Study on Flame Spread over Aviation Kerosene and Diesel

2014 ◽  
Vol 1016 ◽  
pp. 587-591 ◽  
Author(s):  
Man Hou Li ◽  
Shou Xiang Lu ◽  
Jin Guo ◽  
Kwok Leung Tsui

Flame spreading over liquid fuels is a common phenomenon involving in accidental fuel leakage in aircraft crash or oil tanker which may result in many casualties and economic losses. Comparative experiments are conducted concerning flame spread over aviation kerosene (RP5) and 0# diesel at a variety of initial fuel temperatures. The threshold value of initial fuel temperature for liquid-phase and gas-phase controlled flame spread is approximately 17 °C larger than liquid’s flashpoint for both oils. For a given initial fuel temperature, due to low volatility and ignitability of 0# diesel, its flame spread rate is smaller than that of RP5, while the length of the horizontal subsurface convection flow is larger. Given the difference in flame speed, fire accidents for RP5 are potentially more hazardous than those of 0# diesel. Moreover, the variation trend of subsurface convection flow length falls nearly linearly with the initial fuel temperature for both fuels.

2014 ◽  
Vol 51 (3) ◽  
pp. 707-721 ◽  
Author(s):  
Manhou Li ◽  
Shouxiang Lu ◽  
Jin Guo ◽  
Ruiyu Chen ◽  
Kwok-Leung Tsui

Author(s):  
Jan Abel Olsen

Chapter 19 starts by distinguishing between the two contrasting perspectives that an economic evaluation would take: the healthcare sector perspective versus the societal perspective. The former is considered a ‘narrow analysis’ which includes only the costs accruing within the healthcare sector, while the latter represents a ‘broad analysis’ that accounts for all resource implications in all sectors of the economy. After an investigation into various types of costs, a ‘limited societal perspective’ is suggested to be more appropriate than either of the two ‘extreme perspectives’. The chapter continues with a discussion of the cost per quality-adjusted life year (QALY) threshold and explains the difference between a demand side- versus a supply-side approach to determining a threshold value for a QALY.


1971 ◽  
Vol 17 (2) ◽  
pp. 268-269 ◽  
Author(s):  
Kazuo Akita ◽  
Okiharu Fujiwara
Keyword(s):  

2006 ◽  
Vol 17 (3) ◽  
pp. 10-20
Author(s):  
IJ Lambrechts

Price regulation occurs quite commonly amongst natural monopolies which frequently include public utilities. In South Africa and in certain countries in Africa, there has recently been a revival of price regulation in certain industries and enterprises, where competition is limited or non-existent. Price regulation can be applied in a multitude of ways. Because of the importance of the price levels (historical and replacement) in the price setting exercise, the focus in this paper will be on the issue of depreciation to arrive at the final prices. The electricity utility industry was historically viewed as a highly mature and heavily regulated natural monopoly. In many parts of the world, electricity utilities have already been deregulated to a large extent and in the United States the process was preceded by a process of unbundling or ringfencing of the main divisions, i.e. generation and distribution. Even the network component of transmission, traditionally seen as natural monopolies, was deregulated to a large extent. The deregulation process, whether fully or partially, emphasised the requirement for a detailed explanation for a specific price level. The need for acceptable and transparent selling prices has, therefore, not disappeared. Regulatory pricing is consequently a vital component of pricing at this stage and in the restructured industry it will continue to play an important role because of a limited number of participants. In other sectors of the South African energy industry too, the deregulation process has either not started or has not been completed. Price regulation is presently and will in future be applicable to the liquid fuels industry, which includes the pipeline of Petronet as well as gas pipelines. Other industries which are being price regulated at the moment include water, medicine, telecommunication (fixed lines) and postal rates. Although the economic regulation for these industries may differ substantially, the principles applying to depreciation calculations would be similar. Replacement depreciation produces lower profit figures during periods of inflation. Quoted companies often oppose this system because of a lack of taxation recognition on income and the adverse effect on earnings per share. This paper covers the calculation of depreciation by price regulators where assets are not diversified (single assets). Shorter depreciation lifetimes based on historical cost result in an automatic provision for replacement depreciation. The extent of the provision would be a function of the difference between the actual and selected lifetimes, income tax rates, re-investment rates and the extent of the financial gearing ratio. Provision for replacement depreciation may be reduced significantly, if not reduced completely, by reducing depreciation lifetimes.


Author(s):  
Claudio Garuti

This paper has two main objectives. The first objective is to provide a mathematically grounded technique to construct local and global thresholds using the well-known rate of change method. The next objective, which is secondary, is to show the relevance and possibilities of applying the AHP/ANP in absolute measurement (AM) compared to the relative measurement (RM) mode, which is currently widely used in the AHP/ANP community. The ability to construct a global threshold would help increase the use of AHP/ANP in the AM mode (rating mode) in the AHP/ANP community. Therefore, if the first specific objective is achieved, it would facilitate reaching the second, more general objective.   For this purpose, a real-life example based on the construction of a multi-criteria index and threshold will be described. The index measures the degree of lag of a neighborhood through the Urban and Social Deterioration Index (USDI) based on an AHP risks model. The global threshold represents the tolerable lag value for the specific neighborhood. The difference or gap between the neighborhood’s current status (actual USDI value) and this threshold represents the level of neighborhood deterioration that must be addressed to close the gap from a social and urban standpoint. The global threshold value is a composition of 45 terminal criteria with their own local threshold that must be evaluated for the specific neighborhood. This example is the most recent in a large list of AHP applications in AM mode in vastly different decision making fields, such as risk disaster assessment, environmental assessment, the problem of medical diagnoses, social responsibility problems, BOCR analysis for the evolution of nuclear energy in Chile in the next 20 years and many others. (See list of projects in Appendix).


