Sharif Digital Repository

Physics of the present work is 2D two-phase immiscible flow under gravitational effect through fractured porous media and the most practical formulas for transfer function in dual porosity-dual permeability models have been implemented for numerical simulation of naturally fractured reservoir. The models are: Kazemi et al. (1976), Gilman (1986), Sonier et al. (1988), Quandalle and Sabathier (1989), Lim and Aziz (1995), and Rangel-German and Kovscek (2006), which are compared using a benchmark problem and the effects of gravity, capillary, number of matrix block subdomains and dual continuum media model are studied. The benchmark problem was adopted from Gilman (1986) and involves water... 

The present thesis aimed to develop a thermal-hydraulic model for simulation of multi-stream plate-fin heat exchangers. In this study, a multi-scale point of view was employed for three-dimensional simulation of multi-stream plate-fin heat exchangers. This is a cost-effective method that reflects the effects of complex phenomena at the micro-scale in the macro-scale model. In this model, fluid and solid matrix temperature distributions were obtained in the three-dimensional space, considering conduction heat transfer through separating plates, side plates, cap plates, and transverse conduction through fins. The modular form of the model has facilitated layer-by-layer simulation of parallel... 

In this thesis an SPH method is used for simulating multiphase two- and three-dimensional Newtonian fluid flows. The weakly compressible algorithm consists of two steps of prediction and correction. In the prediction step, the velocity field is integrated forward in time without enforcing incompressibility. The correction step consists of enforcing incompressibility by solving the pressure Poisson equation which creates a trade-off between the pressure and density variations. The surface tension force is applied in the linear momentum conservation equation by the divergence of the surface stress tensor. Advanced techniques are applied to achieve better convergence and reduce pressure-related... 

Building simple and effective models are essential to many applications, such as building performance diagnosis and optimal control. Detailed physical models are time consuming and often not cost-effective. Black box models require large amount of training data and may not always reflect the physical behaviors. In this study, a method is proposed to simplify the building thermal model and to identify the parameters of the simplified model. For instance, predicting the next-24-hour load in a building is essential for the optimal control of heating, ventilating and air-conditioning (HVAC) systems that use thermal or cool storage technology. In the first phase of this study, equations for... 

Research on convective heat transfer coefficient around a rod bundle has several applications in industry. So far, many studies have been conducted in correlations related to internal fully developed flow. By comparing Dittus-Boelter, Sieder-Tate and Petukhov found to be more practical. The present study examines the validity of these frequently applied correlations experimentally. A thermohydraulic loop has been designed and manufactured to test and measuring the convective heat transfer coefficient. Due to its generalizibility, the unique geometry of this test facility (hexagonal arranged, 7 vertical rods in a hexagonal tube) has achieved extensive application. The major deviation factors... 

Cleanrooms have a broad scope of applications from electronics, pharmacy, biotechnology to hospital industries, and are susceptible to fine and ultra-fine particles. In this work operating room in the category of hospital applications is chosen. Airborne particles in the operating room depends on many factors such as room geometry, inlet and outlet design, air displacement rate, obstacles, etc. Surgical light is one of the most critical obstacles in the operating room as it is upstream to the surgery zone. The study presented in this thesis aimed to numerically investigate the influence of radiation emitted from the medical lamps on the indoor airflow quality in operating room environment.... 

Improving efficiency of heat exchangers has always been an important concern for the industry. Pulsating Heat Pipes (PHPs) are novel and efficient technology in the field of heat transfer. PHPs are widely used in solar water heaters, solar desalination systems, etc. In this research, thermal performance of Open Loop Pulsating Heat Pipes (OLPHPs) using three different ferrofluids (ferrofluid without surfactant and nanoparticles’ coating, ferrofluid with coating of nanoparticles, and ferrofluid with surfactant) is experimentally investigated. In addition, effects of charging ratio (20, 40, 60, and 80%), heating power (20, 30, 40, 50, 60, 70, 80, 100, 120, 140, 160, 180, 200, 240, 280, 320,... 

