Heat Of Detonation Research Articles

Analysis of Strength Safety of Perforated String Considering Detonation Parameters

The strength safety of perforated string is the premise of safety production of oil well test, detonation parameters of perforating charge is an important factor that affects strength safety of perforated string. On the basis of correctly calculating the detonation parameters such as detonation temperature, detonation heat, detonation volume, detonation pressure and detonation velocity, then adopting the related thermodynamic theory and analyzing the surge pressure of perforated interval, "pocket"of down hole and the packer, thus get the impulsive load of perforation moment and then according to Buckling theory of string to analyze the strength safety of perforated interval tubing string. Considering the fitting sex between the analytic method of the strength safety of perforated interval tubing string and the practical situation of real well cases is very good, and the result of analysis can reflect the state of strength safety of perforated interval tubing string at the moment of detonation, therefore this method can provide primary reference analysis data for the design of strength safety of perforated interval tubing string.

Comparative theoretical studies on energetic substituted 1,2,4-triazole molecules and their corresponding ionic salts containing 1,2,4-triazole-based cations or anions

We have studied the densities, heats of formation, energetic properties, and thermodynamics of formation for a series of substituted 1,2,4-triazole molecules and their corresponding ionic salts containing 1,2,4-triazolium cations or 1,2,4-triazolide anions using density functional theory and volume-based thermodynamics method. The results show that when the 1,2,4-triazole molecules lose a proton to form corresponding 1,2,4-triazole-based anions, their salts have smaller densities than corresponding molecules. When the molecules get a proton to form the 1,2,4-triazole-based cations, their salts have higher densities than corresponding molecules. The transformation of the 1,2,4-triazole derivatives from nonionic molecules to corresponding cations or anions are very helpful for increasing their heats of formation. Changing the 1,2,4-triazole derivatives into corresponding cations or anions produce different effects on their heats of detonation. Overall, as the compound numbering varies, the evolution trend of heat of detonation is very similar to heat of formation. The salts containing the 1,2,4-triazolide anions have smaller detonation velocities and pressures than corresponding 1,2,4-triazole molecules, whereas the salts containing the 1,2,4-triazolium cations have higher detonation velocities and pressures than corresponding molecules. Finally, the lattice enthalpies and entropies were used to construct a thermodynamic cycle for salt formation to predict the possibility to synthesize the salts.

Effect of Different Polymeric Matrices on Some Properties of Plastic Bonded Explosives

AbstractMatrices based on polyisobutylene (PIB), polymethyl‐methacrylate (PA), Viton A 200, Dyneon FT 2481 (Fluorel), and polydimethyl‐siloxane binders were studied as desensitizers. A series of plastic explosives (PBXs) were prepared, based on four different nitramines, namely RDX (1,3,5‐trinitro‐1,3,5‐triazinane), β‐HMX (β‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocane), BCHMX (cis‐1,3,4,6‐tetranitro‐octahydroimidazo‐[4,5‐d]imidazole) and ε‐HNIW (ε‐2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane, ε‐CL‐20), bonded by the matrices mentioned. For comparison, pentaerythritol tetranitrate and certain commercial explosives based on it, Semtex 1A, Semtex 10 and Sprängdeg m/46, were used. Detonation velocities, sensitivities to impact and friction, and peak temperatures of thermal decomposition by differential thermal analysis technique (DTA) for all the explosives studied were determined. Heat of detonation was calculated by means of a thermodynamic calculation program (EXPLO 5 code). Fluoroelastomers have a neutral to positive effect on the thermal stability of nitramines and they have a significant effect on decreasing the friction sensitivity. However, their anti‐impact efficiency is the lowest in this study although they have a positive effect on performance of the corresponding PBXs. PA and PIB matrices markedly decrease thermal stability of nitramines, the anti‐impact influences of PIB‐binders are better than those of PA‐binders, while PA‐binders have a higher anti‐friction effect and slightly less negative influence on the performance of the PBXs in comparison with PIB mixtures. The polydimethyl‐siloxane matrix has a neutral effect on thermal stability of the nitramines studied, it has an influence on the volume thermochemistry of detonation comparable with that of fluoroelastomers although it does not provide comparable performance, and its corresponding PBXs have optimum sensitivity parameters.

