No description available.

The chemiluminescent species CH* and OH* are studied in premixed methane combustion to investigate the possible application of their light emissions in gas turbine combustion monitoring systems. The interpretation of integrated and local chemiluminescence measurements are shown to give important qualitative insights into the burning process. The formation path of OH* chemiluminescence is clarified and an accurate chemical kinetic model predicting OH* chemiluminescence emission is developed using GRIMECH 3.0 as a starting point for methane oxidation. CH* chemiluminescence is also modeled but difficulties in obtaining quenching data make the modeling efforts somewhat less successful than that for OH* chemiluminescence. Two combustion models are developed. The first is a semi-empirical model for a Bunsen type flame. The second is a 1-D model for a ceramic honeycomb flat-flame burner using the full chemical kinetics description of the conversion from fuel to products along with a detailed energy equation, accounting for the radiation energy exchange between hot gases and the honeycomb burner ceramic. The results of the modeling calculations show that OH* is superior to CH* chemiluminescence in terms of indicating heat-release rate. The formation of the ratio between CH* and OH* chemiluminescence is shown to be an accurate indicator of equivalence ratio. / Master of Science

Thesis (M.S.)--University of Michigan, 1975.

Thesis (M.S.)--University of Michigan, 1975.

An automated luminometer was designed and constructed to facilitate the investigation of reaction conditions and quantitation of the chemiluminescence observed during the oxidation of NADH by horseradish peroxidase in the presence of eosin. The luminometer design incorporates a computer controlled reagent induction system, pulse counting detector and real time display of luminescence profiles. Each of the major reaction conditions was studied individually to determine the most favorable conditions for the analytical application of this reaction. In addition, this chemiluminescent reaction was studied to determine if the luminescing species is recycled. If this were the case it would provide the first essential step necessary for the future design of a chemiluminescent probe that could be reusable or be used for continuous monitoring. During the course of this investigation it was observed that the luminescing species, eosin, was being bleached. A number of experiments were undertaken to determine the nature of the bleaching process. Those steps which suppressed the bleaching process, unfortunately, also suppressed the emission process. Despite the fact that this reaction does not appear to recycle the luminescing species, it does provide a chemiluminescent method for the determination of NADH over the range 5x10⁻⁶ M to 5x10⁻⁴ M. This chemiluminescent reaction has also been coupled to several enzyme systems, which reduce NAD⁺ to NADH, in order to obtain a chemiluminescent signal proportional to the substrate concentration. / Ph. D.

No description available.

Graduation date: 1995

none

Electrochemical and electrogenerated chemiluminescence properties of the BODIPY (boron dipyrromethene) dyes are presented. Some specific features of the BODIPY dyes are obtained and described in the current dissertation. Separation of around 1.0-1.2 V is noticed between two oxidation and reduction waves for one center which is very different from 0.5 V seen for the polycyclic hydrocarbons. Cathodic and anodic stability is shown to depend upon absence or presence of certain degree of substitution. Different ways of electrochemical dimerization are explored and compared with the chemical dimerization. Photophysical and electrochemical properties of monomer, chemically synthesized dimer, trimer and polymer are described and the characteristic features determined. / text

Pressure pulsations, or thermoacoustic instabilities, as they are called in the research community, can cause extensive damage in gas turbine combustion chambers. To understand the phenomena related to thermoacoustics, a simple Rijke-type tube combustor was built and studied. Extensive experimental results, as well as theoretical analyses related to the Rijke tube are presented in this thesis. The results, attributable to both the analyses and the experiments, help explain all the phenomena affecting the acoustic pressure in the combustor. The conclusion is that there are three separate yet related physical processes affecting the acoustic pressure in the tube. The three mechanisms are as follows: a main thermoacoustic instability in accordance to the Rayleigh Criterion; a vibrating flame instability where the flame sheet exhibits mode shapes; and a pulsating flame instability driven by heat losses to the flame stabilizer. All these instabilities affect the heat released to the gas in the combustor. The energy from the oscillating heat couples with the acoustics of the volume bounded by the tube structure. The experimental results in the study are important in order to obtain model parameters for prediction as well as for achieving control of the instabilities. / Master of Science