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Microscopic and macroscopic atomization characteristics of a pressure-swirl atomizer, injecting a viscous fuel oil

Chinese Journal of Chemical Engineering 2020年第1期28卷 9-22页

作者： seyed mohammad ali najafi Pouria Mikaniki Hojat Ghassemi School of Mechanical Engineering Iran University of Science and Technology(IUST)P.O.B.16765-163TehranIran

Combustion of heavy fuels is one of the main sources of greenhouse gases, particulate emissions, ashes, NOxand SOx. Gasification is an advanced and environmentally friendly process that generates combustible and clean gas products such as hydrogen. Some entrained flow gasifiers operate with Heavy Fuel Oil(HFO) feedstock. In this application, HFO atomization is very important in determining the performance and efficiency of the *** atomization characteristics of HFO(Mazut) discharging from a pressure-swirl atomizer(PSA) are studied for different pressures difference(Δp) and temperatures in the atmospheric ambient. The investigated parameters include atomizer mass flow rate( _m), discharge coefficient(CD), spray cone angle(θ), breakup length(Lb), the unstable wavelength of undulations on the liquid sheet(λs), global and local SMD(sauter mean diameter) and size distribution of droplets. The characteristics of Mazut sheet breakup are deduced from the shadowgraph technique. The experiments on Mazut film breakup were compared with the predictions obtained from the liquid film breakup model. Validity of the theory for predicting maximum unstable wavelength was investigated for HFO(as a highly viscous liquid). A modification on the formulation of maximum unstable wavelength was presented for HFO. SMD decreases by getting far from the atomizer. The measurement for SMD and θ were compared with the available correlations. The comparisons of the available correlations with the measurements of SMD andθ show a good agreement for Ballester and Varde correlations, respectively. The results show that the experimental sizing data could be presented by Rosin-Rammler distributions very well at different pressure difference and temperatures.

关键词： Gasifier Heavy fuel oil Atomization Pressure-swirl atomizer Mazut Size distribution Wavelength Viscosity

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Experimental study of a heavy fuel oil atomization by pressure-swirl injector in the application of entrained flow gasifier

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Chinese Journal of Chemical Engineering 2019年第4期27卷 765-771页

作者： Pouria Mikaniki seyed mohammad ali najafi Hojat Ghassemi School of Mechanical Engineering Iran University of Science and Technology

The available SMD(Sauter mean diameter) correlations on pressure-swirl injectors predict droplet sizing very different from each other, especially for heavy fuels. Also there was a lack in the literature for comparing available correlations. So an experimental study was conducted on a heavy fuel oil(HFO) spray, Mazut 380. A pressure swirl injector was designed and fabricated. The experiments for Mazut at 40℃ and 80℃ were compared with the results for water, including spray half cone angle, breakup length and mean droplet diameter,at different injection pressures. Lower spray angle, higher breakup length and larger droplets were observed for lower injection pressures and higher liquid viscosity. SMD was about 75 μm for water and about 87 μm for Mazut at 80℃. The results for droplet mean diameter were also compared with correlations from previous studies on pressure swirl atomizers. The SMD results show that for water spray, LISA method was in good agreement,also Babu and Ballester correlations were successful when high viscosity fluid was injected.

关键词： Atomization Pressure-swirl injector Mazut Size distribution Fuel Viscosity

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Effect of ultrasonic irradiation on rheological properties of asphaltenic crude oils

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Petroleum Science 2012年第1期9卷 82-88页

作者： MOUSAVI seyed mohammadreza RAMAZANI Ahmad najafi Iman DAVACHI seyed mohammad Ultrasonic Research Group Chemical and Petroleum Engineering Department Sharif University of TechnologyAzadi Ave. Tehran Iran Chemical and Petroleum Engineering Department Sharif University of TechnologyAzadi Ave. Tehran Iran Ultrasonic Research Group Chemical and Petroleum Engineering Department Sharif University of Technology Azadi Ave. Tehran Iran Chemical and Petroleum Engineering Department Sharif University of Technology Azadi Ave. Tehran Iran

