Fast Combustion Research Articles

The study of ignition and emission characteristics of hydrogen-additive hydro-processed renewable diesel

This study was conducted to understand the effects of hydrogen (H2) addition on the combustion and emission characteristics of hydro-processed renewable diesel. Experiments were performed in a constant volume combustion chamber (CVCC) at varying H2 concentrations (0%, 5%, and 10% (by vol.)) relative to air (100%, 95%, and 90% (by vol.)), initial temperatures (Tini) of 600, 650 and 700 K, equivalence ratios (φ) of 0.5, 1.0, and 1.5 and a fixed initial pressure (Pini) of 10 bar. Overall, HRD has lower ignition delay (ID) and total ID. However, H2 addition to HRD delayed the fuel's auto-ignition due to excess H2 oxidation (H2+OHH2O + H) reaction taking place, which turns the chain reactions from branching to propagation, resulting from increasing in ID. Moreover, increasing of H2 concentrations enhanced the maximum pressure rise (Pmax) and heat release rate (HRR), whereas carbon dioxide (CO2) and unburned hydrocarbon (HC) were decreased due to the higher magnitude of the lower heating value of H2 than that of pure HRD. Since H2 itself is a carbon-free molecule, the carbon content of the fuel is reduced. H2 has the characteristics of fast combustion, resulting in a more flammable and complete mixture, which also makes HC emissions to become lower. However, the higher energy density of H2 significantly raises the combustion temperature, and subsequent nitrogen oxides (NOx) were increased. The kinetic modeling predictions revealed that the IDs for HRD-H2 were elongated due to the increased hydroperoxyl (HO2) and hydrogen peroxide (H2O2) mole fractions which led to improved stability.

Nanocrystalline Ag-doped cobalt oxide as a flexible electrode material for high performance supercapacitor application

Co3-xAgxO4 (x = 0 ~ –0.4) nanocomposite with a spherical shape and porous surface has been synthesized using a simple, fast and scalable combustion method. The highly stable Ag-doped Co3O4 nanocomposite particles were found to be 20‐–50 nm in size with high surface area, crystallinity, and porosity. The specific capacitance value of the Co2.7Ag0.3O4 (CA3) electrode was observed to be higher than other electrodes. Doping of Ag provides a large Ag/Co3O4 interface which enhanced the electrical conductivity of the electrode by moulding ohmic contact. This contributes to a stable and straight passage for rapid charge transfer. The calculated specific capacitance value of CA3 nanocomposite was 648 F g‐−1 at a current density of 0.25A g‐−1 which was 6-fold greater than the undoped Co3O4 and 2‐–4-fold greater than Ag-doped Co3O4 nanocomposites prepared at other concentrations. The electrodes exhibited excellent cyclic stability with capacitance retention of 93% after 10,000 cycles having an energy density of 88.23 Wh kg‐−1 at 1.75 kW kg‐−1 power density indicating a promising material for supercapacitor application. Fabricated symmetric solid-state flexible device of Ag-doped Co3O4 also demonstrated reliable charge storage performance with a maximum energy density. The theoretical study also revealed that Ag doping into Co3O4 introduces additional localized states around the fermi level, between the highest occupied states and lowest unoccupied states. The presence of higher localized states near the Fermi level and smaller bandgap than Co3O4 enhanced the specific capacitance of the system, providing support to the experimental observation on improvement in energy charge storage.

Evaluation of Structural and Functional Properties of La0.6Sr0.4MnO3 Perovskite Prepared by the Fast Solution Combustion Approach

A series of La0.6Sr0.4MnO3 (LSM) perovskite was made using the rapid solution combustion method, which was calcined by varying the temperatures. In order to determine how the calcination temperature affected the nanopowders produced and calcined at various temperatures, their microstructural, morphological, compositional, optical, and electrical properties were analyzed using corresponding characterization tools. The XRD results showed the coexistence of the rhombohedral polymorphs R-3c and Pm-3m for the perovskite phase under a calcination temperature of 1400 °C, which were eliminated with increased calcination temperature. The average grain size was found to increase with increasing calcination temperature. The EDS analysis showed better agreement of the stoichiometry with the theoretical composition. The apparent porosity decreased with increasing temperature due to the coalescence of sintering pores. The sample obtained after calcination at 1500 °C showed 10.3% porosity. The hardness also improved with increasing calcination temperature and reached a maximum value of 0.4 GPa, which matched the bulk density. A similar trend was observed in the resistivity studies as a function of temperature, and all the samples exhibited a low resistivity of ~1.4 Ω·cm in the temperature range of 500–600 °C. The optical characterization showed broad absorption at 560–660 nm and bandwidth values between 3.70 and 3.95 eV, according to the applied heat treatment.

