacer/regenerator, gas transfer line, and provision for modeling a mechanical or thermal compressor. To allow for dynamic processes (such as aerodynamic friction and heat transfer) temperature, pressure, and mass flow rate are varied by sub-dividing the refrigerator into an appropriate number of fluid and structural control volumes. Of special importance to modeling of cryogenic coolers is the inclusion of real gas properties, and allowance for variation of thermo-physical properties such as thermal conductivities, specific heats and viscosities, with temperature and/or pressure. The resulting model, therefore, comprehensively simulates the split-cycle cooler both spatially and temporally by reflecting the effects of dynamic processes and real material properties.

Brown, M. T.↗
NASA NTRS2005

Performance and Mass Modeling Subtleties in Closed-Brayton-Cycle Space Power Systems

Contents include the following: 1. Closed-Brayton-cycle (CBC) thermal energy conversion is one available option for future spacecraft and surface systems. 2. Brayton system conceptual designs for milliwatt to megawatt power converters have been developed 3. Numerous features affect overall optimized power conversion system performance: Turbomachinery efficiency. Heat exchanger effectiveness. Working-fluid composition. Cycle temperatures and pressures.

Barrett, Michael J.↗
DOE OSTI2018

Recompression Closed Brayton Cycle Control Options Nuclear Science

The attractive performance of the S-CO 2 recompression cycle arises from the thermo-physical properties of carbon dioxide near the critical point. However, to ensure efficient operation of the cycle near the critical point, precise control of the heat removal rate by the pre-cooler upstream of the main compressor is required. With respect to the S-CO 2 recompression cycle at SNL, presently an operator is tasked with manually adjusting the opening of the valve that governs the water flow rate through the pre-cooler. This report describes a procedure to design an automatic controller that uses the water flow rate as a controlling variable to regulate the S-CO 2 temperature at the pre-cooler outlet. The work relies on the GPASS control-oriented model of the pre-cooler developed last year. A model-based approach is used to design a PI (Proportional-Integral) controller. Then a transfer function describing the influence of the water flow rate on the S-CO 2 outlet temperature is derived from the pre-cooler model. Suitable values for the controller gains are then derived and finally the gains are tested on the initial time-discrete non-linear model.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2016

The Energy and Environmental Performance of Ground-Mounted Photovoltaic Systems—A Timely Update

Given photovoltaics’ (PVs) constant improvements in terms of material usage and energy efficiency, this work provides a timely update on their life-cycle energy and environmental performance. Single-crystalline Si (sc-Si), multi-crystalline Si (mc-Si), cadmium telluride (CdTe) and copper indium gallium diselenide (CIGS) systems are analysed, considering the actual country of production and adapting the input electricity mix accordingly. Energy pay-back time (EPBT) results for fixed-tilt ground mounted installations range from 0.5 years for CdTe PV at high-irradiation (2300 kWh/(m 2 ·yr)) to 2.8 years for sc-Si PV at low-irradiation (1000 kWh/(m 2 ·yr)), with corresponding quality-adjusted energy return on investment (EROI PE-eq ) values ranging from over 60 to ~10. Global warming potential (GWP) per kWh el averages out at ~30 g(CO 2 -eq), with lower values (down to ~10 g) for CdTe PV at high irradiation, and up to ~80 g for Chinese sc-Si PV at low irradiation. In general, results point to CdTe PV as the best performing technology from an environmental life-cycle perspective, also showing a remarkable improvement for current production modules in comparison with previous generations. Finally, we determined that one-axis tracking installations can improve the environmental profile of PV systems by approximately 10% for most impact metrics.

14 SOLAR ENERGY↗
DOE OSTI2012

Internal cycle modeling and environmental assessment of multiple cycle consumer products

