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Journal articleLeonzio G, Triantafyllou N, Shah N, 2024,
A sustainability analysis for a circular power-to-liquid process for diesel production
, Sustainable Production and Consumption, Vol: 51, Pages: 657-669, ISSN: 2352-5509The power-to-liquid process is a key emerging technology for fossil-free raw materials and energy systems. In this work, techno-economic, and environmental analyses are carried out for a Fischer-Tropsch process producing diesel and characterized by the recovery of carbon dioxide through direct air capture, as well as the recovery of water and heat. The main aim of this study is to verify with respective analyses the circularity of carbon dioxide, water and heat and to conduct a global sensitivity analysis to identify significant system process parameters for some key performance indicators, when changed simultaneously. Despite the proven circularity based on material and energy balances ensuring a power-to-liquid efficiency of about 44 %, results show that the water closed loop is not ensured from an environmental point of view. The water consumption impact category is, in fact, a positive value (0.58–0.74 m3depriv/kgdiesel), while the climate change impact category is a negative value (−1.22 to −0.28 kgCO2eq/kgdiesel). A heat closed loop is attained according to the pinch analysis. The diesel production cost is competitive with the market price (1.76 and 2.07 $/literdiesel respectively when solar and wind energy are used). Regarding the sensitivity analysis, it is found that only costs and efficiency depend on the geographic location of the plant, in contrast to other key performance indicators. Overall, an additional optimization of the process is hence required to ensure a closed water loop from an environmental point of view and reduce further the production cost.
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Journal articleNguyen T-T-G, Wedler C, Pohl S, et al., 2024,
Experimental speed-of-sound data and a fundamental equation of state for normal hydrogen optimized for flow measurements
, The Journal of Chemical Thermodynamics, Vol: 198, ISSN: 0021-9614Speed-of-sound measurements for normal hydrogen (n-hydrogen) in a temperature range between 273 K and 323 K were carried out using a cylindrical resonator at pressures from 1 MPa to 10 MPa and a dual-path pulse-echo system at pressures from 20 MPa to 100 MPa. The relative expanded uncertainties (k = 2) of the measurements range from 0.04 % to 0.08 %. Based on these measurements and data from the literature, a fundamental equation of state (EOS) was developed for the calculation of thermodynamic properties of n-hydrogen. It is expressed in terms of the Helmholtz energy with the independent variables temperature and density. Due to the fundamental nature of the Helmholtz energy, the equation can be used to calculate all thermodynamic properties from one mathematical expression. In contrast to typical EOS of this kind, the boundary conditions are somewhat more restricted. The relevant temperature and pressure ranges are limited to typical pipeline and storage conditions of gaseous hydrogen, including temperatures relevant for measurements with critical nozzles (140 K to 370 K with pressures up to 100 MPa). The computational speed for the implementation of the correlation in measurement sensors plays a superior role. Therefore, the equation is kept as short as possible, and exponents are of integer-kind. Most of the experimental data are still reproduced within their measurement uncertainties.
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Journal articleSaleh MA, Shiel H, Ryan MP, et al., 2024,
Enhanced Olivine Reactivity in Wet Supercritical CO<sub>2</sub> for Engineered Mineral Carbon Sequestration
, ENERGY & FUELS, Vol: 38, Pages: 21028-21041, ISSN: 0887-0624 -
Journal articleNarciso CRH, Martinez CG, O'Connell B, et al., 2024,
Thermophysical behavior of carbonated aqueous solutions containing monoethanolamine and degradation products
, Journal of Chemical and Engineering Data, Vol: 69, Pages: 3435-3449, ISSN: 0021-9568The impact of the degradation of monoethanolamine (MEA) on the physicochemical properties of the solvent is experimentally characterized. Based on the identification of three main degradation products of MEA: oxazolidine-2-one (OZD), N-(2-hydroxyethyl)ethylenediamine (HEEDA), and 1-(2-hydroxyethyl)-2-imidazolidinone (HEIA), new measurements for the density, surface tension, and viscosity of partially carbonated solutions containing water, MEA and those products were conducted at different MEA/degradation product molar ratios. The experiments covered a temperature range from 298.15 to 353.15 K at atmospheric pressure. The more stable and impactful degradation product, HEIA, was analyzed separately to determine its vapor pressure, as well as the density and viscosity of aqueous solutions with HEIA mass fractions of 100, 75, 50, and 25% in the same temperature range. The reported data demonstrate the difference in the performance of aqueous MEA solutions containing degradation products as compared to a fresh solution. This aspect is crucial for understanding the impact and effectiveness of postcombustion CO2 capture using aqueous amine systems in an industrial setting.
