scholarly journals The Suppression Characteristics of NH4H2PO4/Red Mud Composite Powders on Methane Explosion

2018 ◽  
Vol 8 (9) ◽  
pp. 1433 ◽  
Author(s):  
Yimin Zhang ◽  
Yan Wang ◽  
Xiangqing Meng ◽  
Ligang Zheng ◽  
Jianliang Gao
Keyword(s):  
Red Mud ◽  
Pressure Rise ◽  
Test System ◽  
Maximum Pressure ◽  
Scanning Calorimetry ◽  
Composite Powders ◽  
Suppression Effect ◽  
Explosion Suppression ◽  
Pressure Peak ◽  
Methane Explosion

The composite powders composed of red mud (RM) and NH4H2PO4 (NH4H2PO4/RM) were successfully prepared by the anti-solvent method. The composition and structure of the NH4H2PO4/RM composite powders were characterized by the techniques of X-ray diffraction (XRD), SEM, N2 adsorption-desorption and Thermogravimetry-Differential scanning calorimetry (TG-DSC). The analysis results indicate that the as-prepared samples are composed with uniform nanoparticles and possess the porous structure. The methane explosion suppression characteristics of the NH4H2PO4/RM composite powders were tested by a 20 L spherical explosion system and a 5 L pipe test system. The results show that the NH4H2PO4/RM composite powders possess considerable suppression properties on methane explosion. When the loading content of NH4H2PO4 reached 30%, the maximum pressure and the maximum pressure rise rate of methane explosion were decreased by 35.1% and 95.8%, respectively. When comparing with no powder addition, the time to reach the pressure peak was extended from 0.07 s to 0.50 s. The NH4H2PO4/RM composite powders presented a synergistic suppression effect between NH4H2PO4 and RM, which made it exhibit considerable suppression property than that of pure NH4H2PO4 or red mud powders.

scholarly journals Suppression Effects of Hydroxy Acid Modified Montmorillonite Powders on Methane Explosions

Energies ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 4068 ◽  
Author(s):  
Yan Wang ◽  
Hao Feng ◽  
Yimin Zhang ◽  
Chendi Lin ◽  
Ligang Zheng ◽  
...  
Keyword(s):  
Functional Groups ◽  
Gluconic Acid ◽  
Pressure Rise ◽  
Experimental System ◽  
Hydroxyl Groups ◽  
Scanning Calorimetry ◽  
Suppression Effect ◽  
Explosion Pressure ◽  
Pyrolysis Characteristics ◽  
Explosion Suppression

In this paper, montmorillonite inhibitors modified with polyhydroxy functional groups by gluconic acid (GA) were successfully prepared. The particle size distribution, composition, surface functional groups, and pyrolysis characteristics of the pure montmorillonite powders (Mt) and the gluconic acid modified powders (G-Mt) were analyzed by using a laser particle analyzer, X-ray diffraction (XRD), Fourier transform infrared (FTIR) and thermogravimetry–differential scanning calorimetry (TG-DSC), respectively. The suppression effect of Mt and G-Mt on the 9.5% methane–air premixed gas was tested in a 20 L spherical explosion device and a 5 L pipeline experimental system. The results show that G-Mt displays a much better suppression property than that of Mt. The optimal explosion suppression effect concentration of Mt or G-Mt powders is about 0.25 g·L−1. In this concentration, for G-Mt, the maximum explosion pressure declined by 26.7%, the maximum rate of pressure rise declined by 74.63%, and the time for the flame front to reach the top of the pipe was delayed by 242.5%. On the basis of the experimental data, the better suppression effect of G-Mt than Mt might be attributed to the presence of more hydroxyl groups on the surface.

scholarly journals Effect of Pristine Palygorskite Powders on Explosion Characteristics of Methane-Air Premixed Gas

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2496 ◽  
Author(s):  
Yimin Zhang ◽  
Yan Wang ◽  
Ligang Zheng ◽  
Tao Yang ◽  
Jianliang Gao ◽  
...  
Keyword(s):  
Flame Propagation ◽  
Low Cost ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Flame Propagation Velocity ◽  
Explosion Pressure ◽  
Pyrolysis Characteristics ◽  
Explosion Suppression ◽  
Adsorption Desorption ◽  
Methane Explosion

