1,720,975 research outputs found
MODELLING OXY-COAL FLAMES IN A SEMI-INDUSTRIAL FURNACE
No full textComputational Fluid Dynamics (CFD) simulations of oxy-coal combustion experiments
conducted at the IFRF at the semi-industrial scale with two different burners, i.e. the
Aerodynamically Air Staged Burner (AASB) and the low-NOx TEA-C burner, were
performed in order to investigate the performance of different sub-models for oxy–fired
conditions. Special attention was devoted to the reduction of computational cost by
using proper modelling strategies based on reduced and complete computational
domains. The uncertainties due to the choice of different sub-models and boundary
conditions are discussed, highlighting the need for accurate and comprehensive
experimental datasets to validate computational models. Discussion is made of the use
of proper validation metrics to quantify the level of agreement between predictions and
experiments
Analysis of oxy-coal combustion through measurements in a pilot-scale entrained flow reactor
Full text linkCoal combustion is investigated in both air and oxy-fuel conditions in a pilot-scale entrained flow reactor able to provide high temperatures, heating rates and residence times. Measurements are carried out with
different levels of complexity and are aimed at: assessing the thermal field inside the reactor; evaluating conversions of devolatilization or char combustion tests; identifying phenomena such as volatiles ignition
and measuring the ignition delay time. Computational Fluid Dynamics was also used in order to provide a better understanding of the experimental evidences. Among the results, the ignition delay time was found
to be larger in oxy-fuel conditions than in air, mainly because of the larger specific heat of the oxy-fuel environment. The proposed investigation may help the qualification of advanced experimental apparatus
as entrained flow reactors, with the purpose to make them suitable for heterogeneous kinetics studies in oxy-fuel conditions
CFD MODELLING OF COMBUSTION SYSTEMS: EXAMPLES OF APPLICATION OF VERIFICATION AND VALIDATION APPROACH
No full textDriver speed behaviour on tangent sections of two-lane rural highways
No full textThe models that correlate the road characteristics and the operating speed on tangent are studied all around the world. Although the issue of speeds on tangent sections has not been studied extensively, several U.S. and international researchers have studied operating speeds and average running speeds, design speeds, speed limits, and the impact of geometric and traffic measures on speeds.
The objective of this experimental study is to get relationships of general validity for the prediction, in phase of project, of the speeds that will be indeed practiced on the infrastructure.
The experimental investigation has been conducted employing traffic counters, able to record, for every vehicular passage in both senses: length, instant speed and direction of the vehicle. The plan of survey has been elaborated to satisfy different objectives of search and it has been applied to some roads belonging to the network of the Province of Salerno.
The measures have been performed holding every section under observation for 2 or 3 hours.
Then the data have been used for starting the formalization of some analytical relationships to predict the operating speeds. Speeding is a general problem in traffic and exploring factors
underlying the choice of speed is an important task.
The relationship between various measures of traffic speed, under free flow conditions, and speed limits is investigated in Southern Italy. The effect of speed limits on traffic speed is
estimated. Increased speeding will likely result in augmenting the number of traffic accidents, as well as the severity of the injuries, resulting from high-speed accidents.
Many drivers are aware of the negative effects of speed, exceeding the speed limit is nevertheless one of the most frequent traffic violations.
This paper introduces a prediction model of operating speed and the other parameters of free flow conditions. In meaningful way, the surveyed operating speeds, always superior to posted
speed limits, are correlated to the entrance one that depends on geometric parameters of the preceding curve
Analysis of Coal Combustion in Oxy-fuel Conditions through Pulsed Feeding Experiments in an Entrained Flow Reactor
Full text linkCoal combustion is investigated in both air and oxy-fuel conditions in a pilot-scale entrained flow reactor able to provide high temperatures, heating rates and residence times. Measurements are carried out with different levels of complexity and are aimed at: assessing the thermal field inside the reactor; evaluating conversions of devolatilization or char combustion tests; identifying phenomena such as volatiles ignition and measuring the ignition delay time. Computational Fluid Dynamics was also used in order to provide a better understanding of the experimental evidences. Among the results, the ignition delay time was found to be larger in oxy-fuel conditions than in air, mainly because of the larger specific heat of the oxy-fuel environment. The proposed investigation may help the qualification of advanced experimental apparatus as entrained flow reactors, with the purpose to make them suitable for heterogeneous kinetics studies in oxy-fuel conditions
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