DFT study on the structure and detonation properties of amino, methyl, nitro, and nitroso substituted 3,4,5-trinitropyrazole-2-oxides: New high energy materials

The structure, band gap, thermodynamic properties and detonation properties of methyl, amino, nitro, and nitroso substituted 3,4,5-trinitropyrazole-2-oxides are explored using density functional theory at the B3LYP/aug-cc-pVDZ level. It is found that the NH2 or CH3 group substitution for the acidic proton at the N4 position of trinitropyrazole-2-oxide (P20) decreases the heat of detonation and crystal density. The density (2.20–2.50 g/cm3), detonation velocity (10.20–10.92 km/s), and detonation pressure (52.30–59.84 GPa) of the title compounds are higher compared with 1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20), and octanitrocubane (ONC).

Theoretical investigation on the heats of formation and detonation performance in polydinitroaminocubanes

A series of polydinitroaminocubanes have been designed computationally. We calculated the heats of formation, the detonation velocity (D) and detonation pressure (P) of the title compounds by density function theory (DFT) with 6-311G** basis set. The relationship between the heats of formation and the molecular structures is discussed. The result shows that all cubane derivatives have high and positive heats of formation, which increase with increasing number of dinitroamino groups. The detonation performances of the title compound were estimated by Kamlet-Jacobs equation, and the result indicated that most cubane derivatives have good detonation performance over RDX (hexahydro-1,3,5-trinitro-1,3,5-trizine) and HMX (1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane). In addition, we also found that the heat of detonation (Q) is another very important impact in increasing detonation performance except density. The relative stabilities of the title compound are discussed in the terms of the calculated heats of formation, and the energy gaps between the frontier orbitals. The results have not only shown that these compounds may be used as high energy density compounds (HEDCs), but also provide some useful information for further investigation.

Theoretical investigations on the structure, density, thermodynamic and performance properties of amino-, methyl-, and nitroimidazoles and their N-oxides

Density functional theory calculations at the B3LYP/aug-cc-pVDZ level have been performed to explore the structure, stability, heat of explosion, density, and the performance properties of amino-, methyl-, and nitroimidazoles. N-Nitroimidazoles have shown lower densities compared with those of C-nitroimidazoles. Detonation properties of title compounds were evaluated by using Kamlet–Jacob semi-empirical equations based on the predicted densities and the calculated heats of detonation. It has been found that some compounds with the calculated densities 2.0 g/cm3, detonation velocities over 9.10 km/s and detonation pressures of about 45 GPa (some even over 50 GPa) may be novel potential high energy materials. The higher performance of nitroimidazole-N-oxides is apparently due to their higher densities (2.0–2.515 g/cm3). Heat of explosion, stability, density, and performance properties are related to the number and relative positions of –NO2, –NH2, and –CH3 groups of the imidazole ring. The designed nitroimidazoles satisfy the criteria of high energy materials.

Density functional calculations for a high energy density compound of formula C6H6−n (NO2) n

A series of polynitroprismanes, C(6)H(6-n )(NO(2))(n) (n = 1-6) intended for use as high energy density compounds (HEDCs) were designed computationally. Their electronic structures, heats of formation, interactions between nitro groups, specific enthalpies of combustion, bond dissociation energies, and explosive performances (detonation velocities and detonation pressures) were calculated using density functional theory (DFT) with the 6-311 G** basis set. The results showed that all of the polynitroprismanes had high positive heats of formation that increased with the number of substitutions for the prismane derivatives, while the specific enthalpy of combustion decreased as the number of nitro groups increased. In addition, the range of enthalpy of combustion reducing is getting smaller. Interactions between ortho (vicinal) groups deviate from the group additivity rule and decrease as the number of nitro groups increases. In terms of thermodynamic stability, all of the polynitroprismanes had higher bond dissociation energies (BDEs) than RDX and HMX. Detonation velocities and detonation pressures were estimated using modified Kamlet-Jacobs equations based on the heat of detonation (Q) and the theoretical density of the molecule (ρ). It was found that ρ, D, and P are strongly linearly related to the number of nitro groups. Taking both their energetic properties and thermal stabilities into account, pentanitroprismane and hexanitroprismane are potential candidate HEDCs.