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Journal articleAi L, Maitland GC, Hellgardt K, 2024,
Formation and phase equilibria of gas hydrates confined in hydrophobic nanoparticles
, Chemical Engineering Science, Vol: 298, ISSN: 0009-2509The promotion of gas hydrate formation is of fundamental importance to facilitate its great potential applications in, for example, gas separation, transportation and energy storage. The employment of Dry Water (DW), which is a powdery Pickering system composed of macro water droplets surrounded by stabilising hydrophobic nanoparticles, is considered an effective method for enhancing hydrate formation. The promotion mechanism underlying this observation, however, has yet to be well understood. In this work, the effect of DW on both formation kinetics and thermodynamic stability of gas hydrates was investigated using a micro differential scanning calorimetry (µDSC) in CH4 and CO2 hydrate systems, using two different hydrophobic nanoparticles. Distinctly shorter induction times and higher conversion ratios were observed for DW compared to bulk water. The DW system stabilised by more hydrophobic nanoparticles showed benefits in accelerating nucleation, while the other system, which consisted of smaller DW droplets, led to a superior enhancement of hydrate growth. Besides the effect on formation kinetics, it was also noted that DW influenced the µDSC hydrate dissociation peak characteristics, including melting points and melting peak shapes. This phenomenon suggested that the centre- and surface-droplet hydrates in DW may have different structures, due to the “hydrophobic effect” of the nanoparticles structuring the near-surface water, so exhibiting melting points corresponding to bulk hydrate or to a more structured surface hydrate (with raised melting point), respectively. To support this “hydrophobic effect” hypothesis, a series of hydrate and ice formation experiments were conducted in porous media having different hydrophobicity, the results of which demonstrated that hydrates adjoining confined hydrophobized surfaces, in other systems similar to DW, also displayed higher melting temperatures.
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Journal articleEluwah C, Fennell PS, 2024,
Novel carbon-free innovation in centralised ammonia cracking for a sustainable hydrogen economy: the hybrid air-volt ammonia cracker (HAVAC) process
, Energy Advances, Vol: 3, Pages: 2627-2647, ISSN: 2753-1457The Hybrid Air-Volt Ammonia Cracker (HAVAC) represents a novel approach to centralised ammonia cracking for hydrogen production, enhancing both efficiency and scalability. This novel process integrates renewable electricity and autothermal operation to crack blue or green ammonia, achieving a high thermal efficiency of 94% to 95%. HAVAC demonstrates impressive ammonia conversion rates up to 99.4% and hydrogen yields between 84% and 99.5%, with hydrogen purity of 99.99% meeting ISO 14687:2019 standards.Key innovations include the process's flexibility to operate in three modes: 100% renewable electricity, 100% air autothermal, or a hybrid approach. This versatility optimizes energy use and adapts to varying conditions. The Gas Heated Cracker (GHC) within HAVAC efficiently reduces energy demands by utilizing waste heat.Modelled using the Aspen Plus Simulator and validated against experimental data, HAVAC's economic analysis indicates a levelized cost of hydrogen (LCOH) between $3.80/kg-H₂ and $6.00/kg-H₂. The process's environmental benefits include reduced greenhouse gas emissions and effective NOx waste management. Future research will focus on scaling up, reducing ammonia feed cost, optimizing catalysts, and enhancing waste management. HAVAC offers substantial promise for advancing hydrogen production and supporting a sustainable, carbon-free hydrogen economy. The technical and economic data generated by this analysis will assist decision-makers and researchers in advancing the pursuit of a carbon-free hydrogen economy.
