Increase In Rate Pressure Research Articles

Opinion formation analysis for Expressed and Private Opinions (EPOs) models: Reasoning private opinions from behaviors in group decision-making systems

In group decision-making, the expressed opinion of a social individual may be inconsistent with or even opposite to his/her own private opinion or inner thought. Expressed and private opinions (EPOs) models were then developed to study decision-making mechanisms with private opinions. However, most of the existing EPOs models assumed that the individual private opinion is often fixed, or updated by his/her own private opinion and neighbors’ expressed opinions, ignoring the behavior characteristics of social individuals. In this paper, a novel EPOs model is built under a more realistic scenario where the individual private opinions are updated by reasoning the neighbors’ private opinions from their behaviors while the expressed opinions are subject to social pressure. Meanwhile, we investigate the group opinion formation under the proposed EPOs model over a Leader–Influencer–Follower hierarchical network. The evolution process under the proposed EPOs model shows that, on the one hand, when the social pressure is monotonically increasing, group expressed opinions often reach consensus, and the consensus reaching time is closely related to the pressure increase rate. On the other hand, group private opinions and behaviors of the individuals show polarization. The simulation results reveal the sociological phenomena of “the golden mean” and “inconsistent words and deeds”, respectively.

Thermal hazards assessment of three azo nitrile compounds

Commercially available azo radical compounds provide efficient initiation of many chemical reactions. However, such energetic azo group initiators have thermal stability issues at ambient or even sub-ambient temperatures. Azo decomposition initiated by heat and/or light can generate significant amounts of nitrogen gas with rapid pressure increases, presenting a safety challenge for shipping, storage and usage. In this study, three azo nitrile compounds were examined using various thermal calorimetry techniques with only 5 mg to 1 g scale samples. We obtained calorimetric data on exothermic activity and gas generation. The testing results were subsequently analyzed by using differential iso-conversional methods to obtain key decomposition kinetics parameters, including activation energy and pre-exponential factor. The model was then validated and utilized for prediction of several key safety parameters for scale-up applications, including Self-Accelerating Decomposition Temperature (SADT), Time to Maximum Rate (TMR), temperature profiles at iso- or non-isothermal conditions for shelf-life evaluation, adiabatic temperature rise, and rate of pressure increase. For compounds such as 2,2’-azobis-(2,4-dimethylvaleronitrile) and 1,1’-azobis(cyclohexane-1-carbonitrile) which went through phase transitions associated with thermal decomposition, the thermal decomposition behavior of liquid and solid state was found to differ in characteristic. This methodology for thermal decomposition kinetics assessment enables safe storage, handling, and scale-up process preparation.

Evaluation of detailed combustion, energy and exergy analysis on ethanol-gasoline and methanol-gasoline blends of a spark ignition engine

This study discusses the combustion behaviour of an SI engine and evaluates the engine's thermodynamic performance through energy and exergy analysis. The test results compared the fuels obtained by adding small amounts of ethanol (and equal amounts of methanol) to gasoline with each other and with gasoline as the reference fuel. The study was conducted at a constant engine speed and five different engine loads (2, 2.5, 3, 3.5, and 4 Nm). Upon examining the study results, it was observed that the addition of ethanol and methanol to gasoline increased the maximum in-cylinder pressure. While the gasoline-alcohol mixtures relatively reduced the average in-cylinder gas temperature, the pressure increase rates significantly increased. It was observed that the volumetric addition of ethanol/methanol to gasoline had a relatively decreasing effect on thermal and exergetic efficiency values.

