Theoretical investigation of (tetrazine-3,6diyl) dihydrazinecarboxamide-based high-nitrogen-containing energetic macromolecules

2018 ◽  
Vol 17 (04) ◽  
pp. 1850028
Author(s):  
Alka Devi ◽  
Vikas D. Ghule
Keyword(s):  
Solid Phase ◽  
Specific Impulse ◽  
Flame Temperature ◽  
Heat Of Formation ◽  
Detonation Pressure ◽  
Macrocyclic Compounds ◽  
Combustion Heat ◽  
Explosive Power ◽  
Energetic Plasticizer ◽  
Reliable Methods

Density-function-theory calculations were performed to find the performance of a series of 2,2’-(1,2,4,5-tetrazine-3,6diyl) dihydrazinecarboxamide-based nitrogen-rich macrocyclic compounds as an energetic plasticizer. Reliable methods have been used to predict energetic properties such as gas-phase and solid-phase heat of formation (HOF), density, detonation velocity, detonation pressure, explosive power, heat of combustion, heat of detonation, specific impulse, flame temperature, brisance, and sensitivity. All the designed macrocycles possess a nitrogen content of over 48%. The designed compounds show positive HOFs and high predicted densities ranging from 1.81[Formula: see text]g/cm3 to 1.86[Formula: see text]g/cm3. The predicted properties were compared with GAP, polyGLYN and their monomers which establish the designed macrocycles of interest for further investigations concerning their suitability as plasticizers in energetic formulations.

Calculation of the molar heat of formation of fatty acid triglycerides from the heat of combustion of vegetable oils

2021 ◽  
Vol 11 (4) ◽  
pp. 8-15
Author(s):  
Łukasz Jęczmionek
Keyword(s):  
Fatty Acid ◽  
Vegetable Oils ◽  
Calculation Method ◽  
Formation Enthalpy ◽  
Heat Of Formation ◽  
Heat Of Combustion ◽  
Calorimetric Method ◽  
Combustion Heat ◽  
Natural Oils ◽  
Fatty Acid Triglycerides

The results of the research on estimation the molar heat of formation (enthalpy) of model triglycerides found in natural oils and fats are presented. In this work a calculation method and calorimetric one were used. It was found that combustion heat values determined by separate methods are comparable; their difference was a maximum of 155 kJ/kg, and thus was significantly lower than the tolerance for the calorimetric method according to PN 86/C-04062.

scholarly journals Metals and Alloys Additives as Enhancer for Rocket Propulsion: A Review

2021 ◽  
Vol 90 (1) ◽  
pp. 1-9
Author(s):  
Izham Izzat Ismail ◽  
Norhuda Hidayah Nordin ◽  
Muhammad Hanafi Azami ◽  
Nur Azam Abdullah
Keyword(s):  
Specific Impulse ◽  
Flame Temperature ◽  
High Energy ◽  
Combustion Efficiency ◽  
High Energy Density ◽  
Regression Rate ◽  
High Entropy ◽  
Rocket Propulsion ◽  
Wide Range ◽  
Metal Additives

A rocket's engine usually uses fuel and oxygen as propellants to increase the rocket's projection during launch. Nowadays, metallic ingredients are commonly used in the rocket’s operation to increase its performance. Metallic ingredients have a high energy density, flame temperature, and regression rate that are important factors in the propulsion process. There is a wide range of additives have been reported so far as catalysts for rocket propulsion. The studies show that the presence of metal additives improves the regression rate, specific impulse and combustion efficiency. Herein, the common energetic additives for rocket propulsion such as metal and light metals are reviewed. Besides the effect of these energetic particles on the regression behaviors of base (hybrid) fuel has been exclusively discussed. This paper also proposed a new alloy namely high entropy alloys (HEAs) as a new energetic additive that can potentially increase the performance of the rocket propellant system.

scholarly journals Role of capping in peptide synthesis

2020 ◽  
Vol 11 (4) ◽  
pp. 5225-5228
Author(s):  
Deepshikha Verma ◽  
Pillai V N R ◽  
Giriraj Tailor
Keyword(s):  
Peptide Synthesis ◽  
Solid Phase ◽  
Solid Phase Peptide Synthesis ◽  
Protecting Groups ◽  
Amino Groups ◽  
Peptide Chemistry ◽  
Fmoc Spps ◽  
Reliable Methods ◽  
Important Test

