scholarly journals Effect of Venting on the Explosion of Aluminium-Silver Powder Mixtures

2020 ◽  
Vol 20 (1) ◽  
pp. 11
Author(s):  
Khairiah Mohd Mokhtar ◽  
Che Rosmani Che Hassan ◽  
Rafiziana Md Kasmani ◽  
Mahar Diana Hamid ◽  
Mohamad Iskandr Mohamad Nor ◽  
...  
Keyword(s):  
Silver Powder ◽  
Pressure Rise ◽  
Economic Loss ◽  
Experimental Results ◽  
Dust Explosion ◽  
Powder Mixtures ◽  
Metal Mixtures ◽  
Explosion Pressure ◽  
Lower Heat ◽  
Comparative Results

Dust explosion is considered as a serious threat for the industry that use or handle combustible materials as it may lead towards a significant economic loss in terms of damage to the facilities and suspension of activities, severe workplace injuries and fatalities. The rapid pressure developed during a dust explosion can be mitigated by venting. The present work explored the effects of venting on the explosion of different mixing weight ratios of aluminium and silver powder mixtures. The explosion characteristics of aluminium-silver mixtures were assessed in a 0.0012 m3 confined and vented cylindrical vessel. It was found that the application of 0.1 bar static burst pressure (Pstat) venting membrane gives one tenth reduction on explosion pressure and maximum rate of pressure rise for 70:30 and 50:50 mixing weight ratios of aluminium-silver mixtures explosion, respectively. This finding suggests that besides the venting application effect, the oxidation reaction of aluminium could be disrupted due to the presence of silver powder in the metal mixtures which results in lower heat transfer and reduction of the mass burning rate, hence, lessen flame speeds and explosion severity. However, the venting effectiveness is reduced when the Pstat increases. In order to assess the applicability of the dust explosion venting standard; NFPA 68 and EN 14491, the experimental results were compared with the calculated values according to the standards. The comparative results show that, both NFPA 68 and EN 14491 give underestimated values for explosion venting as compared with the experimental results.

scholarly journals Comparative study of the explosion pressure characteristics of micro- and nano-sized coal dust and methane–coal dust mixtures in a pipe

2020 ◽  
Vol 7 (1) ◽  
pp. 68-78 ◽  
Author(s):  
Bo Tan ◽  
Huilin Liu ◽  
Bin Xu ◽  
Tian Wang
Keyword(s):  
Coal Dust ◽  
Pressure Rise ◽  
Dust Explosion ◽  
Nano Particle ◽  
Explosion Pressure ◽  
Deflagration Index ◽  
Pressure Maximum ◽  
Explosion Accidents ◽  
The Impact ◽  
Pressure Characteristics

AbstractCoal dust explosion accidents often cause substantial property damage and casualties and frequently involve nano-sized coal dust. In order to study the impact of nano-sized coal on coal dust and methane–coal dust explosions, a pipe test apparatus was used to analyze the explosion pressure characteristics of five types of micro-nano particle dusts (800 nm, 1200 nm, 45 μm, 60 μm, and 75 μm) at five concentrations (100 g/m3, 250 g/m3, 500 g/m3, 750 g/m3, and 1000 g/m3). The explosion pressure characteristics were closely related to the coal dust particle size and concentration. The maximum explosion pressure, maximum rate of pressure rise, and deflagration index for nano-sized coal dust were larger than for its micro-sized counterpart, indicating that a nano-sized coal dust explosion is more dangerous. The highest deflagration index Kst for coal dust was 13.97 MPa/(m·s), indicating weak explosibility. When 7% methane was added to the air, the maximum deflagration index Kst for methane–coal dust was 42.62  MPa/(m·s), indicating very strong explosibility. This indicates that adding methane to the coal dust mixture substantially increased the hazard grade.

scholarly journals Determination of Explosion Characteristics of Sugar Dust Clouds

2018 ◽  
Vol 13 (1) ◽  
pp. 15-20
Author(s):  
Richard Kuracina ◽  
Zuzana Szabová ◽  
Matej Menčík
Keyword(s):  
Maximum Rate ◽  
Dust Cloud ◽  
Pressure Rise ◽  
Dust Explosion ◽  
Explosion Pressure ◽  
Maximum Explosion Pressure ◽  
Dust Clouds ◽  
Maximum Value ◽  
Explosion Limit

