Crashworthiness design and optimisation of windowed tubes under axial impact loading

© 2019 Elsevier Ltd Thin-walled structures are frequently used as energy absorbers in the automotive, railway and aviation industries. This paper addresses the crashworthiness performance of thin-walled windowed tubes under dynamic impact loading. Different shapes of cut-outs were introduced to thin-walled tubes with different cross-sectional shapes to create windowed tubes. Explicit finite element code, LS-DYNA, was used to simulate the crushing behaviour of the windowed tubes under axial impact loading. The Finite Element (FE)model was validated by conducting experimental tests and showing that the numerical and experimental responses are comparable. The crashworthiness responses of the different windowed tubes were compared and the best performing tube was identified using a multi-criteria decision-making method known as Technique of Order Preference by Similarity to Ideal Solution (TOPSIS). It was found that a circular tube with a square window shape outperforms all other sections and exhibits the best energy absorption characteristics. Subsequently, a multi-objective optimisation analysis was performed to find the optimal configuration of the best tube. Response Surface Methodology (RSM)was used to develop models for the energy absorption responses of the tube. The design variables were selected to describe size, number, and distributions of the windows, while specific energy absorption (SEA)and peak crush force (PCF)were set as design responses. Parametric analysis was conducted to understand the effects of the design variables on the crashworthiness behaviour and the optimal configuration was identified.Accepted versio

Mechanical pretreatment effects on macroalgae-derived biogas production in co-digestion with sludge in Ireland

Cell walls and lignin component disruption treatments are needed to enhance the hydrolytic phase and the overall biodegradability of lignocellulosics during an anaerobic digestion process. Given their abundant availability in nature, low impact on food market prices and low lignin content, aquatic plants result in being particularly suitable for biofuel conversion. A preliminary study on the effects of a Hollander beater mechanical pretreatment has been conducted in batch mode focusing on biogas yields from five different species of Irish seaweeds in co-digestion with sludge. A second experiment on Laminaria Digitata species has been carried out using a ResponseSurface Methodology (RSM) with treatment times (0-10min), mesophilic range of temperatures (35-39°C) and sludge amounts (100-300ml). Results from biogas yields of treated macroalgae have been found to be up to 20% higher when compared to untreated ones. A mathematical model of the biogas volume behaviour has been developed and the ideal conditions identified. © 2013 Elsevier Ltd

Quasi-static, impact and energy absorption of internally nested tubes subjected to lateral loading

This is an accepted manuscript of an article published by Elsevier in Thin-walled Structures on 20/10/2015, available online: https://doi.org/10.1016/j.tws.2015.10.001 The accepted version of the publication may differ from the final published version.© 2015 Published by Elsevier Ltd. This paper presents the responses of nested tube systems under quasi-static and dynamic lateral loading. Nested systems in the form of short internally stacked tubes were proposed as energy absorbing structures for applications that have limited crush zones. Three configurations of nested tube systems were experimentally analysed in this paper. The crush behaviour and energy absorbing responses of these systems under various loading conditions were presented and discussed. It was found that the quasi-static and dynamic responses of the nested systems were comparable under an experimental velocity of v=4.5 m/sec. This is due to insignificant strain rate and inertia effects of the nested systems under the applied velocity. The performance indicators, which describe the effectiveness of energy absorbing systems, were calculated to compare the various nested systems and the best system was identified. Furthermore, the effects of geometrical and loading parameters on the responses of the best nested tube system were explored via performing parametric analysis. The parametric study was performed using validated finite element models. The outcome of this parametric study was full detailed design guidelines for such nested tube energy absorbing structures.Published versio

Particle size reduction optimization of Laminaria spp. biomass for enhanced methane production

Recent studies have reported improved biogas and methane yield from marine biomass when the particle size is mechanically reduced and the specific surface area available to enzymes is increased prior to anaerobic incubation. Although the advantage of reducing the particle size has been identified, an ideal particle size that would offer greater yield with a positive energy balance has not been identified for such substrate to date. As particle size reduction by mechanical means is often highly demanding in energy, this paper attempts to fill this gap for macroalgal biomass by identifying the particle size distribution allowing the highest biogas and methane yields obtained in a previous work. The study estimated that when about 80% of the particles are sized below 1.6mm2, a biogas and methane yield improvement of up to 52% and 53% respectively can be achieved. The results are discussed in relation to the biogas yield, related methane content and potential inhibitory phenomena occurred during the fermentation

