Sharif Digital Repository

Due to the energy crisis in recent years, much of which is due to excessive energy consumption in the air conditioning of buildings, many studies have been conducted from the perspective of engineering sciences on the subject of insulation and optimization of buildings. This study aims to investigate the conditions of thermal comfort from the mental and psychological perspective of human beings, which is the basis of the individual's decision to accept thermal adaptation behavior in the standard temperature range. In this study, the thermal adaptation model was designed on the theory of programmed behavior, which can explain the adaptation of individuals to the comfort temperature region.... 

Using energy storage systems has been remarkably improved the energy systems efficiency and reliability indicators of the system and also reduced the operating costs of these systems. Thus using them in an energy system would count as an advantage. Lately, the procedure of implementation of these systems has been studied widely and various motives behind implementing them have been reviewed. For example, the effect of cost optimization in electrical vehicles on reliability indicators from the load management perspective can be addressed. Therefore this thesis has studied the effect of electrical and thermal storage systems on the reliability indicators of an energy hub and the effect of... 

Today, due to increasing electricity consumption and demand, the use of conventional systems such as thermal, hydro and nuclear power plants is not enough to convert energy. Over the past century, scientists have sought to discover new technologies for exploiting different forms of energy and converting them into high-efficiency electrical energy. One of these ways is to use the phenomenon of magnetohydrodynamics (magnetic fluid dynamics) to convert thermal energy directly into electrical energy. Magnetohydrodynamics is a theoretical field that studies the dynamics of fluids with electrical conductivity. Induction magneto-hydrodynamic generators use ionized hot plasma (a quasi-neutral gas of... 

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, renewable energy resources (especially wind power as the fastest-growing energy source) have increasingly been employed for providing electrical energy all over the world given to the rising energy demands, reduction in non-renewable fossil fuels as well as severe restrictions applied to the utilization of these fuels because of their contribution in environmental pollution, generating greenhouse gas emissions, and consequently earth warming. The main factors in the development of wind energy systems to date are the easy access to this energy source in all seasons and its cost-effectiveness compared to other counterparts. One of the key components utilized for converting... 

The purpose of this study is to develop a new optimal solution method for controlling the greenhouse climate and minimizing energy demand for heating and cooling the greenhouse. As greenhouses move towards more advanced structures and technologies, the need for advanced control will be more important in order to reduce energy consumption. More comprehensive and accurate mathematical models are needed for complex systems, multiple inputs and multiple outputs to make system behavior perform better and more efficiently. In this research, a new method has been developed for optimal control of the greenhouse and a specific greenhouse climate model is used which is based on optimal closed loop... 

Heating demand required for greenhouses is mainly met by fossil fuels. On the other hand, anxieties over usage of fossil fuels have led the societies to move toward renewable energies. With this in mind, the purpose of this research is to analyze using both solar energy for satisfying the heating demand of greenhouses and heat storage for compensating the intermittence of renewable energy.Considering the mentioned points, in the current research, a linear optimization framework has been developed for design and operation of energy systems including long-term heat storage to meet heating demand of greenhouses. The objective of this framework is to minimize annual cost. The developed method... 

The issue under discussion in this paper is to optimize the fuel consumption of the Toyota Prius hybrid car. In order to solve this problem, the ADVISOR design model used by NREL in the Matlab / Simulink environment has been used. Various parts of this model are described. The optimization performed on this issue is based on the emotional controller. This controller works by simulating learning in animals based on encouraging and punishing them. With the introduction of the controller, the model and its inclusion in the fuel consumption control and its implementation have achieved good results. In the initial state and the controller in the model, the fuel consumption was 4.9 liters per 100... 

The building sector consumes a significant amount of potable water. It also consumes 30-40% of the world's end-use energy, and this will be even higher, considering the amount of energy consumed in water and wastewater treatment processes. In Iran, buildings account for about 35% of end-use energy consumption. Therefore, the focus on green buildings has increased as a response to growing concerns about climate change and global warming. This study seeks to develop an optimal model to meet the energy and water demand of a building considering the water and energy nexus. This model has been developed for the Energy Engineering Department in order to become a green building. As a result, the... 

The objective of the present study is the development of an optimization model to identify the best configuration of renewable-based integrated energy systems. The system includes a combination of renewable energy systems such as wind, solar, hydropower and hydrogen production, storage facilities, and conventional fossil-fuel generators. The developed tool consists of various modules where water-heating assumes the utilization of waste energy as an option. Furthermore, the application, which is demonstrated for a case study in Tehran has been considered. The power exchange with the distribution network and injection of hydrogen produced from excess renewable sources into gas network are... 

