Detailed chemical kinetic models are important to the understanding and prediction of combustion properties. Better estimations require an accurate description of thermochemistry and kinetic rate parameters. This study identifies important reaction pathways at the low temperature chemistry of branched conventional and alternative fuels. Rate constants and branching ratios for important reactions are provided and important phenomena are investigated. The thermochemistry and kinetics of the 2-methylhexane model, an important component in gasoline surrogate, is updated using recent group values and rate rules from the literature. New reactions, such as hydroperoxyalkylperoxy (OOQOOH) alternative isomerization, are also added to the model. The results show that both conventional and alternative isomerization of OOQOOH radicals significantly affect the model reactivity. The kinetics of a biofuel; iso-butanol, is also investigated in this study to understand alcohol combustion chemistry and identify sensitive reactions that require more attention. The results indicate that iso-butanol is sensitive to the chain propagation reaction of α-RO2 radical and the water elimination of γ-QOOH. Because both reactions decrease model reactivity, accurate rate constants are needed to correctly determine fuel reactivity. In light of the above mentioned kinetic modeling studies, high levels computational chemistry calculations were performed to provide site-specific rates rules for OOQOOH conventional isomerization considering all possible reaction sites. This is also one of the first studies to investigate the effect of chirality on calculated rate constants. Results indicate that chirality is important when two chiral centers exist in the reactant. OOQOOH alternative isomerization rate constants are usually assigned in analogy to the isomerization of an alkylperoxy (RO2) radical which may introduce some uncertainty. To test the validity of using analogous rates, this study calculates the rate constants for selected alternative isomerization reactions. The effect of intramolecular hydrogen bonding in the calculated energies and rate constants for different reaction pathways is investigated. The result shows that alternative isomerization is a competing pathway only when it proceeds via a less strained transition state relative to the conventional isomerization transition state. A detailed analysis of the hydrogen bonding effect helped to identify cases where assigning rates in analogy may not be valid.

Porous materials have application in adsorption based processes due to their high internal surface area and tailorable pore size. They find uses in fields such as catalysis, separation, biotechnology, and microelectronics. Fluids confined in such materials exhibit interesting behavior in regards to the condensation and evaporation mechanisms. Understanding study the behavior of fluids confined in these porous materials is necessary for the efficient design of these materials. The adsorption/desorption isotherm provides valuable information about the effect of network features like pore connectivity and pore size distribution on fluid behavior during pore condensation and evaporation. Such insight can be useful in the characterization of these porous materials. Three dimensionally ordered mesoporous (3DOm) carbon is a porous material that has recently emerged and is of interest. These porous structures are obtained from templating colloidal crystals formed from lysine-silica nanoparticles. The resulting structure consist of spherical pores connected to each other by windows. Due to the use of silica nanoparticles a range of tunable pore sizes can be obtained. These structures have high degree of order. They find applications in the synthesis of zeolites due to their highly controllable pore size. Hence a study of the adsorption properties of these structures is of importance. Molecular modeling has proved effective in the study of porous materials. The development of the density functional theory (DFT) and the dynamic mean field theory (DMFT) has led to great advances in the study of the behavior of confined fluids. The DFT enables the study of the adsorption desorption hysteresis phenomena of confined fluids. The DMFT describes the density profile versus time for a step change in relative pressure on the isotherm. These theories have been applied in the past to two dimensional model pore networks to investigate the mechanisms of adsorption and desorption. In this research project we aim to apply the same to various model 3DOm carbon pore networks. Studying the density distributions in these networks can help understand the thermodynamics of fluid adsorption and desorption in these structures. The results could be useful in understanding the effect of pore structure features like pore size and windows on adsorption and desorption. Also the effect of disorder in the pore network as well as effect of variation in pore size on fluid behavior can be studied. Study of the dynamics of adsorption gives an insight into the nucleation mechanisms that govern the condensation of fluid in the pore. These results could prove useful in the characterization of these porous structures.

This study was performed under the motivation to find a scheme that could describe the complex behavior of cardiovascular homeostasis. This is hypothesized to be manifested in a thermodynamic description of the cardiovascular system (CVS). Seen from a thermodynamic framework, the mechanics of blood flow can be gauged in similar terms as metabolic exchange at the capillaries - thereby providing a holistic and novel perspective on overall CVS function. Entropy generation, a thermodynamic calculation, represents lost work and is hypothesized to reveal something about the "optimal" state of the CVS. In particular, it is hypothesized that the CVS state that generates minimal entropy, given certain constraints, will be physiologically preferred and that cardiovascular control operates to find this state. This will be tested by first proposing a method to calculate entropy generation in the CVS, and secondly characterizing entropy generation across unique CVS states by simulation of a mathematical model.

