Pure Propane Research Articles

Small-scale BLEVE: Near-field aerial shock overpressure and impulse

This paper presents an investigation into one of the most damaging hazards associated with Boiling Liquid Expanding Vapor Explosion (BLEVE), specifically focusing on the near-field overpressure and impulse effects. Experiments were conducted at a small-scale to study the overpressure and impulse using aluminum tubes with a diameter of 50 mm and a length of 300 mm. The tubes were filled with pure propane liquid and vapor. The controlled variables, in this work included the failure pressure, the liquid fill level, and the weakened length along the tube top. These variables control the strength of the overpressure characterized by the peak overpressure amplitude, duration of this overpressure event, and the resultant impulse. Notably, these experiments at a small scale included experiments with a 100 % liquid fill level. This further confirmed that the vapor space is the main driver of the lead overpressure hazard. High-speed cameras and blast gauges effectively illustrated the progressive formation of the shock wave in both temporal and spatial dimensions. Furthermore, various predictive models available in the literature are discussed in this paper and new correlations were developed to quantify the overpressure duration and impulse. The current analysis aims to predict the potential consequences of overpressure events during a BLEVE.

Partial molar and microstructural properties of binary propane + o-toluidine system near the critical point of pure solvent based on the VLE measurements and modeling with CP-PC-SAFT and mg-SAFT equation of states

The isothermal VLE properties (PTxy relationship) of a binary supercritical (SC) C3H8 + o-toluidine mixture was measured by means of static-analytic method with fluid phase sampling at equilibrium conditions. The measurements were made at three temperatures of (393.15, 433.15, and 473.15) K and pressures up to 10.41 MPa. An experimental VLE apparatus, a high-temperature and high-pressure optical cell, has been used to measure the phase equilibrium properties (PTxy) of the binary SC C3H8 + o-toluidine mixture. The combined expanded absolute and relative uncertainties of the temperature, pressure, and the phase concentration measurements at 0.95 confidence level with a coverage factor of k = 2 is estimated at 0.15 K, 0.5 %, 4.2 % (for x) and 4.8 % (for y), respectively. The critical curve data, TC−x,PC-x, and PC− TC projections, have been derived based on the measured VLE data. The measured VLE and the derived critical curve data were used to estimate the theoretically important and physical meaning of Krichevskii parameter, ∂P∂xTCVC∞. Thermodynamic (partial molar properties, V¯2∞,H¯2∞,C¯P2∞, and distribution equilibrium constant KD), and microstructural (cluster’s size, Nexc∞) properties of infinite-dilute C3H8 + o-toluidine mixture near the critical point of pure solvent (C3H8) were calculated based on the derived Krichevskii parameter and pure solvent (SC C3H8) properties. CP-PC-SAFT and mg-SAFT equation of state (EoS), with zero interaction parameter, k12 = 0, for both models (pure prediction models, no adjustable parameters) were successfully applied to the present PTxy phase equilibria for the SC C3H8 + o-toluidine mixture. The present measured VLE data for C3H8 + o-toluidine system along with the reported pure compound properties of pure propane and o-toluidine have been used to examine the predictive capabilities of the theoretically based CP-PC-SAFT and mg-SAFT models of EoS. It was demonstrated that mg-SAFT is superior in predicting VLE of the C3H8 + o-toluidine system with k12 = 0.

Comparative Study of PtM (M=Cu, Zn, Ga, Mn, Fe, In, Ce) Bimetals on Zincosilicate for Propane Dehydrogenation Reaction.

Silicoaluminate zeolites have relatively strong Brönsted (B) acid properties that can easily lead to deep cracking reactions, making them less favourable as carriers for propane dehydrogenation. Here, we utilise zincosilicate zeolite with less B-acid produced by the introduction of the heteroatom Zn into the framework as a carrier, followed by simultaneous ion exchange (IE) of M monometallic or PtM bimetallic (M = Cu, Zn and Ga, etc.). The optimized PtZn/Zn-4 exhibits a superior propane dehydrogenation performance over PtCu/Zn-4 and PtGa/Zn-4, which can achieve a propane conversion of about 30% in a pure propane atmosphere at 550 °C and can be operated for at least 168 h without significant deactivation. Characterization techniques such as spherical aberration corrected transmission electron microscopy, in situ X-ray photoelectron spectroscopy, and in situ diffuse reflectance infrared fourier transform spectroscopy with different gas adsorptions are used to investigate these PtM@zeolite catalysts in order to deepen the understanding of acid site identification, promoter effect and catalysis.

