Studying Supercapacitive Performance of Cobalt-based Hierarchical Nanostructures

, M.Sc. Thesis Sharif University of Technology Afsahi, Nikan (Author) ; Naseri, Naimeh (Supervisor)

Abstract

One of the pillars of reaching a steady development is to utilize sustainable energies. In order to make use of these modern means of energy, appropriate energy storage devices are inevitable. One of the families of these devices is the supercapacitors. Moving toward the 4th industrial revolution, we are encountering modern technologies such as internet of things and wearable electronics. Therefore, designing and fabricating microsupercapacitors is of paramount importance in order to reduce the weight and size of these devices. Cobalt and nickel are considered as two important elements to be used in synthesizing supercapacitive materials and composites, because of their good electrochemical...

Immobilization of cellulase on non-porous ultrafine silica particles

, Article Scientia Iranica ; Volume 14, Issue 4 , 2007 , Pages 379-383 ; 10263098 (ISSN) Afsahi, B ; Kazemi, A ; Kheirolomoom, A ; Nejati, S ; Sharif University of Technology

Sharif University of Technology 2007

Abstract

The immobilization of cellulase onto non-porous ultrafine silica particles was studied. Cellulase was extracted from a Trichoderma reesei culture after partial purification with ammonium sulfate (pH = 5.0), which was then immobilized onto non-porous ultrafine silica particles, with or without the use of glutaraldehyde as a crosslinking agent. Cellulase was immobilized by adsorption onto ultrafine silica particles efficiently, as well as by covalent cross-linking with glutaraldehysde. Increasing the concentration of the free form of enzyme increased the amount of immobilized cellulase. The maximum enzyme immobilization happened at the free enzyme concentration of 0.48 mg/ml. In general, the...

CFD simulation of melting process of phase change materials (PCMs) in a spherical capsule

, Article International Journal of Refrigeration ; Volume 73 , 2017 , Pages 209-218 ; 01407007 (ISSN) Sattari, H ; Mohebbi, A ; Afsahi, M. M ; Azimi Yancheshme, A ; Sharif University of Technology

Elsevier Ltd 2017

Abstract

The present study is focused on CFD simulation of constrained melting of Phase Change Materials (PCMs) in a spherical container. To investigate the melting process of the PCM, its melting fraction was analyzed at different times. The results indicated the existence of thermally stable layers on the top of the sphere. Moreover, inspection of the calculated temperatures at different points along the vertical axis indicates the existence of some disturbances at the bottom of the sphere due to the natural convection. After the validation of the results, the effects of different parameters such as the surface temperature of the capsule, the initial temperature and the size of the spherical...