In an effort to reduce NOX emissions both in the landing and take-off (LTO) cycle as well as in cruise, significant research has been conducted on novel aero-engine low emissions combustor design concepts. Preliminary combustor design and emissions prediction software tools are becoming increasingly important during the conceptual design phase of aero-engine combustors. They allow a large number of designs to be explored, in a relatively short amount of time, thereby identifying the most promising designs to consider for further development. There are three methods for NOX emission prediction; correlations, stirred reactor models and CFD models. Correlation methods are derived from experimental results and are therefore only applicable for combustors for which data is available. The stirred reactor modelling approach provides a reasonably good compromise with respect to computational time and robustness relative to correlation and CFD based methods. The stirred reactor method assumes finite rate chemistry inside the combustor using simplified chemical kinetic models. The basic concept of the reactor-based method is to split the combustor into a number of reactors (perfectly or partially stirred) to compute the overall emissions. The primary objective of this doctoral research was to assess the suitability and limitations of the stirred reactor modelling approach to predict NOX emissions of a Rich-Burn Quick-Quench and Lean-Burn (RQL) combustor concept. The geometry of the RQL combustor and the model constraints were assumed from a NASA test rig experiment. The stirred reactor emission prediction model developed was verified using this test data. The results suggest that, based on the modelling assumptions made, the stirred reactor modelling approach is able to capture the trends of emissions (with changing boundary conditions) even though there are discrepancies in the absolute values. This suggests that the stirred reactor model is a useful tool during the preliminary design phase to quantify the impact of changes in boundary conditions/design parameters on changes in NOX emissions.

This dissertation focuses on the application of Monte Carlo (MC) molecular simulation and Molecular Dynamics (MD) in modeling thermodynamics and flow of subsurface reservoir fluids. At first, MC molecular simulation is proposed as a promising method to replace correlations and equations of state in subsurface flow simulators. In order to accelerate MC simulations, a set of early rejection schemes (conservative, hybrid, and non-conservative) in addition to extrapolation methods through reweighting and reconstruction of pre-generated MC Markov chains were developed. Furthermore, an extensive study was conducted to investigate sorption and transport processes of methane, carbon dioxide, water, and their mixtures in the inorganic part of shale using both MC and MD simulations. These simulations covered a wide range of thermodynamic conditions, pore sizes, and fluid compositions shedding light on several interesting findings. For example, the possibility to have more carbon dioxide adsorbed with more preadsorbed water concentrations at relatively large basal spaces. The dissertation is divided into four chapters. The first chapter corresponds to the introductory part where a brief background about molecular simulation and motivations are given. The second chapter is devoted to discuss the theoretical aspects and methodology of the proposed MC speeding up techniques in addition to the corresponding results leading to the successful multi-scale simulation of the compressible single-phase flow scenario. In chapter 3, the results regarding our extensive study on shale gas at laboratory conditions are reported. At the fourth and last chapter, we end the dissertation with few concluding remarks highlighting the key findings and summarizing the future directions.

This master's thesis informs its reader about actual energetical situation of Poland and its probable future. The thesis focus on shale gas resesources in the world and Poland and methods of its mining and procesing. Main problematics of determining, designing and technology of TEG dehydration unit were described in this thesis.