Design and production of a mini-turbo reactor and study of its dual-fuel (gas-hydrogen) operation

The objective of this research was to investigate the effects of hydrogen injection on the performance of a mini turbo reactor. To achieve this, an experimental test bench was constructed, incorporating a specially designed mini turbo reactor capable of operating on various fuel mixtures and a dry cell electrolyzer for on-site hydrogen production. A comprehensive testing campaign was conducted, comparing the mini turbo reactor performance when fueled with pure propane and a propane-hydrogen blend at varying concentrations. Parameters evaluated included power output, thermal efficiency, fuel mass flow rate, flame temperatures, and pollutant emissions (CO, CO2, NOx). The experimental results unequivocally demonstrated that the addition of hydrogen to propane significantly enhances the mini turbo reactor specific power while concurrently reducing CO and CO2 emissions. Furthermore, data analysis revealed an improvement in the thermal efficiency of the cycle, suggesting potential reductions in specific fuel consumption. These findings highlight the promising potential of hydrogen injection as a strategy to enhance the performance and environmental impact of mini turbo reactor.

Dynamics of direct hydrocarbon PEM fuel cells

Hydrocarbon fuels contain approximately 50 times more energy per unit mass than commercial batteries, thus converting even 10% of the energy contained in hydrocarbon fuels to electrical energy could present a more mass-efficient electrical energy source than batteries. Considering the storability of hydrocarbon fuels compared to hydrogen, the viability of direct hydrocarbon polymer electrolyte membrane fuel cells was examined. With extremely pure (> 99.99%) propane, the cell Open-Circuit Voltage (OCV) was only 0.05 V and produced negligible power. However, with addition of trace quantities of unsaturated hydrocarbons, the cell had an OCV of 0.85 V and produced power, even after the unsaturated hydrocarbon addition was discontinued. At sufficiently high current densities, power output gradually decreased then the cell rapidly “extinguished” but by periodically shutting off the current for short time intervals the average power density could be increased significantly. Chemical analysis revealed that no significant amounts of hydrocarbon intermediates or CO were present in the effluent and that conversion of the hydrocarbon fuel to CO2 and H2O was nearly complete. An analytical model incorporating the relative rates of conversion of active anode catalyst sites to inactive sites and vice versa was developed to interpret this behavior. The model predictions were consistent with the experimental observations; possible physical mechanisms are discussed.

Highly efficient and stable hydrogen permeable membrane reactor for propane dehydrogenation

The synthesis of SAPO-34 hollow fiber membranes employs the ball-milling assistant method to enhance membrane yield and quality. These membranes are then combined with CrOx/Al2O3 catalyst to create a packed bed membrane reactor (PBMR) for propane dehydrogenation (PDH). The study investigates the impact of operating temperatures, weight hourly space velocities (WHSV), and sweep gas flow rates on the SAPO-34 zeolite membrane reactor's performance, comparing it to a traditional packed bed reactor (PBR). The removal of hydrogen from the reaction side significantly improves propane conversion, surpassing thermodynamic equilibrium. In PBMR, propylene selectivity slightly exceeds that in PBR, influenced by side reactions like hydrogenolysis and cracking after hydrogen removal. Furthermore, the SAPO-34 zeolite membrane reactor undergoes a prolonged stability test with frequent regeneration using pure propane as feedstock to simulate industrial conditions. It exhibits consistent performance over 120 regeneration cycles within 240 h, maintaining similar H2 permeability and H2/C3H8 selectivity as the fresh membrane post long-term testing.

Stable anchoring of single rhodium atoms by indium in zeolite alkane dehydrogenation catalysts.