In this work, the rheological changes of several crude oil samples exposed to ultrasonic waves for different time intervals in addition to the effect of temperature on viscosity behavior of heavy crude oils were investigated using a series of steady shear flow and oscillatory tests. The colloidal structural evolutions of flocs in oil samples were illustrated by analysis of the size distribution of flocculated asphaltene particles （confocal microscopy tests）. The rheological investigations indicate that the ultrasonic irradiation dissolved heavy components in crude oil. After ultrasonic treatment, the Kouh-e-Mond crude oil was found to be pseudoplastic. In addition, confocal microscopy confirms that there was an optimum duration for ultrasonic irradiation, at which the viscosity and flocculation rate of asphaltenic crude oils reduced to the minimum values. The optimum was found to be approximately 40 min for the Kouh-e-Mond crude oil. Experimental results illustrate that the ultrasonic irradiation could disaggregate heavy colloid components in crude oil, and breakdown of asphaltene molecules would only occur in a specific time interval of irradiation. Also according to the temperature sweep test, the oil temperature rise caused by ultrasonic irradiation was not the main reason for theological changes of the crude oil and this alteration may be due to physical and chemical phenomena induced by sonication in crude oil.

关键词： Asphaltene ultrasonic technology pseudoplastic property viscoelastic property yield stress,flocculation time

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Presentation of regression analysis,GP and GMDH models to predict the pedestrian density in various urban facilities

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Frontiers of Structural and Civil Engineering 2022年第2期16卷 250-265页

作者： Iraj BARGEGOL seyed Mohsen HOSSEINIAN Vahid najafi MOGHADDAM GILANI mohammad NIKOOKAR alireza OROUEI School of Civil Engineering University of GuilanRasht41996-13776Iran School of Civil Engineering Iran University of Science and Technology(IUST)Tehran13114-16846Iran School of Civil Engineering Islamic Azad UniversitySemnan35131-37111Iran

In this study,the relationship between space mean speed(SMS),flow rate and density of pedestrians was investigated in different pedestrian facilities,including 1 walkway,2 sidewalks,2 signalized crosswalks and 2 mid-block ***,statistical analysis was performed to investigate the normality of data and correlation of *** analysis was then applied to determine the relationship between SMS,flow rate,and density of ***,two prediction models of density were obtained using genetic programming(GP)and group method of data handling(GMDH)models,and k-fold and holdout cross-validation methods were used to evaluate the *** the use of regression analysis,the mathematical relationships between variables in all facilities were calculated and plotted,and the best relationships were observed in flow rate-density *** also indicated that GP had a higher R2 than GMDH in the prediction of pedestrian density in terms of flow rate and SMS,suggesting that GP was better able to model SMS and pedestrian ***,the application of k-fold cross-validation method in the models led to better performances compared to the holdout cross-validation method,which shows that the prediction models using k-fold were more ***,density relationships in all facilities were obtained in terms of SMS and flow rate.

关键词： pedestrian density regression analysis GP model GMDH model

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Prediction of cavity growth rate during underground coal gasification using multiple regression analysis

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International Journal of Coal Science & Technology 2015年第4期2卷 318-324页

作者： Mehdi najafi seyed mohammad Esmaiel Jalali Reza KhaloKakaie Farrokh Forouhandeh Department of Mining and Metallurgical Engineering YazdUniversity Safayieh P.O. Box 89195-741 Yazd Iran Faculty of Mining Engineering Petroleum and GeophysicsShahrood University Shahrud Iran Department of Mathematics Shahrood University ShahrudIran

During underground coal gasification （UCG）, whereby coal is converted to syngas in situ, a cavity is formed in the coal seam. The cavity growth rate （CGR） or the moving rate of the gasification face is affected by controllable （operation pressure, gasification time, geometry of UCG panel） and uncontrollable （coal seam properties） factors. The CGR is usually predicted by mathematical models and laboratory experiments, which are time consuming, cumbersome and expensive. In this paper, a new simple model for CGR is developed using non-linear regression analysis, based on data from 1 l UCG field trials. The empirical model compares satisfactorily with Perkins model and can reliably predict CGR.

