Sharif Digital Repository

Dimethyl ether (DME) as a clean fuel is a suitable alternative for diesel fuel. It has a high cetane number and does not contain any sulfur or metal compounds. Furthermore, DME does not form any soot and has a potential to reduce NOx emissions. In addition, it is not corrosive to any metal and not harmful to the human body. Two approaches are currently used for the production of DME from synthesis gas. The first is an indirect two-step process involving methanol synthesis followed by catalytic dehydration of methanol to DME over solid-acid catalysts, while the second method enables direct synthesis of DME using a bifunctional catalyst. At present, indirect synthesis of DME is a more... 

In view of environmental problems and the limited energy supply, synthesis of new liquid fuel from coal or natural gas is becoming a hot research in recent years. Dimethyl ether (DME) is one of the most promising alternates of such synthetic fuels. In this project the kinetics of direct DME synthesis from syngas (H2 and CO) over the new bifunctional catalyst has been investigated in slurry reactor system. A new mechanism and rate law expression were established. The kinetic model has been fitted the experimental data, which has been obtained by other researchers. The new bifunctional catalyst was composed of Cu/ZnO/ZrO2 and Al-modified H-Mordenite zeolite. The calculated apparent... 

In this research, direct synthesis of dimethyl ether (DME) from CO2 hydrogenation in three phase slurry reactor was investigated. Bifunctional catalysts composed of Cu- ZnO-Al2O3-ZrO2 as hydrogenation component and zeolite Na-Mordenite as dehydration component, with different Al2O3 and ZrO2 contents were synthesized by coprecipitating sedimentation and influences of Al2O3 and ZrO2 on CO2 conversion and DME selectivity were evaluated. Results show, both Al2O3 and ZrO2 enhanced conversion, but Al2O3 markedly increase selectivity of DME. However, when the total contents of Al2O3 and ZrO2 was increased up to 16 wt% , CO2 conversion and DME selectivity remarkably decreased. BET and XRD analyzes... 

This thesis deals with the development of a hypothetical micronized powder factory and trying to test and engage in this hypothetical development of the following plant, it considers following factors:
1-Domestic & International market
2-Plant location
3-Plant design & development
a.machinery
b.technology & equipment
c.human resource
d.environment
e.packing
4-raw material
5-shipping & transport
To evaluate above factors the UNIDO methodology is used in this research work. The UNIDO methods are using a process by which feasibility studies of production facilities or plant are base on. After reviewing a variety of factors, ranging from financial... 

The methodology proposed by UNIDO , to investigate feasibility study of industrial project, is a useful tool in pre-investment decision making. In this work feasibility of investing on "Gas To Liquid" GTL Plant of Asalouye is investigated. Having gathered required information, including gas field potential, required technology and machineries, cost of investments , required manpower to run the UNIDO methodology is used to investigate the investment, the result of the work shows that the project is feasible and it would have internal rate of return of 24% ( by sale cost= 81 $ per barrel of GTL product)  

Water hammer is a pressure surge or wave resulting when a pressurized fluid in motion is forced to stop or change direction suddenly. This phenomenon can cause great amount of damage to the system and should be considered in designing of pipe systems. So, researchers have derived and proposed numerous models using different approaches. In this study a one-dimensional model using Time Splitting Method (TSM) and Double Sweep Method (DSM) are proposed to simulate transient flow in deformable pipes in networks. To solve the equations of momentum and continuity TSM is applied. In addition Brunone model is used to study the effect of unsteady friction on water hammer wave shape and attenuation. To... 

This thesis is devoted to prove the existance of solution and structure of solu­ tion for some partial differential equations by using some modern topological and variational thechniques. Taking direction from the literature, this thesis is interested in existence, uniqueness, blow-up in finite time for some evolution equations, multiplicity and radial solution for certain elliptic partial differential equations.-Employing Fibrering, Galerkins, Mountain Pass-Lemma and lions com­ pactness Lemma are sharp in this thesis to prove the exsistence and multiplicity of solutions and overcome lack of compactness in some cases  

Aabsal Co. was established in north east of Tehran in 1956, under the name of Loab Iran Private LTD.  Co.  and  continued  its  activity  in  manufacturing  enameled  dishes,  bowl,  tea  pots  and  etc.  until 1964. In  this  thesis  we  have  paid  attention  to  basics  of  TPM  and  how  to  implement  PM  procedures.  First we have paid attention to all the maintenance forms and how these forms work together in the company, and then the relationship between departments sections like manufacturing and maintenance are considered. Finally we have attempted to implement TPM. For this purpose we have taken a section of the factory as a pilot plant and have started to implement TPM there to... 

In this research ,lean and agile indexes in S.G.S Co. are evaluated. This company is the first company in engineering and supplying automotive parts as well as the first supply chain management and organization of Saipa Group. In the part of evaluating the lean management level it is the developed model of the suggested approach by Jackson “implementing a lean management system” (Jackson, 1996). As S.G.S is engaged in servicing activities not in production, we have changed some factors in Jackson's methodology. Different with the last model, we got the results and used AHP method for getting the level in each key. Finally by using another AHP the lean index of the S.G.S Co. was identified.... 

In this thesis , we consider nonnegative (continuous) weak solutions of the porous medium equation with source , u_t-∆u^m=u^p, and p>m>1 .
Assume that, m>1 and 1< p/m u_t-∆u^m=u^p,xϵR^n ,tϵR
has no nontrivial, bounded radial solutions u≥0 .
In one space-dimensional, the conclusion of the result mentioned above remains true without the assumption of the radial symmetry. The proof is based on the intersection-comparison arguments , zero number argum- ents and a key step is to show the...