scholarly journals Effects of Discharge Area and Atomizing Gas Type in Full Cone Twin-Fluid Atomizer on Extinguishing Performance of Heptane Pool Fire under Two Heat Release Rate Conditions in an Enclosed Chamber

2021 ◽  
Vol 11 (7) ◽  
pp. 3247
Author(s):  
Dong Hwan Kim ◽  
Chi Young Lee ◽  
Chang Bo Oh
Keyword(s):  
Heat Release ◽  
Flow Rate ◽  
Heat Release Rate ◽  
Release Rate ◽  
Water Mist ◽  
Pool Fire ◽  
Sauter Mean Diameter ◽  
Discharge Area ◽  
Fire Extinguishing ◽  
Enclosed Chamber

In this study, the effects of discharge area and atomizing gas type in a twin-fluid atomizer on heptane pool fire-extinguishing performance were investigated under the heat release rate conditions of 1.17 and 5.23 kW in an enclosed chamber. Large and small full cone twin-fluid atomizers were prepared. Nitrogen and air were used as atomizing gases. With respect to the droplet size of water mist, as the water and air flow rates decreased and increased, respectively, the Sauter mean diameter (SMD) of the water mist decreased. The SMD of large and small atomizers were in the range of approximately 12–60 and 12–49 μm, respectively. With respect to the discharge area effect, the small atomizer exhibited a shorter extinguishing time, lower peak surface temperature, and higher minimum oxygen concentration than the large atomizer. Furthermore, it was observed that the effect of the discharge area on fire-extinguishing performance is dominant under certain flow rate conditions. With respect to the atomizing gas type effect, nitrogen and air appeared to exhibit nearly similar extinguishing times, peak surface temperatures, and minimum oxygen concentrations under most flow rate conditions. Based on the present and previous studies, it was revealed that the effect of atomizing gas type on fire-extinguishing performance is dependent on the relative positions of the discharged flow and fire source.

The Effect of Sauter Mean Diameter Fluctuations on the Heat Release Rate in a Lean-Burn Aero-Engine Combustor

2019 ◽  
Author(s):  
Nicholas C. W. Treleaven ◽  
Andrew Garmory ◽  
Gary J. Page
Keyword(s):  
Heat Release ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Release Rate ◽  
Release Rate ◽  
Sauter Mean Diameter ◽  
Lean Burn ◽  
Thermoacoustic Instability ◽  
Mean Diameter

Abstract It has been shown that the fluctuations of pressure caused by a thermoacoustic instability can affect the mass flow rate of air and atomisation of the liquid fuel inside a gas turbine. Tests with premixed flames have confirmed that the fluctuations of the mass flow rate of air can affect the heat release rate through purely aerodynamic phenomenon but little work has been done to test the sensitivity of the heat release rate to changes in the fuel atomisation process. In this study, a lean-burn combustor geometry is supplied with a fuel spray fluctuation of SMD (Sauter mean diameter) of 20% with respect to the mean value and the heat release rate predicted using Large Eddy Simulation (LES) with combustion predicted using a presumed probability density function (PPDF), flamelet generated manifolds (FGM) method. Previous work has shown that at atmospheric conditions the SMD may fluctuate by up to 16% percent and at low frequencies may be reasonably well predicted by using a correlation based on the instantaneous velocity and mass flow rate of air close to the air-blast atomiser. Analysis of the flow fields highlights a complicated spray, flame and wall interaction as being responsible for this observed fluctuation of heat release rate. The heat release rate predicted by the LES shows a 20% fluctuation which implies that even small fluctuations of SMD will significantly contribute to thermoacoustic instabilities.

Heat release rate determination of pool fire at different pressure conditions

2018 ◽  
Vol 42 (6) ◽  
pp. 620-626 ◽  
Author(s):  
Qiuju Ma ◽  
Jiachen Chen ◽  
Hui Zhang
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Pool Fire

Experimental Study on Water Mist Suppression of Poly(Methyl Methacrylate) PMMA Fires

Volume 4 ◽  
2004 ◽  
Author(s):  
B. Yao ◽  
J. Qin ◽  
W. K. Chow
Keyword(s):  
Methyl Methacrylate ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Water Mist ◽  
Doppler Velocimetry ◽  
Confined Space ◽  
Surface Cooling ◽  
Fuel Surface ◽  
Poly Methyl Methacrylate

Suppression of Poly(methyl methacrylate) PMMA fires by water mist will be studied in this paper. A simple test is developed to study the critical water flow rate under different radiant heat flux. The test is found to be suitable for studying the extinguishment effects of fine water droplets involving oxygen displacement, gas phase and fuel surface cooling. Water mist is generated by a single pressure nozzle, with the water mist characteristics measured by the Laser Doppler Velocimetry or the Adaptive Phase Doppler Velocimetry System (LDV/APV system). The interaction between water mist and the PMMA flame will be studied in a confined space with ventilation control in a cone calorimeter. The heat release rate, oxygen, carbon dioxide and carbon monoxide concentrations, and other important parameters of the interaction under various conditions are measured. It is found that discharging adequate amount of water mist would suppress the diffusion flame in the confined space. Reignition might occur once water mist stopped discharging to the fuel surface. Higher heat release rate and more smoke and toxic gases were produced than from those in first ignition.

scholarly journals ANALYSIS OF HEAT RELEASE RATE IN ENGINE ROOM FIRES OF 300 GT FERRY RO-RO PASSENGER BY USING WATER MIST SYSTEM AND CO2 SYSTEM

2021 ◽  
Vol 15 (2) ◽  
Author(s):  
Wira Setiawan ◽  
Distyan Kotanjungan
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Fire Suppression ◽  
Water Mist ◽  
Engine Room ◽  
Passenger Ships ◽  
Dynamic Simulator ◽  
Fire Dynamic Simulator ◽  
Suppression System