Author(s):  
Manhou Li ◽  
Shouxiang Lu ◽  
Jin Guo ◽  
Xiujuan Wu ◽  
Kwok-Leung Tsui

Author(s):  
Qiuyu Zheng ◽  
Xu Wang ◽  
Yi Liu ◽  
Feng Jiang ◽  
Tianqi Liu

With the rapid scale expansion of the first generation of bio-liquid fuels, its impact on the prices of agricultural products, food security and the environment has begun to emerge and attracted extensive attention from governments and academia. A new multi-dimensional model of biodiesel spray combustion in an internal combustion (IC) engine is designed. Firstly, the BP neural network mining model is used to extract the spray combustion data of the IC engine. Then, based on the combustion data of biodiesel load in an internal combustion engine, burning rate and heat release, the principle of spray combustion of biodiesel is analyzed. Finally, from the two aspects of gas-phase control and liquid phase control, a multi-dimensional model of biodiesel spray combustion in IC engine is established and the spray combustion characteristics of biodiesel in IC engine are analyzed. The research results show that the model can effectively analyze the effect of load and fuel temperature on the spray combustion characteristics of biodiesel and the results of the model are almost the same as the actual data and the calculation accuracy is high. It is an effective method for studying the spray combustion characteristics of biodiesel.


Trudy NAMI ◽  
2021 ◽  
pp. 74-86
Author(s):  
G. G. Ter-Mkrtich'yan

Introduction (problem statement and relevance). Hydrocarbon emissions from vaporizationtank fuel contribute significantly to the total emissions of hazardous substances from vehicles equipped with spark ignition engines. To meet the established standards for limiting hydrocarbon emissions caused by evaporation, all modern vehicles use fuel vapor recovery systems, the optimal parameters of which require the availability and application of mathematical models and methods for their determination.The purpose of the research was to develop a model of vapor generation processes in the car fuel tank and a methodology for determining the main quantitative parameters of the vapor-air mixture.Methodology and research methods. The analysis of the processes of vapor generation in the fuel tank was carried out. It was shown that the mass of hydrocarbons generated in the steam space was directly proportional to its volume and did not depend on the amount of fuel in the tank.Scientific novelty and results. New analytical dependences of the vaporization amount on the saturated vapor pressure, barometric pressure, initial fuel temperature and fuel heating during parking have been obtained.Practical significance. A formula was obtained to estimate the temperature of gasoline boiling starting in the tank, depending on the altitude above sea level and the volatility of gasoline, determined by the pressure of saturated vapors. Using the new equations, the vaporization analysis in real situations (parking, idling, refueling, explosive concentration of vapors) was carried out.


1992 ◽  
Vol 114 (4) ◽  
pp. 928-935 ◽  
Author(s):  
C. Gau ◽  
K. A. Yih ◽  
W. Aung

Buoyancy-assisted convection flow and heat transfer processes in a heated vertical channel are studied experimentally for situations where the buoyancy parameter Gr/Re2 is relatively large. The channel wall is made of two parallel plates, with one wall heated uniformly and the opposite wall insulated. A uniform air flow is made to enter the channel from the bottom. The reversed flow is visualized, which occurs initially near the channel exit for the case when Gr/Re2 is greater than a threshold value. The cold reversed flow enters the channel from the outside and forms a V-shaped recirculating flow region in the downstream part of the duct. This region gradually propagates upstream as the buoyancy parameter Gr/Re2 increases. The counterflow motion, leading to mixing between the heated buoyant fluid and the V-shaped recirculation, is shown to be highly unstable and characterized by generation of eddies and vortices when the value of Gr/Re2 is large. An increase in Re has the effect of pushing the reversed flow downstream and making the recirculating region wider. Temperature fluctuations are measured to provide insight into the complex phenomena being studied. The penetration depth of the reversed flow is measured and compared with prediction based on a simple model. Local and average Nusselt numbers are also measured and presented.


2012 ◽  
Vol 27 (4) ◽  
pp. 954-971 ◽  
Author(s):  
Trevor I. Alcott ◽  
W. James Steenburgh ◽  
Neil F. Laird

Abstract This climatology examines the environmental factors controlling the frequency, occurrence, and morphology of Great Salt Lake–effect (GSLE) precipitation events using cool season (16 September–15 May) Weather Surveillance Radar-1988 Doppler (WSR-88D) imagery, radiosonde soundings, and MesoWest surface observations from 1997/98 to 2009/10. During this period, the frequency of GSLE events features considerable interannual variability that is more strongly correlated to large-scale circulation changes than lake-area variations. Events are most frequent in fall and spring, with a minimum in January when the climatological lake surface temperature is lowest. Although forecasters commonly use a 16°C lake–700-hPa temperature difference (ΔT) as a threshold for GSLE occurrence, GSLE was found to occur in winter when ΔT was only 12.4°C. Conversely, GSLE is associated with much higher values of ΔT in the fall and spring. Therefore, a seasonally varying threshold based on a quadratic fit to the monthly minimum ΔT values during GSLE events is more appropriate than a single threshold value. A probabilistic forecast method based on the difference between ΔT and this seasonally varying threshold, 850–700-hPa relative humidity, and 700-hPa wind direction offers substantial improvement over existing methods, although forecast skill is diminished by temperature and moisture errors in operational models. An important consideration for forecasting because of their higher precipitation rates, banded features—with a horizontal aspect ratio of 6:1 or greater—dominate only 20% of the time that GSLE is occurring, while widespread, nonbanded precipitation is much more common. Banded periods are associated with stronger low-level winds and a larger lake–land temperature difference.


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