A Simple Way to Predict Heats of Detonation of Energetic Compounds only from Their Molecular Structures

A simple method to predict heats of detonation of important classes of energetic compounds including nitroaromatics, nitramines, nitroaliphatics, and nitrate esters is introduced. It is based on the ratios of oxygen to carbon and hydrogen to oxygen as well as the contribution of some specific functional groups or structural parameters. Predicted heats of detonation of pure explosives and explosive formulations with water as product in the liquid state for 77 energetic compounds provide more reliable results than those obtained using two empirical and quantum mechanical methods. This new method improves an earlier effort of previous models through its application for different categories of energetic compounds, which contain the energetic bonds ArNO2, NNO2, CNO2, and CONO2. In addition, the novel model provided good results for some miscellaneous explosives and several new synthesized explosives, where experimental data were available.

Erratum: A Simple Way to Predict Heats of Detonation of Energetic Compounds only from Their Molecular Structures

3 Results and Discussion – Page 96 As shown in Table 2, the rms deviation of this new method (4.4 kJg−1) is lower than the ones of both methods of R-H (1.61 kJg−1) [5] and K-P (1.43 kJg−1) [10]. should be read: As shown in Table 2, the rms deviation of this new method (0.44 kJg−1) is lower than the ones of both methods of R-H (1.61 kJg−1) [5] and K-P (1.43 kJg−1) [10].

Simple Pathway to Predict the Power of High Energy Materials

A new method has been introduced to predict the power of important classes of energetic compounds including nitroaromatics, acyclic and cyclic nitramines, nitrate esters and nitroaliphatics. In this method, the predicted specific impulse and the corrected heat of detonation on the basis of H2O-CO2 arbitrary decomposition, have been used to calculate the power of an explosive with the molecular formula CaHbNcOd as determined by the Trauzl test. The predicted results show good agreement with respect to the measured values for both pure and mixture of explosives. The calculated volume expansions of pure energetic compounds have a root mean square (rms) deviation of 33 cm3 from 73 measured values (corresponding to 58 molecules). For 9 explosive mixtures, the predicted volume expansions have an rms deviation of 39 cm3 from the experimental results.

Stability of ZND detonations for Majda’s model

We evaluate by direct calculation the Lopatinski determinant for ZND detonations in Majda’s model for reacting flow and show that on the nonstable (nonnegative real part) complex half-plane it has a single zero at the origin of multiplicity one, implying stability. Together with results of Zumbrun on the inviscid limit, this recovers the result of Roquejoffre–Vila that viscous detonations of Majda’s model also are stable for sufficiently small viscosity, for any fixed detonation strength, heat release, and rate of reaction.

A new approach to predict the strength of high energy materials

This paper presents a new approach to predict the strength of energetic compounds in which there are important classes of high explosives including nitroaromatics, acyclic and cyclic nitramines, nitrate esters and nitroaliphatics. For CaHbNcOd compounds, the ratio of carbon to oxygen atoms and the predicted heat of detonation on the basis of the H2O–CO2 arbitrary have been used to calculate the strength of an explosive. The new model can give good predictions for mentioned energetic compounds as determined by the Trauzl test. The novel correlation will be useful in predicting the strength or power of a new energetic compound that has significant potential in the field of explosives and propellants.

Titania Nanocrystalline Prepared by Detonation Method and Calculation of Detonation Parameters

AbstractAs a promising method for synthesizing nanosized materials, detonation method was used to prepare TiO2 nanoparticles. A new method for predicting the Chapman‐Jouguet (C‐J) detonation parameters of CaHbOcNdTie explosives, such as detonation heat, detonation temperature, and detonation pressure, was introduced according to the approximate reaction equations of detonation. The coefficient of oxygen balance of explosive was also calculated according to the specific detonation synthesis experiment. The calculation method was more useful in predicting the formation processes of detonation products and optimizing the experimental procedure. It could also support theory foundation for further experiments to some extent.