Protecting groups like Fmoc and coupling both steps are essential to monitoring the Fmoc SPPS (Solid Phase Peptide Synthesis) reaction completion. Reliable methods are used to detect the unreacted number of amino groups for monitoring these two essential reaction steps of coupling and cleavage. The ability to detect the complete coupling, incomplete coupling or failure of coupling we use many colour tests in the laboratory and based on this the Fmoc peptide chemistry allows the control of the completion of the Fmoc cleavage. The most important test used is the Kaiser test and highly recommended to monitor the coupling and cleavage steps. If the result of colour tests is positive after coupling, then the second coupling should be performed. Then again use the colour test to detect the level of coupling. If the result is still slightly positive, repeat coupling with the smaller modification of reagents such as used PyBOP instead of HOBT AND HOAT. These colour tests help in revealing the presence of unreacted amino-functional groups. Thus, we need to block these free N-terminal of amino- acids which help in avoiding the making of deletion of sequence.

scholarly journals Gas Turbines and Biodiesel: A Clarification of the Relative NOX Indices of FAME, Gasoil, and Natural Gas

2009 ◽  
Author(s):  
Pierre A. Glaude ◽  
Rene´ Fournet ◽  
Roda Bounaceur ◽  
Michel Moliere
Keyword(s):  
Natural Gas ◽  
Gas Turbines ◽  
Methyl Esters ◽  
Flame Temperature ◽  
Field Tests ◽  
Animal Origin ◽  
Combustion Heat ◽  
Independent Field ◽  
Key Factor ◽  
The Usa

There is currently a sustained interest in biofuels as they represent a potential alternative to petroleum derived fuels. Biofuels are likely to help decrease greenhouse gases emissions and the dependence on oil resources. Biodiesels are Fatty Acid Methyl Esters (FAMEs) that are mainly derived from vegetable oils; their compositions depend from the parent vegetables: rapeseed (“RME”), soybean (“SME”), sunflower, palm etc. A fraction of biodiesel has also an animal origin (“tallow”). A key factor for the use of biofuels in gas turbines is their Emissions Indices (NOx, CO, VOC, PM) in comparison with those of conventional “petroleum gasoils”. While biodiesels reduce carbon-containing pollutants, experimental data from diesel engines show a slight increase in NOx. The literature relating to gas turbines is very scarce. Two recent, independent field tests carried out in Europe (RME) and in the USA (SME) showed slightly lower NOx while a lab test on a microturbine showed the opposite effect. To clarify the NOx index of biodiesels in gas turbines, a study has been undertaken, taking gasoil and natural gas (NG) as reference fuels. In this study, a calculation of the flame temperature developed by the 3 classes of fuels has been performed and the effect of their respective compositions has been investigated. The five FAMEs studied were RME, SME and methyl esters of sunflower, palm and tallow; these are representative of most widespread vegetable and animal oil bases worldwide. The software THERGAS has been used to calculate the enthalpy and free energy properties of the fuels and GASEQ for the flame temperature (Tf), acknowledging the fact that “thermal NOx” represents the predominant form of NOx in gas turbines. To complete the approach to structural effects, we have modeled two NG compositions (rich and weak gas) and three types of gasoil using variable blends of eleven linear/branched/cyclic molecules. The results are consistent with the two recent field tests and show that the FAMEs lie close to petroleum gasoils and higher than NG in terms of NOx emission. The composition of the biodiesel and regular diesel fuel influences their combustion heat: methyl esters with double bonds see a slight increase of their Tf and their NOx index while that of gasoil is sensitive to the aromatic content.

scholarly journals METHOD OF DETERMINING THE EFFECTIVENESS OF A MISSILE’S BLAST-FRAGMENTATION WARHEAD BY USE OF COMPUTATIONAL METHOD AND EXPERIMENT

2020 ◽  
pp. 83-91
Author(s):  
S. Moskalets ◽  
V. Zhyrnyi ◽  
A. Rudyk ◽  
A. Artikula
Keyword(s):  
High Speed ◽  
Specific Impulse ◽  
Development Trend ◽  
Computational Method ◽  
Total Probability ◽  
Explosive Power ◽  
Operational Characteristics ◽  
Blast Fragmentation ◽  
Debris Impact ◽  
Injurious Effects

