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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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78 records · Page 5

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NASA NTRS2004

History of Sulphur Content Effects on the Thermal Stability of RP-1 under Heated Conditions

As technologies advance in the aerospace industry, a strong desire has emerged to design more efficient, longer life, reusable liquid hydrocarbon fueled rocket engines. To achieve this goal, a more complete understanding of the thermal stability and chemical makeup of the hydrocarbon propellant is needed. Since the main fuel used in modern liquid hydrocarbon systems is RP-1, there is concern that Standard Grade RP-1 may not be a suitable propellant for future-generation rocket engines due to concern over the outdated Mil-Specification for the fuel. This current specification allows high valued limits on contaminants such as sulfur compounds, and also lacks specification of required thermal stability qualifications for the fuel. Previous studies have highlighted the detrimental effect of high levels of mercaptan sulfur content (^50 ppm) on copper rocket engine materials, but the fuel itself has not been studied. While the role of sulfur in other fuels (e.g., aviation, diesel, and automotive fuels) has been extensively studied, little has been reported on the effects of sulfur levels in rocket fuels. Lower RP-1 sulfur concentrations need to be evaluated and an acceptable sulfur limit established before RP-1 can be recommended for use as the propellant for future launch vehicles. (5 tables, 8 figures, 9 refs.)

ASTM METHOD D-5623↗

DOE OSTI2024

Computational analysis of flame initiation, quenching, and re-ignition in a prechamber natural gas engine under varying EGR-dilution levels

The on-road natural-gas (NG) fueled transportation relies on stoichiometric spark-ignition engines for the advantages of simple after-treatment system despite the efficiency penalty relative to lean-burn combustion strategies. Exhaust gas recirculation (EGR) has the potential to reduce this efficiency gap at low to moderate loads without the need for complex lean-exhaust aftertreatment systems. However, EGR dilution leads to reduced combustion stability and increased cycle-to-cycle variability. A promising technology that has the potential to achieve reliable operation under diluted conditions is the prechamber ignition (or turbulent jet ignition) which uses chemically active turbulent jets generated from combustion inside a prechamber to initiate, stabilize and accelerate combustion of the mixture inside the main chamber. The present work focusses on developing a RANS-based CFD approach to accurately reproduce in-cylinder phenomena in a stoichiometric NG prechamber-assisted heavy-duty engine without relying on complex combustion models that account for turbulence-chemistry interactions. This is necessary because reactive prechamber jets at high EGR dilution tend to extinguish while emerging into the main chamber, which is followed by a phase of re-ignition — a phenomenon that conventional G-equation or well-stirred reactor combustion models cannot reproduce. With addition of a damping multiplier to the well-stirred reactor model, the predictions are seen to show good agreement with experimental pressure evolution and combustion images acquired from a single cylinder Cummins N-14 optical diesel engine retrofitted with a prechamber ignition system. Model predictions of local heat release in the flame and temperature evolution inside the flame are used to investigate combustion dynamics in the prechamber and the main chamber. It is seen that the well-stirred reactor model with the inclusion of damping is able to reproduce the temporary reduction in heat release within the flame, which can be considered equivalent to quenching of jets, and the subsequent re-ignition of the flame inside the main chamber. The delay between quenching and re-ignition depends on the amount of dilution, as explained by an illustration of flame evolution in a Borghi diagram.

Prechamber ignition↗

DOE OSTI2018

Evaluation of Shot-to-Shot In-Nozzle Flow Variations in a Heavy-Duty Diesel Injector Using Real Nozzle Geometry

Cyclic variability in internal combustion engines (ICEs) arises from multiple concurrent sources, many of which remain to be fully understood and controlled. This variability can, in turn, affect the behavior of the engine resulting in undesirable deviations from the expected operating conditions and performance. Shot-to-shot variation during the fuel injection process is strongly suspected of being a source of cyclic variability. This study focuses on the shot-to-shot variability of injector needle motion and its influence on the internal nozzle flow behavior using diesel fuel. High-speed x-ray imaging techniques have been used to extract high-resolution injector geometry images of the sac, orifices, and needle tip that allowed the true dynamics of the needle motion to emerge. These measurements showed high repeatability in the needle lift profile across multiple injection events, while the needle radial displacement was characterized by a much higher degree of randomness. A robust and previously validated computational setup from the authors’ research group using a commercial computational fluid dynamics (CFD) code has been adapted for the eight-hole heavy-duty common-rail diesel injector used for the measurements. The simulation results obtained using the x-ray-scanned geometry have been validated against available experimental data of mass flow rate at the nozzle exit. The fuel mass flow rate has then been analyzed at three different injection pressures that cover the conditions at which the injector typically operates during normal engine operation. Finally, the average off-axis motion of the needle has been perturbed (based on the variability found in the experimental measurements) to generate three new cases that present different amplitude and phasing of the radial displacement with respect to the baseline average motion. Furthermore, this revealed the effects of off-axis motion on shot-to-shot and orifice-to-orifice variations.

