Heat Release Rate (HRR)

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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

Various fire accidents including the Daegu subway fire in 2003 and the Austria mountain tunnel fire in 2001 have shown that fire accidents in underground tunnels are more dangerous than those above ground. Many studies have been conducted to anticipate and analyze tunnel fire phenomena. However, research on railcar fires as fire sources that determine the type and characteristics of a train tunnel fire remains insufficient. In particular, the characteristics of a passenger railcar fire vary depending on the structures and interior materials of the railcar. Previous studies on railcar fires include Amtrak’s full-scale passenger railcar fire test [1] by the NBS (National Bureau of Standards) in 1984, the EUREKA 499 test [2] program in 1991, and the reduced-scale and full-scale fire research by Peacock et al. [3] in 1994. Ingason [4] has studied the change in the heat release rate (HRR) according to the conditions of ventilation by using a reduced-scale model railcar. Recently, full-scale fire tests for subway and inter-city railcars have been conducted [5] and analyzed [6]. Although full-scale experiments are ideal for collecting and analyzing accurate data, they incur considerable amounts of expense and effort. Therefore, reduced-scale tests have been actively conducted. Although these tests have limitations such as turbulence intensity, thermal inertia of materials, radiation heat effects,
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Engine performance, combustion and 
		emissions evaluations of a diesel natural gas dual fuel engine

Engine performance, combustion and emissions evaluations of a diesel natural gas dual fuel engine

This project’s goal is to evaluate the performance and combustion characteristics from diesel derivative dual fuel engines on a 6-cylinder John Deere 6068H. Additionally, exhaust emissions measurement is performed in order to maintain compliance with Tier 2 emissions levels. The engine does not have any after treatment system. It is theorized that at part load conditions, the natural gas - air mixture is below the flammability limit in the cylinder, while penetration of the diesel fuel jet does not extend across the cylinder. Consequently, regions near the edge of the combustion chamber with natural gas and air mixtures below the flammability limit are either unburned or partially combusted. For the baseline conditions, the primary parameters presented here are in-cylinder pressure trace, heat release rate (HRR), mass fraction burned profile, brake specific fuel consumption (BSFC), efficiency, NOx, PM, CO and THC. An analysis is also presented showing the dual fuel performance in terms of ISO weighted average emissions based on the appropriate ISO test cycle. EXPERIMENTAL APPARATUS AND PROCEDURE Experiments were carried out on a four-stroke, turbocharged and after cooled, 6 - cylinder direct injection diesel engine. The engine has a 6.8 liter cylinder volume and compression ratio of 17:1. The engine was loaded with an eddy-current dynamometer. The dynamometer is manufactured by Marathon Electric, model number JVN. It is controlled by a variable frequency drive by Eaton Corporation that has a rating of 350hp at 480 VAC. A LabView Virtual Instrument VI is programmed to remotely control the system. The default manufacture injection timing was set at 6.5° before top dead center (bTDC) and speed at 1800 rpm were used throughout the diesel experiments. The instrument panel on the test bed indicated engine speed, brake power and various temperatures. A sketch of the instrumented engine setup and its specification is shown in Figure-1 and Table-1. The photo of the experimental apparatus is shown in Figure-2.
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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

The use of ventilation systems to control smoke movement is common in most road tunnel designs. The operation of the tunnel ventilation system is critical as its purpose during a fire emergency is to control the movement of smoke and heated gas away from the fire to provide a tenable environment along the egress path allowing for safe evacuation of motorists. The secondary purpose is to facilitate fire fighters access to the incident by providing a clear path to the fire site (Bendelius 2003). The risk of having a fire in a tunnel and designing an effective tunnel ventilation system through the provision of sufficient airflow to achieve tenable conditions in the egress path is dependent on multiple parameters including heat release rate (HRR), tunnel geometry, tunnel gradient, operation (whether bi-directional traffic is required) (Bendelius 2003) and legislation (whether vehicles carrying dangerous goods are allowed to access the tunnel, e.g. petrol tankers). Among these parameters, the heat release rate is the primary parameter for tunnel ventilation design and it is the most difficult to identify as this value is dependent on the types of vehicles and any associated loads carried by the vehicles. In current practice, the heat release rate for various types of fires proposed by the PIARC 1999 technical committee reports (PIARC 1999), NFPA 502 (NFPA 2004), BD78/99 (BD 1999) have generally been used for the design of tunnel ventilation systems. The heat release rates for the various types of vehicle fire range from 2.5 MW to 5 MW for passenger cars to 20 MW to 30 MW for heavy goods vehicles (HGV). However, recent fire experiments conducted in the Runehamar Tunnel showed that vehicles with burning goods may result in higher HRR (approx 66.4 to 201.9 MW peak) outputs (Ingason and Lonnermark 2005). These experiments seriously hinted that previous data regarding heavy goods vehicles might have been underestimated.
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Thermal Degradation and Fire Properties of Fungal Mycelium and Mycelium: Biomass Composite Materials

