Sharif Digital Repository

In this thesis a general model for simulation of solar cooler for domestic usage is developed. The model consists of 2 main parts: thermo-dynamical and economical calculations. The thermodynamic part consists of 4 sub models: a model for calculation of incoming solar radiation, cooling load demand calculation, the refrigeration cycle and the solar cycle with heat storage.As for hourly calculation of system performance part of the model produces the hourly received radiation data based on geographical position and orientation of the receiving surface. Base on results of the cooling load calculation for a 9 m2 studying room located in western part of Tehran, 1 TBR (3.516 kW) is chosen as... 

Relying on current fuels and technologies in vehicle industry in recent years has led to an enormous challenge such as air pollution, climate change and energy security. In the other hand, fossil fuel reservoirs are being depleted with an intensive rate. Nowadays, hydrogen, as a substitute for current fuels and hybrid, fuel cell and electric vehicles, as substitutes for current vehicular technologies are under research and development. Because of abundant advantages such as high efficiency and long cycle life, no depreciation for parts and scalability, fuel cell vehicles is of interest for many car manufacturers throughout the world and lots of them have demonstrated their prototype fuel... 

Inappropriate effects of fossil fuels and conventional power generation systems on the environment have necessitated a sustainable energy system for the next decade by growing interests in renewable energy systems. The world’s most fast-growing renewable energy resource is the wind energy. The main problem of wind power is the power fluctuations at the load side caused by the variable nature of wind speed, and the main issue in case of remote locations is the long-term storage of power generated by wind turbines. Batteries can be used to store a limited amount of energy for a short time. Although new advances in this field have been achieved, most common type of batteries is hardly able to... 

With the current demands in alternative methods of energy production and increased utilization of existing energy sources, microbial fuel cells have become an important field of research. In a microbial fuel cell, organic and inorganic compounds can be oxidized by microbial catabolism at the anode to generate direct electricity. A kind of microbial fuel cell (MFC) is sediment microbial fuel cell (SMFC) consists of an anode electrode embedded in the anaerobic sediment and a cathode electrode suspended in the overlying aerobic water. microorganisms produce electrons by oxidation of organic or inorganic compounds in the sediment at anode electrode, while oxygen is reduced in the water by... 

Focusing on fossil fuel to secure energy demand lead to big challenges. Hydrogen as alternative for fossil fuel has attracted a lot of attentions. Fuel cell with an electrochemical reaction which it’s byproducts are water and heat convert Hydrogen into electricity. High efficiency and low environmental pollution, persuade many researchers toward fuel cell commercialization. But problems such as high cost, high power oscillation and inertia, avoid fuel cell from significant development. One way to deal with these problems is using the fuel cell and battery hybrid system. In recent decade too many research has been made in utilizing this hybrid system in transportation. This project... 

The present study was aimed at developing a model to optimize the sizing of wind turbines according to the region’s wind condition and the capital costs of each part of the turbine. The proposed model, which consists of technical aerodynamic, economic and optimization sub-models, is used to achieve maximum annual energy production by a fixed cost of a single or a number of wind turbines. A cost model has been used to determine the detailed cost of the turbine’s components. The model’s results are presented for two regions in Iran, Khaf and Ahar, and the optimized configurations for a single turbine and a wind farm have been investigated.A case study for the region- Manjil that has some... 

Nowadays, the reduction of crude oil quality and the growth of environmental restrictions are the main challenges in oil refineries worldwide. The high demand of lighter refinery products and the shrinking market of the heavy products, highlighted the role of heavy residues conversion technologies.Gasification technology consumes these heavy refinery residues and produces clean syngas. By this way and the integration of gasification with power generation cycles, more value added products such as electrical energy, steam and hydrogen can be provided. For this aim to be achieved, three different scenarios are developed and investigated in this project. The first scenario includes the... 

The phenomenon of vortex flow, is one of the most predominant streams in the nature. This phenomenon yielded by the motion of vortices, produces up to 1000 times acceleration of the Earth’s gravity. The issues of uncontrolled harvesting of oil wells and increase the life of the wells, which cause to increase in the extracted crude salt, reveal the importance of waste management and both handling and refining petroleum. According to global statistics, for every extracted barrel of oil, three barrels of water are yielded. Therefore, 250 million produced water barrels per day is produced.The separator technology with vortex core (brand Voraxial) is one of the latest technologies in waste-water... 

Ever-increasing energy consumption and consequent extensive greenhouse gas (GHG) emissions are two major urgent problems faced by all human beings in the 21st century. As a major contributor, the energy production section appears to be the most suitable field where further improvements could be explored to tackle these problems. Multi carrier energy system is a typical type of next generation energy production technology with higher energy efficiency and lower/zero GHG emissions. The conversion of energy between different carriers establishes a coupling of the corresponding power flows resulting in system interactions. The investigation of such phenomena requires the development of tools for... 

One of the processes for energy carriers creating from biomass is Gasification process. The main products of this process are hydrogen and carbon monoxide. Output of this process has an average calorific value and sensible heat. Using sensible heat for preheating inlet air is one the ways for enhancement gasification processes. In this study gasification process is modeled as zone modeling. The humidity, pressure and air preheating effects on output gas composition and system’s layout were investigated. In the first and second scenario comparing the shifting of gas blower from downstream to upstream of gasification reactor is studied. It is showed the average temperature and number of... 