Optical study on multi-time ignition mixed-mode combustion with gasoline and PODE

In this study, multi-time ignition mixed mode combustion (MIMC) strategy is proposed to improve the dual fuel combustion, based on observation of the ignition and flame development in conventional dual fuel combustion. Gasoline and polyoxymethylene dimethyl ethers (PODE) serve as the premixed and pilot fuel through port fuel injection and direct injection (DI). As PODE have good auto-ignition property and extremely low sooting tendency, MIMC strategy can realize multi-time ignition in conditions which should be avoided by conventional dual fuel strategies. Firstly, the combustion of gasoline-PODE in typical single DI mode is investigated under different conditions. It is found that the ignition location in the intermediate region of radius causes the fastest combustion among the test cases. The independent auto-ignition events during the flame development are also discussed. Then, the idea of MIMC mode is proposed, considering both the spatial and temporal aspects of different batches of ignition. Different with the typical reaction-controlled compression ignition (RCCI) strategy, the MIMC strategy can directly controls the ignition time with the in-cylinder DI time, providing more flexibility for the dual fuel combustion. Optical and thermal data indicate that the MIMC strategy can fasten or slowdown the combustion by combining the control of ignition position and ignition time. When the locations of the ignition events are spatially alternated and their heat release are overlapped temporally, the combustion will be the fastest under the same DI mass.

Enhanced combustion of ammonia engine based on novel air-assisted pre-chamber turbulent jet ignition

Ammonia has demonstrated great potential for achieving zero carbon emissions from internal combustion engines. However, the application of ammonia in engines faces the risks of ignition failure, low burning rate, and high nitrogen oxides emissions. Pre-chamber turbulent jet ignition (TJI) can provide multi-point ignition and fast combustion. Thus, in this study, a novel self-designed air-assisted pre-chamber apparatus is proposed to optimize the engine performance and combustion in a spark-ignition ammonia engine. The effects of high-reactivity pre-chamber fuels, including hydrogen, gasoline, and methane, on the performance of a TJI engine are investigated for the first time. The results show that, in the TJI mode considering the pre-chamber fueled with high-reactivity fuels, both the indicated mean effective pressure and indicated specific fuel consumption are improved compared with those in the spark-ignition mode. The enhanced combustion process involving shortened ignition delay and combustion duration is achieved by using the TJI mode. Double-peak phenomena are observed in both the pressure and heat release rate curves. In the TJI mode with the pre-chamber fueled with hydrogen, an optimal engine performance involving a high indicated mean effective pressure, low fuel consumption, and low coefficient of indicated mean effective pressure variation is obtained. Moreover, both peaks of the heat release rate are higher, and the ignition delay and combustion duration are further shortened owing to the jet effect produced by hydrogen combustion in the pre-chamber. Low NOx and NH3 emissions are observed in the TJI mode, particularly when the pre-chamber is fueled with hydrogen.

Mn-doped ZnO microspheres prepared by solution combustion synthesis for room temperature NH3 sensing

Despite being the most favorable ammonia (NH3) gas sensors, metal oxide semiconductors fail to deliver high selectivity and room temperature (RT) sensing. Tuning the metal oxide with doping is an attractive way of overcoming these disadvantages. Herein, we report Mn-doped ZnO microspheres as promising sensors for highly sensitive and selective RT sensing of NH3. ZnO and 2 wt% Mn-doped ZnO microspheres were synthesized by a low-cost and fast solution combustion synthesis, and their structure, morphology, and gas sensing properties were investigated. Mn-doping resulted in a change in the lattice parameters, an increase in the oxygen vacancies, and surface acidity of ZnO as confirmed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Temperature programmed desorption (TPD), respectively. Mn-doped ZnO showed a response (Ra/Rg) of 20.2 in 100 ppm NH3, which is significantly higher than ZnO. The sensor showed high selectivity, three times higher than that of ZnO, and good stability. Improvement in the sensing performance of Mn-doped ZnO is attributed to the increase in the defects and surface acidity with Mn-doping.

