scholarly journals Effect of initial temperature and initial pressure on the lower explosion limit of aviation kerosene

2021 ◽  
Vol 772 (1) ◽  
pp. 012072
Author(s):  
Yongqian Ning ◽  
Liang Zhang ◽  
Zhi Wang ◽  
Xiaoyao Ning ◽  
Jian Wang
Keyword(s):  
Initial Temperature ◽  
Initial Pressure ◽  
Aviation Kerosene ◽  
Explosion Limit

Microstructural and Mechanical Characterization of Solder Joints Fabricated by Explosively Reacting Nanolayers

2008 ◽  
Author(s):  
Michael Tong ◽  
Jenn-Ming Yang
Keyword(s):  
Initial Temperature ◽  
Mechanical Characterization ◽  
Solder Joints ◽  
Initial Pressure ◽  
Processing Parameters ◽  
Joint Shear Strength ◽  
Lap Shear ◽  
Joint Shear ◽  
Solder Interface

The unique heat-releasing characteristics of explosively reactive nanolayers (RN) are used in this study to produce Si/solder/Si joints. The microstructure of the RN in the reacted state as well as the post-joining foil/solder interface is characterized via XRD, SEM, and TEM, which have never been done. Additionally, RN solder joints are mechanically characterized by single lap shear and nanoindentation to obtain a set of optimized processing parameters, specifically initial pressure applied (Pa) and initial temperature of the system (Ti). A maximum joint shear strength of ∼ 30MPa at Pa = 15MPa and Ti = 75°C. Furthermore, nanoindentation is used to clarify the mechanical behavior of individual layers and interfaces across the joints as a result of thermal aging.

Monte-Carlo Parametric Performance Analysis of A/C and H/P Transcritical R744 Compressor

Solar Energy ◽  
2005 ◽  
Author(s):  
Yousef M. Abdel-Rahim
Keyword(s):  
Monte Carlo ◽  
Initial Temperature ◽  
Initial Pressure ◽  
Optimization Methods ◽  
Evaluation Study ◽  
Complete Analysis ◽  
Working Fluid ◽  
Saturation Region ◽  
Unit Work ◽  
Compressor Performance

Thermal engineers usually face two kinds of problems: design of new systems, where multiple alternatives for each composing unit of the system can fulfill the design requirements and/or assessment of exiting systems, where they usually work at off-the-design conditions due to deterioration of their efficiencies. The present paper addresses possible solutions to such problems via the Monte-Carlo method (MCM) applied to compressors as major units in airconditioning (A/C) and heat pump (H/P) systems having Carbon Dioxide (R744) as working fluid. Diversity of the effects of system design, process parameters and fluid properties within and across the saturation line hinders an overall-view of hidden capabilities and limitations of the compressors. Thus, it is hard to apply any appropriate optimization methods for their better design, besides the difficulty in assessing their performance along their working lifetime. In an answer to the above two points, the present paper utilizes the powerful MCM to investigate and expose the effects on compressor performance of all controlling parameters, randomly selected from their variation ranges within and across wet/saturation region to the transcritical dry region of R744. For each selected set of parameters, a complete analysis is calculated to determine the performance of the compressor. This process is repeated about 500 times to randomly cover the variation spaces of the parameters. The study reveals that MCM can fairly handle the parametric design and evaluation study of compressor performance. It shows that the initial temperature has a greatly decreasing effect on compressor specific displacement volume per unit work and to a less extent on size of compressor, while its effects on all other parameters are insignificant. Initial pressure has similar expected trends. Final to initial temperature ratio has increasing effects on both final pressure and work of compressor and decreasing effects on both second law efficiency and specific displacement volume per unit work. The application of MCM to the parametric compressor performance presented here could open many ways for further theoretical design optimization and experimental justification of the compressors and hence greatly limits the trade-off methods that are usually adopted in the selection of such units.

