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Heat Release Rate in a Reduced-Scale Model of a Subway Car on Fire

Heat Release Rate in a Reduced-Scale Model of a Subway Car on Fire

Abstract: The heat release rate of a subway car on fire is measured for various positions of an ignition source and simulated materials differing in combustibility by using a reduced-scale model. Although the maximum HRR value is nearly independent of the position of the ignition source, the time required to reach this value varies greatly for different ignition positions. The open area of a subway car is a key factor that determines the maximum HRR value, although material combustibility also has an effect. Finally, the HRR curve is compared with that of a fire test in a real-scale subway car.
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Heat release rate estimation in laminar premixed flames using laser-induced fluorescence of CH2O and H-atom

Heat release rate estimation in laminar premixed flames using laser-induced fluorescence of CH2O and H-atom

with computations of one-dimensional freely-propagating flames. The performance of these markers is studied based on the following two aspects: the spatial accuracy of the local heat release rate and the trend in the total heat release rate with equivalence ratio. The measured trend in the spatial distribution of radicals and the deduced heat release rate agree well with the computational values. The variation in the spatially integrated heat release rate as a function of equivalence ratio is also investigated. The results suggest that the trend in the variation of the integrated heat release rate and the spatial location of heat release rate can be evaluated by either of these markers. The OH-based marker showed certain sensitivity to the chemical mechanism as compared to the H-atom based marker. Both the OH-based and H-atom based techniques provide close estimates of heat release rate. The OH based technique has practical ad- vantage when compared to the H-atom based method, primarily due to the fact that the H-atom LIF is a two-photon process.
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Modeling of Thermal Cycle CI Engine with Multi-Stage Fuel Injection

Modeling of Thermal Cycle CI Engine with Multi-Stage Fuel Injection

The amount of nitrogen oxide formed de- pends primarily on the amount of free oxygen and the increase in temperature and rate of heat release in the first kinetic stage of the combustion process [20,21]. Figure 9 shows the NO emis- sions for the three analyzed injection strategies. The use of fuel injection has a positive effect on reducing nitric oxide emissions. The best re- sult was achieved with two pilot doses. The NO concentration for the two pilot doses was lower compared to the 10% unadjusted dose. Reduction of NO concentration in the flue gas is associated with a reduction in the rate of combustion of the charge and heat generation due to pilot doses.
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Influence of Injection Timing on Performance and Combustion Characteristics of Simarouba Biodiesel Engine

Influence of Injection Timing on Performance and Combustion Characteristics of Simarouba Biodiesel Engine

With advancement of injection timing, the peak rate of pressure rise increases but it shifts before TDC with shorter delay period. On retarding the injection, the rate of pressure rise decreases slightly with a shift away from TDC and the ignition delay also increases. Similar effects are seen on the rate of heat release. With retardation, larger amount of heat is released in mixing controlled combustion regime resulting in higher mean pressure in the cycle

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Simulation Studies of Diesel Engine Combustion Characteristics with Oxygen Enriched Air

Simulation Studies of Diesel Engine Combustion Characteristics with Oxygen Enriched Air

By using the above model, the simulated working condition is kept unchanged, and according to the equal con- centration interval, the oxygen mole fraction of the inlet air is respectively selected 21%, 24%, 27% and 30%. Then, some parameters of the diesel engine are simulated under 4 different inlet oxygen concentration condi- tions, such as cylinder pressure curve, rate of heat release , temperature field and the concentration distribution of emissions, etc., so as to explore the influence of different inlet oxygen concentration on diesel engine com- bustion characteristic.
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Experimental Investigation to Evaluate the Performance, Emission and Combustion Characteristics of Diesel Engine with Mahua Oil Biodiesel

Experimental Investigation to Evaluate the Performance, Emission and Combustion Characteristics of Diesel Engine with Mahua Oil Biodiesel

Figure 9 shows the heat release rate for biodiesel blends in comparison of standard diesel at different engine operating conditions. After burning of fuel, fluctuation of heat release rate occurs. However, at B100 shows highest rate of heat release compare to diesel and other biodiesel blends, because of the higher cetane number and higher oxygen capacity of biodiesel that improves the burning quality of fuel and helps in firing at higher charge per units. Moreover B10, B20 and B50 have been established a corresponding rate of heat release with diesel. This is because, in low blends the concentration of biodiesel is low, that is way fuel does not cause a significant force on certain number, but it touches the air fuel mixture formation due to changes in viscosity and evaporation properties of the fuel. That is way lower blends showed a less charge per unit of heat release than B100.
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Numerical Study of a Spark Assisted Compression Ignition (SACI) Engine Using the One-Dimensional Turbulence (ODT) Model.