Lift-off behaviors of the partially-premixed jet flame in a supersonic vitiated coflow

Achieving fast and efficient combustion is considered as the primary difficulty in overcoming the high-Mach-number scramjet. A novel injection strategy with coflows has been proposed to improve the combustion efficiency, however, the inherent dynamics that drives the partially-premixed combustion is still not very clear. Numerical simulation is adopted to investigate the supersonic partially-premixed flame formed by the coflows of inner jet and annular vitiated air. Validation of numerical results has been conducted by comparing with the experimental data, and the predicted values show a reasonably good agreement with that in the experiments. Numerical results indicate that the supersonic jet flame is stabilized with a certain of lift-off height, with the dynamics balance of flow transport and flame propagation in the autoignition-dominated flame base. According to the flame index, the supersonic reactive flow fields are divided into three stages, including the no reaction region, premixed flame region and diffusion flame region. On this basis, the influence of equivalence ratio and injecting velocity of inner jet on the lift-off behaviors of jet flame, is explored by a series of contrastive analysis.

A study of ignition and combustion of liquid hydrocarbon droplets in premixed fuel/air mixtures in a rapid compression machine

The combustion of two fuels with disparate reactivity such as natural gas and diesel in internal combustion engines has been demonstrated as a means to increase efficiency, reduce fuel costs and reduce pollutant formation in comparison to traditional diesel or spark-ignited engines. However, dual fuel engines are constrained by the onset of uncontrolled fast combustion (i.e., engine knock) as well as incomplete combustion, which can result in high unburned hydrocarbon emissions. To study the fundamental combustion processes of ignition and flame propagation in dual fuel engines, a new method has been developed to inject single isolated liquid hydrocarbon droplets into premixed methane/air mixtures at elevated temperatures and pressures. An opposed-piston rapid compression machine was used in combination with a newly developed piezoelectric droplet injection system that is capable of injecting single liquid hydrocarbon droplets along the stagnation plane of the combustion chamber. A high-speed Schlieren optical system was used for imaging the combustion process in the chamber. Experiments were conducted by injecting diesel droplet of various diameters (50 µm < do < 400 µm), into methane/air mixtures with varying equivalence ratios (0 < ϕ < 1.2) over a range of compressed temperatures (700 K < Tc < 940 K). Multiple autoignition modes was observed in the vicinity of the liquid droplets, which were followed by transition to propagating premixed flames. A computational model was developed with CONVERGE™, which uses a 141 species dual-fuel chemical kinetic mechanism for the gas phase along with a transient, analytical droplet evaporation model to define the boundary conditions at the droplet surface. The simulations capture each of the different ignition modes in the vicinity of the injected spherical diesel droplet, along with bifurcation of the ignition event into a propagating, premixed methane/air flame and a stationary diesel/air diffusion flame.

Effect of barium on LSGM electrolyte prepared by fast combustion method for solid oxide fuel cells (SOFC)

Effect of barium on LSGM electrolyte prepared by fast combustion method for solid oxide fuel cells (SOFC)

Combustion model for thermite materials integrating explicit and coupled treatment of condensed and gas phase kinetics

Nanothermites are interesting energetic systems as their combustion driven by the oxidation of the metallic fuel associated with the reduction of the oxidizer, can produce extremely fast burning rates exceeding hundreds of m s−1. In addition, by changing the reactant (composition, stoichiometry) geometry and compaction conditions, the control of the burning rate can be achieved, allowing the designer to customize the chemical energy for each application. To date, only rough combustion models exist, most restricting the combustion mechanisms to only condensed phase processes, thus providing an approximative prediction of structure-combustion performance relationships. This work presents a tri-phasic model for the combustion of Al/CuO powder considering 9 gaseous species (Al, Cu, O2, O, Al2O, Al2O2, AlO, AlO2, N2) and 4 condensed species (Al, Cu, CuO, Al2O3) that can be liquid or solid. The reactionnal scheme involves 12 heterogeneous reactions and 2 phase changes based on diffusional kinetics, while gaseous reactions are considered through a chemical equilibrium. A detailed description of the theoretical formulation and numerical method is presented, followed by a discussion of a closed-bomb simulation. This work highlights the great impact of the Al particles initial diameter on the pressure development in the chamber. After the initiation stage, the decomposition of CuO releases gaseous O2, which is spontaneously absorbed on the surface of submicronic Al particles and diffuses through alumina to react with pure Al. At high temperature, gaseous copper, aluminum sub-oxides and aluminum condense on both particle types. By contrast, Al particle micron-size limits the quantity of O2 absorption and gaseous species surface condensation, leading to the formation of a pressure pre-peak 4 times higher than the final chamber pressure.

