Direct demonstration of complete combustion of gas-suspended powder metal fuel combustion using bomb calorimetry

Off-the-shelf calorimeters are typically used for hydrocarbon-based fuels and not designed for simulating metal powder oxidation in gaseous environments. We have developed a method allowing a typical bomb calorimeter to accurately measure heat released during combustion and achieve nearly 100% of the reference heat of combustion from powder fuels such as aluminum. The modification uses a combustible organic dispersant to suspend the fuel particles and promote more complete combustion. The dispersant is a highly porous organic starch-based material (i.e., packing peanut) and allows the powder to burn as discrete particles thereby simulating dust-type combustion environments. The demonstrated closeness of measured Al heat of combustion to its reference value is evidence of complete metal combustion achieved in our experiment. Beyond calorific output under conditions simulating real reactive systems, we demonstrate that the calorimeter also allows characterization of the temporal heat release from the reacting material and this data can be extracted from the instrument. The rate of heat release is an important additional parameter characterizing the combustion process. The experimental approach described will impact future measurements of heat released during combustion from solid fuel powders and enable scientists to quantify the energetic performance of metal fuel more accurately as well as the transient thermal behavior from combusting metal powders.

Annealing of aluminum nanoparticle and the formation of ethanol–ether binary coating layer on aluminum nanoparticle surface: A molecular dynamic study

Aluminum (Al) nanoparticle (ANP), as a metal fuel agent, has excellent combustion rate and energy density. However, several critical research gaps of ANP still exist. This study is focused on the annealing properties of ANP and its coating performances under the mixture of ethanol and ether molecules. According to those obtained molecular dynamic (MD) simulation results, the microstructure of ANP in the annealing process and the formation of ethanol–ether binary coating are discussed in this paper. During the melting process, the melting point of ANP could be analyzed by the inflection point of its atomic potential energy and the mean square displacement, then the accuracy of EAM force field could be verified. Because surface atoms have lower potential energy than inner atoms, it seems that the melting of ANP started from the particle surface and diffuses from surface to the core. When the melted Al cluster is solidified until 300 K, the microstructure of the crystallized particle is largely affected by the cooling rate. If the cooling rate if too fast, it is not enough for the Al cluster to recrystallize, which is called as the “freezing effect” for ANP. Next, the binary “competitive adsorption” behavior of ethanol and ether on the surface of ANP was simulated according to different ethanol–ether molecular ratios. Analyses of ethanol–ether binary coating layer show that the main component of binary coating is ethanol, but not ether. This competitive superiority of ethanol is caused by its own adsorption mechanism and molecular migration in this mixture of ethanol and ether.

Effect of the thermal and gas-dynamic properties of solid rocket propellant particles on the propellant combustion rate

The aim of this work is to eliminate the explosion possibility of a rocket engine that operates on a fast-burning solid propellant. The problem is considered by analogy with experiments conducted earlier. Various ways to increase the propellant combustion rate are presented. Examples of how the solid propellant combustion rate depends on the metal fuel and the oxidizer particle size are given. It is shown that unstable combustion of a solid propellant at high combustion chamber pressures is due to unstable combustion of the gas phase in the vicinity of the bifurcation point. Zeldovich’s theory of nonstationary powder combustion is applied to analyzing the explosion dynamics of the Hrim-2 missile’s solid-propellant sustainer engine. This method of analysis has not been used before. The suggested version that this phenomenon is related to the aluminum particle size allows one to increase the combustion rate in the combustion chamber of a liquid-propellant engine, thus avoiding the vicinity of the bifurcation point. The combustion of solid propellants differing in aluminum particle size is considered. The metal fuel and the oxidizer particle sizes most optimal in terms of explosion elimination are determined and substantiated. The use of submicron aluminum enhances the evaporation of ammonium perchlorate due to the infrared radiation of aluminum particles heated to an appropriate radiation temperature. This increases the gas inflow into the charge channel, thus impeding the suppression of ammonium perchlorate sublimation by a high pressure, which is important in the case where the engine body materials cannot withstand a high pressure in the charge channel. This increases the stability and rate of solid propellant combustion. It is shown that the Hrim-2 missile’s solid propellant cannot be used in the Hran missile. The combustion rate is suggested to be increased by using fine-dispersed aluminum in the solid propellant.