Calorimetrically determined ΔH° values are given for the stepwise formation of chelate species between serinate ion and the divalent metal ions of Co, Ni, Cu, Zn, and Cd. These values of ΔH° are compared with those reported in the literature and were combined with values of ΔG° (log K) found in the literature to calculate values of ΔS°. These values of ΔG° and ΔS° are listed also. A new method of standardizing dilute ferrous ion solutions is reported. This procedure makes use of the thermometric titration technique to detect the equivalence point for the reaction of K_2Cr_2O_7 with ferrous ion. A method is described which makes use of dilute ferrous ion solutions to determine the concentration of 2,2'-bipyridine in aqueous solution. It was found that the 2,2'-bipyridine concentration decreases with time.

A thesis submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 1990 / This work was carried out in response to the need for a simple engineering method for the thermal analysis of direct-contact air-water heat exchangers. A simple method of performance analysis is developed which is directly analogous and consistent with the fundamental approach used in conventional heat exchanger analysis and one in which the algebraic form of the overall equation and the grouping of each of the parameters are apparent. The range of conditions considered are air and water temperatures of between 0 and 50 DC and barometric pressures ranging from 80 to 120 kPa. The air conditions considered range from completely dry to completely satucated with water vapour. Both air cooling and water cooling processes are considered. [Abbreviated abstract. Open document to view full version]

The problem consists of measuring accurately the free energy of formation, heat of formation, entropy, and solubility product constant of silver and mercury sulfides, and is a part of a larger study extending to many other metal sulfides. The confusion now existing in the chemical literature amply justifies a study of this nature. The thermodynamic properties of several important metal sulfides have never been measured, and the only values available for them are estimates. Determinations of the properties of many other metal sulfides have been carried out, but the results given by different authors often differ widely.

Charge transfer complexes were studied spectrophotometrically in the liquid state by a modified Benesi-Hildabrand method. TiCl_4 - Benzene and TiCl_4 - diphenyl ether solutions were found to form contact charge transfer complexes, that is complexes with very weak and non-directional interactions. The systems TiCl_4 - anisole and TiCl_4 - diethyl ether form complexes of the types AD and AD_2 where A stands for TiCl_4 and D stand s for the organic donor. The formation constants for the complexes were, for the TiCl_4 - anisole, K_1 = 0.077, K_2 = 0.01; and TiCl_4 - diethyl ether, K_1= 3.0, K_2 = 1.0. The system TiCl_4 - tetrahydrofuran was also examined and found to form a complex whose formation constant is 0.58. An infrared spectrophotometric study was made of the contact charge transfer complexes TiCl_4 - diphenyl ether and TiCl_4 - p-xylene, and there was no evidence of any band due to the complex itself. However, the TiCl_4 - ether complexes were studied by infrared in the liquid state for the ethers p-dioxane, dimethyl ether, diethyl ether, tetrahydrofuran, and anisole, and absorption maxima were present which were due to the complexes. It was concluded that AD and AD_2 complexes exist in each of these systems. It was also concluded that the bonding in each case was from the oxygen of the ether to the titanium of the TiCl_4 , and that the Ti was dsp^3 hybridized for the DA complexes and d^2sp^3 for the D_2A complexes. An x-ray study was made of the solid 1:1 TiCl_4 - anisole complex. The crystal was found to be orthorhombic with parameters a = 19.426, b = 17.098 and c = 6.744 Å. The space group was found to be Cmcm. The density of the solid was 1.7. From this it was concluded that there were eight molecules per unit cell. The most reasonable way the eight molecules could be arranged in the unit cell consistent with the symmetry requirements is with the oxygen bonded to the titanium. A heat of mixing calorimeter was constructed in which the heats of mixing of volatile liquids could be measured. The calorimeter was a two piece metal container whose top and bottom compartments were separated by aluminum foil. The calorimeter had internal vanes which increased heat conduction and aided the solenoid actuated plunger-stirrer. The calorimeter was equipped with a poly ethylene diaphragm so that, when pressure loaded, there was no vapor phase and near constant pressure was maintained. The heat capacity of the calorimeter and its contents were determined with every run and used in the calculation of the heat of mixing of that run. The heat of mixing of the system N,N-dimethylacetamide - CCl_4 was measured as a function of mole fraction CCl_4 (x). The data can be expressed to within 1% of the maximum value by the equation Δ H_M = x(1-x)[- 590.8+294.7(2x-1)+89.5(2x-1)^2+187.5(2x-1)^3+264(2x-1)^4)

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