Preparation of LSGM electrolyte via fast combustion method and analysis of electrical properties for ReSOC.

Preparation of LSGM electrolyte via fast combustion method and analysis of electrical properties for ReSOC.

Investigations on combustion system optimization of a heavy-duty natural gas engine

Nowadays, the carbon-free policies and the crisis of crude oil make natural gas get increasing attention. However, spark-ignited natural gas engines continually suffer from problems of thermal efficiency and NOx emissions. Optimizing intake and combustion systems are effective ways to improve combustion and emission performance, but comprehensive work involving both intake and combustion systems is still lacking, especially for heavy-duty commercial engines. In this work, both intake and combustion systems of spark-ignited heavy-duty natural gas engines were investigated using muti-dimensional numerical simulations. Two intake ports and four combustion chambers were considered. An optimized chemical model was employed to accelerate the computation efficiency of combustion processes. The optimal combination of intake and combustion systems was obtained, with impressive thermal efficiency and acceptable emission performance. The results show that the mixed-flow intake port performs better than the swirl intake port for the natural gas engine with premixed combustion mode, manifesting increased in-cylinder tumble ratio and turbulent kinetic energy. Meanwhile, the eccentric hemispherical combustion chamber (EHCC) combined with mixed-flow intake ports presents the best optimal combustion performance, exhibiting an effective thermal efficiency beyond 41.53%. However, the EHCC scheme shows an increased NOx emission due to fast combustion speed and high combustion temperature while negligible CO and CH4 emissions. Despite this, natural gas engines equipped with three-way catalysis after-treatment can still meet emission regulations under stoichiometric operating conditions.

Evaluation of La0.8 Sr0·2MnO3 perovskite prepared by fast solution combustion

La0·8Sr0·2MnO3 (LSM) perovskite as oxygen electrode material for the reversible solid oxide fuel cells (ReSOFC) was synthesized by the fast solution combustion method and assessed for subsequent calcination influence. The microstructural, morphological, compositional and optical properties of the obtained material were analyzed with X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM) coupled with an energy-dispersive X-ray spectroscopy detector (EDS) and UV–visible spectroscopy techniques. The XRD results showed the coexistence of rhombohedral R-3c and Pm-3m polymorphs for the perovskite phase, with a decreased fraction of the cubic phase as the temperature and/or time used for the calcination were increased. The HR-TEM images confirmed the existence of the R-3c and Pm-3m polymorphs for the sample subjected to calcination at 1300 °C, showing that the rapid combustion method did not allow the pure formation of the La0·8Sr0·2MnO3 phase for the calcination temperatures below 1400 °C, due to the swiftness of the combustion synthesis 500 °C for 5 min. The average grain size was found to be increased with the calcination time. The EDS analysis depicted a better agreement in stoichiometry with the theoretical composition. The apparent porosity was decreased with the increase in the temperature and calcination time due to the coalescence of the sintering pores. The sample obtained after the calcination at 1400 °C for 8 h exhibited 1.6% of porosity. The hardness was improved with the higher calcination time and temperature and reached a maximum value of 5.7 GPa that merely matched the bulk density. A similar trend was observed in the temperature dependence resistivity studies and all the samples presented a low resistivity of ∼1.2 Ω cm in the temperature range of 600–700 °C. The optical characterization exhibited a broad absorption in 560–660 nm.

Condense-luminescence and global characterization of metal particle suspension combustion

Thermal processing of aluminum (Al) particles such as annealing followed by rapid quenching had been previously shown to affect single metal particle burning rates. This study extends single particle combustion to a global material-based energy exchange model. Experiments were designed to investigate the global energy exchange resulting from Al powder suspensions processed to induce different (fast and slow) burning regimes. Thermally processed and untreated Al particles were reacted as suspended powder in a closed bomb calorimeter. The calorimeter monitored the transient temperature changes resulting from energy release upon powder combustion. The product residue was analyzed for species concentration using X-ray diffraction. Results link the phase fractions of the aluminum oxide combustion products with global radiant fluxes in the calorimeter system. Metastable alumina associated with nano-oxide formation is in substantially higher concentration for thermally processed powder reactions and also produces greater energy transfer rates. The increased energy transfer rates correspond to higher radiant energy emission which may result from condensation energy associated with nano-oxide particle formation. This study qualifies condense-luminescence as a means for increasing the energy release rates of aluminum particles. By strategically altering metal fuels to control formation of nano-oxide particles upon combustion, appreciable increases in the radiant energy flux can transform energy release rates.

