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Metal foam recuperators on micro gas turbines: Multi-objective optimisation of efficiency, power and weight
Get PDFSmall size and high efficiency of micro gas turbines require a higher surface-to-volume ratio of recuperators. Conventional recuperators can achieve a range of 250–3600 m2/m3. Advances in materials and manufacturing, such as metal foams, can increase significantly the exchange surface and improve compactness ranging approximately from 500 to over 10,000 m2/m3, due to their exceptional micro geometry. The main advantage is that the increase of surface area does not impact the cost of the heat exchanger as much as conventional recuperators due to their easy manufacturing. This work addresses the optimisation of the recuperator using multiple objectives satisfying efficiency, power output and weight criteria, offering a holistic approach that takes into account the entire system rather than individual components or channels. A model is developed to represent the performance of a compact heat exchanger in micro gas turbines. The recuperator is an annular heat exchanger with involute profile filled with porous media in a counterflow arrangement on the hot and cold sides. The model allows the evaluation of the effect of the recuperator geometry features on the electrical efficiency, power output and weight savings in a micro gas turbine. Existing models for the global heat transfer coefficient, effective thermal conductivity, surface area and pressure drop of porous media are selected and implemented. The design variables of multi-objective are the pore density, porosity and number of channels, whilst the objectives are the overall electrical efficiency, power output and recuperator weight. The problem is solved using the Non-Dominated Sorting Genetic Algorithm (NSGA-II) to determine an approximation of the Pareto front, whilst the accuracy of the approximation is assessed against the solution obtained by an exhaustive search. The comparison shows that NSGA-II outperforms an exhaustive search by at least 90 % in terms of computational efficiency. These results allow the quantification of the impact of metal foam technology on performance metrics of the recuperator as well as the entire system. This quantitative analysis provides valuable insights into the behaviour of metal foam recuperators in micro gas turbines. An optimal design with 30 % efficiency and 28 kW power output appears in pore densities of approximately 10 and 20 pores per inch (PPI) for the air and gas side respectively, and a porosity of 85 %, which leads to a state-of-the-art recuperator weight of 48 kg. The efficiency improvement over the industry standard is 15 %, with only a 2.5 % reduction in power output.Applied Thermal Engineerin
A review on vibration characteristics of additively manufactured metal alloys
No full textThe advent of additive manufacturing (AM) has dramatically shifted the manufacturing sector conceptualization, design, and creation of products. AM can facilitate the production of complicated geometries and create functioning components with distinctive features for aerospace and automotive applications. However, defects such as pores, voids, interfaces, and inclusions can impair the quality and functionality of AM components. Vibration analysis (VA) has become a popular tool for the dynamic qualification and testing of products and nondestructive testing, but the literature lacks a comprehensive review of VA applied to AM. Hence, in this article, recent advances in the application of VA for identifying and characterizing flaws in metal alloys, including titanium, aluminum, and nickel-based alloys produced by AM, are summarized. In this review, studies on defects such as porosity, cracks, and inclusions and their effect on VA are also included. Herein, this article concludes with a discussion of the limitations of VA for defect characterization and future research directions. Overall, VA is a promising nondestructive testing method for quality assurance in AM and offers insights on overcoming the difficulties for further development and application of this technology.H2020 Marie Skłodowska-Curie Actions. Grant Number: 101034425
Türkiye Bilimsel ve Teknolojik Araştırma Kurumu. Grant Number: 120C158Advanced Engineering Material
Towards decarbonisation of sugar refineries by calcium looping: Process integration, energy optimisation and technoeconomic assessment
Get PDFThe sugar refinery process as a food industry is at the pinnacle of the energy hierarchy. Depending on the source of carbon in this industry that could be either from biomass or fossil fuel hydrocarbons, this sector has the potential to become a carbon–neutral or negative industry depending on the type of fuel for power generation. This work will deliver a new proof of concept model for simultaneous sugar refining and carbon capture, thereby transforming sugar into the carbon negative commodity which relies on the utilisation of CO2 and fresh lime in the sugar refineries carbonisation tanks and in return byproduction of calcium carbonate that can be converted in the calciner of a calcium looping process. This study begins with the design and development of the calcium looping (CaL) process for the integration to the sugar refineries using various coupled and decoupled scenarios for the boiler units based on the type of the fuel, continues with an energy optimisation and techno-economic assessment of the proposed process, and finally culminates with the parametric study on the thermodynamic and economic performance of the sugar refinery retrofitted with the calcium looping. The process simulations revealed that the integrated CaL-sugar refinery can support the electricity exporter by installation of an onsite steam cycle which is able to generate electricity from surplus carbonation heat. The cost of CO2 avoided for integration of CaL to the reference sugar refinery for natural gas boilers and calciner will be 62 £/tCO2 which drops to 25 £/tCO2 if the carbon tax is considered in the analysis and negative carbon emissions are credited. This is equivalent to 61% costs reductions associated refining sugar combined together with carbon capture and storage (CCS).Energy Conversion and Managemen
Solid-phase denitrification for tertiary nitrate removal from municipal wastewater
Get PDFAlibardi, Luca - Associate SupervisorElevated levels of nitrate in surface water and groundwater can lead to
eutrophication, algal blooms, and depletion of dissolved oxygen, causing harm to
aquatic ecosystems. Solid-phase denitrification (SPD) offers a promising
approach for removing nitrate from wastewater sources using carbon-based
materials to promote the activity of microorganisms that convert nitrate into
nitrogen gas. This study evaluated the suitability of six common cheap and readily
available materials as external carbon sources for denitrification in SPD systems.