Combined cycle power plants consist of three main sections, namely gas turbine, Heat Recovery Steam Generator (HRSG) and steam turbine. Occurring failure in HRSG causes the steam turbine trip, so the reliability assessment of HRSG has a great importance for forecasting the probability of occurring failure and also reducing failure causes. In this project, the reliability of HRSG considering effects of aging phenomenon, maintenance and, environmental and operational conditions on reliability is modeled. Afterward a method to estimate the model parameters is introduced. Using present method, failure data of six HRSGs of a plant each with a capacity of 50 MW is analyzed and the model parameters... 

Diabetic patients, unlike other people whose blood glucose vary in a limited and normal range, encounter hyperglycemia and hypoglycemia, so their glucose level should be measured periodically and kept in the normal range. The aim of this research is to design an implantable integrated microfluidic system in order to regularly measure the glucose level in the human body, using the microdialysis method. The main compartments of this system are a micropump, array of hollow microneedles at the base of them located semipermeable membranes, the channels of dialysis fluid and an electrochemical sensor for measuring the glucose level. The micropump of this system is designed and simulated based on... 

Ground-Source Heat Pumps (GSHPs) are efficient means of space heating and cooling. However, owing to their high installation costs, their development in societies has not grown as it should. Therefore, it is crucial to have a meticulous design of these systems. The first step in designing GSHPs is determining the ground and grout thermal properties. Thermal Response Tests (TRTs) are developed for this purpose. The previous methods of estimating the unknown thermal properties are either computationally inefficient or yield inaccurate estimates for the ground volumetric heat capacity, to which the mean fluid temperature has the slightest sensitivity among all thermal properties. Among previous... 

Naturally Fractured Reservoirs (NFRs) play an important role in petroleum industry and the global economy.. The reservoirs of the most complex geological structures in petroleum engineering science, on the other hand the largest sources of hydrocarbons are considered throughout the world and especially in our country. Therefore, characterization and modeling them frst step to develop best practices for hydraulic fracturing gap, optimal design of production Method and evaluate potential reservoirs. Physics of the present work is 2D two-phase immiscible flow under gravittational effect through fractured porous media and the most practical formulas for transfer function in dual porosity-dual... 

If the reservoir temperature lies between the critical temperature and cricondentherm of the reservoir fluid, the reservoir is classified as a retrograde gas-condensate reservoir. When the pressure is decreased on these mixtures, instead of expanding or vaporizing as might be expected, they vaporize instead of condensing. If the reservoir pressure is above the upper dew-point pressure, the hydrocarbon system exists as a single phase in the reservoir (region 3). As the reservoir pressure declines isothermally during production from the initial pressure to the upper dew-point pressure, the attraction between the molecules of the light and heavy components move further apart. As this occurs,... 

Multilateral wells are relatively new alternatives in field development and because they can increase the productivity per well and reduce the cost of field development, they are rapidly replacing old methods. In order to predict the performance of well, three methods are usually used: Analytical methods which use closed-forms models, semi-analytical methods which entails line-source model and numerical methods which is based on techniques such as finite volume or finite difference. In this thesis, line-source model is extended from two dimensional forms to three dimensional forms in order to be used to optimize the path of multilateral wells. Optimization entails direct optimization... 

The gas flow field geometry influences the transport phenomena inside PEMFCs and hence affecting their overall performance. Radial force and secondary flows resulting from curvature of the spiral channels in PEMFCs can improve mass transport limits and so does to their overall performance. Studying the effects of curvature of spiral channels on fuel cell performance and comparing them with similar designs is the aim of this thesis. The geometries are generated using concentric Archimedes’ spirals and categorized as axial or radial depending on the direction of the vector perpendicular to their MEA . Each category has five geometries which are the result of branching the main channel into...