Thermal stability and decomposition of diesel fuel under subcritical and supercritical conditions

A novel concept of clean diesel combustion using supercritical fluids is proposed and being investigated to address some key challenges encountered in the fuel and transportation sector. The core of this concept is to inject diesel fuel (DF) in the supercritical state to achieve clean, high-efficient combustion in diesel engines. Among other challenging issues that must be addressed for the implementation of this new concept is the thermal stability of DF and the potential decomposition and solid deposit formation under engine conditions. In this work, thermal stability of DF was experimentally evaluated under subcritical and supercritical conditions in both static (batch system) and dynamic (continuous flow system) thermal stressing systems. The effects of thermal stressing temperature (200-440 oC) and duration (10-600 min) and CO2 concentration (~10 wt%) were examined. DF decomposition is characterized by the average absolute deviation (AAD) of GC peak area percentages of all individual components. A temperature-time window (400-420 2 oC, 0-60 min) where supercritical DF combustion in diesel engines may be possible was determined. CO2 as a diluent could prevent or reduce accumulation of solid deposits inside fuel pipes mainly due to an increased solubilization capacity of DF. Finally, different structures and morphologies of solid deposits observed under different batch thermal stressing conditions were discussed

Determination of Particle Size Distributions from Acoustic Wave Propagation Measurements

The wave equations for the interior and exterior of the particles are ensemble averaged and combined with an analysis by Allegra and Hawley @J. Acoust. Soc. Am. 51, 1545 ~1972!# for the interaction of a single particle with the incident wave to determine the phase speed and attenuation of sound waves propagating through dilute slurries. The theory is shown to compare very well with the measured attenuation. The inverse problem, i.e., the problem of determining the particle size distribution given the attenuation as a function of frequency, is examined using regularization techniques that have been successful for bubbly liquids. It is shown that, unlike the bubbly liquids, the success of solving the inverse problem is limited since it depends strongly on the nature of particles and the frequency range used in inverse calculations

Genetic determinants of risk in pulmonary arterial hypertension: international genome-wide association studies and meta-analysis

Background Rare genetic variants cause pulmonary arterial hypertension, but the contribution of common genetic variation to disease risk and natural history is poorly characterised. We tested for genome-wide association for pulmonary arterial hypertension in large international cohorts and assessed the contribution of associated regions to outcomes. Methods We did two separate genome-wide association studies (GWAS) and a meta-analysis of pulmonary arterial hypertension. These GWAS used data from four international case-control studies across 11744 individuals with European ancestry (including 2085 patients). One GWAS used genotypes from 5895 whole-genome sequences and the other GWAS used genotyping array data from an additional 5849 individuals. Cross-validation of loci reaching genome-wide significance was sought by meta-analysis. Conditional analysis corrected for the most significant variants at each locus was used to resolve signals for multiple associations. We functionally annotated associated variants and tested associations with duration of survival. All-cause mortality was the primary endpoint in survival analyses. Findings A locus near SOX17 (rs10103692, odds ratio 1·80 [95% CI 1·55–2·08], p=5·13×10– ¹⁵) and a second locus in HLA-DPA1 and HLA-DPB1 (collectively referred to as HLA-DPA1/DPB1 here; rs2856830, 1·56 [1·42–1·71], p=7·65×10– ²⁰) within the class II MHC region were associated with pulmonary arterial hypertension. The SOX17 locus had two independent signals associated with pulmonary arterial hypertension (rs13266183, 1·36 [1·25–1·48], p=1·69×10– ¹²; and rs10103692). Functional and epigenomic data indicate that the risk variants near SOX17 alter gene regulation via an enhancer active in endothelial cells. Pulmonary arterial hypertension risk variants determined haplotype-specific enhancer activity, and CRISPR-mediated inhibition of the enhancer reduced SOX17 expression. The HLA-DPA1/DPB1 rs2856830 genotype was strongly associated with survival. Median survival from diagnosis in patients with pulmonary arterial hypertension with the C/C homozygous genotype was double (13·50 years [95% CI 12·07 to >13·50]) that of those with the T/T genotype (6·97 years [6·02–8·05]), despite similar baseline disease severity. Interpretation This is the first study to report that common genetic variation at loci in an enhancer near SOX17 and in HLA-DPA1/DPB1 is associated with pulmonary arterial hypertension. Impairment of SOX17 function might be more common in pulmonary arterial hypertension than suggested by rare mutations in SOX17. Further studies are needed to confirm the association between HLA typing or rs2856830 genotyping and survival, and to determine whether HLA typing or rs2856830 genotyping improves risk stratification in clinical practice or trials. Funding UK NIHR, BHF, UK MRC, Dinosaur Trust, NIH/NHLBI, ERS, EMBO, Wellcome Trust, EU, AHA, ACClinPharm, Netherlands CVRI, Dutch Heart Foundation, Dutch Federation of UMC, Netherlands OHRD and RNAS, German DFG, German BMBF, APH Paris, INSERM, Université Paris-Sud, and French ANR

