نشریه سوخت و احتراق
سال چهاردهم شماره 3 (پیاپی 36، پاییز 1400)

The use of organic fraction municipality solid waste (OFMSW) in the process of anesthetic digestion (AD) can be a good way to manage and extract energy. In the present study, the effect of adding ZnO nanoparticles (ZnO) nanoparticles and iron oxide nanoparticles (Fe3O4) and cobalt oxide nanoparticles (Co2O3) on the production of biomass and biomass from anaerobic digestion organic fraction municipality solid waste (OFMSW) and cattle manure (CM) reviewed and studied. The results showed that using nanoparticles with low and essential nutrients with optimal concentrations in digesters could potentially have positive effects on the stability of the digestion process, the reduction of further impurities and pollutants in the biogas, reduction of volatile fatty acids (VFA) and biogas production has been increased. Due to the toxicity of ZnO nanoparticles on bacterial bacteria in the first days, it directly affected the toxicity of bacterial bacteria and reduced the production of biogas. But after a few days, bacterial bacteria became familiar with the toxicity of added substances and were able to survive in such conditions, and increased the production of biogas. The anaerobic digestion process is highly dependent on nanoparticles. Increasing the iron oxide nanoparticles (Fe3O4) and ZnO nanoparticles (ZnO) and reducing the cobalt oxide nanoparticles (Co2O3) have a positive effect on the biogas production rate and methane yield. The best concentration of nanoparticles for the biogas production rate and maximum methane yields are 20-28 milligrams of iron oxide nanoparticles (Fe3O4) for zinc (ZnO) 0.8 to 1.5 nanoparticles and 0.25 to 0.35 milligrams for cobalt oxide nanoparticles (Co2O3). Most produced biogas and methane were obtained during the digestion process at the points mentioned..

In present study, the optimization of hydrogen production by water splitting over TiO2/treated clinoptilolite photocatalyst was investigated using Box–Behnken design (BBD) combined with response surface methodology (RSM). In the photocatalyst preparation, the combined ion exchange-alkaline treatment was used to achieve a chemical homogenous, reproducible and effective natural support. Moreover, 10 wt.% of TiO2 nanoparticles was loaded over zeolitic supports using facile and cost effective solid state dispersion (SSD) method in the presence of ultrasound irradiation. The characterization results indicated suitable optical and physico-chemical properties of the as-synthesized photocatalyst which making it effective in the water splitting reaction. The operational variables considered in Box-Behnken method included pH solution, photocatalyst dosage and sacrificial agent concentration. Based on the ANOVA results, all three process variables affect the hydrogen production. Among them, the most significant effect is attributed to pH solution. The application of the RSM resulted in the formulation of several models out which the quadratic model with the highest value of the determined R2 coefficients (R2=0.9967 and R2adj=0.9942) was adjudged to adequately fit the experimental data. By examining how the process variables and their interactions affect the response, it can be found that the maximum efficiency of hydrogen production was obtained at optimum conditions of alkaline solution pH of 10, catalyst dosage of 1.1 g/L and sacrificial agent concentration of 12.5 vol.%.

 In this research, an attempt has been made to use experimental and numerical methods to measure the powdering parameters of a heavy non-Newtonian oil fuel called Mazut and a light petroleum fuel called diesel, as well as to investigate the spray behavior of these fuels. Very powerful imaging equipment was used to record the spray images of the fuels and the data were extracted by analyzing the images. Finally, the method of maximum entropy was used for numerical analysis of the distribution function of fuels spray. From a pressure difference of 15 bar onwards, the mass flow rate of the fuel remains almost constant (between 1.6 and 1.8 g/s). The angle of the Mazut fuel spray cone initially increases, and after the flow approaches full atomization (at temperatures above 90 ° and pressures above 15 bar), it reaches approximately a constant value of 80° (the diesel spray cone angle also reaches an almost constant value of 85°). The breakup length and droplets diameter also decrease with increasing fuel temperature and pressure, and with the full development of the flow, they tend to almost zero. The diameter size distribution of droplets becomes smoother and more uniform by increasing the viscosity of the fluid. Also, the velocity distribution of droplets becomes smoother and more uniform by decreasing the viscosity of the fluid.