Numerical Study of a Spark Assisted Compression Ignition (SACI) Engine Using the One-Dimensional Turbulence (ODT) Model.

6 kernel growth (EKG) stage. However, due to limitations in diagnostic methods, the effect of the spark plasma in this stage could not be measured. This limitation was overcome in the study conducted by Natarajan and Reuss, [9], and the first conclusion of the previous study was confirmed. However, it was found that the spark ignition system did not affect the EKG cyclic variations, but the charge composition distribution did. Pastor et al. [10], combined direct visual diagnostic methods and spectroscopic analysis of natural radiation, with analysis of Rate of Heat Release, to validate the works of Reuss [8,9]. The spectral analysis of the combustion reaction radicals was used to study the progress of the combustion process and identify the transition of the SACI stages. A similar research was conducted by Benajes et al. [11], for a gasoline partially premixed spark assisted compression ignition engine at low load to better observe the combustion process. It was found that, apart from spark assistance and ignition timing, the fuel injection timing and duration had an important role in improving combustion stability, cyclic stability and combustion phase duration. The author continued this work in [12] to show the effect on emissions due to single and double direct fuel injection strategies, and by varying the fuel fraction in the double injection case. It was concluded that air/fuel mixture distribution was improved using double injection strategy and increased the fuel energy conversion efficiency.
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Assessment of Vehicle Fire Development in Road Tunnels for Smoke Control Ventilation Design

Assessment of Vehicle Fire Development in Road Tunnels for Smoke Control Ventilation Design

It should be recognised that it is not possible to design a smoke control system for every potential fire that might occur in a tunnel. Depending on the length and usage of a particular tunnel it is feasible that in an extreme case up to several tens or hundreds of vehicles could be involved in a severe collision. The cost and practicality to design for such events is beyond what might be considered a reasonable worst case. Thus the selection of the design fire scenario is best made on the basis of a risk analysis and the peak rate of heat release becomes the critical consequence component in this analysis. In many tunnel smoke control system designs the peak rate of heat release is chosen without proper regard for the effect of the tunnel characteristics on the fire growth or the traffic mix expected to use the tunnel. Often the rate of heat release for a single vehicle fire taken from an experiment published in the literature and it is unlikely to account for the specific conditions within the tunnel being designed, the regulatory environment in place or the likely vehicle usage during the operation of the tunnel (Biollay et al 1999). The selection does not always consider whether such a vehicle is likely to enter the tunnel or whether a multiple vehicle collision scenario might be a more credible event. The type of vehicles allowed access to the tunnel is an important consideration when analysing the fire risk level. As vehicles on the road can vary from motorcycles to heavy goods vehicles or even a petrol tanker, the magnitude of their heat release rate in the event of a fire can vary significantly, restricting certain vehicles from entering the tunnel is therefore an effective means to reduce the tunnel fire risk.
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A New Strategy for Reduction of Emissions and Enhancement of Performance Characteristics of Dual Fuel Engines at Part Loads

A New Strategy for Reduction of Emissions and Enhancement of Performance Characteristics of Dual Fuel Engines at Part Loads

The scaled absolute cylinder pressure data and the TDC pickup signal were used to estimate the ignition delay, duration of combustion and the rate of heat release. In this paper, the first and second derivatives of cylinder pressure were used to predict the start of combustion and so the ignition delay period [18]. Also, the heat release rate diagrams provided valuable information about combustion and its related parameters. The net heat release rate was determined by applying the first law of thermodynamics for each measured cylinder pressure data using the following expression [19]:
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Sustainability of Aluminium Oxide Nanoparticles Blended Mahua Biodiesel to the Direct Injection Diesel Engine Performance and Emission Analysis

Sustainability of Aluminium Oxide Nanoparticles Blended Mahua Biodiesel to the Direct Injection Diesel Engine Performance and Emission Analysis