Highlights: Black-Right-Pointing-Pointer Dynamic flow models are presented for remanufactured, reused or recycled products. Black-Right-Pointing-Pointer Early loss and stochastic return are included for fast and slow cycling products. Black-Right-Pointing-Pointer The reuse-to-input flow ratio (Internal Cycle Factor, ICF) is determined. Black-Right-Pointing-Pointer The cycle rate, which is increasing with the ICF, monitors eco-performance. Black-Right-Pointing-Pointer Early internal cycle losses diminish the ICF, the cycle rate and performance. - Abstract: Dynamic annual flow models incorporating consumer discard and usage loss and featuring deterministic and stochastic end-of-cycle (EOC) return by the consumer are developed for reused or remanufactured products (multiple cycle products, MCPs), including fast and slow cycling, short and long-lived products. It is shown that internal flows (reuse and overall consumption) increase proportionally to the dimensionless internal cycle factor (ICF) which is related to environmental impact reduction factors. The combined reuse/recycle (or cycle) rate is shown capable for shortcut, albeit effective, monitoring of environmental performance in terms of waste production, virgin material extraction and manufacturing impacts of all MCPs, a task, which physical variables (lifetime, cycling frequency, mean or total number of return trips) and conventional rates, via which environmental policy has been officially implemented (e.g. recycling rate) cannot accomplish. The cycle rate is shown to be an increasing (hyperbolic) function of ICF. The impact of the stochastic EOC return characteristics on total reuse and consumption flows, as well as on eco-performance, is assessed: symmetric EOC return has a small, positive effect on performance compared to deterministic, while early shifted EOC return is more beneficial. In order to be efficient, environmental policy should set higher minimum reuse targets for higher trippage MCPs. The results may serve for monitoring, flow accounting and comparative eco-assessment of MCPs. They may be useful in identifying reachable and efficient reuse/recycle targets for consumer products and in planning return via appropriate labelling and digital coding for enhancing environmental performance, while satisfying consumer demand.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Development of a Life Cycle Inventory of Water Consumption Associated with the Production of Transportation Fuels

The production of all forms of energy consumes water. To meet increased energy demands, it is essential to quantify the amount of water consumed in the production of different forms of energy. By analyzing the water consumed in different technologies, it is possible to identify areas for improvement in water conservation and reduce water stress in energy-producing regions. The transportation sector is a major consumer of energy in the United States. Because of the relationships between water and energy, the sustainability of transportation is tied to management of water resources. Assessment of water consumption throughout the life cycle of a fuel is necessary to understand its water resource implications. To perform a comparative life cycle assessment of transportation fuels, it is necessary first to develop an inventory of the water consumed in each process in each production supply chain. The Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) model is an analytical tool that can used to estimate the full life-cycle environmental impacts of various transportation fuel pathways from wells to wheels. GREET is currently being expanded to include water consumption as a sustainability metric. The purpose of this report was to document data sources and methodologies to estimate water consumption factors (WCF) for the various transportation fuel pathways in GREET. WCFs reflect the quantity of freshwater directly consumed per unit production for various production processes in GREET. These factors do not include consumption of precipitation or low-quality water (e.g., seawater) and reflect only water that is consumed (i.e., not returned to the source from which it was withdrawn). The data in the report can be combined with GREET to compare the life cycle water consumption for different transportation fuels.

energy-water nexus↗
DOE OSTI2019

Predicting Cycle-to-cycle Variations in a Spark-ignition Engine using Multi-cycle Large Eddy Simulation

Multi-cycle large eddy simulation (LES) of a spark-ignition engine has been performed to predict cycle-to-cycle variations (CCV). To describe spark-ignited premixed flame propagation, the front propagation formulation (FPF) method is combined with a laminar-to-turbulent flame transition model that describes the non-equilibrium flame development processes during the initial stage of the kernel growth. In the laminar-to-turbulent flame transition model, the effects of turbulence on the variations in the laminar-to-turbulent flame transition time are modeled based on the Kolmogorov energy cascade. 15 consecutive cycle LES of in-cylinder processes in a spark-ignition four-valve single cylinder engine is conducted. The predicted in-cylinder pressure is compared with the experimental measurements. The range of CCV observed in the experiment is reproduced to an acceptable degree. The predicted CCV is found to be closely related to the difference in the turbu- lence field near the spark plug around the time of spark discharging, which is consistent with the previous LES studies. The current results also suggest the importance of capturing the variations of the laminar-to-turbulent flame transition in predicting CCV.

Su, Yunde↗
DOE OSTI2019

Predicting Cycle-to-cycle Variations in a Spark-ignition Engine using Multi-cycle Large Eddy Simulation

Multi-cycle large eddy simulation (LES) of a spark-ignition engine has been performed to predict cycle-to-cycle variations (CCV). To describe spark-ignited premixed flame propagation, the front propagation formulation (FPF) method is combined with a laminar-to-turbulent flame transition model that describes the non-equilibrium flame development processes during the initial stage of the kernel growth. In the laminar-to-turbulent flame transition model, the effects of turbulence on the variations in the laminar-to-turbulent flame transition time are modeled based on the Kolmogorov energy cascade. 15 consecutive cycle LES of in-cylinder processes in a spark-ignition four-valve single cylinder engine is conducted. The predicted in-cylinder pressure is compared with the experimental measurements. The range of CCV observed in the experiment is reproduced to an acceptable degree. The predicted CCV is found to be closely related to the difference in the turbulence field near the spark plug around the time of spark discharging, which is consistent with the previous LES studies. The current results also suggest the importance of capturing the variations of the laminar-to-turbulent flame transition in predicting CCV.

Yu, Yunde↗