Sharif Digital Repository

In recent years, energy storage systems have received widespread attention from researchers to increase the reliability of the power grid. These systems have different types that compressed air system is of special importance due to its high stored energy and long life. In this system, the surplus of electricity generated from renewable energy sources or grid electricity at low power consumption is compressed and stored in a tank. When there is a need for power consumption or peak power consumption, compressed air will generate electricity by passing through the turbine and will help the network. Large-scale type of the system requires special geographical location for air storage; for this... 

Nowadays, variable generation and renewable energy resources are increasingly penetrating the energy systems to supply the users' demand at the distribution grid. Variable Energy Resources (VER) can provide energy at a lower cost, and they also guarantee cleaner energy. Still, the uncertainty and variability from these resources' output can affect the net-load of the system at each hour. Besides, the issue of energy balance has always been a challenge for the energy distribution networks. A comprehensive way to unravel this problem is to use flexible resources. One of the crucial issues in the flexibility debate is meeting this need by different energy resources. It is always an issue for... 

In recent decades, the trend towards renewable energy sources has increased dramatically. Rising fossil fuel prices and concerns about the effects of greenhouse gases and carbon dioxide emissions have drawn the attention of many energy experts to the use of renewable energy sources such as wind farms as an alternative to fossil fuel energy sources. Therefore, the issue of reliability related to these sources and whether such units can be considered as a source of generation has gained more importance. Due to the random nature of wind power, the share of these power plants in providing system adequacy is less than their nominal value. Therefore, determining the capacity value of wind power... 

Flow turbulators have crucial importance in heat transfer and energy harvesting applications. Therefore, in this study, the thermo-hydraulic and vibrational behavior of the floe inside a circular tube with vibrational ball turbulators (VBTs) on an axial elastic wire is experimentally studied for the first time. In this novel design, the elastic wire facilitates turbulence by allowing VBTs to move transversally and rotationally and agitate the flow substantially. The effects of diameter and longitudinal distance (pitch) ratios of VBTs, the Reynolds number, and the axial tension of the wire, on the flow friction factor (f), the Nusselt number (Nu), the thermal performance factor (η), in... 

Natural disasters such as storms, earthquakes, floods, etc. are among the factors that can damage the elements of the power grid and cause them to leave the grid. The result of these outages will be a widespread power outage, which will create many economic and social problems. Therefore, in recent years, the concept of resiliencey has been introduced in power system studies, which examines the extensive outputs in the network as a result of natural disasters.One way to improve the power system resiliency is to strengthen the network by upgrading existing equipment, installing new equipment, and modifying the operation of the network. Among these, the installation of distributed generation... 

The search for sustainable and clean energy sources to replace fossil fuels has become one of the most important scientific and technological challenges today due to the threat of fossil fuel shortages and environmental pollution. Therefore, the need for clean energy production and storage resources, including supercapacitors, has increased day by day. Today, supercapacitors have been considered suitable for energy storage due to their high-power density, appropriate energy density, long cycle life, and high safety. The aim of the present study was to obtain activated carbon fabric as electrode material in electrochemical energy storage applications and specifically supercapacitors. The... 

Zinc-bromine redox flow batteries are promising for large-scale energy storage applications due to their high energy density and open-circuit voltage. Proposed models for predicting these batteries' performance are limited due to challenges such as zinc deposition during the charging step and the utilization of a complexing agent. In this study, a 2D dynamic model was developed to investigate the battery performance. The kinetic equations for half-reactions are considered according to their two-step electron transfer mechanism. The model predictions were validated against experimental data reported in the literature for different current densities. Afterward, effects of various operating... 

Energy conversion and storage as well as life sciences are among the areas of our daily life. Interest in carbon nanomaterials for energy storage systems such as supercapacitors has enormously risen due to their attractive electrical conductivity, chemical inertness, and charge storage capacity. Producing these nanomaterials with a simple, scalable, and cost-effective method is the major problem for commercializing them. The reduction of graphitic oxide is a versatile procedure to prepare 3D graphene. Despite many green methods, the dynamics behind ultrafast thermal graphitization have remained elusive. Here, we demonstrate an effort to understand the graphitization mechanism of graphitic... 

Energy conversion and storage as well as life sciences are among the areas of our daily life. Interest in carbon nanomaterials for energy storage systems such as supercapacitors has enormously risen due to their attractive electrical conductivity, chemical inertness, and charge storage capacity. Producing these nanomaterials with a simple, scalable, and cost-effective method is the major problem for commercializing them. The reduction of graphitic oxide is a versatile procedure to prepare 3D graphene. Despite many green methods, the dynamics behind ultrafast thermal graphitization have remained elusive. Here, we demonstrate an effort to understand the graphitization mechanism of graphitic... 

The severe wildfires in California, Australia, Canada, and Iran have interrupted the power system operation, caused multiple blackouts, took many lives, and caused damages to power grid infrastructure to the extent of millions and billions of dollars. Most of the recent wildfires occur in the distribution system. Therefore, enhancing power system distribution resilience against wildfire is crucial.To this end, two groups of measures are proposed: the hardening of the power network and the operational measures. The past published papers mainly studied the resilience enhancement strategies against wildfire from an operational perspective. There is a considerable gap between the past works... 