Maintaining the stability of single-atom catalysts in high-temperature reactions remains extremely challenging because of the migration of metal atoms under these conditions. We present a strategy for designing stable single-atom catalysts by harnessing a second metal to anchor the noble metal atom inside zeolite channels. A single-atom rhodium-indium cluster catalyst is formed inside zeolite silicalite-1 through in situ migration of indium during alkane dehydrogenation. This catalyst demonstrates exceptional stability against coke formation for 5500 hours in continuous pure propane dehydrogenation with 99% propylene selectivity and propane conversions close to the thermodynamic equilibrium value at 550°C. Our catalyst also operated stably at 600°C, offering propane conversions of >60% and propylene selectivity of >95%.

Numerical Simulation of a Gas Burner Using Mixed Propane/Ammonia Fuel

In recent years, ammonia has received more and more interest to be used as carbon-free energy. In the present study, a computational model of a burner for the domestic hot water boiler in the building has been developed. The combustion characteristics of propane/ammonia-mixed fuel in the burner were investigated by numerical simulation under different ammonia blending ratios and equivalence ratios. Based on the flue gas concentration distribution of the numerical simulation results, the baseline carbon emission of hot water supply in a community was calculated. The results show that as the ammonia blending ratio increases, the overall combustion temperature decreases. At the outlet of the burner, when the ammonia blending ratio is 0.5, the emission concentration of carbon dioxide can be reduced by 31.4% compared to pure propane combustion. When the ammonia blending ratio increases from 0 to 50%, the carbon baseline emission decreases from 9.89 kg/GJ to 6.87 kg/GJ, and the carbon emission under the baseline decreases from 17.20 T to 11.94 T. The emission of NO pollutants remains basically unchanged due to the decrease of combustion temperature. It indicates that the mixed fuels can effectively reduce carbon emissions in domestic water heaters and have good potential for future application.

Enthalpy of dissociation of the mixed methane + propane sII hydrate along the three-phase equilibrium line

ABSTRACT We present a detailed overview of the calculation of the enthalpy of dissociation of structure II pure propane or mixed methane + propane hydrates, focussing primarily on methods that are based on either the Clausius-Clapeyron equation or the direct calculation of the enthalpies of all the components that are involved in the hydrate dissociation reaction. Molecular dynamics simulations are used extensively in order to calculate the enthalpies and molar volumes of water, methane, propane, and the sII mixed hydrate (with variant degree of occupancy) at pressure and temperature conditions along the three-phase (Hydrate–Liquid water–Vapor or Hydrate–Liquid water–Liquid hydrocarbon) equilibrium line.

Purification of Industrial Effluent by Gas Hydrate-based (HyPurif) Process

This study presents a sustainable HyPurif process for managing and recycling industrial water effluent, utilizing gas hydrate-based technology to purify complex effluent. This work purifies two effluents: one from a wastewater treatment plant (WWTP) and the other from a spent caustic treatment plant (SCTP). Various hydrate formers, including propane, HFC134a, and cyclopentane (6 mol %), were selected, as they typically form hydrates closer to ambient conditions. Hydrate formation experiments with effluent water were performed at 278.30 K using pure propane and HFC134a gas. Based on the kinetics of hydrate growth, the study was extended to a mixture (50:50%) of propane and HFC134a, operating at a pressure of 0.6 MPa. The mixture of propane and HFC134a has shown the desired result of forming the hydrate in the gas phase and having high separation efficiency. The results showed that the formation and dissociation of hydrates resulted in a separation efficiency of 80–95%. For instance, in the purified water, the biological oxygen demand (BOD) decreased from 2097 mg/L in the effluent sample to 220 mg/L in purified water (purification efficiency of 90.5%). The chemical oxygen demand (COD) decreased from 3100 mg/L in the effluent sample to 503 mg/L in purified water (purification efficiency of 84%). Total dissolved solids (TDS) were reduced from 89,632 mg/L in the effluent water to 14,698 mg/L in purified water (purification efficiency of 84%). Total suspended solids (TSS) were reduced from 35 mg/L in the effluent water to 3.5 mg/L in purified water (purification efficiency of 90%). However, the purification efficiency for free ammonia and residual chlorine was lower. The concentration of free ammonia decreased from 7 mg/L in the effluent sample to 1.89 mg/L in the purified water (purification efficiency of 73%), and residual chlorine reduced from 0.8 mg/L in the effluent sample to 0.2 mg/L in the purified water (purification efficiency of 75%). Water recovery of ≥40% was achievable per pass, which could be increased, but at the expense of purification efficiency. To the best of our knowledge, this is the first study on the purification of such complex wastewater containing organic and inorganic compounds, heavy metals, and various minerals using the HyPurif process.

