On the mobility of pyroclastic currents in light of deposit thickness and clast size trends

2019 ◽  
Vol 384 ◽  
pp. 64-74
Author(s):  
Danilo M. Palladino ◽  
Guido Giordano
Keyword(s):  
Deposit Thickness

Modeling of Diesel Particulate Filter Regeneration under the Urban Dynamometer Driving Schedule

2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Di Huang ◽  
Jason M. Keith
Keyword(s):  
State Standards ◽  
Particulate Filter ◽  
Transient Temperature ◽  
Dimensional Model ◽  
Thermal Regeneration ◽  
Diesel Particulate ◽  
One Dimensional ◽  
Deposit Thickness ◽  
Particulate Filters ◽  
Exhaust Temperature

Abstract Particulate Matter (PM) emissions from either on-road or off-road diesel engines are subject to federal and/or state standards. Recently, Diesel Particulate Filters (DPF) have been shown to be the most efficient way to reduce the PM emissions. However, DPFs need to be regenerated periodically. In order to predict when to regenerate the DPF under real-time driving conditions, a regeneration model for the DPF is needed. In this study, a transient one-dimensional model is used to track gas and solid temperatures and the particulate deposit thickness, and is studied under the Urban Dynamometer Driving Schedule (UDDS) which has variable exhaust flow rate, exhaust temperature, and PM concentration. In order to determine the best conditions, the thermal regeneration is initiated at different time points during the UDDS cycle. Moreover, we also calculate the transient temperature profile and the deposit thickness for each case. We found that the regeneration efficiency is the highest when the regeneration is initiated at 180 seconds into the UDDS cycle which corresponds to a period of extended city driving without stopping.

In-Situ Thermophysical Properties of an Evolving Carbon Nanoparticle Based Deposit Layer Utilizing a Novel Infrared and Optical Methodology

2015 ◽  
Author(s):  
Ashwin A. Salvi ◽  
John Hoard ◽  
Dan Styles ◽  
Dennis Assanis
Keyword(s):  
Thermal Conductivity ◽  
Internal Combustion Engines ◽  
Linear Increase ◽  
Outlet Temperature ◽  
Combustion Engines ◽  
Deposit Thickness ◽  
Exhaust Gases ◽  
Gas Recirculation ◽  
Deposit Layer

The use of exhaust gas recirculation (EGR) in internal combustion engines has significant impacts on engine combustion and emissions. EGR can be used to reduce in-cylinder NOx production, reduce fuel consumption, and enable advanced forms of combustion. To maximize the benefits of EGR, the exhaust gases are often cooled with liquid to gas heat exchangers. However, the build up of a fouling deposit layer from exhaust particulates and volatiles result in the decrease of heat exchanger efficiency, and increase the outlet temperature of the exhaust gases, and decrease the advantages of EGR. This paper presents experimental data from a novel in-situ measurement technique in a visualization rig during the development of a 378 micron thick deposit layer. Measurements were performed every 6 hours for up to 24 hours. Results show a non-linear increase in deposit thickness with an increase in layer surface area as deposition continued. Deposit surface temperature and temperature difference across the thickness of the layer was shown to increase with deposit thickness while heat transfer decreased. The provided measurements combine to produce deposit thermal conductivity. A thorough uncertainty analysis of the in-situ technique is presented and suggests higher measurement accuracy at thicker deposit layers and with larger temperature differences across the layer. The interface and wall temperature measurements are identified as the strongest contributors to the measurement uncertainty. Due to instrument uncertainty, the influence of deposit thickness and temperature could not be determined. At an average deposit thickness of 378 microns and at a temperature of 100°C, the deposit thermal conductivity was determined to be 0.044 ± 0.0062 W/mK at a 90% confidence interval based on instrument accuracy.

scholarly journals EXPERIMENTS ON THE DENSITY OF TSUNAMI INUNDATION WATER AND ITS INFLUENCE ON THE TSUNAMI RUN-UP AND DEPOSIT

2018 ◽  
pp. 41
Author(s):  
Hideo Matsutomi ◽  
Fumiko Konno
Keyword(s):  
Small Scale ◽  
Distance Ratio ◽  
Sediment Grain Size ◽  
Tsunami Inundation ◽  
Deposit Thickness ◽  
Historical Tsunami ◽  
Run Up ◽  
Tsunami Run Up ◽  
Tsunami Sediment ◽  
Sediment Deposit

For the sophistication of the tsunami load, future and historical tsunami scale evaluations, the dependency of the density of tsunami inundation water with sediment on the hydraulic quantities, and then the dependencies of the tsunami run-up distance, sediment deposit distance, mean sediment deposit thickness on the density of the tsunami inundation water are examined through a devised small-scale hydraulic experiment. Within the experimental range of this study, it is verified that the density of the tsunami inundation water depends on the Froude number of the incident tsunami inundation flow and the sediment grain size, and the relative tsunami run-up distance (= the run-up distance of the inundation water with sediment/the run-up distance of the inundation water without sediment (= fresh water)), ratio of the tsunami sediment deposit distance to the tsunami run-up distance, ratio of the mean tsunami sediment deposit thickness to the tsunami sediment deposit distance depend on the density of the tsunami inundation water, and four empirical expressions for those dependencies are proposed.

A Mössbauer spectroscopic study of the cooling history of hypersthene from selected members of the Taupo Pumice formation, New Zealand

1979 ◽  
Vol 43 (326) ◽  
pp. 279-285 ◽  
Author(s):  
J. H. Johnston ◽  
K. E. Knedler
Keyword(s):  
New Zealand ◽  
Spectroscopic Study ◽  
Cooling Rate ◽  
Analytical Data ◽  
Equilibrium Isotherms ◽  
Cooling History ◽  
X Ray ◽  
Deposit Thickness ◽  
History Of ◽  
Cation Sites

Summary57Fe Mössbauer spectroscopy has been used to determine the Mg2+-Fe2+ distribution between the two crystallographically inequivalent cation sites in hypersthenes from a stratigraphic tephra sequence of the Taupo Pumice formation, North Island, New Zealand. From these distributions and X-ray fluorescence analytical data, cooling histories were constructed using previously determined Mg2+-Fe2+ equilibrium isotherms for orthopyroxenes. The results showed that this cooling history geothermometer could be used to enable airfall and airflow tephra to be distinguished. In addition, they showed that the cooling rate of the above deposits correlated better with the deposit thickness, than with the distance of the deposit from the source.

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