关键词： Underground coal gasification (UCG) - Cavity growth rate . Multiple regression analysis ~ Empirical model

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Presentation of machine learning methods to determine the most important factors affecting road traffic accidents on rural roads

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Frontiers of Structural and Civil Engineering 2022年第5期16卷 657-666页

作者： Hamid MIRZAHOSSEIN Milad SASHURPOUR seyed Mohsen HOSSEINIAN Vahid najafi Moghaddam GILANI Civil–Transportation Planning Department Faculty of Technical and EngineeringImam Khomeini International University(IKIU)Qazvin 34148-96818Iran School of Civil Engineering Iran University of Science and Technology(IUST)Tehran 13114-16846Iran

The purpose of this research was to develop statistical and intelligent models for predicting the severity of road traffic accidents(RTAs)on rural *** Logistic Regression(MLR)was used to predict the likelihood of *** more accurate prediction,Multi-Layer Perceptron(MLP)and Radius Basis Function(RBF)neural networks were *** indicated that in MLR,the model obtained from the backward method with the correct percent of 84.7%and R2 value of 0.893 was the best method for predicting the likelihood of ***,MLR showed that the variables of not paying attention to the front not paying attention to the frontroad ahead,followed byand then vehicle-motorcycle/bike accidents were the greatest *** the models,MLP had a better performance,so that the prediction accuracy of MLR,MLP,and RBF were 84.7%,96.7%,and 92.1%,*** model,due to higher accuracy,showed that the variable of reason of accident had the highest effect on the prediction of accidents,and considering MLR results,the variables of not paying attention to the front and then vehicle-motorcycle/bike accidents had the most influence on the occurrence of ***,motorcyclists and cyclists are more prone to accidents,and appropriate solutions should be adopted to enhance their safety.

关键词： safety rural accidents multiple logistic regression artificial neural networks

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Sediment contribution from different geologic formations and land uses in an Iranian small watershed,case study

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International Journal of Sediment Research 2017年第2期32卷 210-220页

作者： seyed Hamidreza Sadeghi Saeed najafi alireza Riyahi Bakhtiari Department of Watershed Management Engineering Faculty of Natural ResourcesTarbiat Modares University Department of Environmental Sciences Faculty of Natural ResourceTarbiat Modares University

Many intra and extra problems occurred due to unsustainable human use of natural resources leading to increasing sediment loads in the ***,few studies have been comprehensively conducted in progressing countries to prioritize sediment sources from different points of views,particularly in some countries like Iran where such valuable information is essential for proper watershed resources *** present study was therefore planned to assess the importance of potential sediment sources viz.,spatial sources(geologic units) and source types(land use units) in sediment yield in Idelo watershed as one of the important sub-watersheds of Sefidrood large Watershed in Zanjan Province,Iran,using composite *** addition,the results of the sediment fingerprinting approach were compared with those of field measurement data obtained from studying soil erosion types(viz.,sheet,rill and gully erosion).Toward this attempt,16 tracers were detected in different geologic units and land uses and the sediment yielded at the watershed *** results showed that the composite fingerprints of the different geologic units comprising As,N,Cu,Zn,OC and Co tracers could correctly distinguish 86% of the sediment source *** red gypsiferous marl contributed 85 percent in sediment *** regard to source types,the optimum composite fingerprint encompassed only N and Cu and provided a discriminatory efficiency of 90%.Besides that,the rangelands with 48.8% study area coverage had a significant contribution of 88% in sediment *** field measurements confirmed the reliability of results of fingerprinting approach in apportioning watershed scale sediment sources on the base of consistency of the two sets of *** was also understood from the results,besides successful applicability of composite fingerprinting in assessing the provenance of the sediment yielded at the watershed outlet that the geologic formations and land use types played differe

关键词： Composite fingerprinting Multivariate mixing model Soil erosion Spatial sources Source types

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Gluten sensitive enteropathy in patients with iron deficiency anemia of unknown origin

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World Journal of Gastroenterology 2008年第48期14卷 7381-7385页

作者： Farhad Zamani Mehdi Mohamadnejad Ramin Shakeri Afsaneh Amiri Safa najafi seyed Meysam alimohamadi seyed Mohamad Tavangar Ardeshir Ghavamzadeh Reza Malekzadeh Gastrointestinal and Liver Disease Research Centre Iran University of Medical Sciences Digestive Disease Research Centre Tehran University of Medical Sciences Hematology Oncology BMT research Center Tehran University of Medical Sciences Department of Pathology School of Medicine Tehran University of Medical Sciences