The materials tested were woodchips, barley straw, spruce wood bark, beech
sawdust, and polycaprolactone (PCL). The study focused on the leaching rates
of organic compounds and their impact on denitrification efficiency, with particular
attention to the potential for secondary pollution. Results indicated that
woodchips and wood bark exhibited a good balance between carbon content and
secondary pollution risk, while barley straw posed the highest risk for secondary
pollution and potential for the rapid depletion of organic compounds. PCL showed
promise as a carbon source for nitrate removal and released minimal nitrate or
ammonium-nitrogen. The low concentrations of metals found in the media
suggest that they would not inhibit denitrification or pose significant health risks.
The method was transferred to a pilot scale to evaluate the potential of woodchips
in removing nitrate from wastewater sources and the performance of four
columns for solid-phase denitrification using woodchip media, based on the
results of the first part of the study, was studied for a period of 168 days. The
nitrate removal efficiency was observed to be between 62-75% with the best
performance seen in the hardwood seeded with sludge column. The addition of
sludge from a wastewater treatment plant helped to speed up the start-up
process. The results suggest that higher removal rates can be expected with
higher influent nitrate concentrations. Over time, significant variability in the
performance was observed. However, the variability in the results could not be
clearly explained. In conclusion, all tested media have the potential to be used as
supporting carbon sources for SPD, but their efficacy and potential for secondary
pollution must be evaluated on a case-by-case basis.MSc by Research Wate
Meta-analysis of the safety effect of electronic stability control
Get PDFObjective:
Electronic Stability Control (ESC) is a standard feature on most modern cars, due to its reported efficiency to reduce the number of crashes of several types. However, empirical studies of safety effects of ESC for passenger vehicles have not considered some methodological problems that might have inflated the effects. This includes self-selection of drivers who buy/use ESC and behavioral adaptation to the system over long time periods, but also the dominant method of induced exposure. This study aimed to investigate whether such methodological problems might have influenced the results.
Method:
A meta-analysis was undertaken to investigate whether there are systematic differences between published studies. Moderators tested included when the study was undertaken, the type of vehicle studied, the percent ESC in the sample, size of sample, the length of the study, whether matched or un-matched vehicles were studied, whether induced exposure was used, and two variants of types of crashes used as controls.
Results:
The effects found ranged from 38% to 75% reduction of crashes for the main targets of singles, running off road and rollover crashes. However, these effects were heterogeneous, and differed depending on the methods used. Most importantly, information that could have allowed more precise analyses of the moderators were missing in most publications. Conclusions: Although average effects were large and in agreement with previous meta-analyses, heterogeneity of the data was large, and lack of information about important moderators means that firm conclusions about what kind of mechanisms were influencing the effects cannot be drawn. The available data on ESC efficiency are not unanimous, and further investigations into the effects of ESC on safety using different methodologies are warranted.Engineering and Physical Sciences Research CouncilThis work is supported by the Engineering and Physical Sciences Research Council [grant number: EP/V026763/1].Journal of Safety Researc
Dataset relating to "Permeability measurements for the Investigation of a practical approach to the measurement of magnetic permeability of ferrofluids"
No full textFerrofluids are colloids of magnetic particles in a fluid. Ferrofluids have wide range of application in engineering and medicine. Their relative magnetic permeability is one of the important parameters that needs to be measured. This dataset contains the measurements observed in the process of using an existing technique to measure magnetic permeability with a solenoid and LCR meter to identify experimental factors relevant to the accuracy of measurement
Towards 6G satellite–terrestrial networks: analysis of air mobility operations
Get PDFThis article belongs to the Special Issue Satellite-Terrestrial Integrated Internet of ThingsThis paper presents an analytical exploration of sixth-generation (6G) satellite–terrestrial integrated networks, focusing specifically on their applications within air mobility operations, such as those involving unmanned aerial vehicles (UAVs). As the integration of satellite and terrestrial networks promises to revolutionize mobile communication by extending coverage and enhancing connectivity, this study delves into two critical aspects: link budget analysis and handover and mobility analysis for UAVs. The link budget analysis assesses the communication requirements necessary to ensure robust and consistent connectivity between satellites and UAVs, accounting for factors such as path loss, antenna gains, and power transmission. Meanwhile, the handover and mobility analysis investigates the challenges and solutions associated with UAVs transitioning between different network nodes and layers in a dynamic aerial environment. This paper utilizes theoretical models and simulations to provide insights into the design and optimization of these networks, aiming to enhance the reliability and efficiency of UAV operations in the context of the emerging 6G landscape. The findings propose not only technological advancements in network architecture but also practical guidelines for the deployment of UAVs in complex environments, marking a significant step toward the realization of a fully integrated, satellite-terrestrial ecosystem.Electronic