Position-Specific Isotope Analysis of Propane by Mid-IR Laser Absorption Spectroscopy.

Intramolecular or position-specific carbon isotope analysis of propane (13CH3-12CH2-12CH3 and 12CH3-13CH2-12CH3) provides unique insights into its formation mechanism and temperature history. The unambiguous detection of such carbon isotopic distributions with currently established methods is challenging due to the complexity of the technique and the tedious sample preparation. We present a direct and nondestructive analytical technique to quantify the two singly substituted, terminal (13Ct) and central (13Cc), propane isotopomers, based on quantum cascade laser absorption spectroscopy. The required spectral information on the propane isotopomers was first obtained using a high-resolution Fourier-transform infrared (FTIR) spectrometer and then used to select suitable mid-infrared regions with minimal spectral interference to obtain the optimum sensitivity and selectivity. We then measured high-resolution spectra around 1384 cm-1 of both singly substituted isotopomers by mid-IR quantum cascade laser absorption spectroscopy using a Stirling-cooled segmented circular multipass cell (SC-MPC). The spectra of the pure propane isotopomers were acquired at both 300 and 155 K and served as spectral templates to quantify samples with different levels of 13C at the central (c) and terminal (t) positions. A prerequisite for the precision using this reference template fitting method is a good match of amount fraction and pressure between the sample and templates. For samples at natural abundance, we achieved a precision of 0.33 ‰ for δ13Ct and 0.73 ‰ for δ13Cc values within 100 s integration time. This is the first demonstration of site-specific high-precision measurements of isotopically substituted non-methane hydrocarbons using laser absorption spectroscopy. The versatility of this analytical approach may open up new opportunities for the study of isotopic distribution of other organic compounds.

Experimental analysis and performance of refinery fuel gas on lean and rich fuel–air premixed combustion

Refinery fuel gas (RFG) is a blend of gas streams produced as by-products in various refinery processes. Large amounts of RFG are burning around the clock in the air with thermal energy waste and adverse effects on the environment. The present work investigates experimentally the performance of different compositions of RFG from lean to rich fuel–air premixed combustion, with focus on an efficient and low-emission combustion for its heat recovery. Radiant and porous media burners are the combustion technologies used. For the radiant burner, fuel compositions are propane and ethane with an average ethane ratio of 5%, 10%, and 15% (E05, E10, E15 respectively), which are contrasted with pure propane and liquefied petroleum gas (LPG). The pure gases fluxes are fixed as 1 and 2 m3/h for low and high flame configurations, respectively. The lean fuel–air flames investigated are stable for all ethane ratios with low carbon monoxide (CO) and nitrate oxides (NOx) emissions. Maximum temperature is given by pure propane flame (besides LPG), followed by E05, E10 and E15, for both flame configurations. Then, the radiation heat flux of ethane mixtures exhibits a reduction in comparison with LPG. For the porous media burner, lean and rich fuel–air mixture composed by natural gas (NG, 97% methane) and representative flue samples of 55% (C1) and 70% (C2) methane concentration are tested. The C1 and C2 flue samples present high combustion temperatures, showing a positive swap from NG. The NG rich-fuel combustion exposes high hydrogen conversion (27%) at high equivalence ratio (ϕ=1.8). Finally, for both burners lean fuel–air premixed combustion shows high combustion efficiencies, 74.8% with E05 and 80.7% with C1 flue sample.

