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When developing new combustion concepts, CFD simulations is a powerful tool. The modeling of spray formation is a challenging but important part when it comes to CFD modelling of non-premixed combustion. There is a large difference in the accuracy and robustness among different spray models and their implementation in different CFD codes. In the work presented in this paper a spray model, designated as VSB2 has been implemented in OpenFOAM. VSB2 differ from traditional spray models by replacing the Lagrangian parcels with stochastic blobs. The stochastic blobs consists of a droplet size distribution rather than equal sized droplets, as is the case with the traditional parcel. The VSB2 model has previously been thoroughly validated for spray formation and combustion of n-heptane. The aim of this study was to validate the VSB2 spray model for ethanol spray formation and combustion as a step in modelling dual-fuel combustion with alcohol and diesel.

In this work, the influences of ethanol and iso-butanol blended with gasoline on engine-out and post three-way catalyst (TWC) particle size distribution and number concentration were studied using a General Motors (GM) 2.0L turbocharged spark ignition direct injection (SIDI) engine. The engine was operated using the production engine control unit (ECU) with a dynamometer controlling the engine speed and the accelerator pedal position controlling the engine load. A TSI Fast Mobility Particle Sizer (FMPS) spectrometer was used to measure the particle size distribution in the range from 5.6 to 560 nm with a sampling rate of 1 Hz. U.S. federal certification gasoline (E0), two ethanol-blended fuels (E10 and E20), and 11.7% iso-butanol blended fuel (BU12) were tested. Measurements were conducted at 10 selected steady-state engine operation conditions. Bi-modal particle size distributions were observed for all operating conditions with peak values at particle sizes of 10 nm and 70 nm.

We describe a study to identify potential biofuels that enable advanced spark ignition (SI) engine efficiency strategies to be pursued more aggressively. A list of potential biomass-derived blendstocks was developed. An online database of properties and characteristics of these bioblendstocks was created and populated. Fuel properties were determined by measurement, model prediction, or literature review. Screening criteria were developed to determine if a bioblendstock met the requirements for advanced SI engines. Criteria included melting point (or cloud point) < -10°C and boiling point (or T90) <165°C. Compounds insoluble or poorly soluble in hydrocarbon were eliminated from consideration, as were those known to cause corrosion (carboxylic acids or high acid number mixtures) and those with hazard classification as known or suspected carcinogens or reproductive toxins.

A key component of an Advanced Life Support (ALS) system is the solid waste handling system. One of the most important data sets for determining what solid waste handling technologies are needed is a solid waste model. A preliminary solid waste model based on a six-person crew was developed prior to the 2000 Solid Waste Processing and Resource Recovery (SWPRR) workshop. After the workshop, comments from the ALS community helped refine the model. Refinements included better estimates of both inedible plant biomass and packaging materials. Estimates for Extravehicular Mobility Unit (EMU) waste, water processor brine solution, as well as the water contents for various solid wastes were included in the model refinement efforts. The wastes were re-categorized and the dry wastes were separated from wet wastes. This paper details the revised model as of the end of 2001. The packaging materials, as well as the biomass wastes, vary significantly between different proposed Mars missions.

Spark-ignition engine fuel standards have been put in place to ensure acceptable hot and cold weather driveability (HWD and CWD). Vehicle manufacturers and fuel suppliers have developed systems that meet our driveability requirements so effectively that drivers overwhelmingly find that their vehicles reliably start up and operate smoothly and consistently throughout the year. For HWD, fuels that are too volatile perform more poorly than those that are less volatile. Vapor lock is the apparent cause of poor HWD, but there is conflicting evidence in the literature as to where in the fuel system it occurs. Most studies have found a correlation between degraded driveability and higher dry vapor pressure equivalent or lower TV/L = 20, and less consistently with a minimum T50. For CWD, fuels with inadequate volatility can cause difficulty in starting and rough operation during engine warmup.

Regulated and unregulated emissions (individual hydrocarbons, ethanol, aldehydes and ketones, polynuclear aromatic hydrocarbons (PAH), nitro-PAH, and soluble organic fraction of particulate matter) were characterized in engines utilizing duplicate ISO 8178-C1 eight-mode tests and FTP smoke tests. Certification No. 2 diesel (400 ppm sulfur) and three ethanol/diesel blends, containing 7.7 percent, 10 percent, and 15 percent ethanol, respectively, were used. The three, Tier II, off-road engines were 6.8-L, 8.1-L, and 12.5-L in displacement and each had differing fuel injection system designs. It was found that smoke and particulate matter emissions decreased with increasing ethanol content. Changes to the emissions of carbon monoxide and oxides of nitrogen varied with engine design, with some increases and some decreases. As expected, increasing ethanol concentration led to higher emissions of acetaldehyde (increases ranging from 27 to 139 percent).