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Journal articleStrunge T, Küng L, Sunny N, et al., 2024,
Finding least-cost net-zero CO2 strategies for the European cement industry using geospatial techno-economic modelling
, RSC Sustainability, Vol: 2, Pages: 3054-3076, ISSN: 2753-8125Cement production is responsible for approximately 7% of anthropogenic CO2-equivalent (CO2e) emissions, while characterised by low margins and the highest carbon intensity of any industry per unit of revenue. Hence, economically viable decarbonisation strategies must be found. The costs of many emission reduction strategies depend on geographical factors, such as plant location and proximity to feedstock or on synergies with other cement producers. The current literature lacks quantification of least-cost decarbonisation strategies of a country or region's total cement sector, while taking stock of these geospatial differences. Here, we quantify which intervention ensembles could lead to least-cost, full decarbonisation of the European cement industry, for multiple European regions. We show that least-cost strategies include the use of calcined clay cements coupled with carbon capture and storage (CCS) from existing cement plants and direct air capture with carbon storage (DACCS) in locations close to CO2 storage sites. We find that these strategies could cost €72–€75 per tonne of cement (tcement−1, up from €46–€51.5 tcement−1), which could be offset by future costs of cement production otherwise amounting to €105–€130 tcement−1 taking the cost of CO2e emission certificates into account. The analysis shows that for economically viable decarbonisation, collaborative and region-catered approaches become imperative, while supplementary cementitious materials including calcined clays have a key role.
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Journal articleWard A, Papathanasiou M, Pini R, 2024,
The impact of design and operational parameters on the optimal performance of direct air capture units using solid sorbents
, Adsorption, Vol: 30, Pages: 1829-1848, ISSN: 0929-5607Direct capture of CO2 from ambient air is technically feasible today, with com mercial units already in operation. A demonstrated technology for achievingdirect air capture (DAC) is chemical separation of CO2 in a steam-assistedtemperature-vacuum swing adsorption (S-TVSA) process. However, the poten tial to develop scalable solutions remains high, requiring a detailed understandingof the impact of both process design and operation on the performance of theDAC unit. Here, we address this knowledge gap by presenting a state-of-the-artprocess simulation tool for the purification of CO2 from ambient air by a 5-stepS-TVSA process. By considering the benchmark adsorbent APDES-NFC, we con duct multi-objective productivity/energy usage optimization of the DAC unit,subject to the requirement of producing a high purity CO2 product (≥95%).For the base case scenario, we find a maximum productivity of Prmax = 6.20kg/m3/day and a minimum specific equivalent work of WEQ,min = 1.66 MJ/kg.While in reasonable agreement with published data, our results indicate thatthe description of both competitive adsorption and adsorption kinetics are keyfactors in introducing uncertainty in process model predictions. We also demon strate that the application of formal optimization techniques, rather than designheuristics, is central to reliably assess the process performance limits. We identitythat system designs employing moderate CO2 sorption kinetics and contactorswith low length-to-radius ratios yield the best performance in terms of systemproductivity. Finally, we find that moderate-high ambient relative humidities (50-75%) offer significantly favourable performance, and that a wide range of feed temperatures (5-30oC) can be accommodated via process optimization withouta significant impact on performance.
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Journal articlevan de Berg D, Shah N, del Rio-Chanona EA, 2024,
Hierarchical planning-scheduling-control — Optimality surrogates and derivative-free optimization
, Computers and Chemical Engineering, Vol: 188, ISSN: 0098-1354Planning, scheduling, and control typically constitute separate decision-making units within chemical companies. Traditionally, their integration is modelled sequentially, but recent efforts prioritize lower-level feasibility and optimality, leading to large-scale, potentially multi-level, hierarchical formulations. Data-driven techniques, like optimality surrogates or derivative-free optimization, become essential in addressing ensuing tractability challenges. We demonstrate a step-by-step workflow to find a tractable solution to a tri-level formulation of a multi-site, multi-product planning-scheduling-control case study. We discuss solution tractability-accuracy trade-offs and scaling properties for both methods. Despite individual improvements over conventional heuristics, both approaches present drawbacks. Consequently, we synthesize our findings into a methodology combining their strengths. Our approach remains agnostic to the level-specific formulations when the linking variables are identified and retains the heuristic sequential solution as fallback option. We advance the field by leveraging parallelization, hyperparameter tuning, and a combination of off- and on-line computation, to find tractable solutions to more accurate multi-level formulations.