The energy systems efficiency is a great issue confront power plants professionals. Besides using high-tech components in power plants, plant operation optimization can significantly improve energy efficiency and economic performance, as efficiency of plant components generally depends on operating conditions. In addition, system preventive maintenance can reduce plant operation and failure costs, however it is also costly when done frequently. Therefore, optimizing operating conditions and preventive maintenance intervals can minimize the expected total cost of plant due to operation, failures and preventive maintenances. In recent years, the use of optimization models to determine plant... 

Fuel cells are a reliable technology for electrical power generation, widely regarded as a promising alternative for stationary and mobile applications. In order to supply vehicle required power, fuel cell must possess suitable transient response. In this work, a mathematical zero dimensional control-oriented model for a PEM fuel cell stack is developed. Afterwards, to increase the efficiency, four parameters including cathode air inlet flow rate, return manifold cross section area, anode hydrogen inlet flow rate and hydrogen humidity are optimized in different vehicle current demand. Also, in order to decrease water production inside the fuel cell membrane, considered parameters are... 

CCHP systems have attracted much attention in recent decades due to their economic and environmental benefits and high returns. Therefore, in this research due to the necessity of using high energy efficiency technologies and low cost of operation while also releasing minimum environmental pollutants such as carbon dioxide, a Solar-assisted CCHP system is studied. The performance of the CCHP systems is deeply dependent on the operation strategy of the system. In this research, in order to improve the techno-economic performance of the system, an optimization model is applied to optimize the proposed operation strategy using minimum distance methodology. In order to measure the proposed... 

In the last three decades, the world has experienced enormous increases in energy consumption as a consequence of the economic and population growth. This causes renewable energy and energy recovery to become a requirement in building designs rather than option. A direct expansion (DX) air conditioning system is an efficient way to supply fresh and dehumidified air to a built environment a long side it plays a key role in preventing the spread of respiratory diseases. To improve the efficiency of a conventional DX system in hot and humid regions, fresh air dehumidification and conditioning systems with energy recovery measures are the key equipment to reach such a goal. To achieve this goal... 

Upstream Oil and Gas due to the high energy consumption offer multiple degree of freedom that can be exploited to reduce capital and/or operating costs. Be use combination of optimization methods (Retrofit and Operational Problems) due to the complex nature of the optimization in UOG. To achieve the optimization Details need to identify relationships between variables. System modeling based on demand in two categories, can be divided: the demand for water and oil based and model based on electricity demand. Existing and new technologies in both evaluated and identificated the application of the system in upstream sections. The linear programming model used to determine the export of... 

Urban energy systems are responsible for the majority of the energy consumption around the world and they play an important role in energy issues such as economic security and climate change. Furthermore, there are growing concerns about the depletion of fossil fuel resources and the negative effect they have had on the ecosystem. To this end, a holistic and integrated approach is necessary for the optimal design and operation of urban energy systems that makes expressive betterment in energy efficiency and environmental impact. The aim of this research is to develop an optimum methodology for communities in the context of energy hub. The energy hub is a novel concept to systematically... 

The purpose of this research is developing an analytical and decision-making tool that examines the interactions between greenhouse energy demand and yield production. Greenhouseholders can use the analytical tool to design and operate existintg and newly built greenhouses in an optimal way. Becides, the decision making tool helps planners and policymakers to improve the performance of greenhouses and extend greenhouse cultivation with respect to their economic or environmental objectives.In order to develop this decision making tool, existing models for greenhouses have been investigated and various algorithms have been combined to develop an integrated energy demand-plant growth model. The... 

The population growth and scarcity of resources such as water and land make the food security as one the most important critical priorities in the world. Development of food production in greenhousesinstead of the traditional agriculture in rural areas is an efficient and applicable approache to reach food security and optimum use of water resources. However, this requires more capital. An important part of this cost is related to the cost of energy supply for heating and cooling in order to provide a suitable condition for the growth of plants. Optimal design of a rural energy supply and optimal operation of existing greenhouses to maximize the benefit of the greenhouse owners and to... 

Two major challenges facing countries all around the world are the demand for renewable energy resources and treatment of large quantities of industrial and household wastewaters. One of the new and environmentally acceptable methods to produce green energy is Microbial Fuel Cells (MFCs), which has been noted by many researchers in recent years. MFC is a new technology which has the ability to produce green energy along with treatment of wastewater stream, based on oxidation of organic maters through microbial metabolism. In this study we investigated the effects of different cathode chamber parameters on operation and efficiency of a two chamber MFC at laboratory scale. These parameters... 

According to, increasing use of energy in the world, issues such as increasing reenhouse gas’ emission, rising temperature on planet earth and air pollution have appeared Carbon dioxide is a major greenhouse gas that has a significant impact on increasing the temperature of earth. In recent years, attentions to carbon dioxide capturring and sequestration technologies have been increased. In this project molten carbonate fuel cell which is used as a new method for separating carbon dioxide from gaseous compounds of combustion process, is discussed. The aim of the project is to, investigate technical and
economic feasibility of using molten carbonate fuel cell for separating carbon...