Biological wastewater processing has been under investigation by AlliedSignal Aerospace and NASA Johnson Space Center (JSC) for future use in space. Testing at JSC in the Hybrid Regenerative Water Recovery System (HRWRS) in preparation for future closed human testing has been performed. Computer models have been developed to aid in the design of a new four-person immobilized cell bioreactor. The design of the reactor and validation of the computer model is presented. In addition, the total organic carbon (TOC) computer model has been expanded to begin investigation of nitrification. This model is being developed to identify the key parameters of the nitrification process, and to improve the design and operating conditions of nitrifying bioreactors. In addition, the model can be used as a design tool to rapidly predict the effects of changes in operational conditions and reactor design, significantly reducing the number and duration of experiments required.

Two crops of lettuce (Lactuca sativa cv. Waldmann's Green) were grown in the Regenerative Life Support Systems (RLSS) Test Bed at NASA's Johnson Space Center. The RLSS Test Bed is an atmospherically closed, controlled environment facility for the evaluation of regenerative life support systems using higher plants. The chamber encloses 10.6 m2 of growth area under cool-white fluorescent lamps. Lettuce was double seeded in 480 pots, each containing about 250 cm3 of calcined-clay substrate. Each pot was irrigated with half-strength Hoagland's nutrient solution at an average total applied amount of 2.5 and 1.8 liters pot-1, respectively, over each of the two 30-day crop tests. Average environmental and cultural conditions during both tests were 23°C air temperature, 72% relative humidity, 1000 ppm carbon dioxide (CO2), 16h light/8h dark photoperiod, and 356 μmol m-2s-1 photosynthetic photon flux.

Previous studies indicated evidence of opportunistic pathogens in samples obtained during missions to the International Space Station (ISS). This study utilized TaqMan quantitative PCR to determine specific gene abundance in potable and non-potable ISS waters. Probe and primer sets specific to the small subunit rRNA genes were designed and used to elucidate overall bacterial rRNA gene numbers. In addition, primer-probe sets specific for Burkholderia cepacia and Stenotrophomonas maltophilia were optimized and genes of these two opportunistic pathogens quantified in the pre- and post-flight drinking water as well as coolant waters. This Q-PCR approach supports findings of previous culture-based studies however; the culture based studies may have underestimated the microbial burden of ISS drinking water.

This paper describes results acquired from E-Tongue 2 and E-Tongue 3 which are arrays of planar three-element electrochemical cells and pH sensors. The approach uses ASV (Anodic Stripping Voltammery) to achieve a detection limit, which in the case of Pb, is below one μM which is needed for water quality measurements. The richness of the detectable species is illustrated with Fe where seven species are identified using the Pourbiax diagram. The detection of multiple species is illustrated using Pb and Cu. The apparatus was used to detect the electroactivity of the metabolic-surrogate, PMS (phenazine-methosulphate). Finally, four types of pH sensors were fabricated and characterized for linearity, sensitivity, and responsiveness.

The recovery of potable water from waste water produced by humans in regenerative life support systems is essential for success of long-duration space missions. The Lunar-Mars Life Support Test Project (LMLSTP) Phase II test was performed to validate candidate technologies to support these missions. The test was conducted in the Crew and Thermal Systems Division (CTSD) Life Support Systems Integration Facility (LSSIF) at Johnson Space Center (JSC). Discussed in this paper are the water recovery system (WRS) results of this test. A crew of 4-persons participated in the test and lived in the LSSIF chamber for a duration of 30-days from June 12 to July 12, 1996. The crew had accommodations for personal hygiene, the air was regenerated for reuse, and the waste water was processed to potable and hygiene quality for reuse by the crew during this period. The waste water consisted of shower, laundry, handwash, urine and humidity condensate.

Providing water necessary to maintain life support has been accomplished in spacecraft vehicles for over forty years. This paper will investigate how previous U.S. space vehicles provided potable water. The water source for the spacecraft, biocide used to preserve the water on-orbit, water stowage methodology, materials, pumping mechanisms, on-orbit water requirements, and water temperature requirements will be discussed. Where available, the hardware used to provide the water and the general function of that hardware will also be detailed. The Crew Exploration Vehicle (CEV or Orion) water systems will be generically discussed to provide a glimpse of how similar they are to water systems in previous vehicles. Conclusions, questions, and recommendations on strategies that could be applied to CEV based on previous spacecraft water system lessons learned will be made.

A relationship has been observed between increasing ethanol content in gasoline and increased particulate matter (PM) emissions from direct injection spark ignition (DISI) vehicles. The fundamental cause of this observation is not well understood. One potential explanation is that increased evaporative cooling as a result of ethanol’s high HOV may slow evaporation and prevent sufficient reactant mixing resulting in the combustion of localized fuel rich regions within the cylinder. In addition, it is well known that ethanol when blended in gasoline forms positive azeotropes which can alter the liquid/vapor composition during the vaporization process. In fact, it was shown recently through a numerical study that these interactions can retain the aromatic species within the liquid phase impeding the in-cylinder mixing of these compounds, which would accentuate PM formation upon combustion.