Study of general relativistic shocks and their propagation in neutron stars

Astrophysical shocks are very common and are interesting as they are responsible for particle acceleration in supernovas, blazers, and neutron stars. In this work, we study general relativistic shocks in which the shock front is at rest. We derive the jump conditions and the Taub adiabat equation for both the space-like and time-like shocks. We solve these equations for a neutron star where the shock wave is followed by a combustion front deconfining hadronic matter to quark matter. We find that the maximum mass of the daughter quark star (generated from the combustion of the parent neutron star) is consistent with the maximum mass limit for the equation of state sequence. The matter velocities under some conditions become super-luminous, which although disputed may indicate a very fast combustion process. Also, the matter velocities imply that for space-like shocks, the combustion process is most probably a deflagration, and for time-like shocks, it is a detonation and can even proceed with velocities that are super-luminous.

Optimization of biodiesel production via transesterification of soybean oil using α-MoO3 catalyst obtained by the combustion method

A catalyst based on MoO3 was synthesized by a simple and fast pilot-scale combustion reaction method and applied to the conversion of soybean oil to biodiesel via transesterification. For that, the statistical analysis of the catalyst amount and temperature, factors that influence the process, was evaluated by means of central composite design 22. MoO3 was characterized in terms of structure by X-ray diffraction (XRD), textural characterization Brunauer-Emmett-Teller (BET), density by helium pycnometry (DE), particle size analysis (DG) and acidity tests by temperature-programmed desorption of ammonia (NH3-TPD), chemical analysis by X-ray fluorescence (EDX), morphology by scanning electron microscopy (SEM) and catalytic properties. The transesterification products were characterized by gas chromatography (GC), acidity index (AI) and kinematic viscosity (KV). The results indicate the catalyst formation with a surface area of 1.36 m2g−1, and density of 4.5 g/cm3 which consists of a single crystalline phase of orthorhombic configuration, with total NH3 acidity of 33.61 μ.mol/g. Morphological characterization revealed that the catalyst is formed by irregular plates of various sizes and shapes, with a wide sizes range of agglomerated particles. In the soybean oil transesterification reactions, the catalyst was active showing 96.9% conversion to ethyl esters. The experimental design was meaningful and predictive, with a reliability level of 95%. The statistical analysis identified temperature as a significant variable for the adopted planning. To conclude, a new single-phase catalyst (α-MoO3) has been developed and successfully applied to the biodiesel Synthesis from soybean oil. These results have a positive and promising impact for biodiesel production by transesterification of soybean oil against ethanol.

Turbulent Non-Stationary Reactive Flow in a Cement Kiln

The reduction of emissions from large industrial furnaces critically relies on insights gained from numerical models of turbulent non-premixed combustion. In the article Mitigating Thermal NOx by Changing the Secondary Air Injection Channel: A Case Study in the Cement Industry, the authors present the use of the open-source OpenFoam software environment for the modeling of the combustion of Dutch natural gas in a cement kiln operated by our industrial partner. In this paper, various model enhancements are discussed. The steady-state Reynolds-Averaged Navier-Stokes formulation is replaced by an unsteady variant to capture the time variation of the averaged quantities. The infinitely fast eddy-dissipation combustion model is exchanged with the eddy-dissipation concept for combustion to account for the finite-rate chemistry of the combustion reactions. The injection of the gaseous fuel through the nozzles occurs at such a high velocity that a comprehensive flow formulation is required. Unlike in Mitigating Thermal NOx by Changing the Secondary Air Injection Channel: A Case Study in the Cement Industry, wave transmissive boundary conditions are imposed to avoid spurious reflections from the outlet patch. These model enhancements result in stable convergence of the time-stepping iteration. This in turn increases the resolution of the flow, combustion, and radiative heat transfer in the kiln. This resolution allows for a more accurate assessment of the thermal NO-formation in the kiln. Results of a test case of academic interest are presented. In this test case, the combustion air is injected at a low-mass flow rate. Numerical results show that the flow in the vicinity of the hot end of the kiln is unsteady. A vortex intermittently transports a fraction of methane into the air stream and a spurious reaction front is formed. This front causes a transient peak in the top wall temperature. The simulated combustion process is fuel-rich. All the oxygen is depleted after traveling a few diameters into the kiln. The thermal nitric oxide is formed near the burner and diluted before reaching the outlet. At the outlet, the simulated thermal NO concentration is equal to 1 ppm. The model is shown to be sufficiently mature to capture a more realistic mass inflow rate in the next stage of the work.