Abstract A dust explosion occurs when an airborne combustible dust cloud encounters an effective ignition source. The resulting pressure and temperature increase can severely injure people and damage surrounding equipment and buildings, and therefore needs to be prevented or controlled (Taveau, 2016). The article deals with the measurement of maximum explosion pressure and maximum rate of explosion pressure rise of sugar dust cloud. The measurements were carried out according to STN EN 14034-1+A1:2011 Determination of explosion characteristics of dust clouds. Part 1: Determination of the maximum explosion pressure pmax of dust clouds, the maximum rate of explosion pressure rise according to STN EN 14034-2+A1:2012 Determination of explosion characteristics of dust clouds - Part 2: Determination of the maximum rate of explosion pressure rise (dp/dt)max of dust clouds and Determination of explosion characteristics of dust clouds. Part 3: Determination of the lower explosion limit LEL of dust clouds. The sugar dust cloud in the chamber is achieved mechanically. The testing of explosions of sugar dust clouds showed that the maximum value of the pressure was reached at concentrations of 1000 g/m3 and its value is 6,89 bars.

scholarly journals The effect of selected inhibitors on the characteristics of wood dust explosion

2018 ◽  
Vol 247 ◽  
pp. 00056
Author(s):  
Łukasz Zubek ◽  
Mirosław Sobolewski
Keyword(s):  
Pressure Rise ◽  
Magnesium Carbonate ◽  
Wood Dust ◽  
Dust Explosion ◽  
Dry Powders ◽  
Explosion Pressure ◽  
Pressure Time ◽  
Fire And Explosion ◽  
Derivatives Of ◽  
Rock Dust

The mass concentration of four inhibitors which is required to suppress pine dust explosion were measured in laboratory-scale system. Measurements were conducted using four commercially available additives commonly used to decrease the fire and explosion hazards, three extinguishing powders: BC FOREX C, ABC Favorit X90, BC 101K and rock dust powder consisting calcium carbonate CaCO3 and magnesium carbonate MgCO3. The inhibition effect was investigated by measuring explosion pressure of various dust/powder mixtures using a 20 dm3 sphere by PN-EN 14034. On the basis of pressure-time curves the derivatives of pressure with respect to time (dp/dt), maximum explosion pressure pmax and maximum rate of explosion pressure rise (dp/dt)max were determined. It was found that inhibiting dust explosions with additives of various dry powders is a very effective way to decrease explosion effects. The experimental results have also shown that inhibiting effectiveness is strictly related to chemical composition of the powder. The order of effectiveness was monoammonium phosphate, sodium bicarbonate, potassium bicarbonate and rock dust.

Novel fractional hybrid impedance control of series elastic muscle-tendon actuator

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mohammad Javad Fotuhi ◽  
Zafer Bingul
Keyword(s):  
Contact Stress ◽  
Impedance Control ◽  
Robustness Analysis ◽  
Simulation Models ◽  
Experimental Results ◽  
Uncertain Environments ◽  
Content Type ◽  
Force Tracking ◽  
Comparative Results ◽  
Series Elastic

Purpose This paper aims to develope a novel fractional hybrid impedance control (FHIC) approach for high-sensitive contact stress force tracking control of the series elastic muscle-tendon actuator (SEM-TA) in uncertain environments. Design/methodology/approach In three different cases, the fractional parameters of the FHIC were optimized with the particle swarm optimization algorithm. Its adaptability to the pressure of the sole of the foot on real environments such as grass (soft), carpet (medium) and solid floors (hard) is far superior to traditional impedance control. The main aim of this paper is to derive the dynamic simulation models of the SEM-TA, to develop a control architecture allowing for high-sensitive contact stress force control in three cases and to verify the simulation models and the proposed controller with experimental results. The performance of the optimized controllers was evaluated according to these parameters, namely, maximum overshoot, steady-state error, settling time and root mean squared errors of the positions. Moreover, the frequency robustness analysis of the controllers was made in three cases. Findings Different simulations and experimental results were conducted to verify the control performance of the controllers. According to the comparative results of the performance, the responses of the proposed controller in simulation and experimental works are very similar. Originality/value Origin approach and origin experiment.

