http://hdl.handle.net/2268.2/22265 Thu, 05 Mar 2026 22:42:44 GMT 2026-03-05T22:42:44Z http://hdl.handle.net/2268.2/25228 Title: Master's thesis and Internship : Thermal modelling and experimental measures of a French-type masonry stove for Low-Tech heating applications Abstract: This thesis supports the Renolow project of the non-profit organisation LowTech Liège, which promotes low-tech renovation strategies, by focusing on a French-type masonry stove used for household heating. To help the association in their goal of spreading this heating system, a transient numerical model of the stove’s thermal behaviour is developed. This model can be used by LowTech Liège as a tool to evaluate temperature evolution, thermal comfort, and energy use quantitatively. The numerical model is implemented in Python and relies on a discretised representation of the stove. The model is separated in two parts: a representation of the time-varying heat released by batch wood combustion, and the heat transfer processes described through a resistance–capacitance (RC) network. Experimental temperature measurements from two test campaigns are used both to explore model parameters and to assess the validity of the simulations. The comparison with experimental data shows that the model captures the main transient thermal behaviour of the masonry stove, with simulated temperature profiles closely matching the experimental trends. The absolute root means square error, between simulated and experimental external wall surface temperatures is approximately 8 °C, corresponding to a mean absolute error of about 6.5 °C. Given the experimental uncertainties, the external surface temperatures ranging from 20 °C to about 130 °C, and the modelling assumptions, this level of agreement is considered satisfactory for a first-generation numerical model and provides a solid basis for further research and future thermal comfort and energy performance assessments. Thu, 22 Jan 2026 23:00:00 GMT http://hdl.handle.net/2268.2/25228 2026-01-22T23:00:00Z http://hdl.handle.net/2268.2/25210 Title: Master's thesis and Internship : Techno-economic assessment of BioCarbon biomass pyrolysis technology Abstract: Climate change mitigation requires rapid and deep decarbonisation of energy-intensive industries reliant on fossil fuels, particularly those characterised by high-temperature operations and unavoidable process-related CO2 emissions. Replacing fossil fuels with low-carbon alternatives therefore represents a key lever for reducing industrial emissions. In this context, BioCarbon’s biocoal, produced from biomass via a novel “spontaneous carbonisation” technology, emerges as a promising renewable substitute for fossil fuels, particularly coal, due to its comparable, and in some cases superior, fuel properties. The objective of this study is to assess the techno-economic performance of biocoal produced using BioCarbon’s pyrolysis technology across different regional contexts. Belgium, representing a reference European industrial environment, and Senegal, a region characterised by abundant agricultural residues (particularly peanut shells), are selected as contrasted case studies. Using BioCarbon’s business model, specific production costs of approximately 530~€/t in Belgium and 358~€/t in Senegal are obtained. These values are subsequently integrated into a system-level optimisation framework for the lime industry enabling a direct comparison of lime production costs across different fuel-switching and carbon capture configurations. The results show a strong dependence of biocoal competitiveness on regional cost structures. In the Belgian reference case, the high production cost of biocoal leads to lime production costs exceeding 170~€/t of lime, which remain non-competitive under current market conditions. The system-level optimisation further shows that combining biogenic fuels with carbon capture enables net-negative \ce{CO2} emissions, albeit at higher costs. The integration of post-combustion capture using MEA leads to an increase in lime production costs of approximately 67\%. Oxy-combustion coupled with an air separation unit (ASU) and cryogenic purification (CPU) leads to a smaller cost increase of approximately 47\%. In contrast, the Senegalese case benefits from low-cost biomass and labour, resulting in lower biocoal production costs and positioning biocoal as one of the most competitive alternative fuels, with lime production costs of approximately 100~€/t. A sensitivity analysis performed on the main input parameters shows that substantial cost reductions can be achieved through the integration of low-cost biomass supply chains and the valorisation of pyrolysis by-products. These findings motivated the definition of a best-case scenario for the Belgian context resulting in a reduced price of approximately 305~€/t. In contrast, no equivalent best-case scenario was defined for Senegal, as the absence of adapted markets for pyrolysis by-products limits the realism of such assumptions. Under these favourable conditions, biocoal-based lime production pathways shifted into the identified competitiveness range, achieving lime production costs close to 150~€/t, confirming that biocoal can become a viable transitional fuel for industrial decarbonisation. More fundamentally, these results indicate that the economic performance of biocoal production should not be regarded as a standalone energy product, but as part of a broader biorefinery concept. This systemic perspective is therefore essential when assessing the real potential of biocoal as an industrial decarbonisation solution. Overall, this work demonstrates that, when deployed under appropriate conditions, BioCarbon’s technology enables biocoal to be a viable alternative fuel for industrial decarbonisation, contributing to significant emission reductions while maintaining economic feasibility. Thu, 22 Jan 2026 23:00:00 GMT http://hdl.handle.net/2268.2/25210 2026-01-22T23:00:00Z http://hdl.handle.net/2268.2/25204 Title: Master's thesis and Internship : A methodology for