• Thermodynamic Analysis and Process System Comparison of the Exhaust Gas Recirculated, Steam Injected and Humidified Micro Gas Turbine

      Ali, Usman; Font Palma, Carolina; Hughes, Kevin J.; Ingham, Derek B.; Ma, Lin; Pourkashanian, Mohamed; University of Leeds (ASME Proceedings, 2015-08-12)
      Stringent environmental emission regulations and continuing efforts to reduce carbon dioxide (CO2) from the energy sector, in the context of global warming, have promoted interest to improve the efficiency of power generation systems whilst reducing emissions. Further, this has led to the development of innovative gas turbine systems which either result in higher electrical efficiency or the reduction of CO2 emissions. Micro gas turbines are one of the secure, economical and environmentally viable options for power and heat generation. Here, a Turbec T100 micro gas turbine (MGT) is simulated using Aspen HYSYS® V8.4 and validated through experimental data. Due to the consistency and robustness of the steady state model developed, it is further extended to three different innovative cycles: (i) an exhaust gas recirculated (EGR) cycle, in which part of the exhaust gas is dried and re-circulated to the MGT inlet; (ii) a steam injected (STIG) cycle, and (iii) a humid air turbine (HAT) cycle. The steam and hot water are generated through the exhaust of the recuperator for the STIG and HAT cycle, respectively. Further, the steam is directly injected into the recuperator for power augmentation, while for the HAT cycle; the compressed air is saturated with water in the humid tower before entering the recuperator. This study evaluates the impact of the EGR ratio, steam to air ratio, and water to air ratio on the performance and efficiency of the system. The comparative potential for each innovative cycle is assessed by thermodynamic properties estimation of process parameters through the models developed to better understand the behavior of each cycle. The thermodynamic assessment indicates that CO2 enrichment occurs for the three innovative cycles. Further, the results indicate that the electrical efficiency increases for the STIG and HAT cycle while it decreases for the EGR cycle. In conclusion, the innovative cycles indicates the possibilities to improve the system performance and efficiency.
    • Towards sustainable methanol from industrial CO2 sources

      Douven, Sigrid; Benkoussas, Hana; Font Palma, Carolina; Leonard, Gregoire; University of Liege; University of Chester (Walter de Gruyter GmbH, 2019-10-21)
      This chapter discusses the opportunity of using CO2 from industrial sources to produce sustainable methanol. Some important industrial sectors that could be seen as potential sources of CO2 are reviewed: ammonia, steel, ethanol, ethylene, natural gas, cement and power industries. In most cases, despite a promising potential for CO2 re-use, only few projects have been identified and methanol production from CO2 is still marginal. A model for the CO2-to-methanol process is presented based on CO2-rich gas coming from ammonia production process. This model takes into account the different steps from the CO2 capture to the methanol purification, and heat integration is performed in order to determine the reduction of heat consumption achievable for the global process. Even if the economic relevance of the CO2 re-use into methanol still has to be qualified, it offers an estimation of the process efficiency.
    • Treating wastewater by indigenous microalgae strain in pilot platform located inside a municipal wastewater treatment plant

      Han, Jichang; Laurenz, Thomsen; Pan, Kehou; Wang, Pu; Wawilow, Tatjana; Osundeko, Olumayowa; Wang, Song; Theilen, Ulf; Thomsen, Claudia; Jacob University Bremen, Germany
      Various resources from a municipal wastewater treatment plant (MWTP) are available for microalgae cultivation plants, suggesting that a combination of these technologies can be used to produce microalgae biomass and remove contaminants at a low cost. In this study, the growth performance and nutrient removal efficiency of an indigenous Scenedesmus sp. in various wastewater media with different exchange patterns were investigated firstly, then transferred to a pilot-scale photobioreactor (located inside a MWTP) for bioremediation use. The temperature and pH of the platform were maintained at 15–30°C and 7.6, respectively. The NH+4− N, NO−3− N, and PO3−4− P of the wastewater could be reduced to below 0.05, 0.40, and 0.175 mg L–1, respectively. Our results indicate that microalgae cultivation using the resources of a MWTP can achieve high algal biomass productivity and nutrient removal rate. Our study also suggests that efficient technology for controlling zooplankton needs to be developed.
    • Trion formation in a two-dimensional hole-doped electron gas

      Spink, Graham G.; López Ríos, Pablo; Drummond, Neil D.; Needs, Richard J.; University of Cambridge; University of Chester; Lancaster University (American Physical Society, 2016-07-22)
      The interaction between a single hole and a two-dimensional, paramagnetic, homogeneous electron gas is studied using diffusion quantum Monte Carlo simulations. Electron-hole relaxation energies, pair-correlation functions, and electron-hole center-of-mass momentum densities are reported for a range of electron-hole mass ratios and electron densities. We find numerical evidence of a crossover from a collective excitonic state to a trion-dominated state in a density range in agreement with that found in recent experiments on quantum-well heterostructures.
    • Using Mathematical Modelling and Electrochemical Analysis to Investigate Age‐Associated Disease

      McAuley, Mark; Morgan, Amy (University of Chester, 2019-04-02)
      People are living longer. With this rise in life expectancy, a concomitant rise in morbidity in later life is observed; with conditions including cardiovascular disease (CVD), and cancer. However, ageing and the pathogenesis of age related disease, can be difficult to study, as the ageing process is a complex process, which affects multiple systems and mechanisms. The aim of this research was two‐fold. The first aim was to use mathematical modelling to investigate the mechanisms underpinning cholesterol metabolism, as aberrations to this system are associated with an increased risk for CVD. To better understand cholesterol from a mechanistic perspective, a curated kinetic model of whole body cholesterol metabolism, from the BioModels database, was expanded in COPASI, to produce a model with a broader range of mechanisms which underpin cholesterol metabolism. A range of time course data, and local and global parameter scans were utilised to examine the effect of cholesterol feeding, saturated fat feeding, ageing, and cholesterol ester transfer protein (CETP) genotype. These investigations revealed: the model behaved as a hypo‐responder to cholesterol feeding, the robustness of the cholesterol biosynthesis pathway, and the impact CETP can have on healthy ageing. The second aim of this work was to use electrochemical techniques to detect DNA methylation within the engrailed homeobox 1 (EN1) gene promoter, which has been implicated in cancer. Hypermethylation of this gene promoter is often observed in a diseased state. Synthetic DNA, designed to represent methylated and unmethylated variants, were adsorbed onto a gold rotating disk electrode for electrochemical analysis by 1) electrochemical impedance spectroscopy (EIS), 2) cyclic voltammetry (CV) and 3) differential pulse voltammetry (DPV). The technique was then applied to bisulphite modified and asymmetrically amplified DNA from the breast cancer cell line MCF‐7. Results indicated that electrochemical techniques could detect DNA methylation in both synthetic and cancer derived DNA, with EIS producing superiorresults. These non‐traditional techniques ofstudying age related disease were effective for the investigation of cholesterol metabolism and DNA methylation, and this work highlights how these techniques could be used to elucidate mechanisms or diagnose/monitor disease pathogenesis, to reduce morbidity in older people