The purpose of this study was to develop a boiling map for liquid water at an atmospheric pressure. The map indicates the type of pool boiling phenomenon will initially occur in terms of the bulk temperature of the liquid and the interfacial contact temperature. The geometry studied was that of a flat horizontal plate with boiling incipient from the upward facing surface. Previous analytical and experimental studies have been conducted concerning pool boiling. Several of these studies are summarized in this thesis and it is seen that there are gaps and limitations in the existing state of knowledge. Therefore, further research is required especially in the area of subcooled departure from nucleate boiling and the related heat transfer mechanism. A pool boiling map was constructed within the bounds of the available information. The results agree with available experimental data.

Thesis. 1978. Sc.D.--Massachusetts Institute of Technology. Dept. of Chemical Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Bibliography: leaves 421-426. / by Jaime A. Valencia-Chávez. / Sc.D.

No description available.

Physical properties are fundamental to all chemical, biochemical and environmental industries. One of these properties is the normal boiling point of a compound. However, experimental values in literature are quite limited and measurements are expensive and time consuming. For this reason, group contribution estimation methods are generally used. Group contribution is the simplest form of estimation requiring only the molecular structure as input. Consequently, the aim of this project was the development of a reliable group contribution method for the estimation of normal boiling points of non-electrolytes applicable for a broad range of components. A literature review of the available methods for the prediction of the normal boiling points from molecular structure only, was initially undertaken. From the review, the Cordes and Rarey (2002) method suggested the best scientific approach to group contribution. This involved defining the structural first-order groups according to its neighbouring atoms. This definition also provided knowledge of the neighbourhood and the electronic structure of the group. The method also yielded the lowest average absolute deviation and probability of prediction failure. Consequently, the proposed group contribution method was then developed using the Cordes and Rarey method as a starting point. The data set included experimental data for approximately 3000 components, 2700 of which were stored in the Dortmund Data Bank (DDB) and about 300 stored in Beilstein. The mathematical formalism was modified to allow for separate examination and regression of individual contributions using a meta-language filter program developed specifically for this purpose. The results of this separate examination lead to the detection of unreliable data, the re-classification of structural groups, and introduction of new structural groups to extend the range of the method. The method was extended using steric parameters, additional corrections and group interaction parameters. Steric parameters contain information about the greater neighbourhood of a carbon. The additional corrections were introduced to account for certain electronic and structural effects that the first-order groups could not capture. Group interactions were introduced to allow for the estimation of complex multifunctional compounds, for which previous methods gave extraordinary large deviations from experimental findings. Several approaches to find an improved linearization function did not lead to an improvement of the Cordes and Rarey method. The results of the new method are extensively compared to the work of Cordes and Rarey and currently-used methods and are shown to be far more accurate and reliable. Overall, the proposed method yielded an average absolute deviation of 6.50K (1.52%) for a set of 2820 components. For the available methods, Joback and Reid produced an average absolute deviation of 21.37K (4.67%) for a set of 2514 components, 14.46K (3.53%) for 2578 components for Stein and Brown, 13.22K (3.15%) for 2267 components for Constantinou and Gani, 10.23 (2.33%) for 1675 components for Marrero and Pardillo and 8.18K (1.90%) for 2766 components for Cordes and Rarey. This implies that the proposed method yielded the lowest average deviation with the broadest range of applicability. Also, on an analysis of the probability of prediction failure, only 3% of the data was greater than 20K for the proposed method. This detailed comparison serves as a very valuable tool for the estimation of prediction reliability and probable error. Structural groups were defined in a standardized form and the fragmentation of the molecular structures was performed by an automatic procedure to eliminate any arbitrary assumptions. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2004.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1980. / Includes bibliographical references. / by Ifiyenia Kececioglu. / Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1980.

Heat transfer to boiling liquids is of primary industrial importance. Surprisingly enough organized study of the variables which affect heat transfer to boiling liquids has been far less than proportional to the industrial usage of this type of heat transmission. Perhaps the least investigated phenomenon involved in heat transfer to boiling liquids is the so~called critical state or maximum in the rate of heat transfer-thermal driving force relationship. This maximum or peak is believed to be caused by a change in the type or method of heat transfer from the heating surface to the boiling liquid. The system is said to pass from a state of nucleate boiling through the maximum to a state of film boiling. The critical point is known to very for various liquids yet no adequate correlations were found which would provide a prediction of the characteristics of heat transfer for binary mixtures of liquids. In as much es ethanol and benzene are used extensively in industry they were selected for use in this investigation. The purpose of this investigation was to determine the characteristics of heat transfer from a horizontal silver surface to boiling mixtures of ethanol and benzene. A horizontal plate evaporator, with the necessary accessory equipment for measurement and control, was designed and constructed. The test liquids were prepared for concentrations of ethanol in benzene from 0 to 100 per cent in 10 volume per cent increments. These test liquids were charged to the evaporator and the characteristics of heat transfer determined by a series of steady state conditions of heat transfer. The rate of heat transfer was evaluated from the wattage input to the electrical heating unit. The temperature gradient between the heating surface and the main body of liquids was determined by evaluating the readings of thermocouples placed in the liquid space and the heater plate. The maximum rate of heat transfer was considered equivalent to the heat flux which caused the boiling system to shift through the maximum in the heat flux-temperature gradient relationship. The critical temperature gradient was obtained by an extrapolation of the heat flux-temperature gradient curve to maximum heat flux. The general conditions for the tests were: heat transfer surface, silver; cold liquid height in evaporator, 4—1/2 inches; evaporator diameter, 1·31/32 inches. The tests were made at normal atmospheric pressure which varied from 710.0 to 718.0 millimeters of mercury pressure. Steady state conditions of heat transfer were established before data was taken. / Master of Science