The purpose of this study was to investigate experimentally and modeling the process of gasification with supercritical water using waste motor oil. The effect of four important and influential parameters on the process, Temperature (350-450° C), Reaction time (15-45 minutes), Oil-to-Water volume ratio (0.2-0.4) and type of catalyst Consumption (Ni- NaOH- Na2CO3) was evaluated. Experimental experiments were designed and performed on the Design Expert software. The experimental results showed that the purity of hydrogen in the gas stream is more dependent on the temperature parameter and the higher purity is obtained with increasing temperature. Subsequently, as the oil concentration... 

The water and energy demand increase as the population grows. Increased usage of energy leads to scarcity of available resources and limited absorption capacity of environment. Development of efficient and environmentally compatible energy conversion technologies are conceived as an important option for resolving pressing challenges. Compatibility with environment requires considerable reduction in the share of fossil fuels and efficient utilization of renewable energy sources. Hence, development of high-efficiency solar energy systems is becoming an important challenge in the energy sector. The present study is involved with development an integrated solar system based on the application of... 

Condition monitoring and operation optimization framework of water and energy hybrid systems has been developed in the present research work, by taking into account the variation in behavior of the system over time under changing environmental conditions. System modeling is performed using the physical laws governing the behavior hybrid energy-water system. In addition, machine learning has been used to estimate the deviation of the mathematical model from system operation, which may be due to the effect of depreciation of machinery parts and other uncertain parameters. Using machine learning and mathematical modeling together results in increased accuracy in predicting system behavior over... 

Concentrated photovoltaic systems (CPVs) allow simultaneous production of electrical energy and high-temperature thermal energy. These systems consist of a concentrator for collecting solar rays onto the surface of the recipient cells. Moreover, these systems are always facing the sun using a sun tracker. The heat generated by these systems can be used in industrial processes, heating, cooling, and water desalinating. Given the concurrent generation of power and high-temperature heat, it is possible to achieve higher efficiency than that of conventional solar systems. Furthermore, the electrical efficiency is also higher than conventional systems due to the use of multi-junction solar cells... 

Continuous increase of energy demand, scarcity of resources, as well as environmental limitations have led to the need to reduce carbon emissions. In this research, an MINLP model based on the mathematical optimization formulation is proposed to reach this issue in a large cogeneration unit. Advantage of the hierarchical approach for carbon management are avoiding individual carbon reduction policies, and embedding emission control techniques in a hierarchical mathematical model that helps us to select the most appropriate policies and prioritize each other. In the carbon management hierarchy, the optimization of the base cycle is done at the first stage. Then, the use of renewable energies... 

The power generation system of this type of power plants operates on the air flowing through the power plant’s chimney and colliding with the turbine blades within the chimney. When the solar collector warms the nearby air and thus expands the air by absorbing the sunlight, a difference is created in the density. Then, this difference in the density creates the phenomenon of buoyancy, making the air pass to the top of the chimney through the collector.This study simulated and optimized a solar chimney power plant. The simulation and optimization were performed based on the information of Manzanares Solar Chimney Power Plant in Spain (located in 150 km from the south of Madrid). It was... 

One of the best ways to reduce water consumption is using air cooled heat exchangers, because they work in a completely closed cycle which does not require makeup water. However because of their high surface area and high-technology production method, their production cost is significantly high. Air cooled heat exchangers have relatively high exergy destruction because of low U heat-transfer coefficient. In present research, single-objective and multiple objective optimization problems are developed to minimize total annual cost and exergy destruction. Also the influence of temperature changes on these two objective functions have been evaluated by Monte Carlo simulation. In next step,... 

The aim of this research is retrofit of a crude oil distillation refinery unit in terms of water and energy. To do this, the refinery distillation unit is ategorized to different zones from the perspective of water and energy to determine the saving potentials. The energy network consists of the four sub-types includes exchangers and the water network consist of seven sub-sets including water and steam. In the next stage, the retrofit of the energy network and the process heat exchangers are done by using pinch analysis in the commercial software and discussed the economical possibility of pinch analysis for 20 heat exchangers in the crude oil preheating unit. Using the flow of flashed crude... 

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... 

Heat losses and pump electrical energy consumption are inevitable during the operation of a district heating(DH) network. Therefore, the appropriate design and operating strategy of a DH network is required in order to reduce the heat losses and pump energy consumption. This study is aimed at optimizing pipe diameters and mass flow rate in a DH network according to heat demand of the building in order to minimizing operating cost of the network.For this purpose first drawings of the building is modeled in Auto Cad software. Then according to the position of building to the sun, the building is modeled in Desighn Builder software. In this software the buildings charactersitics like materials...