A systematic theoretical investigation of the relationship between heats of detonation and NBO charges and 15N NMR chemical shifts of nitro groups in nitramines and nitro paraffins

A new quantitative method for predicting and calculating the heat of detonation for a series of nitro paraffins and nitramines employing the natural bond orbital (NBO) charge analysis and 15N NMR chemical shifts of the nitro group is established. All calculations, including optimizations, charge analysis and 15N Nitro NMR chemical shifts, were performed using density functional (DFT) methods with 6-311+G(d,p) basis set. The results show a linear correlation between the nitro group charges and C/N-nitro bond lengths. The latter reflect the strength of the corresponding bond and thus the stability of the nitro compounds. A strong correlation was observed between the heat of detonation with the charge and 15N NMR chemical shift on the nitro group in nitramines and nitro paraffins. Nitro compounds with a higher heat of detonation have less negative nitro group charges, (Q Nitro) and a lower value for the 15N Nitro chemical shift in analogous compounds. From the quantitative models, the heat of detonation increase when the Q Nitro values (positive coefficient) are larger and decrease when the 15N Nitro NMR chemical shift (negative coefficient) is higher. The present work provides consistent models (mean square error prediction values below 0.14 MJ kg −1) in a systematic way for quick estimation of heats of detonation – with or without experimental data – for a wide range of energetic materials. This practical approach is particularly useful as a tool for the design of high-energy density materials.

Preparation and Properties of HMX Coated with a Composite of TNT/Energetic Material

AbstractTo improve the safety of HMX without sacrificing energy properties, the composites of TNT and an energetic material (HP‐1) were used to coat HMX particles by a method of integrating solvent–nonsolvent with aqueous suspension‐melting. SEM (scanning electron microscopy) and XPS (X‐ray photoelectron spectrometry) were employed to characterize the samples. The effect of the processing parameters, such as mass ratio of HP‐1 to TNT (MRHT), stirring speed, and cooling rate, on the quality of coated samples were investigated and discussed. The mechanical sensitivity, thermal sensitivity, thermal decomposition characteristic, and heat of detonation of raw and coated HMX samples were also measured and contrasted. Results show that when MRHT, stirring speed in the second stage and cooling rate are 1 : 5, 1000 r⋅min−1 and 5 °C⋅min−1 respectively, the optimal coating effect is achieved. Compared with that of raw HMX, both impact and friction sensitivity of HMX coated with 2.5 wt.‐% TNT and 0.5 wt.‐% HP‐1 decrease obviously, whereas there is a slight change in their thermal sensitivity and thermal decomposition characteristics. Meanwhile, such surface coating does not result in the decrease of its energy properties.

A new computer code to evaluate detonation performance of high explosives and their thermochemical properties, part I

In this paper a new simple user-friendly computer code, in Visual Basic, has been introduced to evaluate detonation performance of high explosives and their thermochemical properties. The code is based on recently developed methods to obtain thermochemical and performance parameters of energetic materials, which can complement the computer outputs of the other thermodynamic chemical equilibrium codes. It can predict various important properties of high explosive including velocity of detonation, detonation pressure, heat of detonation, detonation temperature, Gurney velocity, adiabatic exponent and specific impulse of high explosives. It can also predict detonation performance of aluminized explosives that can have non-ideal behaviors. This code has been validated with well-known and standard explosives and compared the predicted results, where the predictions of desired properties were possible, with outputs of some computer codes. A large amount of data for detonation performance on different classes of explosives from C–NO 2, O–NO 2 and N–NO 2 energetic groups have also been generated and compared with well-known complex code BKW.

Application of pulse detonation technology for boiler slag removal

Pulse detonation technology for removing slag and fouling deposits in coal-fired utility power plant boilers offers great potential. This technology offers a potentially convenient, inexpensive, yet efficient way for on-line slag removal. This paper presents a feasibility study that includes both Computational Fluid Dynamics (CFD) simulations and laboratory experiments. CFD simulations provided visual and quantitative data to study the potential mechanisms for removal of slag. Mechanisms included direct impact, flow scrubbing, wave reflection and negative velocity impact on the back side of the tubes. Several experiments were carried out to verify the potential of the pulse detonation technology. Experiments were done using a pulse detonation engine and heat exchanger tubes with different types of slag placed in different orientations on the tubes. Tubes were placed at various distances from the detonation tube and in different configurations. The results present a strong case for the application of this technology for online slag removal. It is especially effective for removal of slag on the back sides of the tubes where other traditional methods are not very successful. A preliminary cost analysis indicated that the technology can be paid for within the first year itself and provide substantial savings in the subsequent years.