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Journal articleSmith A, Hampson G, Krevor S, 2024,
Global analysis of geological CO2 storage by pressure-limited injection sites
, International Journal of Greenhouse Gas Control, Vol: 137, ISSN: 1750-5836Limiting global warming to a 2 °C rise may require large-scale deployment of carbon capture and storage (CCS). Due to the key role CCS plays in integrated assessment models of climate change mitigation, it is important that fundamental physical constraints are accounted for. We produce a global estimate of CO2 storage resource that accounts for pressure-limits within basin-scale reservoir systems. We use a dynamic physics model of reservoir pressurisation that is sufficiently simple to be incorporated into energy systems models. Our estimates address regionally inconsistent methodologies and the general lack of consideration for pressure limitations in global storage resource estimates. We estimate a maximum pressure-limited resource base and explore scenarios with different injection patterns, and scenarios where the extent of CCS deployment is limited by the history of regional hydrocarbon exploration and the readiness of countries for deployment. The maximum pressure-limited global storage achievable after thirty years of injection is 3640GtCO2 (121GtCO2yr-1), increasing to 5630GtCO2 (70 GtCO2yr-1) at the end of the century. These represent an update to volumetric-based estimates that suggest in excess of 10,000Gt of storage resource available. When CCS deployment is limited to the top ten countries ranked by the GCCSI Storage Readiness Index, our maximum storage estimate decreases to 780GtCO2 (26GtCO2yr-1) at the mid-century and 1177GtCO2 (15GtCO2yr-1) at the end of the century. These latter results fall within the range of projected deployment by the IPCC and IEA and suggest that reservoir pressurisation will limit CCS deployment if development does not rapidly expand beyond the current implementation.
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Journal articleZhang Y, Jackson C, Krevor S, 2024,
The feasibility of reaching gigatonne scale CO<sub>2</sub> storage by mid-century
, NATURE COMMUNICATIONS, Vol: 15 -
Journal articleSendi M, Bui M, Mac Dowell N, et al., 2024,
Geospatial techno-economic and environmental assessment of different energy options for solid sorbent direct air capture
, CELL REPORTS SUSTAINABILITY, Vol: 1- Cite
- Citations: 9
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Journal articleWard A, Pini R, 2024,
Design and performance evaluation of multi-sorbent vacuum-swing adsorption processes for post-combustion carbon capture
, Industrial and Engineering Chemistry Research, Vol: 63, Pages: 13787-13800, ISSN: 0888-5885We present the design and performance evaluation of a novel multisorbent process for CO2/N2 separation based on vacuum-swing adsorption (VSA). We study two process configurations: (i) layered-bed processes, wherein two distinct adsorbent materials are arranged in sequential layers within the adsorption bed, and (ii) mixed-bed processes, wherein two distinct adsorbent materials are homogeneously mixed within the adsorption bed. We develop, validate, and deploy a high-fidelity dynamic adsorption column model for the multisorbent process configurations and apply Bayesian optimization to design processes that achieve maximum separation effectiveness in terms of CO2 purity and recovery with an application to postcombustion carbon capture (PCC) on a coal-fired power plant. We find that the multisorbent process configurations achieve improved CO2/N2 separation effectiveness compared to benchmark classical single-adsorbent processes, increasing the CO2 recovery by up to 5% while achieving high CO2 purity. When operating in compliance with widely adopted performance targets for PCC (PuCO2 ≥ 95%, ReCO2 ≥ 90%), we find that the multisorbent process configurations reduce the energy usage of the separation by approximately 35%. We use the modeling framework to analyze the subcolumn scale adsorption dynamics and identify that the observed improvements in performance are associated with the positioning of the CO2 adsorption front under optimized operating conditions, leading to favorable dynamic interactions with the operation of the VSA process cycle.