In this study, pristine palygorskite powders were used as the inhibition materials to suppress the explosion of methane-air premixed gas for the first time. The composition, porosity and pyrolysis characteristics of the powders were tested by X-ray diffraction (XRD), energy dispersive spectrometry (EDS), N2 adsorption-desorption and Thermogravimetry-differential scanning calorimetry (TG-DSC) techniques. The effects of pristine palygorskite powders concentration on the explosion pressure and the average velocity of flame propagation of the 9.5% methane-air premixed gas were tested by a 20 L spherical explosion system and a 5 L pipeline explosion system. The results indicated the pristine palygorskite powders possess a considerable suppression property on methane explosion. When the mass concentration of pristine palygorskite powders was 0.20 g·L−1, the max-pressure of methane explosion was decreased by 23.9%. The methane explosion flame propagation velocity was inhibited obviously. Owing to the excellent inhibitory performance and the advantage of low-cost and environmental harmlessness, pristine palygorskite powders are potential new materials for the application on gas explosion suppression.

Experimental Study of Explosion Pressure Characteristics of Methane under High Temperature Conditions

2014 ◽  
Vol 687-691 ◽  
pp. 148-152 ◽  
Author(s):  
Run Zhi Li ◽  
Rong Jun Si ◽  
Yan Song Zhang
Keyword(s):  
Environmental Temperature ◽  
Pressure Rise ◽  
Test System ◽  
Coal Bed ◽  
Maximum Pressure ◽  
Explosion Pressure ◽  
Pressure Rise Rate ◽  
Maximum Explosion Pressure ◽  
Rise Rate ◽  
Pressure Characteristics

Methane explosion pressure characteristics under the condition of different temperatures (25°C-200 °C) were studied by the special environment 20L explosion characteristics test system. By the experimental results, in the case of other conditions unchanged, with the increase of environmental temperature, the maximum explosion pressure of the optimum explosion concentration decrease, the maximum explosion pressure and the reciprocal of environmental temperature show linear attenuation law, the maximum pressure rise rate is not influenced by environmental temperature basically; Outside the scope of explosion limits at normal temperature and pressure, with the increase of environmental temperature, no explosion methane-air mixture are explosive gradually, the maximum explosion pressure and maximum pressure rise rate are in the relationship of different exponential growth with the increase of ambient temperature. The conclusions provide an important theoretical basis for prevent mine gas explosion accidents and coal bed methane safely use.

Vibration analysis and combustion parameter evaluation of CI engine based on Fourier Decomposition Method

2021 ◽  
pp. 146808742098819
Author(s):  
Wang Yang ◽  
Cheng Yong
Keyword(s):  
Vibration Analysis ◽  
Decomposition Method ◽  
Combustion Process ◽  
Pressure Rise ◽  
Maximum Pressure ◽  
Vibration Signals ◽  
Loop Control ◽  
Fourier Decomposition ◽  
Surface Vibration ◽  
Rise Rate

As a non-intrusive method for engine working condition detection, the engine surface vibration contains rich information about the combustion process and has great potential for the closed-loop control of engines. However, the measured engine surface vibration signals are usually induced by combustion as well as non-combustion excitations and are difficult to be utilized directly. To evaluate some combustion parameters from engine surface vibration, the tests were carried out on a single-cylinder diesel engine and a new method called Fourier Decomposition Method (FDM) was used to extract combustion induced vibration. Simulated and test results verified the ability of the FDM for engine vibration analysis. Based on the extracted vibration signals, the methods for identifying start of combustion, location of maximum pressure rise rate, and location of peak pressure were proposed. The cycle-by-cycle analysis of the results show that the parameters identified based on vibration and in-cylinder pressure have the similar trends, and it suggests that the proposed FDM-based methods can be used for extracting combustion induced vibrations and identifying the combustion parameters.