Generalized A/C and H/P Transcritical R744 Compressor Performance in Wet and Dry Regions

Solar Energy ◽  
2004 ◽  
Author(s):  
Yousef M. Abdel-Rahim
Keyword(s):  
Design Optimization ◽  
Initial Temperature ◽  
Initial Pressure ◽  
Life Time ◽  
Optimization Methods ◽  
Second Law ◽  
Compression Process ◽  
Compression Performance ◽  
Saturation Region ◽  
Unit Work

Performance of the compression process of Carbon Dioxide (R744) in (A/C) and (H/P) systems depends on many factors related to fluid properties, equipment design and process parameters. Diversity of these factors represents a difficulty to have an overall-view of the hidden capabilities and limitations of the compression process. Thus, it is hard to apply any appropriate design optimization methods for the compressors, specifically for two reasons: (1) when the compression starts from the wet or saturation region and commences through the transcritical dry region of the fluid and (2) when the compressor works at off-design operating point during its working life-time. In an answer to these two points, the present paper utilizes the first and second laws of thermodynamics augmented by Monte-Carlo method to investigate, expose and discuss the compression performance (e.g. final temperature and pressure, work and size of compressor and second law efficiency) starting randomly from the wet/saturation region to the transcritical dry region of R744. The study shows that initial temperature has a greatly decreasing effect on compressor specific displacement volume per unit work and to a less extent on size of compressor, while its effects on all other parameters are insignificant. Initial pressure has similar expected trends as those of the initial temperature due to their linear relationship in the wet region. Final to initial temperature ratio has increasing effects on both final pressure and work of compressor and decreasing effects on both second law efficiency and specific displacement volume per unit work. The method presented here could open many ways for further theoretical design optimization applications of the compressor and hence greatly limits the trade-off methods that are usually adopted in the selection of such units.

The Effects of Initial Conditions on the Composition of the On-Board Fuel Reformation Chamber in an HCCI Engine

2015 ◽  
Vol 733 ◽  
pp. 219-224
Author(s):  
Chun Hua Zhang ◽  
Le Xue
Keyword(s):  
Homogeneous Charge Compression Ignition ◽  
Initial Temperature ◽  
Initial Conditions ◽  
Initial Pressure ◽  
Compression Ignition ◽  
Fuel Reforming ◽  
Hcci Engine ◽  
Main Species ◽  
Fuel Reformation ◽  
Homogeneous Charge

Based on the CHEMKIN software, a model of the reforming chamber was built to simulate the on-board fuel reforming process in a Homogeneous Charge Compression Ignition (HCCI) engine. The effects of the initial pressure and temperature of the chamber on the reformed gas were studied. The results show that the main species in the reformed gas are H2 and CO. This paper investigated the effect of initial temperature on the reformed gas, in order to get the optimum initial temperature. Under the optimum initial temperature (1300 K), some important conclusions have been drawn by changing initial pressures of the chamber. Initial pressure may have great effect on other species, but has a small effect on mole fractions of H2 and CO. By comparing the concentrations of H2 and CO between low and high initial pressures under the optimum initial temperature, it can be concluded that H2 and CO are still the main species in the reformed gas.

Effect of initial pressure on the lower explosion limit of nicotinic acid/acetone mixture

2020 ◽  
Vol 64 ◽  
pp. 104075 ◽  
Author(s):  
Roberto Sanchirico ◽  
Valeria Di Sarli ◽  
Almerinda Di Benedetto
Keyword(s):  
Nicotinic Acid ◽  
Initial Pressure ◽  
Explosion Limit

scholarly journals The Effect of Initial Conditions on the Laminar Burning Characteristics of Natural Gas Diluted by CO2

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2892 ◽  
Author(s):  
Zhiqiang Han ◽  
Zhennan Zhu ◽  
Peng Wang ◽  
Kun Liang ◽  
Zinong Zuo ◽  
...  
Keyword(s):  
Natural Gas ◽  
Dilution Rate ◽  
Initial Temperature ◽  
Initial Conditions ◽  
Burning Velocity ◽  
Initial Pressure ◽  
Chemical Kinetic ◽  
Laminar Burning Velocity ◽  
Flame Instability ◽  
Highly Correlated