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Journal articleRichter M, Trusler JPM, 2024,
Vibrating-wire viscometry
, International Journal of Thermophysics, Vol: 45, ISSN: 0195-928XThe theory and application of the vibrating-wire technique for the measurement of viscosity, as well as both viscosity and density, are reviewed. Theory is presented in the form of practical working equations and well-established limitations on their ranges of validity. The cases of both transient and steady-state excitation of the vibrating wire are considered in detail. For the steady-state mode, we describe a variant of the method in which the density is also measured. Practical details including wire materials, magnet systems and instrumentation are discussed, and several design examples from the literature are reviewed. Relative uncertainties in vibrating-wire viscometry vary from, at best, 0.2 % to about 2 % at 95 % confidence. In an appropriately designed instrument, density can be measured simultaneously with a relative uncertainty of about 0.2 %.
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Journal articleKucherenko S, Sopittakamol N, Shah N, 2024,
Design space identification of a coupled two-stage batch reactor system
, Computers and Chemical Engineering, Vol: 187, ISSN: 0098-1354The design space (DS) is defined as the combination of materials and process conditions that guarantees the assurance of quality. This principle ensures that as long as a process operates within DS, it consistently produces a product that meets specifications. It was originally developed for a single unit system. Many industrial processes frequently involve multiple unit operations. Assessing the interaction of Critical Process Parameters (CPPs) with Critical Quality Attributes (CQAs) across stages enables informed decision-making and the capacity to balance different requirements. Analysis and visualization of the complex, multi-dimensional DS is a challenging task. This paper presents a framework for identification such DSs, considering both joint and decoupled strategies using a detailed analysis of a two-stage batch reactor case study. We assess and discuss the practicality and relevance of these methods.
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Journal articleStreb A, Danaci D, Lively R, et al., 2024,
Towards carbon neutral scientific societies:a case study with the International Adsorption Society
, Adsorption, Vol: 30, ISSN: 0929-5607 -
Journal articleLeonzio G, Hankin A, Shah N, 2024,
CO2 electrochemical reduction: a state-of-the-art review with economic and environmental analyses
, Chemical Engineering Research and Design, Vol: 208, Pages: 934-955, ISSN: 0263-8762The electrochemical reduction of carbon dioxide is an emerging strategy to reduce emissions, allowing the storage of renewable energy and the electrification of the chemical industry according to the principle of carbon dioxide utilization. Valuable fuels and chemical commodities can be obtained by ensuring a closed carbon loop and the main important products are carbon monoxide, formic acid, methanol, methane, ethylene, ethanol, and propanol. Inside this context, here, we explore the state-of-the-art of carbon dioxide electrolysis technologies, showing that efforts have been put into the development of reactor cell architectures and catalysts able to provide high selectivity and efficiency. New insights are currently about the study of reaction mechanisms, optimization of cell design, and development of more performing electro-catalysts. Moreover, an overview of economic and environmental studies based on carbon dioxide electrochemical reduction is conducted in this work and a preliminary screening based on the levelized production cost and climate change impact of several products obtained through carbon dioxide electrochemical reduction is proposed for a large-scale plant. Today, carbon monoxide and formic acid are the primary carbon dioxide reduction product targets from an economic point of view. In the future, production costs are expected to decrease, and other low-carbon products could be competitive with market prices. Renewable energy sources and carbon dioxide with a low carbon footprint contribute to an environmentally friendly electrochemical production process.
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Journal articleBakkaloglu S, Mersch M, Sunny N, et al., 2024,
The role of negative emissions technologies in the UK’s net-zero strategy
, Cell Reports Sustainability, Vol: 1, ISSN: 2949-7906The role of negative emissions technologies (NETs) in climate change mitigation remains contentious. Although numerous studies indicate significant carbon dioxide removal (CDR) requirements for Paris Agreement mitigation goals to be achieved, others point out challenges and risks associated with high CDR strategies. Using a multiscale modeling approach, we explore NETs’ potential for a single country, the United Kingdom (UK). Here, we report that the UK has cost-effective potential to remove 79 MtCO2 per year by 2050, rising to 126–134 MtCO2 per year with well-integrated NETs in industrial clusters. Results highlight that biomass gasification for hydrogen generation with CCS is emerging as a key NET, despite biomass availability being a limiting factor. Moreover, solid DACCS systems utilizing industrial waste heat integration offer a solution to offsetting increases in demand from transportation and industrial sectors. These results emphasize the importance of a multiscale whole-systems assessment for integrating NETs into industrial strategies.