Based on statistical data in recent years, there are still quite a number of ship accidents due to fires, including on passenger ships. The water mist system is a fire suppression system that allows it to be used in the engine room with the advantage that it can keep the heat production rate low during the extinguishing process and can be operated earlier than the CO2 system. The research is conducted by using fire dynamic simulator in the engine room of a 300 GT ferry ro-ro passenger to compare the heat release rate of fire without an extinguishing system, an existing CO2 system, and a water mist system. The result shows that the CO2 fire suppression system reduces the heat release rate more rapidly to the decay phase at 375 seconds while the water mist takes more than 900 seconds. However, the fully developed phase of the water mist suppression system occurs more quickly than CO2 because the sprinklers are activated shortly after a fire occurs. Unlike water mist, the CO2 system is activated at 60 seconds so that the pre-combustion, growth, flashover, and fully developed phases are at the same HRR and time as the natural one.

Temperature effects on the mass flow rate in the SBI and similar heat-release rate test equipment

2007 ◽  
Vol 31 (1) ◽  
pp. 53-66 ◽  
Author(s):  
Bart J. G. Sette ◽  
Erwin Theuns ◽  
Bart Merci ◽  
Paul Vandevelde
Keyword(s):  
Heat Release ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Release Rate ◽  
Release Rate ◽  
Temperature Effects ◽  
Test Equipment ◽  
Rate Test

Numerical and Experimental Study of Fire Whirl Generated in 15 × 15 Square Array Fires Placed in Cross Wind

2008 ◽  
Author(s):  
Kohyu Satoh ◽  
Naian Liu ◽  
Qiong Liu ◽  
K. T. Yang
Keyword(s):  
Heat Release ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Release Rate ◽  
Release Rate ◽  
Large City ◽  
Heat Flow Rate ◽  
Fire Whirl ◽  
Square Array

Fire whirls in large city fires and forest fires, which are highly dangerous and destructive, can cause substantial casualties and property damages. It is important to examine under what conditions of weather and geography such merging fires and fire whirls are generated. However, detailed physical characteristics about them are not fully clarified yet. Therefore, we have conducted preliminary studies about merging fires and swirling fires and found that they can enhance the fire spread. If sufficient knowledge can be obtained by relevant experiments and numerical computations, it may be possible to mitigate the damages due to merged fires and fire whirls. The objective of this study is to investigate the swirling conditions of fires in square arrays, applying wind at one corner, in laboratory experiments and also by CFD numerical simulations. Varying the inter-fire distance, heat release rate and mass flow rate by a wind fan, ‘swirling’ or ‘non-swirling’ in the array were judged. It has been found that the fire whirl generation is highly affected by the inter-fire distance in the array, the total heat release rate and also the mass flow rate by a fan. We obtained the conditions of swirling fire generation in 15 × 15 square array for (1) the ratio between the upward mass flow rate vs. applied mass flow rate in the upward swirling plume and (2) a non-dimensional relationship between the heat flow rate in the swirling plume and the applied mass flow rate.

scholarly journals Estimation of Magnitude and Heat Release Rate of Fires Occurring in Historic Buildings-Taking Churches as an Example

2021 ◽  
Vol 13 (16) ◽  
pp. 9193
Author(s):  
Wen-Yao Chang ◽  
Chieh-Hsin Tang ◽  
Ching-Yuan Lin
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Water Mist ◽  
Smoke Detector ◽  
Fire Dynamics ◽  
Historical Building ◽  
Maximum Heat ◽  
Improvement Measures ◽  
Maximum Heat Release

Historical buildings often fail to meet today’s building and fire protection regulations due to their structure and space restrictions. For this reason, if such buildings encounter fire, serious damage will be resulted. The fire of the Notre-Dame Cathedral in Paris (Notre-Dame de Paris) in April 2019 highlights the seriousness of this problem. In this study, the historical building of “Tamsui Church” was selected as an example. The Fire Dynamics Simulator (FDS) was adopted to analyze the scale of damage and possible hazards when the wooden seats in the church are on fire, and improvement measures were proposed to ensure that such buildings can be used under safer conditions. It was found that the existing seat arrangement will cause the spreading of fire, and the maximum heat release rate is 2609.88 kW. The wooden roof frame above the fire source will also start to burn at 402.88 s (6.6 min) after the fire, which will lead to a full-scale fire. To maintain the safety of the historical building, it is necessary to add active firefighting equipment (smoke detector and water mist system).

Experimental Study on Homogeneous Charge Compression Ignition Combustion With Fuel of Dimethyl Ether and Natural Gas

2005 ◽  
Vol 128 (2) ◽  
pp. 414-420 ◽  
Author(s):  
Mingfa Yao ◽  
Zunqing Zheng ◽  
Jin Qin
Keyword(s):  
Natural Gas ◽  
Heat Release ◽  
Dimethyl Ether ◽  
Flow Rate ◽  
Heat Release Rate ◽  
Release Rate ◽  
Compression Ignition ◽  
Cylinder Pressure ◽  
Hcci Combustion ◽  
Peak Cylinder Pressure

The homogeneous charge compression ignition (HCCI) combustion fueled by dimethyl ether (DME) and compressed natural gas (CNG) was investigated. The experimental work was carried out on a single-cylinder diesel engine. The results show that adjusting the proportions of DME and CNG is an effective technique for controlling HCCI combustion and extending the HCCI operating range. The combustion process of HCCI with dual fuel is characterized by a distinctive two-stage heat release process. As CNG flow rate increases, the magnitude of peak cylinder pressure and the peak heat release rate in the second stage goes up. As DME flow rate increases, the peak cylinder pressure, heat release rate, and NOx emissions increase while THC and CO emissions decrease.

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