Mycotoxin accumulation in dry rot potato tubers from Algeria and toxigenic potential of associated isolates of fusarium genus
Get PDFThe presence of different mycotoxins in 232 tuber samples exhibiting dry rot symptoms and their associated Fusarium strains from two production sites in Algeria was investigated. LC–MS/MS was used to simultaneously detect and quantify 14 mycotoxins, including trichothecenes and non-trichothecenes. A total of 49 tubers were contaminated with at least one mycotoxins, including T-2, HT-2, Diacetoxyscirpenol (DAS), 15-acetoxyscirpenol (15-AS) and Beauvericin (BEA). Positive samples from the Bouira region had a significantly higher level of toxin contamination compared to Ain Defla (56.34% and 5.59%, respectively). A total of 283 Fusarium strains were isolated: 155 from Bouira and 128 from Ain Defla. These strains were evaluated for their ability to produce the targeted mycotoxins. The results showed that 61.29% and 53.9% of strains originate from Bouira and Ain Defla regions were able to produce Nivalenol, Fusarenone-X, DAS, 15-AS, Neosolaniol, BEA and Zearalenone. The phylogenetic analysis of the conserved ribosomal internal transcribed spacer (ITS) sequences of 29 Fusarium strains, representative of the recorded mycotoxins profiles, was distributed into 5 Fusarium species complexes (SC): F. incarnatum-equiseti SC (FIESC), F. sambucinum SC (FSAMSC), F. oxysporum SC (FOSC), F. tricinctum SC (FTSC) and F. redolens SC (FRSC). This is the first study determining multiple occurrences of mycotoxins contamination associated to Fusarium dry rot of potato in Algeria and highlights fungal potential for producing trichothecene and non-trichothecens mycotoxins.This project was funded by a QR-GCRF project from Cranfield University with the Laboratoire de Biologie des Systèmes Microbiens, École Normale Supérieure de Kouba.Current Microbiolog
Engagement logics: How partners for sustainability-oriented innovation manage differences between organizational logics
Get PDFInnovation partnerships frequently experience tensions due to differences in partners' organizational logics. The literature recommends that partners adopt collaborative, empathetic mindsets but even so, tensions can threaten outcomes and partnership continuation. Difficulties can be exacerbated when firms engage stakeholder organizations in sustainability-oriented innovation projects, where each partner is seeking their own combination of social, environmental, and economic objectives. This study explores strategic responses to these differences in logics through eight case studies of sustainability-oriented innovation engagements between a focal business and an external organization. The key finding is that partners can respond to their differing logics by shaping a new “engagement logic” that guides members of both (or all) organizations. A logic frame with four value-related dimensions—value salience, instrumentality, temporality, and language—allows a subtly idiosyncratic engagement logic to be created that is acceptable to both parties. This classification of ingredients of a logic frame forms a wider contribution to the institutional-logics literature. A complementary range of logic practices is identified, covering logic emergence, logic enactment, and boundary defining. The engagement logic aids the partnership by contributing to four partnership-level generative outcomes: partnership commitment, capability integration, scope flexibility, and system orientation. A notable finding is the presence of a logic boundary, specified in work, time, and space, enabling the engagement logic to co-exist with organizational logics; a research direction is whether this boundary also exists in logics at organizational and field levels. The study shows partnerships to be a new context within which novel logics can emerge, contributing to an understanding of how logics evolve.Journal of Product Innovation Managemen
Monitoring natural organic matter in drinking water treatment with photoelectrochemical oxygen demand
Get PDFConventional metrics such as total organic carbon (TOC) and ultraviolet absorbance at 254 nm (UV254) may oversee aspects of natural organic matter (NOM) reactivity in drinking water treatment. The novel photoelectrochemical oxygen demand (peCOD) analyzer indirectly measures the oxygen consumed during NOM oxidation with photo- and electrochemical methods, quantifying NOM reactivity. peCOD was valuable for tracking NOM degradation in nine drinking water treatment facilities, particularly in processes where conventional metrics failed to capture changes in NOM from partial oxidation (e.g., biofiltration and oxidation). However, peCOD exhibited moderate correlations with TOC (R2 = 0.67) and UV254 (R2 = 0.48), indicating the need for its concurrent use with conventional methods. While peCOD was not a significant predictor of disinfection by-product formation potential (R2 < 0.20), its inclusion alongside standard NOM metrics improved the performance of multivariable regression models. Thus, peCOD provided a rapid, standardized, operator-friendly, environmentally conscious, concentration-based approach for evaluating NOM characteristics in drinking water samples.AWWA Water Scienc