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Journal articleDriver JG, Bernard E, Patrizio P, et al., 2024,
Global decarbonization potential of CO2 mineralization in concrete materials
, Proceedings of the National Academy of Sciences of USA, Vol: 121, ISSN: 0027-8424CO2 mineralization products are often heralded as having outstanding potentials to reduce CO2-eq. emissions. However, these claims are generally undermined by incomplete consideration of the life cycle climate change impacts, material properties, supply and demand constraints, and economic viability of CO2 mineralization products. We investigate these factors in detail for ten concrete-related CO2 mineralization products to quantify their individual and global CO2-eq. emissions reduction potentials. Our results show that in 2020, 3.9 Gt of carbonatable solid materials were generated globally, with the dominant material being end-of-life cement paste in concrete and mortar (1.4 Gt y–1). All ten of the CO2 mineralization technologies investigated here reduce life cycle CO2-eq. emissions when used to substitute comparable conventional products. In 2020, the global CO2-eq. emissions reduction potential of economically competitive CO2 mineralization technologies was 0.39 Gt CO2-eq., i.e., 15% of that from cement production. This level of CO2-eq. emissions reduction is limited by the supply of end-of-life cement paste. The results also show that it is 2 to 5 times cheaper to reduce CO2-eq. emissions by producing cement from carbonated end-of-life cement paste than carbon capture and storage (CCS), demonstrating its superior decarbonization potential. On the other hand, it is currently much more expensive to reduce CO2-eq. emissions using some CO2 mineralization technologies, like carbonated normal weight aggregate production, than CCS. Technologies and policies that increase recovery of end-of-life cement paste from aged infrastructure are key to unlocking the potential of CO2 mineralization in reducing the CO2-eq. footprint of concrete materials.
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Journal articleChen Q, Trusler JPM, 2024,
Solubility of CO in water and NaCl(aq) at high pressures
, Chemical Engineering Science, Vol: 293, ISSN: 0009-2509Experimental measurements of CO solubility in water and in NaCl(aq) solutions are reported at temperatures, pressures and salt molalities of relevance to geological carbon storage: (323.15 to 423.15) K, (2 to 28) MPa and (2 and 4) mol·kg−1, respectively. The expanded relative uncertainty of the CO solubility is estimated to be 4.4% at 95% confidence intervals. This study provides the first data for CO solubility in brine with high molality of salt. The results from this study were used to develop simple models for the solubility of CO in aqueous NaCl solutions as a function of temperature, pressure and salt molality dependent, up to 4 mol·kg−1.
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Journal articleSachio S, Ward A, Pini R, et al., 2024,
Operability-economics trade-offs in adsorption-based CO2 capture processes
, Communications Engineering, Vol: 3, ISSN: 2731-3395Dispatchable low-carbon power underpins the transition to a sustain16 able energy system, providing balancing load for the integration of intermittent renewable power. In such load-following operation, the post-combustion carbon capture process must be capable of highly transient operation. Here we have developed a computational frame work that integrates process design, operability and techno-economicassessment of a pressure-vacuum swing adsorption process for CO2 capture. We demonstrate that the cost-optimal design has limited process flexibility, challenging reactiveness to disturbances in the flue gas conditions. Flexibility can be introduced by relaxing the CO2 recovery constraint on the operation, albeit at the expense of thecapture efficiency of the process. We discover that adsorption-based processes can be designed to enhance flexibility, while improving per formance with respect to the operational constraints on CO2 recovery and purity. The results herein demonstrate a trade-off between process economics and process operability, which must be ratio nalised to integrate CO2 capture units in low-carbon energy systems.
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Book chaptervan de Berg D, Shah N, del Rio-Chanona A, 2024,
High-dimensional derivative-free optimization via trust region surrogates in linear subspaces
, Computer Aided Chemical Engineering, Publisher: Elsevier, Pages: 3193-3198, ISBN: 9780443288241Maintaining the benefits of derivative-free optimization in higher-dimensional decision spaces presents challenges for existing optimization methods. We introduce CUATRO_PLS - an extension of the CUATRO quadratic trust region optimizer that leverages intrinsic structures across high-dimensional black-box variables. CUATRO_PLS shows competitive convergence with leading derivative-free optimization algorithms in three high-dimensional chemical engineering case studies even in the absence or underestimation of known intrinsic dimensionality and is significantly faster than other model-based derivative-free optimization algorithms.
