Study of Designing and Operating Parameters of Rotary Air Preheaters

, M.Sc. Thesis Sharif University of Technology Ahmadi Partovi, Ebrahim (Author) ; Saidi, Mohammad Hassan (Supervisor) ; Kazemzadeh, Siamak (Supervisor)

Abstract

In order to promote the efficiency of fossil fuel power stations, rotary air preheaters are used to warm the air entering the boiler. So, knowing the essential parameters of such exchangers and their effect on the efficiency is the primary objective and choosing the appropriate parameters and the dimensions reducing the liquid pressure, weight of exchangers and subsequently the maintenance expenses would be the secondary objective.
In this research we tried to know the principles of regenerative convertors introducing the tentative air preheaters and their functional characteristics .We also assessed the factors in designing the ideal tentative air preheaters including the type of...

A new Leak Detection Method Applicable for Low and High Pressure Vessels

, M.Sc. Thesis Sharif University of Technology Ahadi, Majid (Author) ; Sharif Bakhtiar, Mehrdad (Supervisor)

Abstract

A New method is proposed to find a mother wavelet for the best localization of acoustic emission (AE) signals generated by leakage in a pipe. At the first step, knowing stochastic nature of acoustic emission signals, a leakage signal in time domain was trapped by monitoring the Short Time Fourier transform (STFT) of AE signal over a relatively long time interval to find frequency traces of leakage AE signal. The trapped signal was used to find a mother wavelet for the best signal localization. Then a novel method for AE signal detection using tuned wavelet is discussed. For this purpose experiments were done in predefined situations to collect signals generated in water filled plastic pipe...

Effect of Flatness and Roughness of Sealant Contact Surfaces on Diesel Injectors Performance

, M.Sc. Thesis Sharif University of Technology Fozi, Mostafa (Author) ; Adib Nazari, Saeed (Supervisor)

Abstract

Surface roughness has an enormous influence on many important physical phenomena such as contact mechanics, sealing, adhesion and friction. Contact mechanics was studied as an important topic for long years in order to realize the friction phenomena, contact fatigue and fluid leaking between rough surfaces. Therefore, the contact of rough surfaces has been widely invistageted by engineers for different purposes like rejouvination, prevention of environmental pollution and stress analysis. Failure modes have been studied in this research for a specific type of injector by experimental methods. After that, injector's rough surfaces were modeled. Firstly the proper point cloud was modeled by...

Modeling and Analysis of Cylindrical Swellable Elastomers

, M.Sc. Thesis Sharif University of Technology Namdar, Amir Hossein (Author) ; Arghavani Hadi, Jamal (Supervisor)

Abstract

When swellable elastomer are surrounded by suitable fluid, they absorb the fluid and swell. This capability is used to design different tools. For example, drug release devises, sensors and actuators, in microfluidic devises such as micro-valves and micro-mixers, and seal devises. Most of these devises are shaped cylindrically. Therefore, have a thorough knowledge about how cylindrical swellable elastomer behavior, give us a good vision about how to design such actuators. In this thesis we have used constitutive equation of such materials and have investigated behavior of cylindrical swellable elastomers analytically and numerically. Analytical investigation is focused of transient behavior...