Characterization of Partially Premixed Combustion With Ethanol: EGR Sweeps, Low and Maximum Loads

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Vittorio Manente ◽  
Bengt Johansson ◽  
Pert Tunestal
Keyword(s):  
High Efficiency ◽  
Pressure Rise ◽  
Premixed Combustion ◽  
Maximum Pressure ◽  
Pressure Rise Rate ◽  
Start Of Injection ◽  
Partially Premixed Combustion ◽  
Rise Rate ◽  
Partially Premixed ◽  
Gas Recirculation

Exhaust gas recirculation (EGR) sweeps were performed on ethanol partially premixed combustion (PPC) to show different emission and efficiency trends as compared with diesel PPC. The sweeps showed that when the EGR rate is increased, the efficiency does not diminish, HC trace is flat, and CO is low even with 45% of EGR. NOx exponentially decreases by increasing EGR while soot levels are nearly zero throughout the sweep. The EGR sweeps underlined that at high EGR levels, the pressure rise rate is a concern. To overcome this problem and keep high efficiency and low emissions, a sweep in the timing of the pilot injection and pilot-main ratio was done at ∼16.5 bars gross IMEP. It was found that with a pilot-main ratio of 50:50, and by placing the pilot at −60 with 42% of EGR, NOx and soot are below EURO VI levels; the indicated efficiency is 47% and the maximum pressure rise rate is below 10 bar/CAD. Low load conditions were examined as well. It was found that by placing the start of injection at −35 top dead center, the efficiency is maximized, on the other hand, when the injection is at −25, the emissions are minimized, and the efficiency is only 1.64% lower than its optimum value. The idle test also showed that a certain amount of EGR is needed in order to minimize the pressure rise rate.

Performance of Dual Fuel Engine Running on Jojoba Oil as Pilot Fuel and CNG or LPG

2007 ◽  
Author(s):  
Mohamed Y. E. Selim ◽  
M. S. Radwan ◽  
H. E. Saleh
Keyword(s):  
Methyl Ester ◽  
Natural Gas ◽  
Pressure Rise ◽  
Combustion Noise ◽  
Dual Fuel ◽  
Maximum Pressure ◽  
Injection Timing ◽  
Pressure Rise Rate ◽  
Rise Rate ◽  
Pilot Fuel

The use of Jojoba Methyl Ester as a pilot fuel was investigated for almost the first time as a way to improve the performance of dual fuel engine running on natural gas or LPG at part load. The dual fuel engine used was Ricardo E6 variable compression diesel engine and it used either compressed natural gas (CNG) or liquefied petroleum gas (LPG) as the main fuel and Jojoba Methyl Ester as a pilot fuel. Diesel fuel was used as a reference fuel for the dual fuel engine results. During the experimental tests, the following have been measured: engine efficiency in terms of specific fuel consumption, brake power output, combustion noise in terms of maximum pressure rise rate and maximum pressure, exhaust emissions in terms of carbon monoxide and hydrocarbons, knocking limits in terms of maximum torque at onset of knocking, and cyclic data of 100 engine cycle in terms of maximum pressure and its pressure rise rate. The tests examined the following engine parameters: gaseous fuel type, engine speed and load, pilot fuel injection timing, pilot fuel mass and compression ratio. Results showed that using the Jojoba fuel with its improved properties has improved the dual fuel engine performance, reduced the combustion noise, extended knocking limits and reduced the cyclic variability of the combustion.

A comparative numerical study of the combustion performance of the syngas-fueled HCCI engine using a toroidal piston, square bowl piston, and flat piston shape at different loads

2021 ◽  
pp. 1-27
Author(s):  
Kabbir Ali ◽  
Changup Kim ◽  
Yonggyu Lee ◽  
Seungmook Oh ◽  
Ki-Seong Kim
Keyword(s):  
Numerical Study ◽  
Pressure Rise ◽  
Fuel Mixture ◽  
Combustion Efficiency ◽  
Maximum Pressure ◽  
Cross Sectional ◽  
Combustion Performance ◽  
Hcci Engine ◽  
Heat Loss Rate ◽  
Piston Bowl