Experimental study on suppression of methane-air explosion with different surface dispersants combined with modified attapulgite powder

This paper investigated the Inhibitory effect of attapulgite powder, modified attapulgite powder, and modified attapulgite powder after compounding by adding different types and different quality of surface dispersants to the explosion of methane-air premixed gas. A self-made semi-closed transparent pipe is the leading experimental platform in the research process. The maximum explosion overpressure, average pressure increase rate, and explosion power index under different working conditions are calculated by analyzing the pipeline's flame shape, pressure, and flame spread speed. Comparing methane explosion and adding attapulgite powder and modified attapulgite powder as explosion suppression materials, experiments were carried out, and the experimental results were compared and analyzed, which proved the inhibitory effect of modified attapulgite powder on methane explosion. Adding different qualities of sodium polyacrylate, ammonium hexametaphosphate, and sodium dodecyl benzene sulfonate as surface dispersants to the modified attapulgite powder. The effect of adding different dispersants on the ability of modified attapulgite powder to suppress the explosion of methane premixed gas was explored. Compared with the experiments of methane explosion, attapulgite powder, and modified attapulgite powder to suppress explosion, it is proved that after adding the above three surface dispersants, the modified attapulgite powder has better inhibition on methane explosion. The effect and the influence law and the corresponding inhibition mechanism are analyzed. The experimental results show that the modified attapulgite powder added with 120 mg of sodium dodecyl benzene sulfonate has the best suppression effect on the explosion of 9.5% pure methane-air premixed gas.

Effects of mixing CO and H2 as main components on the explosion characteristics and dynamics properties of methane

This study experimentally examines the effect of the addition of mixed gas (C2H6 + C2H4): (CO + H2) = 1:5 on the explosion characteristics of methane (volume fractions of 7%, 9.5%, and 11%) The explosion pressure, rate of increase in explosion pressure and time to reach the maximum explosion pressure are monitored. The mole fraction of radicals, sensitivity of CH4, and rate of production (ROP) are then calculated. The results show that the addition of mixed gas has the greatest impact on the explosion characteristics of the 7% methane mixture. For methane mixture of 7%, 9.5% and 11%, R1, R107 and R104, respectively, have the greatest impact on the methane sensitivity. The impact on the methane sensitivity in descending order is 7% > 9.5% > 11%. R1 (H + O2 = O + OH) was the most promoting and primary reaction for the consumption of O2 and the production of OH.

Construction of antimicrobial peptides/alginate multilayers modified membrane: Antibiofouling performance and mechanisms

Biofouling remains to be one of major obstacles for membrane-based technology in water and wastewater treatment, calling for the development of antibiofouling membranes. For the traditional release-killing strategy, uncontrollable release of biocides and thus a short lifetime as well as the potentially environmental risk are thorny issues for the modified membranes. Herein, hydrophilic hydrogel multilayers with controllable thickness at nanometer scale on a poly(vinylidene fluoride) (PVDF) microfiltration membrane were constructed via layer-by-layer (LbL) self-assembly of non-drug-resistant antimicrobial peptides (AMPs) and alginate. The AMPs/alginate multilayers modified membranes exhibited enhanced hydrophilicity, well-controlled pore size distribution and prominent antimicrobial ability against Escherichia coli and Staphylococcus aureus. As the number of multilayers of alginate increased, both initial and steady release rate of Ponericin G1 reduced; in particular, the AMPs/alginate modified membranes with fifteen multilayers (MSA15) had the slowest release kinetics (i.e., an initial release rate of 1.79 ± 0.07 μg/cm2 d and a steady release rate of 0.55 ± 0.03 μg/cm2 d), resulting in about 60% less release compared with the AMPs/alginate modified membranes with five multilayers (MSA5). Long-term antibiofouling tests showed that the AMPs/alginate modified membranes with ten multilayers (MSA10) exhibited a significantly reduced transmembrane pressure increase rate of 0.81 ± 0.01 kPa/d which was much lower than that of the control membranes (1.80 ± 0.20 kPa/d), mainly attributed to the antibacterial activity imparted by the lasting release of AMPs and competing membrane basic properties. Furthermore, the AMPs/alginate multilayers modified membranes revealed high stability suffering from long-term operation and chemical cleaning cycles. The novel AMP/alginate-incorporated modifying method provides a new dimension to enhance antibiofouling performance of membranes for water and wastewater treatment.