Isolated Pt Species Anchored by Hierarchical-like Heteroatomic Fe-Silicalite-1 Catalyze Propane Dehydrogenation near the Thermodynamic Limit

The atomic dispersion of precious metals accompanied by maximum atom utilization can provide specific chemical properties compared to nanoparticles and clusters that have attracted widespread interest. The selection of a suitable carrier to stabilize platinum atoms while maintaining high stability and propylene selectivity is of great challenge for propane dehydrogenation reactions operating at extremely high temperatures. Here, we report a conceptually designed catalyst comprising isolated Pt atoms stably bonded through skeleton O in a hierarchical-like heteroatomic ferrosilicate zeolite (H-Fe-S-1–3; denoted as “Fe-3”), capable of achieving high propane conversions at different temperatures and atmospheres close to the thermodynamic limit. No significant deactivation was observed for 3 days in a pure propane atmosphere at 580 °C, outperforming most of the cutting-edge Pt-based catalysts. The moderate acidity of Fe-3 and anchoring of hydroxyl species other than silanol nests were responsible for maintaining a suitable C–H break rather than an excessive C–C cleavage capacity and a high degree of Pt dispersion, respectively. X-ray absorption spectra and atomically resolved high-angle annular dark-field electron microscopy demonstrated major atomic dispersion of Pt species, along with complementary density functional theory calculations to determine the structure of ≡Si–O–Pt–O–Fe≡ corresponding to the T4 location as the key active site. Pt anchoring by sites other than the T4 site with analogous energies, such as T6, could be accountable for the observation that “cluster-like Pt species” are essentially composed of isolated Pt atoms not interacting with each other.

Effects of Fracture Parameters on VAPEX Performance: A Numerical and Experimental Approach Utilizing Reservoir-On-The-Chip

The present research carries out an in-detail study of the VAPEX process as one of the most recent solvent-based heavy oil recovery techniques in fractured reservoirs to evaluate the effect of fracture parameters on process performance. To achieve this purpose, several fractured patterns with distinct features were designed and engraved on glass pieces to manufacture state-of-the-art microfluidic models mimicking a typical Canadian heavy oil reservoir. A heavy oil sample of viscosity 1514 cP was utilized during the conducted experiments with pure propane and pure carbon dioxide as the injection solvents. A thorough image analysis operation was carried out over the experimental models to determine heavy oil produced, residual oil saturation, ultimate recovery factors, and monitor solvent chamber expansion. Numerical simulations of the same experiments were carried out for history matching and predicting other designed scenarios. Error analysis revealed average absolute errors of below 8%, showing convincing precision. Together with the simulation outcomes, a comprehensive data bank was obtained from the 30 scenarios designed and 18 VAPEX experiments conducted. The effects of fracture orientation, length, width, intensity, and position on process performance were identified and numerically evaluated. It was observed that all fractures, regardless of their properties, enhanced heavy oil recovery in comparison to the base case (no fractures) scenario. Moreover, propane proved more efficient owing primarily to its higher solubility and effective dispersion. The highest recovery factor, 65.81%, was obtained when implementing two wide vertical fractures on either side of the well pair. Almost equal to that, 64.93% was the process efficiency by positioning two long horizontal fractures between the wells.

Boiling line and near-critical maxima of propane-nitrogen mixtures.

It is well known that some thermodynamic quantities demonstrate maxima in the vicinity of a critical point. The lines of these maxima in the density-temperature or pressure-temperature planes are called "Widom lines." The behavior of Widom lines of one-component fluids has already been well studied in a number of papers by different authors. However, up to now the understanding of Widom lines in binary mixtures is still lacking. In this paper we study the boiling curve and the near-critical maxima of mixtures of nitrogen and propane by means of molecular dynamics simulation. We calculate the boiling curves and estimate the critical temperatures in a set of concentrations from pure nitrogen to pure propane. The influence of the composition of the mixture on the Widom lines of the system is evaluated. We find that the mixture of propane and nitrogen behaves as a type I mixture in the van Konynenburg-Scott classification, i.e., when the concentration is changed, the critical point and the corresponding Widom lines continuously shift in the density-temperature plane.

Dynamic Dissociation Behaviors of sII Hydrates in Liquid Water by Heating: A Molecular Dynamics Simulation Approach.