Abstract This study analyzes the combustion performance of a syngas-fueled homogenous charge compression ignition (HCCI) engine using a toroidal piston, square bowl, and flat piston shape, at low, medium, and high loads, with a constant compression ratio of 17.1. In this study, the square bowl shape is optimized by reducing the piston bowl depth and squish area ratio (squish area/cylinder cross-sectional area) from (34 to 20, 10, and 2.5) %, and compared with the flat piston shape and toroidal piston shape. This HCCI engine operates under an overly lean air–fuel mixture condition for power plant usage. ANSYS Forte CFD with GRI Mech3.0 chemical kinetics is used for combustion analysis, and the calculated results are validated by the experimental results. All simulations are accomplished at maximum brake torque (MBT) by altering the air–fuel mixture temperature at IVC with a constant equivalence ratio of 0.27. This study reveals that the main factors that affect the start of combustion , maximum pressure rise rate (MPRR), combustion efficiency, and thermal efficiency by changing the piston shape are the squish flow and reverse squish flow effects. Therefore, the square bowl piston D is the optimized piston shape that offers low MPRR and high combustion performance for the syngas-fueled HCCI engine, due to the weak squish flow and low heat loss rate through the combustion chamber wall, respectively, compared to the other piston shapes of square bowl piston A, B, and C, flat piston, and toroidal (baseline) piston shape.

Characterization of Partially Premixed Combustion With Ethanol: EGR Sweeps, Low and Maximum Loads

2009 ◽  
Author(s):  
Vittorio Manente ◽  
Bengt Johansson ◽  
Pert Tunestal
Keyword(s):  
High Efficiency ◽  
Pressure Rise ◽  
Premixed Combustion ◽  
Maximum Pressure ◽  
Pressure Rise Rate ◽  
Partially Premixed Combustion ◽  
Rise Rate ◽  
Low Load ◽  
Partially Premixed

EGR sweeps were performed on Ethanol Partially Premixed Combustion, PPC, to show different emission and efficiency trends as compared to Diesel PPC. The sweeps showed that increasing the EGR rate the efficiency does not diminish, HC trace is flat and CO is low even with 45% of EGR. NOx exponentially decreases by increasing EGR while soot levels are nearly zero throughout the sweep. The EGR sweeps underlined that at high EGR levels, the pressure rise rate is a concern. To overcome this problem and keep high efficiency and low emissions a sweep in timing of the pilot injection and pilot-main ratio was done at ∼16.5 bar gross IMEP. It was found that with a pilot-main ratio of 50–50 and by placing the pilot at −60 with 42% of EGR, NOx and soot are below EURO VI levels, the indicated efficiency is 47% and the maximum pressure rise rate is below 10 bar/CAD. Low load conditions were examined as well. It was found that by placing the SOI at −35 TDC the efficiency is maximized on the other hand when the injection is at −25 the emissions are minimized and the efficiency is only 1.64% lower than its optimum value. The idle test also showed that a certain amount of EGR is needed in order to minimize the pressure rise rate.

Performance of Strongly Bowed Stators in a Four-Stage High-Speed Compressor

2004 ◽  
Vol 126 (3) ◽  
pp. 333-338 ◽  
Author(s):  
Axel Fischer ◽  
Walter Riess ◽  
Joerg R. Seume
Keyword(s):  
Mass Flow ◽  
High Speed ◽  
Static Pressure ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Pressure Rise ◽  
Maximum Pressure ◽  
Controlled Diffusion ◽  
Stage 4 ◽  
The University

The FVV sponsored project “Bow Blading” (cf. acknowledgments) at the Turbomachinery Laboratory of the University of Hannover addresses the effect of strongly bowed stator vanes on the flow field in a four-stage high-speed axial compressor with controlled diffusion airfoil (CDA) blading. The compressor is equipped with more strongly bowed vanes than have previously been reported in the literature. The performance map of the present compressor is being investigated experimentally and numerically. The results show that the pressure ratio and the efficiency at the design point and at the choke limit are reduced by the increase in friction losses on the surface of the bowed vanes, whose surface area is greater than that of the reference (CDA) vanes. The mass flow at the choke limit decreases for the same reason. Because of the change in the radial distribution of axial velocity, pressure rise shifts from stage 3 to stage 4 between the choke limit and maximum pressure ratio. Beyond the point of maximum pressure ratio, this effect is not distinguishable from the reduction of separation by the bow of the vanes. Experimental results show that in cases of high aerodynamic loading, i.e., between maximum pressure ratio and the stall limit, separation is reduced in the bowed stator vanes so that the stagnation pressure ratio and efficiency are increased by the change to bowed stators. It is shown that the reduction of separation with bowed vanes leads to a increase of static pressure rise towards lower mass flow so that the present bow bladed compressor achieves higher static pressure ratios at the stall limit.

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