AIM: To determine the prevalence of gluten sensitive enteropathy (GSE) in a large group of patients with iron deficiency anemia (IDA) of obscure origin. METHODS: In this cross-sectional study, patients with IDA of obscure origin were screened for GSE. Anti- endomysial antibody (EMA) and tissue transglutamin- ase antibody (tTG) levels were evaluated and duodenal biopsies were taken and scored according to the Marsh classification. The diagnosis of GSE was based on a positive serological test and abnormal duodenal histol- ogy. Gluten free diet (GFD) was advised for all the GSE patients. RESULTS: Of the 4120 IDA patients referred to our Hematology departments, 206 (95 male) patients were found to have IDA of obscure origin. Thirty out of 206 patients (14.6%) had GSE. The mean age of GSE pa- tients was 34.6 ± 17.03 (range 10-72 years). The female to male ratio was 1.3:1. Sixteen patients had Marsh 3,12 had Marsh 2, and 2 had Marsh 1 lesions. The sever- ity of anemia was in parallel with the severity of duode- nal lesions. Twenty-two GSE patients (73.3%) had no gastrointestinal symptoms. Fourteen GSE patients who adhered to GFD without receiving iron supplementation agreed to undergo follow up visits. After 6 mo of GFD, their mean hemoglobin levels (Hb) increased from 9.9 ± 1.6 to 12.8 ± 1.0 g/dL (P < 0.01). Interestingly, in 6 out of 14 patients who had Marsh 1/2 lesions (e.g. no villous atrophy) on duodenal biopsy, mean Hb increased from 11.0 ± 1.1 to 13.1 ± 1.0 g/dL (P < 0.01) while they did not receive any iron supplementation. CONCLUSION: There is a high prevalence (e.g. 14.6%) of GSE in patients with IDA of obscure origin. Gluten free diet can improve anemia in GSE patients who have mild duodenal lesions without villous atrophy.

关键词： Gluten sensitive enteropathy Iron deficiency anemia Anti-Tissue transglutaminase antibody Anti-endomysial antibody Gluten free diet

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Nutlet Micromorphological Study on <i>Salvia</i>L. (Lamiaceae) from NE Iran

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American Journal of Plant Sciences 2013年第7期4卷 1457-1460页

作者： seyed mohammad Mousavi Azarnoosh Jafari Shahla najafi Department of Biology Faculty of sciences Mashhad Branch Islamic Azad University Mashhad Iran Department of Biology Faculty of Sciences University of Zabol Zabol Iran.

In the present research, micromorphological features of 10 Salvia L. nutlets (mericarp) growing in NE Iran were studied by SEM. These species were divided into three and four groups based on the shape and ornamentatio... 详细信息

关键词： Salvia Iran Nutlet Mericarp Micromorphological Features

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Study the Effect of High Dialysate Potassium Solution in Comparison to Low Potassium Dialysate Solution in End Stage Renal Disease Patients

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Health 2016年第4期8卷 363-369页

作者： mohammad Nourizadeh Masih Shakeri seyed Seifolah Beladi Mousavi mohammad Hassan Adel mohammad Hossein najafi Zahra Rezaee Mehdi Nourizadeh Sara Nourizadeh Atherosclerosis Research Centre Ahvaz Jundishapur University of Medical Sciences Ahvaz Iran Department of Cell & Molecular Biology Faculty of Biological Sciences Kharazmi University Tehran Iran

Background: Nowadays cardiovascular diseases remain as the single most common cause of death in chronic dialysis patients;the aim of this study was to evaluate the effects of two different regimens of dialysis potassium removal in patients with a tendency to develop arrhythmias during haemodialysis (HD). Methods and Materials: There were 88 (36 men and 52 women) end stage renal disease (ESRD) patients recruited for the study. They received regular haemodialysis three times per week at the haemodialysis units of a university medical centre (Golestan hospital) during year 2011. We compared the arrhythmogenic effects of two dialysis techniques. Results: There was a tendency in the HD solution with constant (3 mEq/l) K for premature ventricular complex (PVC) appearance in to be reduced as compared with constant (2 mEq/l) K in the time of dialysis period, although this reduction was not statistically significant(P = 0.09). There was a significant reduction in SVC in the HD solution with constant (3 mEq/l) K as compared with constant (2 mEq/l) K. Discussion: In conclusion, the use of a model of intra-HD potassium that is more close to potassium serum concentration of ESRD patients can reduce the arrhythmogenic effect of HD in patients on regular HD treatment.

关键词： Arrhythmia Dialysis End Stage Renal Disease

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