Theoretical Analysis and Numerical Simulation of Spectral Radiative Properties of Combustion Gases in Oxy/Air-Fired Combustion Systems

Energy efficiency is one of the major objectives which should be achieved in order to implement the limited energy resources of the world in a sustainable way. Since radiative heat transfer is the dominant heat transfer mechanism in most of fossil fuel combustion systems, more accurate insight and models may cause improvement in the energy efficiency of the new designed combustion systems. The radiative properties of combustion gases are highly wavelength dependent. Better models for calculating the radiative properties of combustion gases are highly required in the modeling of large scale industrial combustion systems. With detailed knowledge of spectral radiative properties of gases, the modeling of combustion processes in the different applications can be more accurate. In order to propose a new method for effective non gray modeling of radiative heat transfer in combustion systems, different models for the spectral properties of gases including SNBM, EWBM, and WSGGM have been studied in this research. Using this detailed analysis of different approaches, the thesis presents new methods for gray and non gray radiative heat transfer modeling in homogeneous and inhomogeneous H2O–CO2 mixtures at atmospheric pressure. The proposed method is able to support the modeling of a wide range of combustion systems including the oxy-fired combustion scenario. The new methods are based on implementing some pre-obtained correlations for the total emissivity and band absorption coefficient of H2O–CO2 mixtures in different temperatures, gas compositions, and optical path lengths. They can be easily used within any commercial CFD software for radiative heat transfer modeling resulting in more accurate, simple, and fast calculations. The new methods were successfully used in CFD modeling by applying them to industrial scale backpass channel under oxy-fired conditions. The developed approaches are more accurate compared with other methods; moreover, they can provide complete explanation and detailed analysis of the radiation heat transfer in different systems under different combustion conditions. The methods were verified by applying them to some benchmarks, and they showed a good level of accuracy and computational speed compared to other methods. Furthermore, the implementation of the suggested banded approach in CFD software is very easy and straightforward.

Extending the Hydra Head to Create a Pluggable, Extensible Architecture: Diving into the Technology of Hydramata

Presentation at Open Repositories 2014, Helsinki, Finland, June 9-13, 2014

Host Parasite Interactions in Damselflies. From Individuals to Populations

The main goal of this thesis is to increase understanding on evolutionary and ecological factors that have contributed to differences in parasite numbers in insects. Furthermore, the thesis addresses the effects of parasites on their hosts. The most important findings were: The Northern damselfly’s (Coenagrion hastulatum) immune response to artificial pathogen increased with increasing parasite numbers (Article I). Marginal, more isolated C. hastulatum populations on the edge of distribution have fewer parasites when compared to distribution’s core populations (Article II). The Banded damselfly Calopteryx splendens individuals with higher homozygosity have more parasites, however, the rate of homozygosity did not differ between populations (Article III). Parasite prevalence was affected by whether the host species occurred in allopatric or sympatric population: sympatric C. splendens populations with sister species the Beautiful damselfly Calopteryx virgo harbored more parasites (Article IV). Parasites were associated with the wing spot size, an ornament under sexual selection, and thus may play an important role in character displacement, i.e. the size of the wing spot (Article V). To conclude with, this thesis brings about new information on the parasite infection patterns in insects, proposing several factors to contribute to these patters, as well as it addresses the effects of parasites on their hosts, from individual to population level.