Made available in DSpace on 2014-10-09T12:26:08Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:10:21Z (GMT). No. of bitstreams: 1 00653.pdf: 2722544 bytes, checksum: 26bcce3d962be5c281c69fd5f50fca70 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

This thesis discusses the results and insights gained from developing a CFD model of a pilot-scale pressurized dry coal-feed system using the Barracuda CFD software and modeling various design concepts and operating conditions. The feed system was required to transport approximately 0.00378 kg/s (30 lb/hr) of pulverized coal from a vertical hopper to a 2.07 MPa (20.4 atm or 300 psi) reactor with a CO2-to-coal mass flow ratio of 1-2. Two feed system concepts were developed and tested for coal mass flow, CO2-to-coal mass ratio, steadiness, and uniformity. Piping system components also were evaluated for pressure drop and coal roping.With the first system concept, Barracuda software model parameters were explored to observe their effect on gas and particle flow. A mesh sensitivity study revealed there exists too fine of a mesh for dual-phase flow with Barracuda due to the particle initialization process. A relatively coarse mesh was found to be acceptable since the results did not change with increasing mesh refinement. Barracuda sub-model parameters that control particle interaction were investigated. Other than the close pack volume fraction, coal flow results were insensitive to changes in these parameters. Default Barracuda parameters were used for design simulations.The gravity-fed system (first concept) relied on gravity to transfer coal from a hopper into the CO2 carrier gas. This design was unable to deliver the required coal mass flow rate due to the cohesion and packing of the particles being greater than the gravity forces acting on the particles. The fluidized bed (second concept) relied on CO2 flow injected at the bottom of the hopper to fluidize the particles and transport them through a horizontal exit pipe. Additional CO2 was added post-hopper to dilute the flow and increase the velocity to minimize particle layout. This concept was shown to decouple the fluidized particle flow and dilution CO2 flow, providing significant design and operating flexibility. A non-uniform mesh was implemented to maintain a high mesh refinement in the 0.635-cm (¼-in) diameter transport pipe with less refinement in the hopper/bed region. The two main hopper diameters evaluated measured 5.08-cm (2-in) and 15.24-cm (6-in). Successful designs were achieved for each with appropriate coal mass flow rates and CO2-to-coal ratios. The particle flow was sufficiently steady for use with a coal burner.A piping system study was performed to test pneumatic transport and the effects of pipe length and bend radius. For a 1-to-1 gas-to-particle mass flow, particle layout occurred after 30 cm of travel. Particle roping occurred to various extents depending on the pipe bend radius. Bend radii of 0.318, 60.96, and 182.88 centimeters were simulated. Roping increased with bend radius and high pressure. Greater gas flow rates increased particle flow steadiness and uniformity. A simple methodology was identified to estimate the pressure drop for different piping system configurations based on the piping components simulated.

Oxy-combustion is a process which removes nitrogen from air prior to combustion in order to produce a high concentration of CO2 in the exhaust. This enables CO2 liquefaction, transport, and storage to greatly reduce CO2 emissions to the atmosphere. Atmospheric oxy-coal combustion has been successfully demonstrated at industrial scales and could be retrofit in existing coal boilers, but thermodynamic efficiencies are low and therefore uneconomical. Pressurized oxy-coal combustion has the potential for higher efficiency and lower cost but requires new technologies related to the coal feed system, the burner, and ash management. This project describes work needed to complete the dry feed pressurized oxy-coal combustor (POC) at BYU. The POC required the software control system (OPTO22) to be completed, a reactor shakedown, and testing of a previously designed burner by recording reactor thermocouple, exhaust concentration, and radiometer measurements. The following has been successfully demonstrated: 1) reactor heat-up with natural gas 2) coal combustion within temperature limits of the reactor 3) slagging that allows ash management.