An integrated water recovery system was operated for 91 days in support of the Lunar Mars Life Support Test Project (LMLSTP) Phase III test. The system combined both biological and physical-chemical processes to treat a combined wastewater stream consisting of waste hygiene water, urine, and humidity condensate. Biological processes were used for primary degradation of organic material as well as for nitrification of ammonium in the wastewater. Physical-chemical systems removed inorganic salts from the water and provided post-treatment. The integrated system provided potable water to the crew throughout the test. This paper describes the water recovery system and reviews the performance of the system during the test.

Several high octane number oxygenates that could be derived from biomass were blended with gasoline and examined for performance properties and their impact on knock resistance and fine particle emissions in a single cylinder direct-injection spark-ignition engine. The oxygenates included ethanol, isobutanol, anisole, 4-methylanisole, 2-phenylethanol, 2,5-dimethyl furan, and 2,4-xylenol. These were blended into a summertime blendstock for oxygenate blending at levels ranging from 10 to 50 percent by volume. The base gasoline, its blends with p-xylene and p-cymene, and high-octane racing gasoline were tested as controls. Relevant gasoline properties including research octane number (RON), motor octane number, distillation curve, and vapor pressure were measured. Detailed hydrocarbon analysis was used to estimate heat of vaporization and particulate matter index (PMI). Experiments were conducted to measure knock-limited spark advance and particulate matter (PM) emissions.

The Energy Independence and Security Act of 2007 requires the U.S. to use 36 billion gallons of renewable fuel per year by 2022. Domestic ethanol production has increased steadily in recent years, growing from less than 5 billion gallons per year (bgpy) in 2006 to over 13 bgpy in 2010. While there is interest in developing non-oxygenated renewable fuels for use in conventional vehicles as well as interest in expanding flex-fuel vehicle (FFV) production for increased E85 use, there remains concern that EISA compliance will require further use of oxygenated biofuels in conventional vehicles. The Environmental Protection Agency (EPA) recently granted partial approval to a waiver allowing the use of E15 in 2001 and newer light-duty vehicles.

Regenerative-type subsystems are being tested at JSC to provide atmosphere revitalization functions of oxygen supply and carbon dioxide (CO2) removal for a future Space Station. Oxygen is supplied by an electrolysis subsystem, developed by General Electric, Wilmington, Mass., which uses the product water from either the CO2 reduction subsystem or a water reclamation process. CO2 is removed and concentrated by an electrochemical process, developed by Life Systems, Inc., Cleveland, Ohio. The concentrated CO2 is reduced in a Sabatier process with the hydrogen from the electrolysis process to water and methane. This subsystem is developed by Hamilton Standard, Windsor Locks, Conn. These subsystems are being integrated into an atmosphere revitalization group. This paper describes the integrated test configuration and the initial checkout test. The feasibility and design compatibility of these subsystems integrated into an air revitalization system is discussed.

This work utilizes previously developed VSB2 (VSB2 Stochastic Blob and Bubble) multicomponent fuel spray model to study significance of using non-ideal thermodynamics for droplet evaporation under direct injection engine like operating conditions. Non-ideal thermodynamics is used to account for vapor-liquid equilibrium arising from evaporation of multicomponent fuel droplets. In specific, the evaporation of ethanol/iso-octane blend is studied in this work. Two compositions of the blend are tested, E-10 and E-85 respectively (the number denotes percentage of ethanol in blend). The VSB2 spray model is implemented into OpenFoam CFD code which is used to study evaporation of the blend in constant volume combustion vessel. Liquid and vapor penetration lengths for the E-10 case are calculated and compared with the experiment. The simulation results show reasonable agreement with the experiment. Simulation is performed with two methods- ideal and non-ideal thermodynamics respectively.

This paper describes an experimental study to determine the potential for fuel efficiency improvements offered by dedicated, high compression E85 engines with optimized powertrain calibration strategies. The study involved a prototype variable fuel engine that could operate using either gasoline or E85, and a high compression version of the same engine that was suitable only for E85. Fuel consumption and engine-out emissions were evaluated using steady-state engine dynamometer tests to represent urban and highway speed/load conditions. For each fuel and engine combination, the fuel efficiency and emissions trade-offs provided by varying Exhaust Gas Recirculation (EGR) levels were determined. For the high compression engine, operation at lower speed/higher load conditions (producing the same power as the standard speed/load settings) was also investigated.

Certain Eubacteria enter a viable but nonculturable (VBNC) state upon encountering unfavorable environmental conditions. VBNC cells do not divide on conventional media yet remain viable and in some cases retain virulence. Here, we describe the VBNC state of two opportunistic pathogens previously isolated from ISS potable waters, Burkholderia cepacia and Stenotrophomonas maltophilia. Artificially inoculated microcosms were exposed to the biocidal agents copper (CuSO4) and iodine (I2) in an attempt to induce nonculturablility. Viability was assessed via fluorescent microscopy (direct viable count assay coupled with BacLight™ staining) and metabolic activity was monitored by quantifying both intracellular ATP and transcribed rRNA (reverse transcriptase quantitative PCR). Culturablility was lost in both B. cepacia and S. maltophilia within two days of exposure to copper or high concentrations of iodine (6 or 8 ppm).