Sharif Digital Repository

Inlet air cooling is a simple and economical method to increase the power output of gas turbines. High-pressure fogging systems and mechanical chillers are two common methods. High water consumption, damage to compressor blades by water droplets, and inefficiency in humid climates are disadvantages of high-pressure fogging systems. Mechanical chillers have high electricity consumption and initial costs. In this research, an earth-to-air heat exchanger (EAHE) is introduced as a new method for inlet air cooling of gas turbines and is technically and economically compared with the two common methods in the long term in the climate of Tehran city. Temperature distribution in the ground is... 

The purpose of this research is the aerodynamic design of a 100 kW transonic ducted fan. Today, the aviation industry is moving towards the design of electric driven aircraft propulsion. Transonic ducted fans are one of the viable options that have been used in medium and heavy aircrafts due to their high specific power. In this research, the meanline model has been used for the initial design. By applying the design constraints, design limitations, design and functional parameters, the initial design point is found and then a sensitivity analysis is performed with respect to the effective design parameters to obtain the optimal design point. For the initial design of the transonic ducted... 

Security Protocols are a set of protocols for the exchange of messages that both side of communication use in order to create the secure communication channel. Usually in such a case, both sides agree on one encrypted key. The purpose of these protocols is to obtain some features such as Authentication, Secrecy, Integrity, Non Repudiation, privacy and freshness. Freshness is one of the most important and vital features in communication protocols which is gained with Challenge and Response, timestamp and sequence number methods. Can interpret freshness as new and up-to-date. From the perspective of a participating agent in execute of protocol, a phrase take into account as fresh when it... 

Carbon dioxide is one of the main geenhouse gases emitted from factories as well as transportation vehicles that adversely affect the atmosphere and cause global warming. Among the proposed solutions to reduce carbon dioxide in the atmosphere, carbon dioxide separation would be the most viable medium-term approach. However, the high cost of carbon dioxide separation prevents the development of carbon dioxide absorption technologies. Therefore, it seems that integrating separation and production processes is the most efficient way to save energy and reduce carbon emissions. This method decrease a high proportion of the energy consumption in upstream operations (carbon dioxide removal,... 

The main purpose of this study was to increase the flow circulation within the flat plate oscillating heat pipes as a result Increase the heat transfer rate by placing diagonal grooves in the evaporator. The project in two stages a simple page and diagonal companion page are provided to investigate the effect of diagonal grooves. First a simple plate and then a second one with diagonal grooves in the evaporator it was made. Thermal performance of the heat pipes at each of the stages at different filling ratios of 40%, 50%, 60% and 70% for variable input capacities have been studied and compared. The results of the second stage showed that the performance of the new heat pipe at the optimum... 

Zirconium is one of the most applicable metals in the production of chemical materials’ industry due to its great corrosion resistance. Coating method of microarc oxidation is a novel method to manufacture oxide coatings on metal substrates. Lots of studies have been done on the creation of these coatings on light metals such as Aluminum, Magnesium and Titanium hitherto; however, there is a scarcity regarding manufacture of zirconium oxide on zirconium metal via MAO method. In the current study, aiming to create proper zirconia coatings on zirconium substrate, firstly, by the change of process parameters like current waveform, electrolyte concentration, current density, time and frequency,...