Estimating Heats of Detonation and Detonation Velocities of Aromatic Energetic Compounds

AbstractA new method is introduced to predict reliable estimation of heats of detonation of aromatic energetic compounds. At first step, this procedure assumes that the heat of detonation of an explosive compound of composition CaHbNcOd can be approximated as the difference between the heat of formation of all H2OCO2 arbitrary (H2O, CO2, N2) detonation products and that of the explosive, divided by the formula weight of the explosive. Overestimated results based on (H2OCO2 arbitrary) can be corrected in the next step. Predicted heats of detonation of pure energetic compounds with the product H2O in the liquid state for 31 aromatic energetic compounds have a root mean square (rms) deviation of 2.08 and 0.34 kJ g−1 from experiment for (H2OCO2 arbitrary) and new method, respectively. The new method also gives good results as compared to the second sets of decomposition products, which consider H2, N2, H2O, CO, and CO2 as major gaseous products. It is shown here how the predicted heats of detonation by the new method can be used to obtain reliable estimation of detonation velocity over a wide range of loading densities.

Substituent effect on the molecular stability, group interaction, detonation performance, and thermolysis mechanism of nitroamino-substituted cyclopentanes and cyclohexanes

Density functional theory (DFT) method has been employed to study the effect of nitroamino group as a substituent in cyclopentane and cyclohexane, which usually construct the polycyclic or caged nitramines. Molecular structures were investigated at the B3LYP/6-31G** level, and isodesmic reactions were designed for calculating the group interactions. The results show that the group interactions accord with the group additivity, increasing with the increasing number of nitroamino groups. The distance between substituents influences the interactions. Detonation performances were evaluated by the Kamlet-Jacobs equations based on the predicted densities and heats of formation, while thermal stability and pyrolysis mechanism were studied by the computations of bond dissociation energy (BDE). It is found that the contributions of nitroamino groups to the detonation heat, detonation velocity, detonation pressure, and stability all deviate from the group additivity. Only 3a, 3b, and 9a–9c may be novel potential candidates of high energy density materials (HEDMs) according to the quantitative criteria of HEDM (ρ ≈ 1.9 g/cm3, D ≈ 9.0 km/s, P ≈ 40.0 GPa). Stability decreases with the increasing number of N-NO2 groups, and homolysis of N-NO2 bond is the initial step in the thermolysis of the title compounds. Coupled with the demand of thermal stability (BDE > 20 kcal/mol), only 1,2,4-trinitrotriazacyclohexane and 1,2,4,5-tetranitrotetraazacyclohexane are suggested as feasible energetic materials. These results may provide basic information for the molecular design of HEDMs.

A guiding simulation research on developing promising energetic materials

AbstractThis investigation is motivated by the representative synthesis reaction of 1,4,5,8‐tetranitro‐1,4,5,8‐tetraazadecalin (TNAD): ethylene diamine is replaced by 1,1,diamino‐2,2‐dinitroethene (FOX‐7) or 1,3,5‐triamino‐2,4,6‐trinitrobenzene (TATB) to react with glyoxal in order to subsequently obtain promising high energy density materials. The hybrid density functional theory method is used in calculations for some series of compounds with NNO2 and CNO2 functional groups. First, we create the corresponding Cartesian coordinates of the molecules under investigation and obtain their optimized molecular geometry; the molecular enthalpy can then be used to calculate the molecular detonation heat upon explosion. Furthermore, the target molecular volumes are obtained using the group additivity approach, which are then transferred into molecular densities. The densities and detonation heats of the corresponding energetics are carried into the Kamlet–Jacobs empirical equations to determine the related detonation velocities and detonation pressures. It was found that 10 of 14 TATB‐ and FOX7‐related molecular derivatives have detonation velocities between 9,302 and 1,1122 m/s and between 396 and 646 kbar, and are superior in performance to the traditional octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) explosive. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009