42 ENGINEERING↗

DOE OSTI2012

Advancing the Renewable Industry in Minnesota

This report deals with seven topics: 1. "Utilizing Ash Wastes as a Nutrient Source for Corn": As forms of gasification and combustion grow in the area of renewable energy in Minnesota the question arises regarding the utilization/application of the ash co product produced from these processes. Currently there are four facilities in Minnesota producing an ash co product (three ethanol facilities and one combusting biomass to produce energy). These ash wastes are generated from using ethanol by-products as a fuel or heating source for fermentation. Other ash wastes from agricultural sources include turkey litter ash. When applied to agricultural fields, ash wastes can be a source of nutrients for agricultural crops. Chemical analyses of ash wastes vary, but 200 to 300 lb of P 2 O 5 and K 2 O per ton of ash is typical. The value of ash wastes as a fertilizer has increased because commercial fertilizer prices have increased significantly over the last few years. Specifically: Compaction/Agglomeration research- Research included development of an appropriate product for use in current delivery systems by densifying the ash into the form of pellets or briquettes which may reduce fertilizer input cost to farmers. The initiative addresses the use of phosphorus and potassium from co-firing or gasification processes as a fertilizer source. 2. "Use of Glycerol as a Corn Replacement in Calf Starter Diets": Glycerol is a sugar alcohol by-product of bio-diesel production. About 1 gallon of glycerin is produced for every 10 gallons of bio-diesel of which the glycerol content may vary between 63 and almost 100%. There is some uncertainty of the exact energy value of glycerol as an ingredient for animal feed but it has been successfully used as a replacement for corn up to 10% of the diet dry matter for lactating dairy cows. There is a lack of information on incorporating glycerol into diets for pre- and post weaned dairy heifer calves which has the potential to expand the market for this by product. Preliminary work at SROC indicates that there are no palatability problems using glycerol up to 6% of the mix in post weaning pellets for group fed dairy heifers. 3. "Intervention Strategies for Reduction of Food-borne Pathogens in Cattle Fed Ethanol Byproducts": Ethanol plants and cattle producers create a symbiotic relationship: The use of wet and dry distiller’s grains in beef cattle rations provides significant improvement in overall feedlot performance for many producers in Minnesota and the Upper Midwest. Distiller’s grain is the coproduct that remains following the distillation of ethanol. It may be dehydrated to produce dried distiller’s grain (DDG) which is then commonly used as livestock feed. The use of distiller’s grains in livestock rations has been the subject of numerous research projects over the past ten years. Recently published research data conducted at Kansas State University (K-State) has created controversy over the feeding of distiller’s grains in beef cattle rations. The research indicates that cattle fed distiller’s grain may have an increased probability of Escherichia coli O157 in their hindgut. Specifically: This research assessment was a two part project consisting of feeding trials conducted at the University of Minnesota and an intervention study conducted at Kansas State University. This report is the Kansas State University portion. This report is a task-level final technical report. 4. "Impact of Distillers' Grains and Glycerin on Cattle Fecal Shedding of Escherichia coli O157:H7" 5. "Study Assessing the Opportunities and Potential of Soybean Based Products and Technologies": Based on demand/market potential, economic feasibility, stage of development and strength of institutional support, Informa Economics, Inc. ("Informa") narrowed down a list of more than 100 emerging soybean products and to 8 of the most promising for soybean, considered to have the greatest potential to add significant value to Minnesota's soybean commodity production. However, as with the potential of any biobased product or technology, the development of these emerging soybean products and technologies will be heavily reliant on future market price environments (especially for petroleum) and government policies. This report identifies what the contractor believes are the top 8 products and technologies for soybeans at the time of publishing. 6. "Study Assessing the Opportunities and Potential of Corn-Based Products and Technologies": Based on demand/market potential, economic feasibility, stage of development and strength of institutional support, Informa Economics, Inc. ("Informa") narrowed down a list of more than 100 emerging corn products and technologies to 8 of the most promising for corn, considered to have the greatest potential to add significant value to Minnesota's corn commodity production. However, as with the potential of any biobased product or technology, the development of these emerging corn products and technologies will be heavily reliant on future market price environments (especially for petroleum) and government policies. This report identifies what the contractor believes are the top 8 products and technologies for corn at the time of publishing. 7. "Distributed Power Generation Technology (Roseau Gasification)."