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Journal articleBöckler H-B, de Huu M, Maury R, et al., 2024,
Metrology infrastructure for high-pressure gas and liquified hydrogen flows. A brief outline of the MetHyInfra project, measurement challenges, and first results
, Measurement, Vol: 232, ISSN: 0263-2241This paper gives an overview of the ongoing Joint Research Project (JRP) 20IND11 “Metrology infrastructure for high pressure gas and liquefied hydrogen flows” (MetHyInfra), which will ensure traceability in the hydrogen distribution chain. For this purpose, very precise nozzles with well-defined geometries have been produced. In this project, Critical Flow Venturi Nozzles (CFVNs) will be traceably calibrated for the first time with hydrogen and pressures up to 100 MPa using a Coriolis Flow Meter (CFM) as a secondary standard. A CFM has been successfully calibrated with hydrogen against a gravimetric primary standard.Equations of State (EoS) are important for the high-pressure calibration of the nozzles, but also for Computational Fluid Dynamics (CFD) simulations. With regard to CFD, a numerical model has been developed to simulate high pressure hydrogen flow in the CFVN. In a parameter study, non-ideal nozzle shapes are investigated using a shape variation parameter. New Speed of Sound (SoS) measurements were conducted at temperatures from 273 to 323 K and pressures from 1 to 100 MPa. These new data were then used to develop a new EoS for normal hydrogen, optimized for gas phase calculations. In addition to gaseous hydrogen, the project has a strong focus on liquefied hydrogen. Here a three-pronged approach allows traceable measurements. Each of the approaches presented is based on a unique flow calibration principle and relies on independent traceability schemes. The results of the project will ensure traceable measurements and thus a higher level of confidence among end users.
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Journal articleWensink G, Mosalman MKS, Geurts P, et al., 2024,
In-situ 3D measurements of water films on the natural grain surface of porous rocks
, ADVANCES IN WATER RESOURCES, Vol: 188, ISSN: 0309-1708 -
Book chapterKucherenko S, Shah N, Zaccheus O, 2024,
Application of active subspaces for model reduction and identification of design space
, Large-Scale Scientific Computations, Editors: Lirkov, Margenov, Publisher: Springer Nature Switzerland AG, Pages: 412-418, ISBN: 978-3-031-56207-5The design space is defined as the combination of materials and process conditions which provides assurance of quality. Identification of the design space is a computationally demanding task especially in high dimensional settings. The active subspaces method is a technique that identifies the most important directions in the parameter space, enabling significant dimension reduction. We show how to apply the active subspaces method for model reductions and identification of design space. The results of constraint global sensitivity analysis match those obtained with the active subspaces method for the considered test case.
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Journal articleFirth AEJ, Nakasu PYS, Fennell PS, et al., 2024,
An Ionic Liquid-Based Biorefinery Approach for Duckweed Utilization.
, ACS Sustain Resour Manag, Vol: 1, Pages: 842-856This study establishes a foundation for the ionic liquid (IL) pretreatment of duckweed biomass. An optimized IL-based process was designed to exploit the unique properties of duckweed including efficient metal removal, potential starch accumulation, and protein accumulation. Two ILs, namely, dimethylethanolammonium formate ([DMEtA][HCOO]) and N,N-dimethylbutylammonium hydrogen sulfate ([DMBA][HSO4]), were investigated for the pretreatment of two duckweed species (Spirodela polyrhiza and Lemna minor). The evaluation focused on starch recovery, sugar release, protein recovery, and metal extraction capabilities. [DMEtA][HCOO] demonstrated near-quantitative starch recoveries at 120 °C, while [DMBA][HSO4] showed similar performance at 90 °C within a reaction time of 2 h. Saccharification yields for most pulps exceeded 90% after 8 h of hydrolysis, outperforming "traditional" lignocellulosic biomasses such as miscanthus or sugarcane bagasse. Approximately 50 and 80 wt % of the protein were solubilized in [DMEtA][HCOO] and [DMBA][HSO4], respectively, while the remaining protein distributed between the pulp and lignin. However, the solubilized protein in the IL could not be recovered due to its low molecular weight. Regarding metal extraction, [DMEtA][HCOO] demonstrated higher efficiency, achieving 81% removal of Ni from Lemna minor's pulps, whereas [DMBA][HSO4] extracted only 28% of Ni with slightly higher pulp concentrations. These findings indicate the need for further optimization in concurrent metal extraction using ILs.