Thermal Degradation and Fire Properties of Fungal Mycelium and Mycelium: Biomass Composite Materials

be attributed to the release of flammable low molecular weight volatiles. Mycelium starts to decompose at approx- imately 225 °C. This event is accompanied by a rapid rise in the HRR spectrum reaching a peak HRR value at 300 °C, after which the heat release rate gradually decreases with temperature. The oxygen consumption reached a Figure 4. (a) Topographic SEM micrographs and (b) TEM transverse section micrographs detailing the ultrastructural, hyphal diameter and cell wall thickness changes in T. versicolor hypha pre- and post-pyrolysis (up to 600 °C in nitrogen). Abbreviations: ab, accumulation body; C, cytoplasm; CW, cell wall; CWR, cell wall reduction; HD, hyphal diameter; HDR, hyphal diameter reduction; M, mitochondria; MV, multivesicular; N, nucleus; P, plasmalemma.
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Fire performance of phase change material enhanced plasterboard

Fire performance of phase change material enhanced plasterboard

From Fig. 9 it can be seen that the material behaves similarly to a charring solid, and thus the peak of both mass loss rate (MLR) and heat release rate (HRR) are reached shortly after ignition. As evaporation and pyrolysis proceeds a char-like layer will develop which will inhibit both heat and mass transfer to the solid phase in-depth [32]. The cause of this behaviour hypothesised to be due to change the change in thermal properties of the gypsum which reduces its thermal conduc- tivity and density, and increases the permeability. The change of properties are due to the loss of moisture, as well as a change in the crystalline structure of gyp- sum at higher temperatures [35]. The heat wave penetrates through the specimen but the temperature distribution arising from the low thermal inertia of the plas- terboard means that fewer PCM vapours are generated. The reduction of heat transfer to the reaction front causes the MLR and HRR to decay over time. As the flow of flammable gases reduces, a pulsing blue flame is observed on the sur- face, suggesting lean combustion of the pyrolysis products and evaporated wax. Eventually insufficient vapours will be generated to maintain the pulsing flame and extinction will occur. Mass will continue to be lost due the dehydration and decomposition of the gypsum as well as pyrolysis of the PCM shell and evapora- tion of the paraffin wax, but without ignition. In the case of the 20 kW m -2 tests Figure 8. Temperature gradient through sample exposed to
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An Intelligence Approach to Predict Fire Flame Length under Tunnel Ceiling

An Intelligence Approach to Predict Fire Flame Length under Tunnel Ceiling

Within [4], tunnel height, fire Heat Release Rate HRR, smoke temperature and upstream air velocity are the main parameters which control fire flame length under the tunnel ceiling .Ingas[r]

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Military Maintenance Hangar

Military Maintenance Hangar

A fire test with this exact storage configuration was not found to provide a heat release rate to input into our FDS modeling. To determine the heat release rate of a fire in the PFE Storage we will have to come up with an estimate based on a similar configuration fire test. The exact composition of the cabinets and contents is not described in the design documents and due to nature of the facility will not likely be made available to the fire protection designer because of military secrecy classification. As discussed in the office space design fire it is not recommended by SFPE to try to extrapolate a design fire HRR by combining other design fire tests as there is too much uncertainty introduced into the results when this is attempted. Since we cannot test a mockup cabinet, we will have to utilize what we determine to be an equivalent stand-in for the cabinet.
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Vol 60, No 2 (2017)

Vol 60, No 2 (2017)

Diesel fuel, ethanol and gasoline were used in the burning experiments done into the 1/10 scale tunnel. These fuels were burned in rectangular stainless steel pans with different dimensions for each liquid in order to obtain a 15 kW Heat Release Rate (HRR), as shown in table 1 (shape of pan is rectangular in order to physically simulate a car shape with a uniform distributed fixed mass).