09 BIOMASS FUELS↗

DOE OSTI2012

Opportunities and Challenges for Solar Minigrid Development in Rural India

The goal of this report is to inform investors about the potential of solar minigrid technologies to serve India’s rural market. India, a rapidly emerging economy with the world’s second largest population, is facing a surging energy demand. A large portion of India’s rural population, which represents 60% of the total population, does not have access to reliable electricity or has limited access and relies heavily on fuels such as wood, diesel, and kerosene to fulfill energy needs. Using the most recent available expenditure data, it is estimated that India’s rural consumers currently spend US$\$$4.86 billion (INR 243 billion ) per year on energy. Because of the linkages between reliable electricity supply, gross domestic product growth, and living standards, the Indian government is accelerating the deployment of electricity to India’s rural population. In January 2010, India’s Ministry of New and Renewable Energy (MNRE) under the Jawaharlal Nehru National Solar Mission (JNNSM) announced the goal of deploying 20 gigawatts (GW) of grid-connected solar power and 2 GW of off-grid solar by 2022. Their objective is to invest in India’s vast solar resources by deploying solar energy on a broad scale and extending modern power services to millions. Specifically, the JNNSM in Phase I of the mission has set the goal of implementing 1 GW of grid-connected solar and 200 megawatts (MW) of off-grid solar power (rural village electrification) by March 2013. By providing many incentives for renewable energy projects, including capital subsidies of up to 90%, tax holidays, and low-interest loans, the government is hoping to spur clean energy development in key areas. India’s electricity demand is expected to increase from 900 billion kilowatt-hours (kWh) to 1,400 billion kWh by March 2017. To meet this demand, India’s power sector overall will need an investment of US$\$$300 billion to US$\$$400 billion during the five-year economic plan that started April 2012 and ends March 2017 to meet its generation targets. MNRE’s target of installing 1,100 MW of solar minigrid capacity in the next five years will require public and private sector investments of roughly $\$$US4.4 billion.

14 SOLAR ENERGY↗

DOE OSTI2013

San Francisco Biofuel Program: Brown Grease to Biodiesel Demonstration (Project Report)

Municipal wastewater treatment facilities have typically been limited to the role of accepting wastewater, treating it to required levels, and disposing of its treatment residuals. However, a new view is emerging which includes wastewater treatment facilities as regional resource recovery centers. This view is a direct result of increasingly stringent regulations, concerns over energy use, carbon footprint, and worldwide depletion of fossil fuel resources. Resources in wastewater include chemical and thermal energy, as well as nutrients, and water. A waste stream such as residual grease, which concentrates in the drainage from restaurants (referred to as Trap Waste), is a good example of a resource with an energy content that can be recovered for beneficial reuse. If left in wastewater, grease accumulates inside of the wastewater collection system and can lead to increased corrosion and pipe blockages that can cause wastewater overflows. Also, grease in wastewater that arrives at the treatment facility can impair the operation of preliminary treatment equipment and is only partly removed in the primary treatment process. In addition, residual grease increases the demand in treatment materials such as oxygen in the secondary treatment process. When disposed of in landfills, grease is likely to undergo anaerobic decay prior to landfill capping, resulting in the atmospheric release of methane, a greenhouse gas (GHG). This research project was therefore conceptualized and implemented by the San Francisco Public Utilities Commission (SFPUC) to test the feasibility of energy recovery from Trap Waste in the form of Biodiesel or Methane gas. The research goals are given below: To validate technology performance; To determine the costs and benefits [including economic, socioeconomic, and GHG emissions reduction] associated with co-locating this type of operation at a municipal wastewater treatment plant (WWTP); To develop a business case or model for replication of the program by other municipal agencies (as applicable). In order to accomplish the goals of the project, the following steps were performed: 1. Operation of a demonstration facility designed to receive 10,000 to 12,000 gallons of raw Trap Waste each day from private Trap Waste hauling companies. The demonstration facility was designed and built by Pacific Biodiesel Technologies (PBTech). The demonstration facility would also recover 300 gallons of Brown Grease per day from the raw Trap Waste. The recovered Brown Grease was expected to contain no more than 2% Moisture, Insolubles, and Unsaponifiables (MIU) combined. 2. Co-digestion of the side streams (generated during the recovery of 300 gallons of Brown Grease from the raw Trap Waste) with wastewater sludge in the WWTP's anaerobic digesters. The effects of the side streams on anaerobic digestion were quantified by comparison with baseline data. 3. Production of 240 gallons per day of ASTM D6751-S15 grade Biodiesel fuel via a Biodiesel conversion demonstration facility, with the use of recovered Brown Grease as a feedstock. The demonstration facility was designed and built by Blackgold Biofuels (BGB). Side streams from this process were also co-digested with wastewater sludge. Bench-scale anaerobic digestion testing was conducted on side streams from both demonstration facilities to determine potential toxicity and/or changes in biogas production in the WWTP anaerobic digester. While there is a lot of theoretical data available on the lab-scale production of Biodiesel from grease Trap Waste, this full-scale demonstration project was one of the first of its kind in the United States. The project's environmental impacts were expected to include: Reduction of greenhouse gas emissions by prevention of the release of methane at landfills. Although the combustion product of Biodiesel and Methane gas produced in the Anaerobic digester, Carbon Dioxide, is also a greenhouse gas; it is 20 times weaker for the same amount (per mole) released, making its discharge preferable to that of Methane. The use of Biodiesel in place of fossil-fuel derived Diesel was expected to reduce net Carbon Dioxide, Ash Particulate, Sulfate, Silicate, and Soot emissions, thereby improving air quality.

09 BIOMASS FUELS↗