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Journal articleWu Y, An S, Tahmasebi P, et al., 2024,
An end-to-end approach to predict physical properties of heterogeneous porous media: Coupling deep learning and physics-based features (vol 352, 128753, 2023)
, FUEL, Vol: 364, ISSN: 0016-2361 -
Journal articleSharifzadeh M, Cooper N, van't Noordende H, et al., 2024,
Operational strategies and integrated design for producing green hydrogen from wind electricity
, International Journal of Hydrogen Energy, Vol: 64, Pages: 650-675, ISSN: 0360-3199Realizing the potential of renewable hydrogen production requires flexible operation of electrolysis systems to integrate with intermittent power sources. This work develops an optimization model to assess flexible operational strategies for alkaline and proton exchange membrane (PEM) electrolysers powered by wind energy. The model quantitatively analyses trade-offs between electrolyser shutdown strategies, overloading capacities, and battery integration to identify optimal regimes balancing efficiency, flexibility, and economics. The results reveal a mixed-integer linear programming approach can optimize system configurations and control strategies to minimize the levelized cost of hydrogen production. Optimal near-minimum load operation is achieved by independently optimizing the load of each electrolyser block, while avoiding shutdowns above a critical load level. Strategic electrolyser overloading can provide economic benefits by reducing installed capital costs, if technical feasibility and accelerated degradation are addressed. Battery energy storage integration significantly improves economics by enhancing asset utilization, provided excess renewable energy is available. The model provides novel insights on integrating alkaline and PEM electrolysis with intermittent wind power to advance renewable hydrogen production. Quantifying trade-offs between operational flexibility and economics will help guide flexible design and control strategies for cost-optimal renewable electrolysis systems.
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Journal articleLiyanage R, Fu X, Pini R, et al., 2024,
Direct comparison of density-driven convective mixing in a three-dimensional porous medium using experiments and simulation
, PHYSICAL REVIEW FLUIDS, Vol: 9, ISSN: 2469-990X -
Journal articleXie M, Zhou M, Chen L, et al., 2024,
Techno-economic assessment of the modified Allam cycle configurations with multi-stage pump/compressor for efficient operation in hot regions
, Energy Conversion and Management, Vol: 306, ISSN: 0196-8904The Allam cycle is renowned for its zero-carbon power generation and high efficiency. However, it faces challenges in hot regions where there is no available cold source for carbon dioxide liquefaction, leading to deterioration in its performance. In this study, a multi-stage pump/compressor is introduced, aiming to enhance the net electric efficiency of the conventional Allam cycle. Various potential enhancement methods are explored and analyzed through comprehensive thermodynamic and economic analyses. Among the configurations under consideration, the Allam cycle combined with two-stage pump/compressor and bypass compressor exhibits the best performance, achieving a 6.71 % increase in the efficiency of the conventional cycle. For the conventional Allam cycle, the efficiency decreases by 0.42 % for every 1 ℃ increase in ambient temperature, however, it is 0.17 % for the Allam-MPC cycle, which indicates it is less responsive to changes in ambient temperature. Moreover, the economic performance of the proposed cycle is better than that of the conventional cycle, which has higher revenue and lower levelized cost of electricity. The capital costs of the modified equipment represent around 1.43 % of the total capital costs of the conventional Allam cycle, and the investment-increment payback period is less than 0.5 years when the ambient temperature exceeds 30 ℃. Sensitivity analyses suggest that the proposed cycle will be more economically viable in hot regions with lower natural gas prices and higher electricity prices. Overall, this study provides a promising approach to improving the performance of Allam cycle in hot regions and offering valuable references for its practical implementation.
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