In the late 1980s, the International Maritime Organization started working on reducing air pollution by ships, and the result was the approval of Annex 6 of MARPOL and its mandatory implementation since 2005. Since then, due to the increasing importance of pollutant emissions in the maritime transport industry and the stricter regulations of the International Maritime Organization and the high cost of fuel for ships, ship owners are looking for ways to reduce fuel consumption. For this purpose, various activities related to reducing the fuel consumption of ships were carried out. Among these, the use of energy saving devices can be a solution. Recently, the hull vane, as a fixed underwater... 

Power harvesters are used to generate energy for electronic devices. These electrical energy generators consist of three main parts: energy source, power electronic converter and energy storage. In order to minimize some of the weaknesses of these devices, including low power density and low reliability, the hybrid power harvesting method can be utilized. In this thesis, we design and build a hybrid energy harvester considering the advantages of simultaneous usage of solar and thermal energies for a wearable sensor, focusing on "efficiency enhancement" and "availability improvement". In the designed device, both solar and thermal energy harvesting units operate independently. In the solar... 

Lithium-ion batteries have the ability to store a significant amount of energy and work at high power, which has led to the wide spread of their use in various industries. In high-power applications, battery heat management increases lifespan, safety, and reduces battery power loss. In this study, the heat management of a very common and widely used 18650 battery using multi-layered phase change material has been investigated. The reason for using multiple layers is that each phase change material has its own weaknesses in addition to its advantages. It is expected that with the proper use of several phase change materials in the thermal management system, the materials will reduce the... 

Sustainable energy supply and preservation of the environment have become the main motivations to integrate more renewable energy sources in electrical networks. However, with an increasing penetration of renewable energy sources in the modern electrical grids, new challenging issues arise regarding the power system planning, operation, control and protection. An important technical issue is the difficulty in achieving the frequency stability of these systems, as the renewables are often operated at the maximum power point, resulting in less generation units that provide reserve power. Moreover, the rotational inertia of the system is reduced due to the decoupling of the renewable energy... 

Recent widespread blackouts around the world have highlighted the fact that power grids must not only ensure reliability against high-probability, low-impact events (HPLI), but also against low-probability, high-impact events (HILP) such as earthquakes, hurricanes, and hurricanes and resist against unnatural events such as cyber attacks. On the other hand, transformation of traditional electricity distribution systems into smart networks that have the ability to automatically perform switching and fault locating can enable utilities to minimize operational costs in case of HILP events occurences. Although the use of distribution automation has been suggested as one of the smart grid... 

In recent years, various studies have been conducted focusing on the optimization and scheduling of energy hubs (EH). EH optimization is important because it tries to create synergy in the energy supply system by considering the relationships between energy carriers. For this purpose, various algorithms such as analytical methods (linear programming) and evolutionary and heuristic algorithms have been used. Also, recently, various studies have addressed the applications of reinforcement learning for energy hub management. In this study, a hybrid model for energy hub management has been developed by combining classical linear models (Known as white-box models) and reinforcement learning... 

One of the main components of any solar power plant is the heat storage. Implementing heat storage reduc-es the cost of power generation by increasing the capacity factor of the system. This Thesis aims to analyze the operation of heat storages by modeling latent heat
storage. In this regard, an efficient method named "Method of Characteristics" is utilized. Models developed based on this method are possible to be used for comparison, sensitivity analysis, and optimization due to their low computation time. Sensitivity analysis was carried out based on various parameters such as void fraction, fiUer material size. Results show that using latent heat storage, storage c-apacity is... 

The aim of this research has been to modeling and optimization of steam injected gas turbine with inlet air cooling using absorption chiller. The whole system consists of compressor, combustion chamber, turbine, heat recovery steam generator, absorption chiller and cooling coil. The tasks carried out in this research include four points of view. The thermodynamic, exergetic, thermo-economic and environmental points of view are considered along modeling and optimization process. Design variables including temperature of combustion chamber exhausted gas, pinch point temperature of heat recovery steam generator and steam injection flow rate. Finally this modeling and optimization process is... 

Smart grids enable the implementation of novel energy management schemes for network operators. The restructuring of the power grid and the smartening of consumers, in addition to addressing environmental issues faced by traditional networks, have enabled many capabilities in the power grid, such as increasing network flexibility, peak shaving, and slowing down equipment obsolescence. The use of novel schemes, however, comes with its own set of challenges. One of these challenges is the uncertainty in the network, particularly on the supply and demand sides. Another challenge is the level of consumer engagement in energy management schemes. In this research, which is based on energy sharing,... 

Peer-to-peer (P2P) tradings are one of the energy management techniques that economically benefit prosumers and they can transact their energy as goods and services. In this work, a robust framework is proposed to address optimal energy management of an energy community considering peer-to-peer and peer-to-grid (P2G) tradings. Adaptive distributionally robust optimization (ADRO) is used to minimizing total community cost. Uncertainties in the load and output power of renewable energy sources (RES) are modeled by using this method. The production cost of prosumers and shared energy storage costs are considered as objective function. The problem is formulated as a bi-level minimum-maximum...