emissions are the significant points observed during their study. Arul Mozhi Selvan et al. (Selvan et al., 2009) observed an improvement in the brake thermal efficiency with a remarkable decrease in HC and NOx emissions when cerium oxide nanoparticles were used as additives in the diesel-biodiesel blends. Sajith et al. (Sajith et al., 2010) explored the effect of cerium oxide on the performance of biodiesel while implementing in a diesel engine. An increase in the amount of viscosity and flash point of biodiesel was found with the implementation of the nanoparticles. Aalam et al. (Aalam et al., 2015) examined the aluminium oxide nanoparticles blended biodiesel in diesel engine and determined that marginal increase in the brake thermal efficiency, reduction in HC, CO, smoke emissions but a slight increase in NOx. Karthikeyan et al. (Karthikeyan et al., 2016) observed that the effect of cerium oxide in the biodiesel blends on diesel engine, increases the brake thermal efficiency and heat release rate and also reduces the brake specific fuel consumption. Mehta et al. (Mehta et al., 2014) examined the Combustion attributes, engine emission and performance parameters of a diesel engine utilizing nano fuels which were prepared through sonicating of aluminium and boron nanoparticles in base diesel with a span as a surfactant for stable suspension. The specific fuel consumption was diminished, CO, HC emissions declines and peak cylinder pressure diminishes at elevated load conditions.
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Experimental Investigation of Performance and Emission Characteristics of Diesel Engine Working on Diesel with Neem Biodiesel and Ethanol Blend with EGR

Experimental Investigation of Performance and Emission Characteristics of Diesel Engine Working on Diesel with Neem Biodiesel and Ethanol Blend with EGR

The variation of Net Heat Release Rate with respect to crank angle for diesel and different blends B20% and B40% of neem biodiesel, at constant pressure 180 bar is shown in figures 32 and 33. At full load condition without EGR heat release rate of 20% and 40% blends with ethanol values found to be 27 j/deg CA and 25.77 j/deg CA.The blends B20% and B40% with ethanol 5% with EGR 5% the values found to be 27.88 j/deg CA and 25.76 j/deg CA. The blends B20% and B40% with ethanol 5% with EGR 10% the values found to be 26.5 j/deg CA. and 27.62 j/deg CA. The pure diesel shows the 28 j/deg CA. It was observed from the graph that there is an increase in the ignition delay for the blends. Among the fuels tested B40% with ethanol 5% with EGR 10% is found to have higher ignition delay. It is observed that the heat release rate curves of the diesel, neem biodiesel and their blends show similar patterns. The peak heat release rates of neem biodiesel and their blends are lower than that of diesel. There is decrease in peak heat release rate for EGR usage. Decrease in heat release rate is indication of incomplete combustion due to a less oxygen content because of using EGR 5% and 10%
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Hydrogen and natural gas comparison in diesel HCCI engines -a review

Hydrogen and natural gas comparison in diesel HCCI engines -a review

Since the mixture is lean and fully controlled by chemical kinetics, there is a new challenge in developing HCCI engines as it is difficult to control the auto-ignition of the mixture and the heat release rate at high load operation, achieve cold start, meet emission standards and control knock[4,5]. The advantages of HCCI engines are:1. the same or even better power band compared to SI or CI engines,2. high efficiency engines due to no throttling losses and high compression ratio, 3. ability to be used in any engine configuration: automobile engines, stationary engines, high load engines or small size engines. However, HCCI engines have their own disadvantages such as high level of unburned hydrocarbons (UHC) and CO [4,6,7]as well as knocking issues if the mixture is relatively inaccurate[4,6,8]. Emissions regulations are becoming more stringent and even though CO, NO x and
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Vol 60, No 2 (2017)

Vol 60, No 2 (2017)

into practice. They require access to a tunnel or to a full-scale mock-up with some basic installations. There are some aspects of the experiments which are difficult to control such as natural ventilation (wind) conditions. For example, the Heat Release Rate data gathered from the Runehamar tunnel full scale fire tests have a 15 – 20 % uncertainty [11, 15].

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Effect of Spark Timing on Combustion Process of SI Engines using MATLAB

Effect of Spark Timing on Combustion Process of SI Engines using MATLAB

The spark timing plays a significant role in the combustion process and in deciding the engine parameters of SI engine. This paper aims at demonstrating the effect of advanced and retarded spark timing on the burn fraction variation versus crank angle, cumulative heat release rate versus the crank angle and the pressure variation as a function of crank angle with the help of MATLAB programs. For this purpose, a basic finite heat release model is used for the combustion process in SI engines. This model can also be extended to evaluate effect of spark timing on engine work and thermal efficiency. In each section of the paper, the codes used for analysis are provided for future research work. Salient results, such as peak pressure crank angles for different spark timings , are derived from analysis.
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Military Maintenance Hangar