An understanding of the dynamic behavior of subtle hydrate dissociation in the liquid water phase is fundamental for gas production from marine hydrate reservoirs. Molecular dynamics simulations are performed in this study to investigate the dissociation kinetics of pure propane and binary propane + methane sII hydrates in a liquid water environment. The results show that faster hydrate dissociation rates are observed at higher initial temperatures. The hydrate phase dissociates from the cluster surface to the inside in a layer-by-layer manner under the simulation temperature conditions, which is similar to the behavior of sI hydrates and is independent of the hydrate crystal type. Compared to the binary sII hydrate, the pure sII hydrate dissociates more easily under the same initial temperature conditions, which can be attributed to the stabilizing effect of guest molecules in the hydrate cages. The empty cages collapse in one step, in contrast to the two-step pathway induced by the guest-host interaction. In addition, a hydrocarbon phase forms in the binary hydrate dissociation system instead of nanobubbles. These results can provide molecular-level insights into the dynamic mechanism of hydrate dissociation and theoretical guidance for gas recovery by thermal injection from marine hydrate reservoirs.

Temperature, soot, and OH*/CH* chemiluminescence measurements of partially-premixed CO2-diluted propane flames on a linear Hencken burner

Recent studies highlight the need for further examination of partially-premixed diffusion flames with applications in modern burner configurations that increasingly rely on technologies such as flue gas recirculation and oxy-fuel combustion, which increase the CO 2 content in the combustion environment. The partially-premixed nature of the linear Hencken burner (LHB) offers a unique platform with many advantages over comparable slot-type or radially-symmetric burner configurations. In this work, partially-premixed laminar propane flames were examined under increasing CO 2 percentages (0 to 50% v ). Prosumer grade digital CMOS cameras were calibrated and used to determine two-dimensional, quantitative measurements of soot, temperature, and OH* and CH* chemiluminescence. Soot values were additionally supported via laser extinction measurements using a 532 nm continuous wavelength laser. The peak soot volume fraction was found to decrease from 318 ppbv for the pure propane case down to 37 ppbv for the 50% v CO 2 case, while the corresponding temperature decreased from 1876 K down to 1742 K. The data also suggested that soot maturity decreased in conjunction with overall concentration. The regions of peak OH* and CH* concentrations maintained their transverse positions as well as their relative positions with respect to one another for all flame conditions, though moved axial further away from the flame base with increasing CO 2 . Additionally, the peak OH* region remained closer to the central flame axis across all conditions, a result that is counter to other studies that examined CO 2 dilution in purely non-premixed flames. • 2D quantitative soot and temperature measurements of CO2 diluted partially-premixed propane flames. • Laser extinction measurements bolster 2D soot values. • Fuel dilution over 40%v CO2 starts to significantly lower soot maturity. • 2D quantitative chemiluminescence measurements of OH* and CH* in CO2 diluted partially-premixed propane flame. • Movement of peak chemiluminescent regions show significant differences versus premixed and dilution flames.

Effect of different properties of silicon-based support on propane dehydrogenation performance of PtZn bimetallic catalyst

In this work, the bimetallic PtZn catalysts are further supported by a simple impregnation method starting from different carriers, including commercial and conventional silicalite-1 (CS1 and SS1) zeolite, self-pillared silicalite-1 zeolites (SP-S-1-n, where n represents different kinds) and amorphous SiO2. All the catalysts are calcined at the same and lower temperature (400 °C) for better and accurate comparison. The different properties of these catalysts, such as phase structure, surface and bulk states, coke content, acidity and initial intrinsic cracking capacity, etc. are compared in great detail and correlated with activity by XAS, AC-STEM, XPS, CO-DRIFTS and so on. The results show that the performance of SS1 supported PtZn bimetallic catalyst is better than that of catalysts with smaller Pt particle size and higher diffusion rate, and no deactivation phenomenon is observed in the 4d reaction in pure propane atmosphere. The compatibility between the support and the bimetal are considered to play a key role in the dehydrogenation of propane.