Armaments are characterized by groups of technical and operational characteristics, each of which is divided into separate indicators. These include effectiveness, ranges of use; combat capability, reliability, operational safety. Under the effectiveness of the missile’s warhead it shall be understood the amount of damage that can cause an explosion in combat environment. The aim of the work is to evaluate the effectiveness of the blast-fragmentation warhead by modeling and analyzing the damaging of injurious effects. Primary blast-fragmentation warhead effects are a shock wave, which is characterized by a specific air pressure on its front and a specific impulse, as well as fragments that move at high speed. Determining the effectiveness of target neutralization by the fragmentation effect of the warhead is described by a set of positions of the j units, each of which is characterized by the fractional volume, the angle of inclination, the type of losses. Due to the independent impact on the target of several effects, their whole impact can be estimated by the total probability of individual injurious effects. The effectiveness of warhead is assessed by the probability of hitting the target. It is most rational to achieve the goal by reducing the distance to the explosion while increasing accuracy. This is a global development trend. Other ways are either to increase its explosive power or structurally - the number of fragments. It is necessary to indicate experimental data on the number of holes per unit area for a given distance and characteristics of the warhead of the missile. Assessing the probability of the debris impact requires clarification of the characteristics of the warhead, the characteristics of the vulnerable spots of the target and the angle of the missile approach. It is advisable to make the trajectory of the missile approach guided, taking into account the modularity of the configuration. This reduces ammunition consumption and increases the efficiency of the warhead.

scholarly journals Some nitrogen-rich heterocycles derivatives as potential explosives and propellants: A theoretical study

2016 ◽  
Vol 81 (6) ◽  
pp. 687-695
Author(s):  
Dany Frem
Keyword(s):  
Condensed Phase ◽  
Detonation Velocity ◽  
Energetic Materials ◽  
Theoretical Study ◽  
Specific Impulse ◽  
Heat Of Formation ◽  
Rocket Propellant ◽  
Crystal Density ◽  
Detonation Velocity And Pressure ◽  
Thermochemical Code

Four types of nitrogen-rich heterocycles substituted with -NO2, -NHNO2 and -C(NO2)3 explosophoric groups were explored as potential explosives and propellants materials. The calculated crystal density (?0)and the condensed phase heat of formation (?H?0f)for each of the twelve structures investigated shows that all these derivatives possess high (1.834-1.980 g cm-3)(?H?0f) and (605-2130 kJ kg-1) values. Interesting properties such as detonation velocity (D), pressure (P) and specific impulse (Isp) were calculated using the Kamlet-Jacobs method and ISPBKW thermochemical code. Detonation velocity and pressure in excess of 8.44 km s-1 and 32.87 GPa was obtained in all cases. Furthermore, trinitromethyl substituted derivatives shows performance exceeding that of HMX with an estimated D = 9.32-9.72 km s-1 and P = 40.61-43.82 GPa. Some -NO2 and -NHNO2 substituted derivatives were shown to be impact insensitive while retaining good detonation performance and thus are regarded as potential replacement for current RDX -based explosives. Finally, the calculated specific impulse (Isp between 248 and 270 s) of all investigated derivatives indicate that these energetic materials can be considered as possible ingredient in future rocket propellant compositions.

scholarly journals Research of the Influence of Temperature Factor on Express Control of Natural Gas Combustion Heat

2020 ◽  
pp. 44-50
Author(s):  
O. E. Seredyuk ◽  
N. M. Malisevich
Keyword(s):  
Natural Gas ◽  
Temperature Measurement ◽  
Flow Rate ◽  
Gas Flow ◽  
Flame Temperature ◽  
Operating Conditions ◽  
Gas Flow Rate ◽  
Combustion Heat ◽  
Gas Combustion ◽  
Functional Scheme

The article is devoted to the study of the influence of the qualitative and quantitative composition of gas environments on the flame temperature of the combusted gas at different values of gas flow rate and changes volume ratio gas-air in its combustion. The functional scheme of the developed labo­ratory stand (Fig. 1), which provides temperature measurement during combustion of natural gas or propane-butane mixture, is considered. The design of the developed burner is described and the expe­rimental researches are carried out when measuring the flame temperature of the combusted gas during the operation of the laboratory stand. The opera­ting conditions of different thermocouples in measuring the temperature of the flared gas are investigated (Fig. 2). The temperature instability in the lower and upper flames was experimentally determined (Fig. 3) and its difference from the reference data [12, 13]. The measurement of the flame temperature with a uncased thermocouple and two thermocouples of different types with protective housings is reali­zed. Methodical error of temperature measurement by different thermocouples was estimated (Fig. 5). An algorithm for the implementation of measurement control in determining the heat of combustion of natural gas according to the patented method is outlined [11]. Experimental studies of temperature changes of combusted gas mixtures at different gas flow rates and different ratios with air, which is additionally supplied for gas combustion, were carried out (Figs. 4, 7). The computer simulation (Figs. 6, 8) of the change in the flame temperature was performed on the basis of the experimental data, which allowed to obtain approximate equations of the functional dependence of the flame temperature on the gas flow rate and the ratio of the additional air and gas consumption. The possibility of realization of the device of express control of the heating value of natural gas by measuring the combustion temperature of the investigated gases, which is based on the expe­rimentally confirmed increase in the flame temperature of the investigated gases with increasing their calorific value, is substantiated (Fig. 9). The necessity of further investigation of the optimization design characteristics of the burner and the operating conditions of combustion of the gases under rapid cont­rol of their combustion heat was established (Fig. 9).