An Investigation of the Predicting Capabilities of a Variable Flow Stress Machining Theory

2001 ◽  
Author(s):  
P. Mathew
Keyword(s):  
Flow Stress ◽  
Material Flow ◽  
Three Dimensional ◽  
Experimental Results ◽  
Two Dimensional ◽  
Variable Flow ◽  
Comparative Results ◽  
Intermittent Cutting ◽  
Theoretical Results ◽  
Modelling Approach

Abstract The Oxley Machining Theory, which has been developed over the last 40 years, is presented in this paper. The capability of the model is described with its initial two-dimensional machining approach followed by the extension to the generalised model for three-dimensional machining. The theoretical results from the model are compared with the experimental results to determine the model capability. A brief description of the work associated with the effect of strain hardening at the interface is presented and comparative results are shown. A further extension of the model to intermittent cutting process of reaming is also presented and a comparison with the experimental results indicates the model developed is quite capable of predicting cutting forces for reaming. In explaining the results obtain, the assumptions made are explained and the inputs required. The limitations of the modelling approach are presented. It is pointed out that the Oxley model is a versatile model as long as proper description of the material flow stress properties is presented.

scholarly journals Shock-induced separated flows on the lee surface of delta wings

1987 ◽  
Vol 91 (903) ◽  
pp. 128-141 ◽  
Author(s):  
S. N. Seshadri ◽  
K. Y. Narayan
Keyword(s):  
Pressure Rise ◽  
Leading Edge ◽  
Experimental Results ◽  
Separated Flows ◽  
Delta Wings ◽  
Number Range ◽  
Pressure Distributions ◽  
Boundary Layer Interaction ◽  
Oil Flow ◽  
Attached Flow

Experiments were conducted to study shock-induced separated flows on the lee surface of delta wings with sharp leading edge at supersonic speeds. Two sets of delta wings of different thickness (10° and 25° normal angle), each with leading edge sweep angles varying from 45° to 70°, were tested. The measurements, carried out in a Mach number range from 1.4 to 3.0, included oil flow visualisations (on both sets of wings) and static pressure distributions (on the thicker wings only). Using the test results, some features of shock-induced separated flows, including in particular the boundary between this type of flow and fully attached flow, have been determined. The experimental results indicate that this boundary does not seem to show any significant dependence on wing thickness within the limit of thicknesses tested. It is shown that this boundary can be predicted for thin delta wings using a well known criterion for incipient separation in a glancing shock wave boundary layer interaction, namely that a pressure rise of 1.5 is required across the shock. Comparison of the predicted boundary with experimental results (from oil flow visualisations) shows good agreement.

scholarly journals Preliminary study on the tea dust explosion: the effect of tea dust size

2019 ◽  
Vol 255 ◽  
pp. 02014 ◽  
Author(s):  
Semawi Nur Hikmah ◽  
Sulaiman Siti Zubaidah ◽  
Ahmad Mutamim Noor Sabrina ◽  
Abdul Mudalip Siti Kholijah ◽  
Che Man Rohaida ◽  
...  
Keyword(s):  
Particle Size ◽  
Pressure Change ◽  
Dust Explosion ◽  
Particle Sizes ◽  
Drying Process ◽  
Chain Reaction ◽  
Explosion Pressure ◽  
Initial Shock ◽  
Preliminary Study ◽  
A Chain

Food-based dust is considered as combustible dust as they composed of distinct particles, regardless of the size or chemical composition and when suspended in air or any other oxidizing medium over a range of concentrations will present a fire or deflagration hazard. The explosion effect from food-based dust can cause catastrophic consequences because the initial shock wave from the explosion lift up more dust and triggers a chain reaction through the plant. One of the parameters that can enhance the explosion is the particle size of the dust. In this study, the effect of four different particle sizes of tea dust on the dust explosion severity was tested in a confined 20 L explosion bomb. Tea dust tends to explode due to its molecular structure which contains a carbon-hydrogen bond that can release the significant amount of thermal energy. The experimental results showed that the values of Pmax and (dP/dt)max of tea dust were more severe for the particle size of 160 ?m for which are 1.97 bar and 4.97 bar/s before drying and 2.09 bar and 7.01 bar/s after drying process. The finer dust reacted more violently than coarser ones. As particle size decreases, the rate of explosion pressure change increases, as long as the size is capable of supporting combustion.

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