No description available.

No description available.

The purpose of this study is to develop an accurate model of the downcomer of the once-through steam generator (OTSG) developed by Babcock & Wilcox, using RELAP5/MOD2. While the physical model can be easily developed, several parameters are left to be adjusted to optimally model the downcomer and match data that was retrieved in a first-of-a-kind (FOAK) study conducted at Oconee Unit I in Oconee, South Carolina. Once the best-fit set of parameters has been determined, then the model must be tested for power levels exceeding that for which the steam generator was originally designed, so as to determine the power level at which a phenomenon known as flood-back becomes a concern. All known previous studies that have been conducted using RELAP5/MOD2 have shown that RELAP over-predicts interphase friction. However, all of those studies focused on heated two-phase upflow, whereas the downcomer is modeled as adiabatic two-phase downflow. In this study, it is found that the original slug drag model for RELAP5/MOD2 developed by Idaho National Engineering Laboratory (INEL) under-predicts the interphase friction between the liquid and vapor phase within the downcomer. Using a modified version of the original slug drag model created by Babcock & Wilcox (B&W), an optimum multiplier is found for each power level. An increase of 1181% in interphase friction over the INEL slug drag model, which equals an increase of 4347% for the default B&W model provides the most accurate results for all power levels studied. Emphasis is also placed on modeling the orifice plate of the OTSG downcomer which has been added to stabilize pressure fluctuations between the downcomer and tube bundle of the OTSG. While several different schemes are explored for modeling the orifice plate, a branch connection with an inlet area 14.22% of that of the downcomer is used to model the orifice plate along with the volume that transitions the two-phase downflow to horizontal flow into the tube nest of the OTSG. Power levels exceeding that for which the steam generator was designed are tested in RELAP using the slug drag multiplier to determine at which power level a liquid level would occur and would flood-back become a concern. In this study, it is determined that a liquid level would form at 135% power and that at any higher power level, flood-back would be of concern for any user of the steam generator. / Master of Science

No description available.

No description available.

This research is concerned with the presentation of pressure drop experimental results across a restriction of trefoil geometry (tube support plate) used in steam generators. The pressure drops were obtained for single-phase and two-phase of air, water, and their mixtures. The tests were performed at atmospheric conditions (pressure and temperature). The loss coefficients associated with these pressure drops were experimentally determined, and empirical correlations for the results were developed. The results were compared with previous studies done on other geometries with air-water mixtures, and also to a similar geometry with steam-water mixture.

The results of an experimental investigation of the separation phenomena in dividing two-phase flow is presented. This work involved the commissioning of a steam-water loop to obtain detailed data on the characteristics of steam-water flow in a horizontal tee junction. Measurements included the pressure and void fraction distributions as well as the total flow rate and quality along the inlet and branching legs. A detailed set of experiments were performed enabling the effects of flow split, inlet quality and inlet mass flux on the separation and pressure characteristics to be determined. For the annular inlet flow conditions considered herein, total separation was approached when more than 40% of the inlet flow was removed through the branch. At lower branch flow rates, the degree of phase separation was strongly dependent on the branch flow split and the inlet quality. The pressure change from the inlet through the run of the tee was modelled from an axial momentum balance at the junction for both homogeneous and separated flow assumptions. The separated flow momentum correction factor was distributed about a value of unity indicating that the branching flow carriers little or no axial component of momentum. The pressure change from the inlet through the branch was considered in terms of reversible an'd irreversible components for separated and homogeneous flow assumptions. Both models yielded loss coefficients that were strongly dependent on the branch flow split and inlet quality. / Thesis / Master of Engineering (ME)

Principles of concurrent development are applied to the design of a small-scale device for converting natural gas or liquefied petroleum gas into hydrogen. The small hydrogen generator is intended for serial production for application in the production of industrial hydrogen, fueling stationary fuel cell power systems and refueling hydrogen-fueled fuel cell electric vehicles. The concurrent development process is contrasted with the traditional, linear development process for petrochemical systems and equipment, and the design is benchmarked against existing small hydrogen generators as well as industrial hydrogen production apparatus. A novel system and hardware design are described, and a single cycle of concurrent development is applied in the areas of catalyst development, thermodynamic optimization, and reactor modeling and design. The impact of applying concurrent development techniques is assessed through economic modeling, and directions for future development work are identified. / Ph. D.

Influence of steam-treatment upon properties, structure, and composition of red oak was investigated. Small specimens of red oak heartwood were submitted to steam-treatments at atmospheric pressure for 1.5, 3, 6, 12, 24, 48, and 96 hours. Short steaming induced little or no changes in the properties and the composition of red oak. Prolonged steaming, however, resulted in significant changes in physical and mechanical properties as well as in structure and chemical composition of wood. Shrinkage increased significantly with increasing steaming time. After 96 hrs of steaming volumetric shrinkage to the air-dry condition was 4.4 times that of the non-treated wood and was thus indicative of cell wall collapse. Specific gravity and equilibrium moisture content were decreasing and air-dry density was increasing with an increase in steaming time. Color of wood became darker and the fluid content brighter with prolonged steaming. / Ph. D.

In attempting to use the 4-1 mixture for Boiler No. 6 in the Virginia Polytechnic Institute Heating and Power Plant, the problem of maintaining proper depth of field bed had arisen. This problem seemed to warrant an investigation, which was subsequently made. The fuel bed depth that will give the best results for a boiler depends on many factors, and it is best determined by boiler tests. Therefore, the authors decided to investigate the effect of the field bed depth on the boiler performance and to determine the optimum field bed depth, when the 4-1 mixture was used and the load was 50,000 pounds of steam per hour. This investigation consisted of the collection and evaluation of data obtained from the boiler tests at various field bed depths. During the boiler tests, some of the variables were held as constant as possible in order to obtain comparative results. The fuel bed depths tested were 2-¾, 4, and 5-½ inches. The optimum depth of fuel bed is that fuel bed which would give the highest boiler efficiency and good boiler control. The results of the tests showed that the boiler efficiency remained approximately constant between 2-¾ and 4 inches of the fuel bed depths and decreased as the fuel bed depth was increased above 4 inches. But, at 2-¾ inches of the fuel bed, close attention was necessary to control the boiler, whenever the load swung, or there was a change of the quality of fuel fed into the furnace. The authors, therefore, conclude that Boiler No. 6 should have a fuel bed depth between 3 and 4 inches deep when the 4-1 mixture is used and the load is about 50,000 pounds of steam per hour. / Master of Science