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The thermal conductivity of gases has been the subject of experimental investigations over a period of several decades (54). The thermal conductivity (hereafter simply referred to as the "conductivity"), being, from a physical point of view, one of the basic properties of a gas, much of the classical kinetic theory was concerned with its interpretation. Its measurement was to examine the validity of the theory. The limits of this validity were similar to those imposed on the theory by other gaseous properities, which lead to the concept of the "ideal gas". As to the conductivity, the behaviour of the majority of naturally occuring gases approximated closely that of the "ideal gas" under normal conditions, i.e. at moderate or room temperatures and a pressure range up to atmospheric pressure. Serious deviations from experimental data occured, however, when it was attempted to apply the theory to gases at higher temperatures and pressures.[...]

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Call number: LD2668 .T4 1963 S82 / Master of Science

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The combustion of a low heating value gas in a swirl burner is investigated. The investigation covers the development of a finite difference analysis of the flow and combustion processes in such a burner. In conjunction with the analytical work, an experimental program was conducted to provide detailed measurements of the three-dimensional velocity distributions within the flow field. The dissertation emphasizes the development and solution of the mathematical model. The finite difference analysis uses the primitive variables of velocity and pressure to describe the flow field. Features of the solution algorithms of several previous authors are incorporated into the analysis. A unique feature of the current approach is the use of a non-staggered grid system. An additional feature is a very straightforward technique for handling boundary conditions which eliminates the need for special treatment of the finite difference equations at boundary points. The solution algorithm is given the acronym CENSIS, derived from CENtered-Cell-Implicitly-Staggered. To illustrate the incorporation of the algorithm into a computer code, a sample program is developed to solve a simplified problem which has a closed form solution. This program, CENCIS-T, is included. Calculations are presented for the swirl burner, and the predicted results are compared with experimental data. The program used for the calculation of swirl burner performance is a more general code called PRIMCO. The PRIMCO code includes variable density and viscosity effects and incorporates a two-equation turbulence model for the Reynolds stress terms. The PRIMCO code also uses a simplified, infinite reaction-rate combustion model. Because of the use of the non-staggered grid system, the CENCIS solution algorithm is less complicated than previous algorithms. As compared to a staggered grid system approach, the current algorithm requires approximately one- third the computations of the former approach. These advantages make this approach considerably easier to code and relatively easy to apply. / Ph. D.

Air may be considered a mixture of diatomic nitrogen and oxygen in which all internal molecular energies including molecular vibration are considered. This leads to an adequate thermodynamic description of air up to dissociation. The thermodynamic and transport properties of this "vibrationally excited" gas are presented and compared with those of a perfect gas (which does not include vibration), and of a dissociating gas in chemical equilibrium. The effects of the vibrationally excited gas on Viscous-Shock-Layer flows are then analyzed and compared for a 7° tangent sphere-cone at zero and five degs angle of attack and at altitudes between 50 and 200 kft. The nose radius is 0.15 ft and the body is 30 nose radii long. The wall temperature and freestream velocity are constant at 2,000 °K and 25,000 ft/sec, respectively. In general, the vibrationally excited gas results are more accurate than perfect gas, and computationally much faster than equilibrium. The vibrationally excited gas also shows potential for use in the nonequilibrium flow regime where the chemical reaction rates are too high for the "stiff" finite-rate equations. This and other areas for additional research are discussed. / M.S.

Thesis. 1976. Sc.D.--Massachusetts Institute of Technology. Dept. of Chemical Engineering. / Microfiche copy available in Archives and Science. / Bibliography: leaves 225-237. / Sc.D.

This thesis examines the transient response of a packed bed heat regenerator when heated from an initial uniform bed temperature. Very large (1700 K) temperature differences were studied as well as the effect of simultaneous chemical reaction in the gas phase. First the effects of temperature on physical and transport properties were studied in detail in the absence of a reaction. Models with compressible flow were compared with conventional models with constant properties and incompressible flow. Several measures of the regenerator's response to a step change in inlet gas temperature were calculated to characterize the spread of the temperature front. Variances of the spatial derivative of the gas temperature profile and the time derivative of the product gas temperature were used to evaluate thermal efficiency. The effects of an exothermic homogeneous gas phase reaction in the regenerator process were also studied. Several simple kinetic schemes and inlet conditions were simulated and the profiles of reaction rate and conversion as well as temperature were analyzed. / Graduation date: 1993