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chemical-alteration
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Investigation of nanostructured surface layer of severe shot peened AISI 1045 steel via response surface methodology
, Article Measurement: Journal of the International Measurement Confederation ; Volume 148 , 2019 ; 02632241 (ISSN) ; Maleki, E ; Kocabas, I ; Yilmaz, H ; Husem, F ; Sharif University of Technology
Elsevier B.V
2019
Abstract
Shot peening (SP) and also severe shot peening (SSP) provide high level compressive residual stress on a certain thickness just beneath the surface. By exposing severe plastic deformation (SPD) via SSP, the nanocrystallization is formed without any chemical alteration and the structure is to be hardened by fully mechanized process. The difference among SP, SSP and repeening (RP) is only related with the selection of the input parameters. Most of the input parameters combination constructs the Almen intensity which is the most powerful condition to be made the decision on the final shot peening of real parts. AISI 1045 medium carbon steel is selected for the optimization of input parameters...
CFD modeling of gasification process in tapered fluidized bed gasifier
, Article Energy ; Volume 191 , 2020 ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
This article presents a two-dimensional simulation of the coal gasification in tapered fluidized bed gasifier. The effects of tapered angle, gasifier temperature, velocity of gasifying agent, and steam-to-air ratio on the gas compositions, lower heating value (LHV), and higher heating value (HHV) were examined. In order to find the appropriate operating conditions of coal gasification, carbon conversion efficiency (CCE) and cold gas efficiency (CGE) were also explored. It was found that with an increase of the gasifier temperature, CCE and CGE of the tapered gasifier diminishes. Increasing tapered angle results in a decrease of the LHV and HHV of the gas products, whereas the CCE of...
Pore-Scale Monitoring of Wettability Alteration by Silica Nanoparticles During Polymer Flooding to Heavy Oil in a Five-Spot Glass Micromodel
, Article Transport in Porous Media ; Volume 87, Issue 3 , 2011 , Pages 653-664 ; 01693913 (ISSN) ; Mohebbi, A ; Kharrat, R ; Ghazanfari, M. H ; Sharif University of Technology
Abstract
It is well known that the oil recovery is affected by wettability of porous medium; however, the role of nanoparticles on wettability alteration of medium surfaces has remained a topic of debate in the literature. Furthermore, there is a little information of the way dispersed silica nanoparticles affect the oil recovery efficiency during polymer flooding, especially, when heavy oil is used. In this study, a series of injection experiments were performed in a five-spot glass micromodel after saturation with the heavy oil. Polyacrylamide solution and dispersed silica nanoparticles in polyacrylamide (DSNP) solution were used as injected fluids. The oil recovery as well as fluid distribution in...