Supercriticalfluidtechnology For Remediation Of Pcb/pah-Contaminated Soils/sediments

Key words: soil/sediments remediation technology, supercritical fluids, PCBs, PAHs A two-stage technology employing green solvents such as supercritical CO 2 (SC-CO 2 ) and supercritical water (SCW) for the extraction and destruction of polychlorinated biphenyls (PCBs)/polycyclic aromatic hydrocarbons (PAHs) from contaminated soils/sediments is proposed. Results of our laboratory and benchscale investigations indicate that SC-CO 2 modified with 5% methanol, is an effective solvent and conditions have been defined to achieve sub 5 ppm in 45-60 minutes for 99.8% removal. Comprehensive data on PCB/PAH solubilities in SC-CO 2 /MeOH, partition equilibria, and desorbtion provide a solid basis to develop models regarding the extraction of these pollutants from solid matrices. Further, the supercritical water oxidation (SCWO) stage, coupled to the extraction process with three possible configurations, would provide clean effluent materials. The ultimate products of the proposed technology are mainly clean soil/sediments and inorganic species such as H 2 O, CO 2 , and small amounts of chlorides. Our SCWO studies indicate that 5245 ppm Aroclor 1248 in methanol-simulated soil extract solutions can be oxidized to 99.95% conversion in less than one minute at 550C. An economic analysis based on three possible configurations of the technological process indicates that the expected cost of $198-318 per m of soil processed is economically competitive

Acoustic Monitor for Solids and Gas Measurements at Low Volume Fractions

This presentation was given at the DOE Office of Science-Environmental Management Science Program (EMSP) High-Level Waste Workshop held on January 19-20, 2005 at the Savannah River Site

Acoustic Probe for Solid-Gas-Liquid Suspensions

The proposed research will develop an acoustic probe for monitoring particle size and volume fraction in slurries in the absence and presence of gas. The goals are to commission and verify the probe components and system operation, develop theory for the forward and inverse problems for acoustic wave propagation through a three phase medium, and experimentally verify the theoretical analysis. The acoustic probe will permit measurement of solid content in gas-solid-liquid waste slurries in tanks across the DOE complex

Acoustic probe for solid-gas-liquid suspensions. 1997 annual progress report

'Acoustic probes have shown promise to be quite effective in determining the solid content in solid-liquid suspensions. However, the presence of small amounts of gas in the waste slurries stored in tanks across the DOE complex prevents straightforward application for characterization of these slurries. The proposed research will develop an acoustic probe for monitoring particle size and volume fraction in slurries in the absence and the presence of gas bubbles. Theoretical Analysis Accomplished: Attenuation of sound waves depends on the size distribution of the solids and the volume fraction of solids. These can in principle be calculated from attenuation measured over a range of frequencies. However, small amounts of bubbles distort the measured attenuation. A typical result from theoretical analysis for the attenuation of solid- gas-liquid systems is given in Figure 1. The total attenuation of a sound wave v(o) equals the sum of contributions by a large number of ''bins'' of particle sizes. This notion yields the following equation for the (hitherto) unknown number density of solid particles as a function of particle radius N(a): j k(o,a)N(a)da = v(o), where the kernel k(o,a) is obtained from analysis. If N(a) is given, the above equation is used to calculate the attenuation v(o). This is referred to as solving the ''forward problem''. Solving for N(a) with v(o) given is the ''inverse problem''. A complication that one faces when trying to solve the inverse problem is that the stated problem is mathematically ill-posed, i.e., small fluctuations in v(o) cause large fluctuations in the result for the number density. Therefore the problem needs to be ''regularized'', i.e., the stated problem needs to be changed slightly such as to make it well-posed. This has been done by others for gas-liquid systems in the past. This approach is currently being applied in the present project to solid-liquid systems. As is shown in Figure 2, it successfully recovers the number density that has been used in the forward problem to generate attenuation data. Having this solution technique giving reliable results for the inverse problems of both gas-liquid and solid-liquid systems, the authors shall apply this method in the near future to solid-gas-liquid systems.