Sharif Digital Repository

Geothermal energy is one of the most important sources of energy that is increasingly becoming more popular all over the world. In this study, the performance of deep geothermal energy as a form of geothermal energy was evaluated using a numerical modeling approach. To do so, first, the thermo-hydraulic behavior of geothermal reservoirs was studied to help achieve the most efficient arrangement for production and injection wells. The results show that to optimize production and injection wells, there are two factors to consider. Firstly, the distance between production and injection wells must be high. Secondly, the production wells must be uniformly distributed throughout the reservoir so... 

In this thesis, three novel geothermal-based ORC systems are proposed to enhance efficiency and to recover the waste heat recovery. The proposed systems are modeled based on basic ORC system (concept 1), ORC system with internal heat exchanger (concept 2), and regenerative ORC system (concept 3). Accordingly, two thermoelectric generators are introduced into the systems to exploit the waste heat of the system. For this purpose, the condenser is replaced by a TEG unit, while the other TEG unit is employed to recover the waste heat of the reinjected geothermal fluid. A comprehensive numerical investigation is conducted to compare the proposed systems from thermodynamic and thermo-economic... 

In this research, a multigeneration system was designed and evaluated, utilizing solar and geothermal energy to generate electricity, fresh water, hydrogen, and oxygen. The system's performance was assessed from energy, exergy, and economic perspectives. The setup involves a solar tower contributing energy to the gas cycle and a geothermal well supplying preheated water for the steam cycle. The system employs a molten salt cycle to capture heat from the solar receiver, transferring it to the air cycle. The remaining energy requirement is met by the Air Brayton cycle, which combines methane and hydrogen as fuels within the combustion chamber. Additionally, a steam cycle is integrated to... 

Economical strategy of developed countries imposes to improve energy efficiency and a rational renewable energies usage in the buildings. Ground source heat pumps are one of the most important tools in the way moving toward this goal. This study focuses on studying the effect of applying different refrigerants in the direct expansion ground source heat exchangers. In order to compare the performance of the ground source heat pumps using different refrigerants, a specific methodology is presented and implemented. First on this study, the thermal performance of a geothermal borehole filled with both CO2 and a zeotropic mixture of CO2 and R32 (20/80) is studied and the quality, temperature, and... 

A heat exchanger pile is a pile that is equipped with absorber pipes so that it can exchange heat with the surrounding soil. These piles couple the structural support role of conventional piles to the heat exchanger role of shallow geothermal systems for any built environment. So They are subjected to both mechanical and thermal loads. The use of these piles can be useful in reducing greenhouse gas emissions and reducing fossil fuel consumption. In order to study the thermomechanical behavior of heat exchanger piles, a physical model has been constructed in the Advanced Soil Mechanics Laboratory of the School of Civil Engineering at Sharif University of Technology. In this physical model,... 

Climate change has overshadowed various aspects of human life due to rising greenhouse gases such as carbon dioxide. The importance of this issue prompted humans to take steps to reduce carbon dioxide emissions from human activities. Turning to geothermal energy instead of using fossil fuels was one of the strategies chosen for this purpose. Geothermal reservoirs are used to exploit this energy. In geothermal reservoirs, cold water is injected through a fracture network and receives heat from the hot rocks; then, the hot water is pumped out. Due to their high transmissivity compared to the surrounding rock matrix, Fractures are the primary conductors in geothermal reservoirs. Flow-through... 

The sun is a clean and sustainable source of energy that can be considered a good alternative to fossil fuels at a low cost. Solar energy can be used for heating and electricity generation. As another source of clean energy, the earth has a good heating and cooling potential, which, due to its lower temperature than the environment in summer and vice versa in winter, makes it a suitable option for heating and cooling. This research aims to design a new system based on desiccant wheels that provides a cooling load for a building with a floor area of 60 square meters and a volume of 185 cubic meters. This system uses solar energy to provide heating and electricity and uses the earth as a heat... 

Nowadays, energy has become a vital issue. Earth to Air Heat Exchanger (EAHE) is a technique that promotes energy saving. EAHE is a non-conventional technique that utilizes the thermal potential of the geothermal energy for space cooling/heating. In the agricultural sector, using the grounds energy for air conditioning of greenhouses can be highly effective. In this study, a transient implicit computational fluid dynamics model is developed to simulate the thermal performance of EAHEs. The developed model is validated against available experimental studies in the literature. Good agreement between simulated results and experimental data is obtained. In the following, the heat exchanger is... 

Energy piles couple the structural support role of conventional piles to the heat exchanger role of shallow geothermal systems for any built environment. So, they are subjected to both mechanical and thermal loads. The use of these piles can be useful in reducing greenhouse gas emissions and reducing fossil fuel consumption. With this in mind, this study is conducted to evaluate the thermomechanical behavior of heat exchanges group piles. For this porpuse, a physical model has been constructed in the Advanced Soil Mechanics Laboratory of the Civil Engineering Department at Sharif University of Technology. In this physical model, four closed-end aluminum pipes with a diameter of 20 mm and a...