Comparative study on ignition and combustion between conventional spark-ignition method and near-wall surface ignition method for small-scale Wankel rotary engine

Due to the existence of the ignition chamber, severe energy loss occurs in the combustion process of small-scale spark-ignition Wankel rotary engines (SI-WREs). Aiming at eliminating the adverse effects caused by the ignition chamber, the near-wall surface ignition (NWSI) method was proposed in this paper. This method eliminates the ignition chamber felicitously, thus shortening the flame propagation distance and reducing the complexity of combustible gas flow. Computational fluid dynamic (CFD) simulations of the conventional SI-WRE and the NWSI-WRE were carried out and analyzed together. The simulation results showed that, by applying the NWSI method, the peak pressure increased by as high as 25.23%. The NWSI method possessed characteristics of shorter ignition delay, faster combustion, and more rapid flame propagation than the conventional SI method. The superiority of the NWSI method is verified, providing a good reference for optimizing the ignition system of small-scale SI-WREs.

Gas Turbine Combustion Optimization Using Neural Network Model and Wavelet Analysis

Abstract Rapid development in data science provides new methods for combustion tuning. This paper describes an artificial neural network (ANN) model that can accurately predict the key parameters in gas turbine combustion tuning and optimization, including NOx emission, combustor vibrational acceleration (ACC), and combustor dynamic pressure (DP). Wavelet denoising method was used in data preprocessing to improve the signal-to-noise ratio (SNR), which greatly improved the prediction accuracy of the neural network model. A combustion tuning simulation was then conducted to optimize NOx emissions using the acquired accurate mappings. By adjusting controllable parameters, optimization can be realized within necessary constraints. The effects of user-defined initialization parameters in the simulation were investigated for fast combustion tuning. An operating window was given considering the tradeoff between optimization results and computing time.

Effect of MnO2 morphology on the thermal properties and combustion behavior of nano-Al/MnO2 thermite

Al/granular MnO2 and Al/rod MnO2 thermite samples were prepared to investigate the effects of different morphologies of MnO2 on the thermal properties and combustion behavior of nano-Al/MnO2 thermite. The morphology and thermal properties of the thermite were characterized by field emission scanning electron microscopy (FE-SEM), x-ray diffractometry (XRD), and differential scanning calorimetry (DSC). DSC results show that the Al/rod MnO2 releases 1274.39 J·mol−1 heat, which is 292.58 J·mol−1 more than the Al/granular MnO2. The initial reaction temperature of Al/rod MnO2 is 567.39 °C, which is delayed by 17.39 °C versus 550 °C of Al/granular MnO2. Non-isothermal thermodynamic analysis was used to measure the activation energy of Al/rod MnO2 to be 234.36 kJ·mol−1, which is 46.53 kJ·mol−1 higher than that of Al/granular MnO2. This corresponds to an increase in the ignition temperature in the DSC curve and indicating a higher safety profile. In the open burning experiment, the burning time of Al/granular MnO2 was longer and sparks sputtered around the flame. The Al/rod MnO2 has a large combustion flame and a fast combustion rate. The light intensity peaks of the two groups of samples are close in the light intensity test. The light intensity existence time of Al/rod MnO2 is 0.0146 s, which is 0.094 s shorter than Al/granular MnO2. This shows that the combustion rate of Al/rod MnO2 is much faster than that of Al/granular MnO2. The closed-tube combustion experiment shows that the combustion wave velocity of Al/rod MnO2 increases first and then decreases; the maximum wave velocity reaches 339.6 m·s−1, and Al/granular MnO2 cannot self-propagate combustion in the microporous environment. In the constant volume combustion experiment, the peak combustion pressure of Al/rod MnO2 is 0.938 Mpa, and the peak value of Al/granular MnO2 combustion pressure is 0.581 Mpa; the difference is obvious. This shows that the rod MnO2 gas production performance is better. According to the duration of the pressure peak, the burning speed of Al/rod MnO2 in the light intensity test is confirmed again to be much faster than that of Al/granular MnO2. The Al/rod MnO2 is better than Al/granular MnO2 in thermal and combustion performance and is also safer. This provides a basis for future performance and safety research on aluminothermic materials.