When installing pipes meant to hold high pressure, there is a requirement that this processis tested and documented. Today this is done manually with a manometer and requires aconstruction worker to monitor this, sometimes over several hours. A customer approached Theengineering bureau Conmore with an idea to streamline this procedure by automation, and inthe process, remove human error and free up work time during construction. A specification listwas created with the company, the students and the customer to ensure the project would resultin a prototype all parties were happy with. The finished product resulted in several additionalfeatures from the initial specification whilst certain features were deemed better suited fora second project, as they were spread among too many different areas of knowledge. Theprototype can measure in real-time, both from the physical monitor and at the applicationsAPI. It can also save earlier measurement sessions to be accessed whenever they might beneeded. / Vid installation av rör som är tänkt att hålla högt tryck så finns ett krav att tester utförs och dokumenteras så att utrustningen håller en viss standard. I dagsläget utförs detta arbete manuellt med en manometer och kräver en byggarbetare som håller översikt, ibland över ett tidsspann av flera timmar. En kund kom med en idé till ingenjörsbyrån Conmore om att automatisera denna process och på så sätt effektivisera arbetet och samtidigt eliminera handhavande fel i processen. En kravspecifikation skapades i samarbete med företaget, kunden och studenterna som arbetat på projektet, för att se till att alla parter skulle bli nöjda med färdig produkt. Den färdiga produkten resulterade i en prototyp som uppfyller alla minimikrav ur specifikation samt många fler funktioner som kunde läggas till utöver. Vissa funktioner bedömdes även mer lämpliga för ett ytterligare projekt då kunskapsområdet blev för brett för tidsspannet. Prototypen kan i dagsläget mäta tryck i realtid både via den fysiska displayen och på applikationens API. Den kan även spara mät sessioner i en databas för att hämtas när det behövs.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE / Bibliography: leaves 112-114. / by Mushtaq Ahmad Malik. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Bibliography: leaves 160-162. / by Altamash Kamal. / M.S.

Thesis (Nucl.E)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Includes bibliographical references. / by Abdelhamid Chenini. / Nucl.E

Thesis. 1975. M.S.--Massachusetts Institute of Technology. Dept. of Nuclear Engineering. / Includes bibliographical references. / This is a report of the experimental results of a program in countercurrent flow critical heat flux. These experiments were performed with Freon 113 at 200 psia in order to model a high pressure water system. An internally heated annulus was used to model a fuel pin in a channel. Only low flowrates were examined. The flow regime was always bubbly or slug, with the liquid primarily on the walls. It was found that critical heat flux of about .9 of the pool boiling value can be expected for up to 20% void. Beyond this, the CHF value decreases uniformly with void. Void fractions up to 70% were investigated, with the results being slightly conservative compared to a similar experiment carried out at atmospheric pressure by Avedisian. / M.S.

Thesis. 1976. Nucl.E.--Massachusetts Institute of Technology. Dept. of Nuclear Engineering. / Microfiche copy available in Archives and Science. / Includes bibliographical references. / by Pablo Moreno. / Nucl.E.

The ability to accurately measure surface and interfacial energies affects our understanding of friction, wear, bonding and adhesion. Although there are accurate ways to measure the surface energies of liquids, the surface energies of solids have been harder to characterize. In order to broaden the knowledge of adhesion of solids, a modification to the constrained blister test is proposed. Most of the previous work on constrained blisters has examined the debonding of the blister from the surface underneath as pressure is applied from below. In this thesis, the contact of the constrained blister with the flat surface above it is considered. In addition, the blister is given specified boundary conditions at its outer radius, which has a fixed value. Three models of the blister behavior are considered: linear plate, nonlinear plate, and membrane. The contact of the blister with the substrate above it is modeled with no adhesion, the JKR-type of adhesion, and the DMT-type of adhesion. Several substrate heights are considered, along with several values for the work of adhesion in the JKR analysis, and several combinations of force magnitude and gap size in the DMT analysis. The effect of adhesion on the contact radius is investigated. Sometimes the contact radius changes discontinuously as the pressure is increased or decreased. Results from the three models of blister behavior and the different models of adhesion are compared. / Master of Science