Studi Awal Distribusi Temperatur Elemen Bahan Bakar Reaktor Cepat Berpendingin Gas

Tujuan dari penelitian ini adalah menganalisis desain reaktor berdasarkan aspek termalhidrolik dan melakukan perhitungan distribusi temperatur elemen bahan bakar pada kondisitunak. Perhitungan dilakukan secara komputasi dengan menggunakan MATLAB (MATrixLABoratory). Metode yang digunakan ialah studi literatur dan perhitungan komputasi. Studi awal distribusi temperatur elemen menggunakan bahan bakar reaktor cepat berpendingin gas atau Gas cooled Fast Reactor (GFR). GFR ini didesain dengan bahan bakar uranium metal (U-10%wtZr), pendingin Helium (He), kelongsong stainless steel 316 (SS316) dan daya 500 MWt. Untuk menghitung distribusi temperatur elemen bahan bakar maka akan digunakan dengan asumsi distribusi kerapatan daya di dalam bahan bakar merata ke segala arah baik untuk arah radial maupun aksial dan transfer panas berlangsung pada keadaan tunak untuk 1 kanal pendingin. Perhitungan distribusi temperatur elemen bahan bakar pada kondisi tunak dilakukan dengan menggunakan persamaan-persamaan yang diadaptasi dari Duderstadt dan Hamilton. Hasil penelitian ini menunjukan bahwa reaktor berada dalam batas aman dengan temperatur maksimum berada di bawah nilai titik leleh bahan bakar, sehingga dari keadaan ini dapat menunjang keamanan pengoperasian reaktor.PRELIMINARY STUDY OF THE ELEMENT TEMPERATURE DISTRIBUTION OF GAS-COOLED FAST REACTORT. The study was aimed at analyzing the design of the reactor based on thermal-aspects and calculating the temperature distribution of the fuel element under steady conditions. The calculations were done computationally using MATLAB (MATrix LABoratory). The method used was the study of literature and computational calculations. Preliminary studiesof the temperature distribution of the elements using a gas-cooled Fast Reactor (GFR). The GFR is designed with uranium metal fuel (U-10% wtZr), Helium cooler (He), 316 stainlesssteel cladding (SS316) and 500 MWt power. To calculate the temperature distribution of the fuel element, assuming the distribution of the power density in the fuel is evenly distributed in all directions. All directions for both radial and axial direction and heat transfer took place under steady-state for 1 cooling channel. The calculation of the temperature distribution of the fuel element under steady-state performed using equations adapted from Duderstadt and Hamilton. The results of this study indicate that the reactor is within safe limits with maximumtemperatures below the value of the melting point of the fuel.The conclusion was it is able to support the safety of the reactor operation.

Additive manufacturing in the oil and gas industries

Additive manufacturing (AM), also known as 3D printing, is a process for creating prototypes and functional components achieved by consolidation of material layer upon layer. Applications of AM technologies have been witnessed in the healthcare, automotive, architecture, power generation, electronics and aviation industries. Some of the main benefits of AM include effective material utilisation, new design possibilities, improved functionality of the products and flexible production. The opportunities for the applications of additive manufacturing in the oil and gas industries are only just being explored. In this study, a review of the potential opportunities of AM technologies in oil and gas industries was reported. The adoption of the AM technologies necessitated the need for a rethink on design for manufacture and assembly of oil and gas component parts such as high-tech end burners, metal fuel nozzles, and submersible pump components amongst others. The possibility of employing AM technologies on-site for the production of spare parts for replacement of damage components in oil and gas equipment and facilities is commendable, as this brings about reduction in production downtime and replacement cost. The future of AM in the oil and gas industries is highly promising, however before AM can actualize its full-fledged potentials in these industries, further research is required in the area of new materials development and processing, improved surface finish of AM fabricated parts, enhanced fabrication speed and parametric optimisation to improve the mechanical properties of the fabricated components.