A study on the impact of fuel injection parameters and boost pressure on combustion characteristics in a diesel engine using alcohol/diesel blends

Engine researchers focused on alcohol fuels since the invention of diesel engines in the 1900s, and the rise in petrochemical costs in the 1970s triggered this concern. This study investigates the impacts of the injection start timing, pilot injection application, and boost air pressure increase, on combustion and exhaust emissions in a common rail diesel engine fueled with ethanol/butan-2-ol/diesel blends. The lowest combustion noise was obtained in the pilot injection application as 83.8 dB in E15B3. The results indicated that the peak point of cylinder gas pressure rose by more than 5 % in the application of pilot fuel injection and advanced injection timing, compared to conventional engine operating conditions. However, maximum CO2 and NOx were seen in the pilot injection application using FBDF as 5.7 % and 670 ppm, respectively. As alcohol rate increases in fuel blends, the average 1.3 °CA in the ignition delay period was increased, while the total combustion period was shortened more than 6 °CA. This result shows that the combustion reactions of alcohol/diesel fuels occur faster than pure diesel. However, the variation in the ignition delay and total combustion periods of the test fuels considerably reduced with pilot fuel injection application. These results indicates that pilot fuel injection may be applied very controlled according to changing engine conditions. It was calculated in statistical analysis that except for the coefficient variation of the maximum pressure increase rate, the other coefficient variation values were relatively stable and below 3 %. In addition, it was determined that the results of the finite element analysis are proportional to the pressure values obtained experimentally.

Research on the effect of low-sulphur marine fuels on the dynamic characteristics of a CI engine

The implementation of low-sulphur, so-called modified marine fuels into operation requires prior laboratory engine tests to assess the energy, emission and structural effects of their usage. This type of research are carried out on the test bed of a diesel engine as a small-scale physical model that reproduces the adequate design and process (parametric) features of a full-size marine engine. Their key stage is to determine the energy characteristics of the engine in the steady state of operation determined on the basis of the analysis of the developed indicator diagram and the dynamic characteristics of the transient processes from idling to the reference steady state of load - and vice versa. In this way, the basic diagnostic parameters of the fuel usable quality are determined: the rate of pressure increase in the cylinder and the average deceleration of the engine crankshaft within the strenuous transient process. This article presents representative results of this type of research carried out on six different, low-sulphur marine fuels used to feed marine engines.

Evaluation of Hydraulic Characteristics of Electrohydraulic Proportional Valve (EHPV) for an Auto-Steering Tractor Application

The performance of the electrohydraulic proportional control valve (EHPV) employed in a tractor’s automatic steering system directly influences the steering performance. To develop a highly reliable EHPV, it is essential to analyze the hydraulic characteristics of the EHPV for several working conditions of tractors. This study aimed to measure and analyze the hydraulic characteristics of the EHPV according to tractor working conditions. The flow rate and pressure data of the EHPV were computed through the valve measuring system, and the required power was computed. The experimental conditions were selected based on engine rotational speed and tractor steering angle. As a result, it was discovered that the flow rate, pressure, and power all increased when the engine rotation speed and steering angle conditions increased. Furthermore, the rates of increase in flow rate, pressure, and power based on the increase in the steering angle were higher than when the engine rotation speed increased. In the regression analysis results between the two variables and the hydraulic characteristics of EHPVs, the steering angle demonstrated a higher correlation than the engine rotation speed. In conclusion, the steering angle and engine rotational speed are the major variables in the hydraulic characteristics of EHPVs, and the influence of the steering angle is greater.

