Thesis (M.Eng. (Chemical Engineering)) -- University of Pretoria, 2007. / Includes bibliographical references (leaves 66-70)

Thesis (Ph. D.)--University of Iowa, 1929. / Vita.

Thesis (Ph.D.)--Lehigh University, 2001. / Source: Dissertation Abstracts International, Volume: 61-11, Section: B, page: 6081. Adviser: Arnold R. Marder.

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.

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

No description available.

Thesis (M.S.)--Virginia Polytechnic Institute, 1951. / Abstract. Vita. Includes bibliographical references (leaves 30-31). Also available via the Internet.

Please read the abstract in the section front of this document / Dissertation (MEng(Metallurgical Engineering))--University of Pretoria, 2006. / Materials Science and Metallurgical Engineering / unrestricted

No description available.

A typical failure in a heat exchanger is the breakdown of a tube due to impact-sliding wear. We investigate the dynamic behavior of a tube subjected to cross flow and study the stability of periodic solutions, bifurcations, and the route to chaos. The fluid-stiffness-controlled mechanism is chosen to represent the fluid forces and the impact forces are modeled by a piece-wise-Iinear spring. A two-point boundary-value algorithm is used to calculate periodic solutions and Floquet theory is used to study their stability. Poincare sections and bifurcation diagrams are used to study non-periodic solutions. Furthermore. for this autonomous system, the method of harmonic balance appears to be less suited than the two-point boundary-value algorithm for calculating periodic motions. For the case of a single-mode approximation. the results show that the tube undergoes relaxation oscillations and hence no bifurcations occur for fluid velocities ranging from 1.1 Ve to 3.0 Ve, where Ve is the critical fluid velocity. For the cases of two- and three-mode approximations. the results show that periodic solutions undergo bifurcations leading to chaos. Consequently. we conclude that chaos is the result of modal interactions. Observing the details of impacts. we also conclude that chaos appears when a second impact occurs on the same stopper. We also found intermittent chaos alternating with transient periodic motions. Lastly, we estimate the mean impact forces and mean impact-sliding wear work rates and compare them with previous results. / Master of Science