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Comparative study of organic and inorganic modification of Chinese fir wood based on the respiratory impregnation method

Comparative study of organic and inorganic modification of Chinese fir wood based on the respiratory impregnation method

Abstract: To compare The effects of organic and inorganic impregnation on the properties of unmodified, phenol formaldehyde oligomer-modified (PFOMCF), and sodium silicate-modified Chinese fir wood (SSMCF) were compared using samples prepared using the respiratory impregnation method. Impregnation and reinforcement effects and water resistance of PFOMCF and SSMCF were compared and the results was showed that the weight percentage gain, density increase rate, bending strength, and compressive strength of SSMCF were clearly higher than those of PFOMCF and had a lower water absorption rate within 60 h. The impregnation and reinforcement effects and dimensional stability of SSMCF were better than those of PFOMCF. FT-IR, XRD, CONE, and TGA examinations were used to test and analyze the chemical structure, crystalline structure, flame retardancy, and heat resistance of these modified woods. The results indicated that SSMCF possessed more hydrogen bonds than PFOMCF and that Si–O–Si chemical bonding with high bond energy was formed. Meanwhile, the weakened degree of the diffraction peak of SSMCF was much less than that of PFOMCF. These results explained that the mechanical properties and water resistance of SSMCF were better than PFOMCF. Compared with PFOMCF, SSMCF had a lower heat release rate (HRR), peak-HRR, mean-HRR, total heat release, smoke production rate, and total smoke production as well as higher thermal decomposition temperature and residual rate. Inorganic sodium silicate was shown to be a better flame retardant, while SSMCF had good smoke suppression effects, thermal stability, and safety performance in the case of fire.
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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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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.

46 The above figures reflect the pressure variations observed for each of the corresponding cases. As observed in the pressure trace of the 50dBTDC sparking case, the autoignition starts later than TDC, represented by the heat release peaks around 7dATDC. Secondly, the heat released is not very high, compared to other cases, especially during autoignition. This could be attributed to the extended flame propagation phase, which begins around 40dBTDC, earlier than the other cases. This extended burning due to flame front propagation could result in a large part of the fuel being consumed before TDC is reached. This phenomenon was also observed and explained by Yun [38]. Also, the conditions favorable for autoignition of the limited lean fuel mixture remaining in the cylinder are reached after TDC, resulting in a late autoignition. In the case of 30dBTDC sparking, the pressure in the cylinder during the combustion cycle is very high, so is the heat releases as seen in Fig. 3.13. The autoignition phase begins very early, around 8 degrees before TDC. This early autoignition during compression stroke, causes a significant increment in heat release rate, which is reflected in the pressure curve as well. Although this high expulsion of heat energy may lead to higher pressures, this case however is not a very favorable one. The multiple spikes, which occur after autoignition begins, signifies instability in the ignition process. The sharp spike of heat release following this section signifies a very high energy release in short time-span, which is possible grounds for knocking. A reason for such an immense energy release for this spark timing could be that the kernel formation occurs at elevated temperature and pressure conditions, which might accelerate the reaction process during the flame propagation stage, causing autoignition to occur earlier.
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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

This work presents a complete thermal cycle modeling of a four-stroke diesel engine with a three-dimensional simulation program CFD - AVL Fire. The object of the simu- lation was the S320 Andoria engine. The purpose of the study was to determine the effect of fuel dose distribution on selected parameters of the combustion process. As a result of the modeling, time spatial pressure distributions, rate of pressure increase, heat release rate and NO and soot emission were obtained for 3 injection strategies: no division, one pilot dose and one main dose and two pilot doses and one main dose. It has been found that the use of pilot doses on the one hand reduces engine hardness and lowers NO emissions and on the other hand, increases soot emissions.
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Combustion, performance and emissions of a diesel power
generator with direct injection of B7 and port injection of ethanol

Combustion, performance and emissions of a diesel power generator with direct injection of B7 and port injection of ethanol

pressure and net heat release rate with the use of ethanol at low loads and an increase at high loads, in.. comparison with B7.[r]

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Experimental Investigations on the Effect of Piston Geometry on CI Engine performance with Alternate Fuels

Experimental Investigations on the Effect of Piston Geometry on CI Engine performance with Alternate Fuels

accomplished by supplying water through the jackets in the engine block and cylinder head. A hole was made on the top of the cylinder head surface area to place the piezoelectric pressure transducer for measuring the heat release rate and cylinder pressure. The engine was stabilised for a particular operating point, fuel flow rate and exhaust gar temperatures are recorded. The engine was allowed to run for 15 to 20 minutes to attain the steady state condition to reach cooling water temperature of 70 C.