A novel precoated anaerobic dynamic membrane bioreactor for real domestic wastewater treatment: In-situ formation, filtration performance and characterization of dynamic membrane

Precoated dynamic membranes (PCDM), commonly formed by retaining external particles on coarse supporting meshes, can accelerate dynamic membrane (DM) formation, change the DM structure, and enhance its filtration performance. An in-situ rapid PCDM formation method via short-time and high-flux initial filtration (at 380 L/m2·h flux for 0.25 min) is proposed using anaerobic sludge as a precoating material. A precoated anaerobic dynamic membrane bioreactor (PC-AnDMBR) was operated in parallel with a self-forming AnDMBR (SF-AnDMBR) to treat domestic wastewater. Extremely low rates of transmembrane pressure (TMP) increase of 0.05 and 0.07 kPa/d were obtained during the long-term operation of the SF-AnDMBR and PC-AnDMBR, respectively. Furthermore, the PC-AnDMBR and SF-AnDMBR showed stable effluent turbidity (27.1 ± 9.44 NTU and 31.35 ± 15.96 NTU, respectively) and satisfactory COD removal (83% and 78%, respectively), which were attributed to the small pore size (<2 μm) of the DM layers. The PCDM and self-forming dynamic membrane (SFDM) with a thickness of 0.7 mm were further characterized as cake and gel layers, whereas the gel layer thickness within the PCDM was higher than that of the SFDM (0.6 mm vs. 0.2 mm). In addition, the porosities of the gel layers (2.87% and 2.95%) were lower than those of the cake layers (3.58% and 3.48%) for the PCDM and SFDM, respectively. Therefore, the compact gel layer, with more accumulated organics, contributed to over 78% of the total filtration resistance. These findings provide new insights into the mechanisms of PCDM formation and the application of AnDMBRs in wastewater treatment.

Comprehensive analysis of the operation of an internal combustion engine fueled by hydrogen-containing mixtures

At present, hydrogen is considered as one of the most promising motor fuels capable of replacing traditional hydrocarbons. This article presents the results of a comprehensive experimental study of the effect of hydrogen additives on the main parameters of a gasoline spark-ignition ICE. The thermophysical parameters of the processes of ignition and combustion inside the cylinder with the addition of hydrogen in the amount of 0%–20% of the air volume, as well as the fuel and energy characteristics of the engine and its impact on the environment, were studied. It has been established that hydrogen leads to significant changes in the engine operation. It increases some parameters and reduces others, improving or worsening them compared to running on pure gasoline. So, with a 20% H2 addition at an average engine load, the following parameters increase: the maximum pressure in the cylinder by almost 20%; the rate of pressure increase in the combustion chamber by 2.8 times; the highest combustion temperature by 140 K. At the same time, the following parameters decrease: average indicator pressure by 18%; ignition timing by 82% (6° to TDC versus 34° for gasoline); crank angle corresponding to the maximum pressure by 32% (9.4° versus 13.9° for gasoline); crank angle corresponding to maximum temperature by 54% (17.7° after TDC versus 38.3° for clean gasoline); ignition delay time (τind=0.32ms) and visible combustion time (τvis=1.58ms) by 4 and 2.3 times, respectively.

Power characteristics with different types of turbochargers for lean boosted hydrogen direct injection engine in NOx-free operation

Lean boosting is a low-temperature combustion technology that can contribute to the expansion of the operation range by reducing the pressure increase rate and the combustion temperature owing to the increase in the intake air amount, even though the amount of heat supplied is the same. By optimizing the boosting device of the direct-injection-type hydrogen engine, it was expected that the operating range could be expanded through the torque increase owing to the increase in the amount of heat supplied according to the increase in the intake air mass, and nitrogen oxides emission was expected to be suppressed owing to lean low-temperature combustion. In the present study, to examine the possible output limit of a hydrogen engine under high-lean boosting conditions by applying a boosting device with a different control method, the performance according to the engine speed was observed under the condition of minimizing nitrogen oxide emission. Owing to the boosting performance by the variable turbocharging device, the output power was improved by 165% compared to that of the naturally aspirated-type combustion at a rotation speed of 5000 rpm.