Military Maintenance Hangar

The Hangar space has a large fire potential due to the stored aircraft and the largest heat release rate potential is the JP-8 jet fuel stored within the aircraft. The hangar is not designed for fuel cell (fuel tank) maintenance, nor is refueling operation allowed in the hangar. Due to these limitations it is not possible to quantify any spill of fuel less than the volume stored within the aircraft as there no process in place that utilizes less fuel as a matter of course during the maintenance performed in this hangar. For this exercise we are relying on the Unified Facilities Criteria UFC 4-211-01 [7] standard to guide our selection of design fire. The UFC requires flame detection sensors and high expansion foam (HEF) suppression systems installed in aircraft maintenance hangars. This requirement stems from the assumption in the standard that a fire within the hangar will cause a fuel spill. This can be assumed since the HEF systems primary function to provide a blanket of foam over the fuel spill to cut off oxygen from the fuel to smother a fire ignited on its surface. Since the UFC considers a fuel spill to be the primary hazard within the space that is the fire we will analyze.
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Advanced Diagnostics, Control and Testing of Diesel Low Temperature Combustion

Advanced Diagnostics, Control and Testing of Diesel Low Temperature Combustion

The heat release in diesel engines is affected by a number of parameters including engine speed, engine load, exhaust gas recirculation (EGR) rate, fuel scheduling and boost[r]

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Reducing Diesel Engine Emission Using Reactivity Controlled Approach

Reducing Diesel Engine Emission Using Reactivity Controlled Approach

In this paper, the effect of adding gasoline to diesel fuel on performance and emissions of IC engine has been investigated using professional ANSYS Forte software. A gasoline port injec- tion and diesel direction injection CI engine has been modeled. In the simulation, the gasoline/ diesel (G/D) ratio was varied from (50–80%) by volume. The cylinder pressure, temperature, heat release rate, power, thermal efficiency, combus- tion efficiency, NOx, CO, and unburned hydro- carbons were calculated and compared with neat diesel fuel for all gasoline/diesel ratios. The effect of (G/D) ratios on the heat release rate is shown in Figure 3. The heat release rate increased when gasoline is added to diesel fuel. The maximum heat release rate occurs with gasoline ratio (50– 60%) in the total fuel. Further increase of gaso- line amount will decrease the heat release rate. When the G/D ratio increases, the first combus- tion stage drop while the second stage improves; this is due to the increase in ignition delay which cause an increase of mixing time [18]. More- over, the addition of gasoline to the mixture with amount more than 60% (by volume) will increase the combustion duration as shown in Figure 4 and consequently expanding the combustion process to expansion stroke, resulting in increased engine losses and incomplete combustion. In addition, when the gasoline percentage is increased over 60% by volume, this could lead to a dramatic in- crease in the combustion durations resulting in a reduction in the combustion rate and a reduction in the peak pressure rising rate [19].
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Experimental Investigations on single cylinder Diesel  Engine using various Bio Diesels

Experimental Investigations on single cylinder Diesel Engine using various Bio Diesels

Figure 9 shows variation of NOx emissions with respect to brake power the shows evidence that at initial brake power Cotton seed biodiesels are have very less emissions 78 PPM. At maximum brake power compared to all bio diesels has less emissions 2000 PPM . In the figure as brake power increases NOx emissions are increasing drastically due to low heat release rate.

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Experimental Investigations on single cylinder Diesel Engine using various Bio Diesels

Experimental Investigations on single cylinder Diesel Engine using various Bio Diesels

The interest on alternative fuels is continuously increasing to meet the growing energy requirement and protect the environment. The comparison of fuel performance and combustion characteristics of various biodiesel (Rapeseed biodiesel, Cotton biodiesel, Mahuva biodiesel, Jatropa biodiesel and Rubber seed biodiesel) has been carried in direct injection diesel engine and best one for application was evaluated on four stroke single cylinder diesel engine under various load at no load, 25%, 50%,75%, and full load was assessed. At full load the Rapeseed biodiesel has been recorded highest rate of pressure rise , heat release and thermal efficiency and lowest brake specific fuel consumption compared to other tested fuels at full load condition. The rapeseed biodiesel has recorded less CO & HC emissions as compared to other bio diesels. So on the basis of performance, combustion and emission parameters Rapeseed Biodiesel appears to be best alternative fuel than other of Cotton seed biodiesel, Mahua biodiesel, Jatropha biodiesel and Rubber seed biodiesel even than diesel.
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Application of Nonlinear Dynamics in Studying Flashover Fire in a Small Open Kitchen

Application of Nonlinear Dynamics in Studying Flashover Fire in a Small Open Kitchen

It is observed that the solid boundary surface area or the floor aspect ratio will change the critical heat release rate and temperature for onsetting flashover, even for the same unit floor area. Consequently, architects can change the geometry of the residential unit with an open kitchen to give favorable conditions to mitigate the oc- currence of flashover. The thermal properties of wall material also have effect on the critical conditions for fla- shover. Fire hazards of units with an open kitchen located in buildings enclosed with material of small thermal inertia should be given more caution.
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