evaluating the operating margin of safety-significant air-operating valves in nuclear power plants Abstract: This thesis presents the development of a methodology for evaluating the operating margin of AirOperated Valves (AOV) within the framework of the Long-Term Operation (LTO) program for Belgian nuclear power plants. The project originated from the implementation of the ASME (American Society of Mechanical Engineers) OM (Operation and Maintenance of nuclear power plants) 2020 standard, which introduces mandatory preservice and in-service testing requirements for pneumatically actuated valves classified as High Safety Significance (HSS). These regulatory requirements highlighted the need to demonstrate that such valves maintain sufficient operating margins under design-basis conditions. The core objective of this work is therefore to establish a structured and physically based approach to calculate the operability margins of safety-significant AOV (Air-Operated Valves). To support the practical application of this methodology and facilitate its use in an industrial context, the developed approach is subsequently implemented in a dedicated and user-friendly software tool, named MAP4AOV (Monitoring and Analysis Program For Air-Operated Valves). The proposed methodology combines a risk-informed selection of valves based on a Probabilistic Safety Assessment (PSA) with a physics-based modeling of all forces acting on the valve, including spring forces, fluid-induced forces, friction forces, and inertial effects. The initial scope consisted of 231 air-operated valves, which was progressively reduced to 39 safety-significant valves through the PSA-based screening process. Particular attention is given to friction force modeling, identified as one of the most uncertain yet dominant contributors to the final operating margin. To address this uncertainty, two complementary friction models are developed and implemented : a Karnopp-based model and a first-principles model. The applicability of the proposed methodology is demonstrated through a case study focusing on the EAA-Vx (auxiliary feedwater circuit) air-operated valves. This group comprises eight valves that are geometrically identical but installed at different locations within the circuit, leading to variations in operating conditions. The methodology is applied using two complementary friction modeling approaches under the most restrictive operating conditions, namely with no water in the circuit and therefore a zero differential pressure (∆Pwater = 0 bar). An operating margin of 55.2% is obtained using the Karnopp friction model, assuming a valve idle period of fourteen days, while an operating margin of 58% is obtained using the first-principles friction model. Overall, this work provides a structured and practical approach for evaluating AOV operating margins and delivers a software-based tool that can support future analyses, contributing to improved safety demonstration and maintenance efficiency in nuclear power plants. Thu, 22 Jan 2026 23:00:00 GMT http://hdl.handle.net/2268.2/25204 2026-01-22T23:00:00Z http://hdl.handle.net/2268.2/25192 Title: Master's thesis and Internship : Integration of Low-Carbon Fuels for Heavy-Duty Transport in the Belgian Energy System toward Carbon Neutrality by 2050 Abstract: Achieving carbon neutrality by 2050 requires profound transformations of national energy systems, particularly in sectors where direct electrification remains technically or economically constrained. Heavy-duty transport, including long-haul road transport, maritime shipping and aviation, is among the most challenging sectors to decarbonize due to high energy density requirements, long operating ranges and limited refueling flexibility. In this context, low-carbon fuels produced through Power-to-X and biogenic pathways are increasingly considered as alternative or complementary solutions to direct electrification. This thesis investigates the integration of low-carbon fuels into the Belgian energy system by 2050, with a particular focus on their role in decarbonizing hard-to-electrify transport sectors under a strict carbon neutrality constraint. Hydrogen, methane, methanol, ammonia and dimethyl ether (DME) are assessed from a system-level perspective using a multi-energy optimization model developed with the Graph-Based Optimization Modeling Language (GBOML). The model integrates electricity, hydrogen, methane and carbon dioxide flows, while jointly optimizing investment and operational decisions over a full annual horizon. The results describe an energy system in which combined-cycle gas turbines (CCGT) provide firm and dispatchable generation, as renewable electricity alone is insufficient to ensure supply adequacy and the future role of nuclear power remains uncertain. The system remains strongly dependent on methane and hydrogen imports, while biomethane plays a limited role in energy supply and primarily contributes to carbon dioxide management. In parallel, electrolyzers and direct air capture (DAC) units mainly operate during periods of renewable electricity surplus, allowing excess generation to be valorized instead of curtailed. From a system-cost perspective, methanol and ammonia emerge as the most economically attractive low-carbon fuels, benefiting from relatively low production costs and good integration within the energy system. However, their direct use as substitutes for diesel in compression-ignition engines remains constrained without blending with a limited share of diesel. Dimethyl ether, by contrast, can directly substitute diesel thanks to its high cetane number, but its large-scale deployment is limited by uncertainties surrounding production costs. The results therefore suggest system configurations in which methanol and ammonia act as central energy carriers, and dimethyl ether is produced at smaller scale through the more mature indirect methanol-based pathway to decarbonize diesel-like transport applications. Thu, 22 Jan 2026 23:00:00 GMT http://hdl.handle.net/2268.2/25192 2026-01-22T23:00:00Z