The Behavior of Hydrothermal Mineralization With Spatial Variations of Fluid Pressure

AbstractIt is assumed that variable fluid pressure states in space control the spatiotemporal evolution of hydrofracture, and their responses on mineralization. In this study, mineral precipitation caused by rapid fluid pressure reduction is incorporated into a cellular automaton model to explore the effects of various spatially structured fluid pressure rates on the behavior of hydrofracture and mineralization. We explore a range of spatial structures, which vary from essentially random to strong spatial structure. In the model, fluid pressure increase induces local hydrofracture to nearest neighbors, and fluid mass is conserved among the cell affected. As the model evolves, internally connected networks merge and a correlation length is established as the system approaches the failure condition and identifies the percolation threshold. The correlation length of the internally connected network scales with the degree of spatial structure of fluid pressure increase rates, resulting in earlier arrival to the percolation threshold for strong spatial structures. At the percolation threshold, large‐scale fluid pressure reduction induces mineral precipitation and facilitate the formation of the spatially structured geochemical patterns. The degree of spatial structure of geochemical patterns correlates with the spatial structure of fluid pressure increase rates because mineral precipitation from fluid pressure reduction occurs over larger scale. The proposed model offers an intuitive and potentially important tool for understanding the role of spatially structured fluid pressure increase and reduction on hydrothermal mineralization patterns in fault‐related ore systems.

Тонзиллярная проблема и ее сердечно-сосудистые аспекты на современном этапе

A comparative assessment of the characteristics of myocardial and vascular damages as well as their occurrence in patients with decompensated chronic tonsillitis (CT) sent to the hospital for planned tonsillectomy were carried out. 179 people aged 18 to 25 years were examined. Two groups were formed: group 1: patients with decompensated СT (102 people) and group 2: control – that is, persons without СТ (77 people). We used 24-hour ECG monitoring (Holter) with a set of additional diagnostic options and EchoCG to determine various characteristics of myocardial activity. The arterial wall was assessed using indicators of vascular stiffness and assessment of blood pressure balance in the vascular territories. We used hardware-diagnostic complexes DMS Advanced Technologies (Russia) and RuSkan-70P (Russia). Myocardial damage was judged by exceeding the upper limit of the permissible norm for such indicators as the number of extrasystoles per hour, the maximum rate of increase in pressure in the aorta (dP/dTmax), and the size of the heart chambers; and damage to the vascular wall was judged by similar changes for the aortic pulse wave (PWVao), aortic reverse pulse wave augmentation index (AIx ao), and ankle-brachial index (ABI). The individual profile of the main cardiovascular risk factors was also assessed. Data processing was carried out using the Statistica 10.0 software package (StatSoft Inc., USA). The results indicated the presence of a negative effect of СТ not only on the myocardium with the development of some moderate changes but also on the vascular wall. The latter violations were recorded significantly more often. Vascular disorders were characterized by increased arterial stiffness and pressure imbalance within the framework of preclinical arterio- and atherosclerosis. It is necessary to develop targeted angioprotective measures with СТ and their inclusion in the comprehensive process of managing this category of patients, including in the preoperative period. Therefore, the management of such patients should be based on the principles of effective interdisciplinary cooperation.

Методика вибору кроку дискретизації індикаторних діаграм у цифрових методах контролю параметрів ДВЗ