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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

Figure 6 represents the effect of injection timing on cylinder pressure and net heat release rate at 60% load conditions. With changes in injection timing, as expected, the in-cylinder pressure, and net rate of heat release also changes. On advancing the injection, the pressure in the cylinder reaches to higher value as compared to the retarded injection scheme. This is mainly due to the fact that, on advancing the injection, larger amount of fuel is injected (injection starting earlier and stopping later). Higher pressure is also found before TDC with advancement due to early start of combustion.
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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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Control Oriented NOx and Soot Emission Estimation for Diesel Engine

Control Oriented NOx and Soot Emission Estimation for Diesel Engine

The objective models for emission estimation for a series PEHV diesel engine-generator set control design, which combine the thermodynamic engine model, NOx model, soot model and EGR model described in Chapter One, have been developed. The heat release model was tuned to match the empirical data until the satisfactory results have been achieved, and the calculated in-cylinder pressure agrees well with the experimental data. Furthermore, the in-cylinder temperature, heat release rate, species mole fraction were calculated and provided as the inputs of the NOx and soot emission estimation models. Comparing to the previous work, the emission estimation model has been modified to take EGR system into account. Additionally, the NOx and soot emission estimation was validated and satisfactory for the Diesel engine-generator set control design. According to the implemented Model Predictive Control (MPC) design, eight operating points were selected to represent the diesel engine output power ranging from 7kW to 28kW. And the NO and soot emission results with EGR sweep for each operating point were provided for the diesel engine-generator controller design.
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Measurements of combustion dynamics with laser based diagnostic techniques

Measurements of combustion dynamics with laser based diagnostic techniques

the combustion instabilities because the values of the Rayleigh indices are larger. The right hand side of Figure 4.5 shows the global average of the flame. The toroidal structure is located in the shear zone where the fuel/air mixture is mixed with the outer air flow, then becoming further leaner, thus forming the weaker heat release rate zone at the boundary flame. Though the flame intensity is greater toward the center (RHS, Figure 4.5), the central region is not much affected by the exciting acoustic waves, in terms of the Rayleigh index (Figures 4.13 through 4.14) and the magnitude of the flame response (Figures 4.26 through 4.28). The greater part of the flow is the axial component (‘low’ swirl). Thus the greater part of energy is released in the center region. Yet the major contribution toward instability and flame response comes from the flame boundary, where the leaner portion of the flame is more heavily affected by the imposed acoustic oscillations.
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Heart rate recovery and blood pressure response during exercise testing in patients with microvascular angina

Heart rate recovery and blood pressure response during exercise testing in patients with microvascular angina

prognostic significance of diminished parasympathetic tone at rest, post-exercise HRR offers a noninvasive and feasible method to assess parasympathetic activation [23, 24]. Reduced HRR after exercise is a powerful predictor of overall mortality in patients without a history of heart failure or coronary revascularization [10]. Because it is simple to calculate from data obtained from standard ex- ercise tests and does not require either 24-h Holter monitoring or specialized baroreflex sensitivity testing, HRR may be useful for assessment of risk in routine clinical practice.
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Estimating relative intensity using individualized accelerometer cutpoints: the importance of fitness level

Estimating relative intensity using individualized accelerometer cutpoints: the importance of fitness level

underrepresentation of activity levels was demonstrated in a study by Stevenson et al. who reported that phase II cardiac rehabilitation patients did not spend any time in VIG PA when measured by traditional absolute cutpoints during a program session. However, during the same program sessions HR monitoring suggested pa- tients were at relative VIG intensities (>60% HRR) [34]. Typical functional capacities expected of cardiac re- habilitation patients have been measured at 19.3 ± 6.1 (5.5 MET) in men, and 14.5 ± 3.9 ml · kg -1 · min -1 (4 MET) in women [35]. With such low aerobic capacities it would not be possible for patients (or any healthy older individ- ual with a similar aerobic capacity) to reach absolute VIG- intensity accelerometer cutpoints even when at maximal efforts. Conversely, 29 of the 33 high fit individuals (>13 MET capacity) in our study achieved absolute activity counts of VIG-intensity, while most of these individuals met the absolute VIG criteria at only a relative intensity of 30-40% HRR. These individuals that reach an absolute level of VIG-intensity (>5725 counts · min -1 ) at lower rela- tive intensities (<60% HRR) would have greater recorded time spent in VIG-intensity PA as defined by the absolute method.
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