Optimization of mechanical pre-treatment of Laminariaceae spp. biomass-derived biogas

Macroalgae have not met their full potential to date as biomass for the production of energy. One reason is the high cost associated with the pretreatment which breaks the biomass's crystalline structure and better exposes the fermentable sugars to anaerobes. In the attempt to overcome this technological barrier, the performance of a Hollander beater mechanical pretreatment is assessed in this paper. This pretreatment has been applied to a batch of Laminariaceae biomass and inoculated with sludge from a wastewater treatment plant. The derived biogas and methane yields were used as the responses of a complex system in order to identify the optimal system input variables by using the response surface methodology (RSM). The system's inputs considered are the mechanical pretreatment time (5-15minrange), the machine's chopping gap (76-836μm) and the mesophilic to thermophilic range of temperatures (30-50°C). The mechanical pretreatment was carried out with the purpose of enhancing the biodegradability of the macroalgal feedstock by increasing the specific surface area available during the anaerobic co-digestion. The pretreatment effects on the two considered responses are estimated, discussed and optimized using the tools provided by the statistical software Design-Expert v.8. The best biogas yield of treated macroalgae was found at 50°C after 10minof treatment, providing 52% extra biogas and 53% extra methane yield when compared to untreated samples at the same temperature conditions. The highest biogas rate achieved by treating the biomass was 685ccgTS-1, which is 430ccgTS-1in terms of CH4yield. © 2013 Elsevier Ltd

Low-temperature heat transfer mediums for cryogenic applications

Copyright © 2023 The Author(s). Background: Researchers and industrialists have grown interested in cryogenic technologies over the years. Cryogenic heat transfer has enabled new applications due to material properties and behaviour at very low temperatures. This domain is still underdeveloped and unfamiliar in various applications. Methods: This work discusses the recent progress on cryogenic mediums and their respective use in different heat transfer applications. After identifying what is commonly designated as a cryogenic medium, i.e., those with a boiling point below -150 °C, the different characteristics and features of such mediums are critically discussed. Significant findings: Liquid He and N2 were found to be the most used cryogenic mediums, mainly due to the very low temperature attained by liquid He, as the closest to the absolute zero, along with the low cost and high availability of liquid N2. The use of liquid-phase cryogenic in a single-phase state was found to be the most common application method. Two-phase applications of the cryogenic medium are mainly for use in a heat pipe, in which both latent and sensible heat is utilized. Cryogenic mediums are essential for critical and niche applications such as in aerospace, superconductivity, advanced machining and manufacturing methods, and more critically in many healthcare applications and advanced scientific research.Air Products PLC under grant agreement: 216-206-P-F

Magnetorheology in an aging, yield stress matrix fluid

Field-induced static and dynamic yield stresses are explored for magnetorheological (MR) suspensions in an aging, yield stress matrix fluid composed of an aqueous dispersion of Laponite® clay. Using a custom-built magnetorheometry fixture, the MR response is studied for magnetic field strengths up to 1 T and magnetic particle concentrations up to 30 v%. The yield stress of the matrix fluid, which serves to inhibit sedimentation of dispersed carbonyl iron magnetic microparticles, is found to have a negligible effect on the field-induced static yield stress for sufficient applied fields, and good agreement is observed between field-induced static and dynamic yield stresses for all but the lowest field strengths and particle concentrations. These results, which generally imply a dominance of inter-particle dipolar interactions over the matrix fluid yield stress, are analyzed by considering a dimensionless magnetic yield parameter that quantifies the balance of stresses on particles. By characterizing the applied magnetic field in terms of the average particle magnetization, a rheological master curve is generated for the field-induced static yield stress that indicates a concentration–magnetization superposition. The results presented herein will provide guidance to formulators of MR fluids and designers of MR devices who require a field-induced static yield stress and a dispersion that is essentially indefinitely stable to sedimentation.Petroleum Research Fund (ACS-PRF Grant No. 49956-ND9)American Chemical Society (ACS-PRF Grant No. 49956-ND9