Peculiarities of measuring equipment usage in the field of internal combustion engines and the rationality of methods for testing and results processing are considered. It is shown that one of the most difficult tasks in the study of the working processes of engines is to obtain a reliable indicator diagram with a given accuracy. It is noted that it is important to consider the features of the flow of rapidly changing and non-stationary processes in the internal combustion engine: high rates of processes change, a wide frequency spectrum, non-identity flow of the processes flow from cycle to cycle. This causes specific requirements to the methodological plan, as well as to measuring instruments themselves in terms of speed, recording frequency and rationality of the techniques of performing the experimental studies. It is proved that in the process of the engines investigation it is necessary to have both single-cycle indicator diagram and averaged, for several hundreds cycles, indicator diagram. It is shown that the objective of the work is to improve the methodology for choosing the discretization step and choosing the number of recorded ordinates of the internal combustion engine indicator diagram during one working cycle, depending on the approximation error and the rate of pressure increase. A general method for determining the sampling frequency of indicator diagrams depending on the required accuracy of its approximation is described; improved expressions for its determination are given. A scheme for determining the sampling frequency by the angle of crankshaft rotation is presented. The essence of improving the methodology for choosing the discretization step of the indicator diagram by dividing it into zones and selecting different sampling steps in each zone is considered in detail. The use of a digital microprocessor complex for the study of the working processes of a particular diesel engine is considered. The initial data and values of discretization angles, necessary for the experiment were determined.

Hydrodynamic effects of shock interactions on initial flame kernel development of close dual-point laser induced sparks

Flame kernel formations of close dual-point laser induced sparks were investigated experimentally, focusing on the hydrodynamic effects induced by an interaction of shock waves produced by the laser induced sparks. Dual sparks were produced near the center of the combustion chamber by splitting of a ray emitted by a 532 nm Nd:YAG laser. Methane/air mixtures were ignited under a quiescent condition in a constant volume chamber with detailed measurements of the ignition energy and the pressure history. The minimum ignition energy was derived as an ignition energy having an ignitability of 50% using the logistic regression method. The flame kernel initiation process was also observed by Schlieren photography using a high-speed video camera. The offset of laser induced sparks were adjusted by tuning angles of mirrors and lenses. The ignition performance of single- and close dual-point laser breakdown induced sparks was investigated in detail in terms of the minimum ignition energy and the combustion induction time. Time resolved Schlieren photographs indicated that two hump shaped kernels grew rapidly during the initial stage in the vicinity of the plane of symmetry defined by the laser sparks under certain conditions. Their formation was due to the hydrodynamic effects induced by Mach shock waves, which resulted from interactions of the dual shock waves. The minimum ignition energy of the close dual-point laser induced sparks near the lean limit at 1.0 MPa was much lower than that of single-point laser induced sparks, although it was greater than that of the single ones at 0.1 MPa. The combustion induction time, which was defined as the time corresponding to the maximum pressure increase rate, was shortened for close dual-point laser induced sparks, especially for lean mixtures at high pressure. Robust flame kernels were formed by close dual-point laser induced sparks with Mach shock wave formation, and improved ignition performance for lean mixtures at high pressure was observed.

Criteria of thermochemical conditions of steam gas explosions in dynamic accident modes at nuclear power units with WWER reactors

The main lessons of the major accident at the Fukushima-Daiichi NPP in 2011 for the nuclear power industry identify the need to model, analyze and develop emergency measures for relatively unlikely events with catastrophic environmental consequences, taking into account multiple failures of safety systems. Steam-gas explosions became one of the main causes of the catastrophic environmental consequences of the Chernobyl and Fukushima accidents. Criteria and conditions for the occurrence of steam-gas explosions in dynamic emergency modes in the "tight" reactor circuit of nuclear power reactor units (NPP) with water-water reactors (WWER) with failures of safety systems valves and emergency steam gas removal are determined by the rate of change of thermodynamic and physico-chemical parameters. A method for determining the criteria and conditions for the occurrence of steam-gas explosions in dynamic accident modes with a "tight" reactor circuit and failure of safety valves for modeling the initial emergency events – seismic effects, falling of massive objects, etc. is presented. The conditions for the occurrence of hydrogen explosions are determined by the maximum rate of increase in the temperature of fuel oil shells, and the conditions for steam explosions are determined by the maximum rate of pressure increase as a result of the intensification of vaporization processes. The criteria for the occurrence of steam explosions in dynamic emergency modes are determined by the maximum pressure amplitude and the propagation speed of acoustic disturbances in the steam volume. And the criteria for hydrogen detonation in dynamic emergency modes are determined by the maximum amplitude of the increase in the temperature of the fuel shells and the average flow rate of the coolant in the active zone of the reactor.