Numerical model of a pulsed subcritical streamer microwave discharge for problems of plasma ignition of fuel mixtures in the gas phase

An approximate model for estimating plasma heating and conversion caused by a subcritical streamer microwave discharge has been considered and verified. Ignition occurs in an environment with a pressure of 13 kPa, a temperature of 150 K, there is an external air flow at a speed of up to 500 m/s, an initiator antenna and a flat mirror are used to focus electromagnetic radiation, a stoichiometric mixture of propane-air and pure propane is supplied through the cavity in the antenna. Radiation power is 3 kW. The model is three-stage and semi-empirical. The plasma region and its conductivity are set based on experimental statistics; this is a key feature that reduces the consumption of computing resources. The finite element method is used. At the first stage, the Boltzmann equation for the electron gas in the medium is solved in the zero-dimensional formulation for the given parameters of the external electric field. The distribution functions of the electronic energy are obtained as well as the functions of the reaction coefficients. At the second stage, the Helmholtz equations are solved to obtain the distribution of electromagnetic fields near the antenna-initiator, taking into account the given conducting region “plasma”. Based on the obtained distributions of the electric field, the Joule heating powers and the values of the reaction coefficients are calculated. At the third stage, the Navier-Stokes and transfer equations of various types of particles for a compressible medium are solved; taking into account combustion processes for given local heating and plasma reactions. The results are compared with the data of a physical experiment. The distributions of temperature, composition of the medium, velocity of the medium are considered for given local heating power and additional reactions in the plasma region. A stoichiometric mixture of propane with air and pure propane supplied through the antenna are ignited by plasma under the conditions under consideration: the mixture burns in a small area, propane is oxidized in a thin layer of mixing with air. The temperature fields and composition of the medium are compared with photographs of the flame from the experiment. The numerical study shows that under all the conditions considered the model gives results close to the experiment, but there is an overestimation of the power required for ignition by up to two times. The study of the processes of ignition of gaseous mixtures by a subcritical microwave discharge is of interest for the design of propulsion systems with increased reliability, with the possibility of using hardly flammable mixtures. The proposed model gives approximate estimates, while the requirements for resources and time are significantly reduced compared to classical models.

Laminar flame speeds and ignition delay times for isopropyl nitrate and propane blends

Laminar flame speed and ignition delay time measurements are presented for blends of isopropyl-nitrate and propane. The laminar flame speeds were measured in a spherical bomb, with the majority of the experiments performed at 373 K and 1 bar, with equivalence ratios between 0.6 <ϕ< 2.1; the fuel composition was 0%, 10%, and 100% isopropyl-nitrate. Additional experiments were performed at 300 K for pure propane as a fuel, and at 0.5 bar for pure isopropyl-nitrate as fuel. The ignition delay measurements were performed in a shock tube, with reflected shock temperatures between 1050 K and 1530 K and a nominal reflected shock pressure of 20 bar. Equivalence ratios of 0.5, 1.0, and 1.5 were considered for fuel blends with 0% and 1% isopropyl-nitrate in propane; additional experiments were performed with 10% isopropyl-nitrate at ϕ = 1. In comparison with the pure propane flames, the pure isopropyl-nitrate have a similar peak flame speed (SL0=60.3 cm/s at ϕ=1.09 for isopropyl-nitrate versus SL0=57.9 cm/s at ϕ=1.10 for propane), but the nitrate is considerably faster under fuel lean conditions, and it exhibits a much broader domain. The ignition delay times for 1% isopropyl-nitrate in propane are indistinguishable from the pure propane experiments for all three equivalence ratios. The 10% isopropyl-nitrate in propane mixture, in contrast, is significantly more reactive. Transition state theory calculations were performed for select RH + NO2 reactions. These calculations were added to a recently developed mechanism for isopropyl-nitrate and propane. Detailed simulations of the experiments were performed in Cantera. The agreement between the models and experiments is excellent. The largest discrepancies occur for the ignition delay times for 10% isopropyl-nitrate at T5<1150 K and for the flame speeds for ϕ>1.8, which suggests that further work needs to be done under these conditions. To the best of our knowledge, these data represent the first published results on the laminar flame speeds of any alkyl nitrate.