Energy Digitalization: Main categories, Applications, Merits and Barriers

Increased consumption of fossil fuels has contributed to a rise in abnormal weather conditions. Utilizing renewable energy sources is one of the most effective methods for combating global warming. The intermittent nature of the majority of renewable energy sources could be mitigated through accurate weather forecasting and the integration of various renewable energy sources with energy storage systems. Artificial Intelligence (AI), digital twins, and other digital technologies have the potential to optimize energy production, storage, and consumption. Through these methods, the energy system can be made more efficient, manageable, and adaptable. This editorial discusses the energy digitalization in terms of prevalent technologies, potential applications, obstacles, and challenges. This editorial also discusses the research presented at the 13th International Conference on Sustainable Energy & Environmental Protection SEEP2021 at Boku University, Austria.European Commission ref: 768772 (HEAT PIPE TECHNOLOGY FOR THERMAL ENERGY RECOVERY IN INDUSTRIAL APPLICATIONS - ETEKINA); European Commissio

Techno-economic feasibility study of coupling low-temperature evaporation desalination plant with advanced pressurized water reactor

Data availability: Data will be made available on request.The increasing demand for freshwater necessitates sustainable desalination solutions, and nuclear power plants offer a promising avenue by utilizing their low-grade waste heat. This study assesses a techno-economic feasibility of coupling a 5 MWth low-temperature evaporation plant with a UAE-based Advanced Pressurized Water Reactor (APR1400). The system addresses freshwater demand, aligning with sustainability goals through low-grade heat utilization. The investigation explores three extraction points for low-grade heat steam, with temperatures ranging from 80 °C to 130 °C. Thermodynamic evaluations using DE-TOP illustrate power requirements and losses, considering variations in maximum brine temperature from 50 °C to 65 °C. Economic analysis using DEEP estimates water production costs. Findings reveal negligible variances in power plant parameters and a minimal reduction in overall efficiency (<0.5 %). The power loss ratio increases proportionally (10 % to 18.6 %) with higher-temperature heat extraction, while the total power requirements for the desalination plant rises by around 30 %, with a negligible power output reduction ratios (0.03 % to 0.07 %). A consistent linear correlation between water production rate and maximum brine temperature doubles water production (∼900 to 1800 m3/day). Applying multiple extraction points across low-grade heat sources demonstrates scalability, reaching three times that of single-point extraction, with marginal increases in power requirements and losses, while maintaining the power reduction ratio below 0.15 %. Economic feasibility indicates competitive water production costs, ranging from 1.53 to 0.87 $/m3 for desalination capacities between 900 and 5400 m3/day. This study provides valuable insights into sustainable water production at the nexus of nuclear energy and desalination, with implications for necessary policy intervention.The Research Institute of Science and Engineering (RISE) at the University of Sharjah, Nuclear Energy System Simulation and Safety (NE3S) research group supported and funded this research

Progress and challenges on the thermal management of electrochemical energy conversion and storage technologies: Fuel cells, electrolysers, and supercapacitors

It is now well established that electrochemical systems can optimally perform only within a narrow range of temperature. Exposure to temperatures outside this range adversely affects the performance and lifetime of these systems. As a result, thermal management is an essential consideration during the design and operation of electrochemical equipment and, can heavily influence the success of electrochemical energy technologies. Recently, significant attempts have been placed on the maturity of cooling technologies for electrochemical devices. Nonetheless, the existing reviews on the subject have been primarily focused on battery cooling. Conversely, heat transfer in other electrochemical systems commonly used for energy conversion and storage has not been subjected to critical reviews. To address this issue, the current study gives an overview of the progress and challenges on the thermal management of different electrochemical energy devices including fuel cells, electrolysers and supercapacitors. The physicochemical mechanisms of heat generation in these electrochemical devices are discussed in-depth. Physics of the heat transfer techniques, currently employed for temperature control, are then exposed and some directions for future studies are provided