Anisotropy of hydraulic properties of the subsurface geologic formations is an essential feature that has been established as a consequence of the different geologic processes that undergo during the longer geologic time scale. With respect to subsurface reservoirs, in many cases, anisotropy plays significant role in dictating the direction of flow that becomes no longer dependent only on driving forces like the pressure gradient and gravity but also on the principal directions of anisotropy. Therefore, there has been a great deal of motivation to consider anisotropy into the subsurface flow and transport models. In this dissertation, we present subsurface flow modeling in single and dual continuum anisotropic porous media, which include the single-phase groundwater flow coupled with the solute transport in anisotropic porous media, the two-phase flow with gravity effect in anisotropic porous media, and the natural gas flow in anisotropic shale reservoirs. We have employed the multipoint flux approximation (MPFA) method to handle anisotropy in the flow model. The MPFA method is designed to provide correct discretization of the flow equations for general orientation of the principal directions of the permeability tensor. The implementation of MPFA method is combined with the experimenting pressure field approach, a newly developed technique that enables the solution of the global problem breaks down into the solution of multitude of local problems. The numerical results of the study demonstrate the significant effects of anisotropy of the subsurface formations. For the single-phase groundwater flow coupled with the solute transport modeling in anisotropic porous media, the results shows the strong impact of anisotropy on the pressure field and the migration of the solute concentration. For the two-phase flow modeling with gravity effect in anisotropic porous media, it is observed that the buoyancy-driven flow, which emerges due to the density differences between the phases, migrates upwards and the anisotropy aligns the flow directions closer to the principal direction of anisotropy. Lastly, for the gas flow modeling in anisotropic shale reservoirs, we observe that anisotropy affects the pressure fields and the velocity fields of the matrix and fracture systems as well as the production rate and cumulative production. It is observed from the results that all of the anisotropic cases produce higher amount of gas compared to isotropic case during the same production time. Furthermore, we have also examined the performance of MPFA with respect to mixed finite element (MFE) method over the lowest-order Raviart-Thomas (RT0) space and the first-order Brezzi-Douglas-Marini (BDM1) space. From the comparison of the numerical results we observe that MPFA method show very good agreement with the BDM1 than RT0. In terms of numerical implementation, however, MPFA method is easier than BDM1 and it also offers explicit discrete fluxes that are advantageous. Combining MPFA with the experimenting pressure field approach will certainly adds another advantage of implementing MPFA method as compared with RT0 and BDM1. Moreover, the computational cost (CPU cost) of the three different methods are also discussed.

Shale gas has emerged as a potential resource to transform the global energy market. Nevertheless, gas extraction from tight shale formations is only possible after horizontal drilling and hydraulic fracturing, which generally demand large amounts of water. Part of the ejected fracturing fluid returns to the surface as flowback water, containing a variety of pollutants. Thus, water reuse and water recycling technologies have received further interest for enhancing overall shale gas process efficiency and sustainability. Thereby, the objectives of this thesis are: - Develop mathematical models to treat flowback and produced water at various salinities and flow rates, decreasing the high environmental impact due to the freshwater withdrawal and wastewater generated during shale gas production at minimum cost. - Develop mathematical programming models for planning shale gas water management through the first stage of the well's life to promote the reuse of flowback water by optimizing simultaneously all operations belonging several wellpads. Within the first objective, we developed medium size generalized disjunctive-programming (GDP) models reformulated as mixed integer non-linear programming problems (MINLPs). First, we focused on flowback water pretreatment and later, in wastewater desalination treatment. Particularly, an emergent desalination technology, Membrane Distillation, has been studied. All mathematical models have been implemented using GAMS® software. First, we introduce a new optimization model for wastewater from shale gas production including a superstructure with several water pretreatment alternatives. The mathematical model is formulated via GDP to minimize the total annualized cost. Hence, the superstructure developed allows identifying the optimal pretreatment sequence with minimum cost, according to inlet water composition and wastewater desired destination (i.e., water reuse as fracking fluid or desalination in thermal or membrane techonologies). As each destination requires specific composition constraints, three case studies illustrate the applicability of the proposed approach. Additionally, four distinct flowback water compositions are evaluated for the different target conditions. The results highlight the ability of the developed model for the cost-effective water pretreatment system synthesis, by reaching the required water compositions for each specified destination. Regarding desalination technologies, a rigorous optimization model with energy recovery for the synthesis of multistage direct contact membrane distillation (DCMD) system has been developed. The mathematical model is focused on maximizing the total amount of water recovered. The outflow brine is fixed close to salt saturation conditions (300 g·kg-1) approaching zero liquid discharge (ZLD). A sensitivity analysis is performed to evaluate the system’s behavior under different uncertainty sources such as the heat source availability and inlet salinity conditions. The results emphasize the applicability of this promising technology, especially with low steam cost or waste heat, and reveal variable costs and system configurations depending on inlet conditions. Within the second objective, large-scale multi-period water management problems, and collaborative water management models have been studied. Thus, to address water planning decisions in shale gas operations, in a first stage a new non-convex MINLP optimization model is presented that explicitly takes into account the effect of high concentration of total dissolved solids (TDS) and its temporal variations in the impaired water. The model comprises different water management strategies: direct reuse, treatment or send to Class II disposal wells. The objective is to maximize the “sustainability profit” to find a compromise solution among the three pillars of sustainability: economic, environmental and social criteria. The solution determines freshwater consumption, flowback destination, the fracturing schedule, fracturing fluid composition and the number of tanks leased at each time period. Because of the rigorous determination of TDS in all water streams, the model is a nonconvex MINLP model that is tackled in two steps: first, an MILP model is solved on the basis of McCormick relaxations for the bilinear terms; next, the binary variables that determine the fracturing schedule are fixed, and a smaller MINLP is solved. Finally, several case studies based on Marcellus Shale Play are optimized to illustrate the effectiveness of the proposed formulation. Later, a simplified version of the shale gas water management model developed in the previous work has been used to study possible cooperative strategies among companies. This model allows increasing benefits and reduces costs and environmental impacts of water management in shale gas production. If different companies are working in the same shale zone and their shale pads are relatively close (under 50 km), they might adopt a cooperative strategy, which can offer economic and environmental advantages. The objective is to compute a distribution of whatever quantifiable unit among the stakeholders to achieve a stable agreement on cooperation among them. To allocate the cost, profit and/or environmental impact among stakeholders, the Core and Shapley value are applied. Finally, the impact of cooperation among companies is shown by two examples involving three and eight players, respectively. The results show that adopting cooperative strategies in shale water management, companies are allowed to improve their benefits and to enhance the sustainability of their operations. The results obtained in this thesis should help to make cost-effective and environmentally-friendly water management decisions in the eventual development of shale gas wells.