Study of Methane Explosion Suppression Characteristics of N2 and CO2 in Variable Cross-Section Ducts.

To investigate the effect of concentration of N2 and CO2 (0, 10, 20, 30, 40, and 50%) on the flame propagation characteristics of CH4/air premixed gases with stoichiometric ratios in variable cross-section ducts, experiments were conducted in four combinations of ducts at initial conditions of 298 K and 1 atm. The results show that the flame propagation velocity, propagation time, and overpressure are greater in the suddenly contracted duct than in the suddenly expanded duct if the dimensions of the ducts are kept constant. However, an increase in inert gas concentration leads to a decrease in flame propagation speed, an increase in flame propagation time, and changes in flame structure and pressure. "Tulip" flames appeared when a duct with a cross section of 100 mm × 100 mm was combined with a duct with a cross section of 70 mm × 70 mm, whether N2 or CO2 was added or what its concentration was. However, when a duct with a cross section of 140 mm × 140 mm was combined with a 70 mm × 70 mm duct, a "tulip" flame is formed only at a CO2 concentration of 50%. As the concentration of inert gas increases, the explosion pressure first decreases and then stabilizes, while the rate of pressure increase showed a monotonically decreasing trend. The explosion pressure is minimized when the concentration of CO2 and N2 is 30 and 40%, respectively.

Effects of fuel component, airflow field and obstacles on explosion characteristics of hydrogen/methane mixtures fuel

To popularise hydrogen/methane mixtures and determine it explosion hazards, explosion experiments were conducted based on a pipeline that can characterise urban pipe gallery scenes. The results showed that the overpressure and rate of pressure first increased and then decreased with an increase in the equivalence ratio, and increased with an increase in the hydrogen blending ratio. The heat loss and adiabatic pressure decrease with an increase in the hydrogen blending ratio, and the combined effects of the two result in different chain-based growth rates of explosion overpressure. The proportion of hydrogen blended was set to 15%. The overpressure and rate of pressure rise increased approximately linearly with the increase in airflow field intensity, and the change in the rate of pressure rise induced by airflow field was more serious than that of the overpressure. The overpressure and rate of pressure increase first increased and then decreased with an increase in the blocking ratio, and the maximum value was reached at a blocking ratio of 0.75. The explosion hazard of a low blocking ratio was less than that of a high blocking ratio. The results can provide important information for the practical use of hydrogen/methane mixtures, particularly in safety protection.

Development and Performance of Hydrocyclone Separator for Biodiesel Production

Hydrocyclone is an equipment that uses a cyclone or tangential injection flow process with centrifugal forces to separate liquids of different densities. The denser liquid move downwards in a spiral path into an underflow chamber, while clean liquid which is less dense move upwards to the center of the spiral, towards the top outlet. Colman and Thew’s hydrocyclone geometry analysis approached was used in the design and the assumed inlet chamber diameter (D) used for this design was 150 mm and a reducing section length of 1500 mm at a reducing angle of 20°. The capacity of the designed hydrocyclone system in volume is 5.5 liters. The developed machine was tested with 15 liters of palm kernel oil (PKO) as raw material using two different pressures gauge (70 and 80 kPa) and also effect acid concentration (sulphuric acid) at 3 different experimental runs. After the experiments, it was deduced that at constant temperature level, as the pressure rate increases, there is a corresponding increase in the discharge rate at the underflow and overflow outlets where 2.04 minutes and 1.67 minutes were used to separate biodiesel and glycerin under 70 and 80 kPa respectively. Also, it was deduced experimentally that PKO with sulphuric acid gives a higher yield of biodiesel of 47.74% while the one without has 38.49% yield under same experimental and operational conditions.