Thesis (M.S.)--University of Wisconsin--Madison, 1968. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

An experimental study was performed in which an ammonia-water solution was desorbed within a branching fractal-like microchannel array. The solution entered in the center of a disk, and flowed out radially until discharging in to a gravity-driven separation chamber. Heat was added to the ammonia-water through a thin wall, above which flowed heat transfer oil in a separate branching fractal-like microchannel array. Such arrays have been shown to utilize the increased heat transfer coefficients seen in parallel channel arrays; however, they do so with a lower pressure drop. An experimental flow loop consisting of ammonia-water and heat transfer oil sub-loops was instrumented along with a test manifold for global measurements to be taken. Temperature, pressure, density and mass flow rate measurements permitted calculation of desorption and heat transfer characteristics. Parameters included oil mass flow rate, oil inlet temperature, and strong solution flow rate, while strong solution concentration, temperature, and weak solution pressure were kept constant. The desorber was assumed to achieve equilibrium conditions between the vapor and weak solution in the separation chamber. The exit plenum was large and acted as a flash chamber, making the assumption reasonable. The vapor mass fraction was determined from knowledge of the weak solution saturation temperature. Heat exchanger analyses (LMTD and ε-NTU) were done to determine the heat transfer characteristics of the desorber. Calculated values of UA are shown to be as high as 5.0 W/K, and desorber heat duties were measured as high as 334 W. Strong solution, at 0.30 mass fraction, was desorbed into weak solution and vapor with concentrations ranging from 0.734 to 0.964. Circulation ratios, defined as strong solution mass flow rate per unit desorbed vapor mass flow rate, varied in this study from 3.4 to 20. A method for specifying desorber operating conditions is described, in which a minimum desorber heat input per unit vapor flow rate is determined at an optimum circulation ratio. A description of how the circulation ratio behaves as a function of strong solution mass flow rate, oil flow rate, and the maximum temperature difference between oil and ammonia-water solution is shown. / Graduation date: 2006

No description available.

No description available.

Bibliography: leaves 114-119.

No description available.

M.Ing. / Heat transfer and pressure drop characteristics during in-tube condensation of nonazeotropic mixtures of R22/R142b in a smooth helically coiled copper tube with an inside diameter of 8.11 mm are investigated. The experimental results are compared with prediction from correlation. The coefficient of performance of.the heat pump built and used for experiments has been studied. The mass flux of the refrigerant was varied during the course of the experiments. At similar mass flow rate of fluids, the average heat transfer coefficients for mixtures were lower than those for pure refrigerant R22 used as reference for comparison. Also, the heat transfer coefficients of all the refrigerants increased with increasing mass flux.

Heat transfer and pressure drop during condensation of propane flowing through minichannels is investigated in this study. Studies of condensation of hydrocarbons are important for applications in the petrochemical industry. Insights into the mechanisms of propane condensation are required for accurate design of heat transfer equipment for use in hydrocarbon processing. At present, there is very little research on vertical condensation, especially of hydrocarbons, for the tube sizes and flow conditions of interest to the present study. An experimental facility was designed and fabricated to measure the frictional pressure drop and heat transfer coefficients during condensation of propane in plain tubes with an inner diameter of 1.93 mm. Measurements were taken across the vapor-liquid dome in nominal quality increments of 0.25 for two saturation temperatures (47°C and 74°C) and four mass flux conditions (75 – 150 kg m‾² s‾¹). The data were compared to the predictions of relevant correlations in the literature. The data from this study were also used to develop models for the frictional pressure drop and heat transfer coefficient based on the measurements and the underlying condensation mechanisms. These results and the corresponding correlations contribute to the understanding of condensation of hydrocarbons in vertical minichannels.