scholarly journals Theoretical studies of novel high energy density materials based on oxadiazoles

2021 ◽  
Author(s):  
Wenxin Xia ◽  
Renfa Zhang ◽  
Xiaosong Xu ◽  
Congming Ma ◽  
Peng Ma ◽  
...  
Keyword(s):  
Density Functional ◽  
High Energy ◽  
Heat Of Formation ◽  
High Energy Density ◽  
Detonation Properties ◽  
Detonation Pressure ◽  
Energetic Compounds ◽  
Functional Theory ◽  
High Energy Density Materials ◽  
Thermal Stability Of

Abstract In this study, 32 energetic compounds were designed using oxadiazoles (1,2,5-oxadiazole, 1,3,4-oxadiazole) as the parent by inserting different groups as well as changing the bridge between the parent. These compounds had high-density and excellent detonation properties. The electrostatic potentials of the designed compounds were analyzed using density functional theory (DFT). The structure, heat of formation (HOF), density, detonation performances (detonation pressure P , detonation velocity D , detonation heat Q ), and thermal stability of each compound were systematically studied based on molecular dynamics. The results showed that the -N 3 group has the greatest improvement in HOF. For the detonation performances, the directly linked, -N=N-, -NH-NH- were beneficial when used as a bridge between 1,2,5-oxadiazole and 1,3,4-oxadiazole, and it can also be found that bridge changing had little effect on the trend of detonation performance, while energetic groups changing influenced differently. The designed compounds (except for A2 , B2 , B4 ) all had higher detonation properties than TNT, A6 ( D = 9.41 km s -1 , P = 41.86 GPa, Q = 1572.251 cal g -1 ) was the highest, followed D6 had poorer performance ( D = 8.96 km s -1 , P = 37.46 GPa, Q = 1354.51 cal g -1 ).

A comparative study of the structure, energetic performance and stability of nitro-NNO-azoxy substituted explosives

2014 ◽  
Vol 2 (48) ◽  
pp. 20806-20813 ◽  
Author(s):  
Yuan Wang ◽  
Shenghua Li ◽  
Yuchuan Li ◽  
Rubo Zhang ◽  
Dong Wang ◽  
...  
Keyword(s):  
Comparative Study ◽  
Nitro Group ◽  
Detonation Velocity ◽  
Heat Of Formation ◽  
Detonation Pressure ◽  
Unique Structure ◽  
Energetic Performance

Nitro-NNO-azoxy group: the unique structure could improve the density, heat of formation, detonation velocity and detonation pressure of an explosive. Compared with the nitro group, the nitro-NNO-azoxy group has a stronger energetic and electron-attracting property.

Characteristics of NEPE Propellant with Ammonium Dinitramide (ADN)

2011 ◽  
Vol 399-401 ◽  
pp. 279-283
Author(s):  
Wei Qiang Pang ◽  
Hui Xiang Xu ◽  
Yang Li ◽  
Xiao Bing Shi
Keyword(s):  
Thermal Decomposition ◽  
Specific Impulse ◽  
Flame Temperature ◽  
Minimum Free Energy ◽  
Ammonium Dinitramide ◽  
Mechanical Sensitivity ◽  
Nitrate Ester ◽  
Nickel Chromium ◽  
Wire Method ◽  
Nepe Propellant

The theoretical performances of NEPE (nitrate ester plasticized polyether) propellant with and without ADN were calculated with minimum free energy method. The burning characteristics and the thermal decomposition of propellants were determined by nickel chromium wire method and TG- DTG, respectively. The SEM of NEPE propellants and the mechanical sensitivity were also detected. The results show that the specific impulse and the adiabatic flame temperature are increase with an increase in the content of ADN oxidizer. The burning rate and pressure exponent of propellant with a change of pat content of ADN can be boosted higher than those of the AP formulations.

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