Sharif Digital Repository

Considering finish ability of fossil fuels and their polluting effects accordingly a need of renewable energies is felt. Among these clean energies biomass considering economical and environmental advantages is one of bests. Therefore a sufficient energy¬-¬efficient process with a good efficiency is needed. In this study an analysis of different mechanism to produce bioethanol from biomass has been done. According to the results from simulation the recovery step of bioethanol from the existing dilute solution from fermentation consumes the most energy in the process. Therefore substituting saline extractive column can result in saving energy. Finally in order to get more accurate result the... 

Nowadays bioethanol is one of the main factors in the fuel market. It is currently produced from sugars and starchy materials, but lignocelluloses can be expected to be major feedstocks for ethanol production in the future. Agricultural residues such as wheat straw are being considered a potential lignocellulose raw material for fuel-ethanol production as an alternative to starch or sugar-containing feedstock. In order to produce bioethanol, it is necessary to decompose the wheat straw into soluble sugars. But lignocellulosic materias needs pretreatment before hydrolysis and fermentation. The main goal of pretreatment is to increase the enzyme accessibility improving digestibility of... 

In this study production of bioethanol from corn fiber that is a lignocellulosic material is investigated. Experiments were performed in a membrane bioreactor. Bioethanol is a second generation biofuel that is considered recently because of the decrease in oil production and pollutions caused by fossil fuels.The feed was corn fiber which is considered suitable due to its low cost and availability in my country. Corn fiber is composed of cellulose, hemicellulose and lignin. We should increase cellulose fraction by pretreatment methods to get a higher conversion rate into bioethanol. We did this by acid pretreatment and the fraction was reached to 41%. In most of previous work experiments were... 

First studies in internal combustion engines have focused on increasing engine power and efficiency, reducing engine volume and improving fuel quality. However, nowadays most studies are concentrated on decreasing exhaust emissions and usage of regenerative fuels while maintaining engine size, efficiency and power. Surveying fuel type in direct injection engines, requires investigation of microscopic and macroscopic spray characteristics including spray tip penetration, spray cone angle, spray area and sauter mean diameter, since these parameters determine air-fuel mixture quality. In this study, spray of ethanol as a regenerative fuel that reduces emissions such as NOx and CO is... 

Clean and Renewable energies are one of the most important part of global policy. In order to reduce greenhouse gas emissions mostly from fossil fuels, many countries have introduced biofuels to avoid depletion of fossil fuels and decrease the pollution. In Iran, large dependency on crude oil and natural gas resources cause barriers for utilization of biofuels. The country has plenty of biomass resources that may guide national decision makers toward biofuels.In this study, biomass supply chain to produce biofuel is studied to reach sustainability. The model enables us to depict the optimal path to reach the economic, environmental, and social sustainability through the whole supply chain.... 

In recent years, access to clean energy sources is the major instruments for sustainable development. Limitation of energy resources and the problems resulting from the use of fossil fuels was caused attention to biomass in different countries as a stable source of renewable energy. Organic waste in municipal solid waste and domestic wastewater are biomasses that can be used as a raw material used in the production of energy. Practical studies show that quality and quantity of municipal solid waste to produce biogas and bioethanol in Iran is very appropriate. In this process, the household solid waste and wastewater are in the anaerobic digestion reactors and fermentation systems without any... 

Fossil fuel usage caused global warming and other environmental problems. Recently, biofuels are considered as an important alternative. However, the efficient usage of water and energy in their production may accelerate their diffusion. ETBE is a kind of oxidizing fuel additive that can be biologically produced from the ethanol reaction. High water and energy consumption in the production and separation process is still a challenge. In this work, the ETBE production from lignocellulosic feed are considered. Then, the effect of different parameters are investigated by performing sensitivity analysis. In the next step, the optimal pathway of water and energy use in the production of ETBE are... 

Increasing greenhouse gases in the atmosphere has many unpleasant consequences. Transportation sector has 23 percent allocation in emitting those gases. Alternative fuels can be considered as a solution in order to decreasing greenhouse gases and less dependency on the fossil fuels. It is noteworthy that between biofuels, bioethanol has the maximum share (based on International Energy Agency, IEA, bioethanol will hold 27 percent share in supplying energy in transportation sector). In this thesis, assessment of exhaust emissions and fuel consumption of a light- duty vehicle with the gasoline and E85 fuels is performed. Note that, engine calibration was not altered. The implemented method is... 

Ethanol is one of the most important solvents in the industry with different applications in various fields, which can be used in disinfection solutions, perfumery, paints, fuels, etc. In this research, a predefined superstructure is examined to investigate the possibility of ethanol production by a process which has the lowest production cost per kilogram of ethanol.Various feeds can be used to produce ethanol, the most important of which are bagasse, wheat starch, sugar beet, sugar cane, corn and dextrose. In this study, the corn is selected as feed, while each of the above feed, and contains a different percentage of glucan, xylan and lignin. Conversion factor of components in... 

Dynamic modeling and process control, especially the equipment of bioreactors and fermenters, have always faced many challenges due to the complexity and high uncertainty of the kinetics of environmental reactions. Among these, semi-continuous fermentation for bioethanol production is one of the important technologies in biochemical industries. The problem of modeling as well as controlling the use of the main discontinuous and semi-continuous methods of ethanol production is the lack of uniform state conditions and the possibility of aerobic and non-aerobic multiplication conditions in two ways. The main goal of this research is to obtain a new method in modeling bioethanol fermentation and... 

Bioethanol is an alcohol that is produced by microbial fermentation from carbohydrates produced in sugar-containing plants such as corn, sugarcane, or lignocellulosic biomass. Bioethanol is mostly used as an additive to gasoline. Cars can run on a 15% blend of bioethanol and gasoline and need to be modified to use pure bioethanol. Ethanol in vehicles is beneficial for the environment Because ethanol pollutants are cleaner than greenhouse gases. Ethanol is also used to produce ethyl acetate, which is a widely used solvent in the printing and packaging industries. In this research, fed-batch bioethanol reactor was investigated. First, the modeling of the bioreactor was done and the behavior of... 

In this thesis, a typical dynamic model of syngas fermentation, refered as hybrid method for biofuels production, coupled with a distillation column is developed in SimDFBA. The bioreactor is simulated in MATLAB/Simulink by using Clostridium ljungdahlii acetogenic micro-organism metabolic network. Bioreactor modeling is accomplished with a bubble column reactor in both liquid and gas phases, while the separator was simulated with ASPEN. PDE equiations of bioreactor modeing are dicretized to ODE equation by using QUICK scheme of finite volume method. A new econometric optimization study for outlet gas purification through a pressure swing adsorption unit to recycle relatively pure hydrogen is...