The initial conditions such as temperature, pressure and dilution rate can have an effect on the laminar burning velocity of natural gas. It is acknowledged that there is an equivalent effect on the laminar burning velocity between any two initial conditions. The effects of initial temperatures (323 K–423 K), initial pressures (0.1 MPa–0.3 MPa) and dilution rate (0–16%, CO2 as diluent gas) on the laminar burning velocity and the flame instability were investigated at a series of equivalence ratios (0.7–1.2) in a constant volume chamber. A chemical kinetic simulation was also conducted to calculate the laminar burning velocity and essential radicals’ concentrations under the same initial conditions. The results show that the laminar burning velocity of natural gas increases with initial temperature but decreases with initial pressure and dilution rate. The maximum concentrations of H, O and OH increase with initial temperature but decrease with initial pressure and dilution rate. Laminar burning velocity is highly correlated with the sum of the maximum concentration of H and OH.

scholarly journals The Equivalent Effect of Initial Condition Coupling on the Laminar Burning Velocity of Natural Gas Diluted by CO2

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 809
Author(s):  
Xueshun Wu ◽  
Peng Wang ◽  
Zhennan Zhu ◽  
Yunshou Qian ◽  
Wenbin Yu ◽  
...  
Keyword(s):  
Dilution Rate ◽  
Initial Temperature ◽  
Coupling Effect ◽  
Burning Velocity ◽  
Initial Pressure ◽  
Rate Of Change ◽  
Equal Weight ◽  
Initial Condition ◽  
Laminar Burning Velocity ◽  
Equivalent Effect

Initial temperature has a promoting effect on laminar burning velocity, while initial pressure and dilution rate have an inhibitory effect on laminar burning velocity. Equal laminar burning velocities can be obtained by initial condition coupling with different temperatures, pressures and dilution rates. This paper analysed the equivalent distribution pattern of laminar burning velocity and the variation pattern of an equal weight curve using the coupling effect of the initial pressure (0.1–0.3 MPa), initial temperature (323–423 K) and dilution rate (0–16%). The results show that, as the initial temperature increases, the initial pressure decreases and the dilution rate decreases, the rate of change in laminar burning velocity increases. The equivalent effect of initial condition coupling can obtain equal laminar burning velocity with an dilution rate increase (or decrease) of 2% and an initial temperature increase (or decrease) of 29 K. Moreover, the increase in equivalence ratio leads to the rate of change in laminar burning velocity first increasing and then decreasing, while the increases in dilution rate and initial pressure make the rate of change in laminar burning velocity gradually decrease and the increase in initial temperature makes the rate of change in laminar burning velocity gradually increase. The area of the region, where the initial temperature influence weight is larger, gradually decreases as the dilution rate increases, and the rate of decrease gradually decreases.

The Effects of Inlet Charge Component on the Formation of Soot in Diesel Engine

2012 ◽  
Vol 610-613 ◽  
pp. 2079-2084
Author(s):  
Yang Zhao ◽  
Zhong Wang ◽  
Ming Di Li ◽  
Rui Na Li
Keyword(s):  
Diesel Engine ◽  
Initial Temperature ◽  
Soot Formation ◽  
Great Influence ◽  
Initial Pressure ◽  
Coupling Model ◽  
Excess Air ◽  
Soot Precursor ◽  
Excess Air Coefficient ◽  
Temperature And Pressure

Air contains oxygen, nitrogen, etc. The gas separated technology and mixed method could increase or decrease the certain components of air. Changing the concentration of the component has a great influence on soot formation of diesel engine. The influences of excess air coefficient and the oxygen, nitrogen proportion of inlet air, the initial temperature and the initial pressure on PAHs (the soot precursor) formation of diesel engine were discussed in this paper. The results showed that the coupling model of diesel PAHs could predict the reaction temperature, the concentration of the reaction intermediates (CO, CO2 and O2), and the ignition delay during the combustion progress accurately. The concentration of the soot and its precursor PAHs could be decreased effectively by changing the proportion of the oxygen and nitrogen in the inlet air. After increasing the excess air coefficient, the numbers of the reaction intermediate free radicals (H and OH) were increased and the concentration of aromatic hydrocarbons was decreased. The beginning angle of chemical reaction was advanced by increasing the initial temperature and pressure. And it is beneficial to decrease the concentration of PAHs.

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