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The price and accessibility of fossil fuels, especially crude oil, are subject to considerable fluctuations due to growing demand on energy, limited resources, and energy security concerns. In addition, climate change caused by burning of fossil fuels is a challenge that energy sector is currently facing. These challenges incentivize development of alternative processes with no greenhouse gas emissions that can meet transportation fuels, chemical liquids, and electricity demands. Coal-based processes are of particular interest because coal price is both low and stable. However, these processes have a large environmental impact and are also less economically attractive than natural gas based plants due to the recent significant drop in natural gas price. However, even for natural gas plants, attempts to reduce CO2 emissions by using traditional CO2 capture and sequestration technologies not only decrease the thermal efficiency and profitability of the plant significantly but still release some CO2 to the atmosphere. The aim of this thesis is to develop, simulate and optimize an integrated polygeneration plant that uses multiple feedstocks and produces multiple products with low to zero CO2 emissions. Several process alternatives are investigated in this work to show the effect of each feedstock and product on the performance of the proposed plant. A comprehensive study is performed in each section, including process simulation in Aspen Plus software, development of custom models required for some units, as well as cost analysis by using Aspen Icarus software and empirical cost estimations from literature. Moreover, derivative free optimization techniques such as particle swarm optimization (PSO), genetic algorithm (GA) and simulated annealing (SA) are implemented to drive the design to economically optimum conditions as a function of the market price and carbon taxes. The final model will also introduce emerging technologies that can achieve higher efficiency and lower CO2 emissions compared to commercial systems, such as chemical looping gasification, chemical looping combustion, nuclear heat reforming, etc. By integrating multiple feedstocks and processes, the model can exploit certain synergies which are unavailable to traditional plants, resulting in significant efficiency improvements. In addition to power and liquid fuels, this polygeneration process offers benefits for petrochemical plants. Despite limited worldwide crude oil reserves, the demand for petrochemical products is still growing fast and it is highly important for petrochemical industry to find new resources as feedstock and diversify their supply chain network. By integration of the polygeneration plant in the same facility with novel processes that produce olefins (petrochemical feedstock) not from oil, but from syngas, it is possible to supply the required feed at lower cost than commercial steam cracking plants. / Thesis / Doctor of Philosophy (PhD)

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