In this study, the simultaneous effect of ethanol-biodiesel-diesel emulsion with TiO2 nanoparticles in different EGRs on emission characteristics and performance of a direct injection diesel engine was investigated. TiO2 nanoparticles at three levels of 0, 40 and 60 ppm were added to biodiesel produced from waste cooking oil at levels of 0, 10 and 20% and ethanol at levels of 0, 4 and 6% and an EGR system was used at rates of 0, 20 and 30 %. A total of 31 mixtures from biodiesel/diesel, ethanol/diesel and ethanol/biodiesel/diesel emulsions with TiO2 nanoparticles and different percentages of EGR were tested at full load at speeds of 1000, 1400 and 1800 rpm. Briefly named with BxEy + EGRw + TiO2z, that x, y, w, and z represent the biodiesel volume percentage, ethanol, EGR, and TiO2 percentage used in the mixture, respectively. The results showed that the use of B10E4 + EGR20 + TiO260 reduced NOx, CO and HC compared to pure diesel by 5.8, 20.3 and 40 percent, respectively. Also, the output power of B10E0 + TiO260 was improved by 11.2 percent compared to pure diesel. In addition, by using B10E4 + EGR30, fuel consumption increased by 26.7 percent compared to pure diesel. .

The aim of this study is to investigate the effect of wall thermal conditions and oxidant composition on the flame structure and map of combustion regimes. For this purpose, non-premixed combustion furnace of the Lisbon University has been investigated using the open source OpenFoam software as well as chemical calculations with the help of counter-flow diffusion flame solver. In numerical study, standard k-ε turbulence model, modified EDC combustion model, and discrete phase radiation model with the calculation of absorption and emission coefficients at six different wavelengths have been used. The results of simulations and kinetic calculations show that the change in oxidant composition and wall thermal conditions leads to changes in reaction pathways. Replacement of CO2 with N2 in the oxidant and presence of heat losses lead to fundamental changes in flame structure. The presence of wall heat loss, especially in conventional and flameless combustion regimes, leads to fundamental changes in the reaction pathways and alters flame structure, while the main contribution to the changes of flame structure is different physical and chemical properties of CO2 in comparison with N2 at conventional and flameless regimes, respectively. In the high temperature combustion regime, the contributions of physical and chemical effects are almost equal.
 
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Among the experimental and numerical studies conducted in the field of fire, the pool fire has been welcomed more than other fire scenarios. In this paper, pool fire is studied to investigate the effect of different combustion models on the fire simulation. For this purpose, the combination model of flamelet generated manifold (FGM) is used and its results are compared with three infinite fast chemistry (IFC), eddy dissipation (EDM) and eddy dissipation concept (EDC) combustion models. By comparing the mean velocity results and its fluctuations, it is observed that the accuracy of the FGM combination model, regardless of radiation effect, is better than other combustion models in predicting of the puffing phenomenon and its frequency, the mean square of vertical velocity, mean turbulence kinetic energy. For example, the FGM combustion model has less than 3% relative error with experimental results in prediction of the puffing frequency; but other combustion models are more than 10% relative error. In the prediction of the mean velocity field, the EDM combustion model has a higher accuracy than the FGM.

In this study, the aim is to extract pure amorphous silica from rice husk ash by acid leaching, then calcination and base leaching, and finally titration by acid. Then, the synthesis of adsorbents was performed through loading of copper, zinc and cerium at the rate of 13% by weight of metal by impregnation method on silica support. Finally, the performance of the synthesized adsorbents in the adsorptive desulfurization process was investigated to remove 4, 6-dimethyldibenzothiophene from the model fuel. Nitrogen adsorption - desorption isotherms for the samples showed that the pores are in the mesopore range. The highest adsorption capacity was obtained at a concentration of 500 ppm for CuO/SiO2 adsorbent equal to 23.7 mg/g. Also, by examining the Langmuir, Freundlich and Dubinin-Radushkevich equilibrium isotherms, the Langmuir isotherm was most consistent with the experimental data. Also, according to Dubinin-Radushkevich isotherm it was proved that the dominant mechanism in adsorption is chemical. In order to investigate the adsorption kinetics in this study, pseudo-first order and pseudo-second order equations were also examined. The pseudo-second order kinetic was fitted with experimental data with R-squared of 0.99 were fitted to the experimental data. BET and FESEM equipped with EDX analyzes have been used to investigate the physicochemical properties of the synthesized adsorbents. Also, the concentration of fuel solution was determined by UV-VIS.