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| 2. |
- Bouchouireb, Hamza, 1991-
(författare)
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Advancing the life cycle energy optimisation methodology
- 2019
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Life Cycle Energy Optimisation (LCEO) methodology aims at finding a design solution that uses a minimum amount of cumulative energy demand over the different phases of the vehicle's life cycle, while complying with a set of functional constraints. This effectively balances trade-offs, and therewith avoids sub-optimal shifting between the energy demand for the cradle-to-production of materials, operation of the vehicle, and end-of-life phases. This work further develops the LCEO methodology and expands its scope through three main methodological contributions which, for illustrative purposes, were applied to a vehicle sub-system design case study.An End-Of-Life (EOL) model, based on the substitution with a correction factor method, is included to estimate the energy credits and burdens that originate from EOL vehicle processing. Multiple recycling scenarios with different levels of assumed induced recyclate material property degradation were built, and their impact on the LCEO methodology's outcomes was compared to that of scenarios based on landfilling and incineration with energy recovery. The results show that the inclusion of EOL modelling in the LCEO methodology can alter material use patterns and significantly effect the life cycle energy of the optimal designs.Furthermore, the previous model is expanded to enable holistic vehicle product system design with the LCEO methodology. The constrained optimisation of a vehicle sub-system, and the design of a subset of the processes which are applied to it during its life cycle, are simultaneously optimised for a minimal product system life cycle energy. In particular, a subset of the EOL processes' parameters are considered as continuous design variables with associated barrier functions that control their feasibility. The results show that the LCEO methodology can be used to find an optimal design along with its associated ideal synthetic EOL scenario. Moreover, the ability of the method to identify the underlying mechanisms enabling the optimal solution's trade-offs is further demonstrated.Finally, the functional scope of the methodology is expanded through the inclusion of shape-related variables and aerodynamic drag estimations. Here, vehicle curvature is taken into account in the LCEO methodology through its impact on the aerodynamic drag and therewith its related operational energy demand. In turn, aerodynamic drag is considered through the estimation of the drag coefficient of a vehicle body shape using computational fluid dynamics simulations. The aforementioned coefficient is further used to estimate the energy required by the vehicle to overcome aerodynamic drag. The results demonstrate the ability of the LCEO methodology to capitalise on the underlying functional alignment of the structural and aerodynamic requirements, as well as the need for an allocation strategy for the aerodynamic drag energy within the context of vehicle sub-system redesign.Overall, these methodological developments contributed to the exploration of the ability of the LCEO methodology to handle life cycle and functional trade-offs to achieve life cycle energy optimal vehicle designs.
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| 3. |
- Bouchouireb, Hamza, 1991-
(författare)
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Life Cycle Energy Optimisation: A multidisciplinary engineering design optimisation framework for sustainable vehicle development
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis explores how the systemic-level environmental footprint of light-duty vehicles could be reduced through integrative design using the Life Cycle Energy Optimisation (LCEO) methodology. This methodology aims at finding a design solution that uses a minimum amount of cumulative energy demand over the different phases of the vehicle's life cycle; while complying with a set of functional constraints, thereby avoiding any sub-optimal energy demand shifts between the vehicle's different life cycle phases. This thesis further develops the LCEO methodology and expands its scope through four main methodological contributions. This work also contributes in establishing the methodology as a standalone design approach and provides guidelines for its most effective use.Initially, an End-of-Life (EOL) model, based on the substitution with a correction factor method, is included to estimate the energy credits and burdens that originate from EOL vehicle processing. Multiple recycling scenarios with varying levels of induced recyclate material property degradation were built, and their associated resulting optimal vehicle subsystem designs were compared to those associated with landfilling and incineration with energy recovery scenarios. The results show how the structural material use patterns, as well as the very mechanisms enabling the embodiment of the Life Cycle Energy (LCE) optimal designs, are impacted by taking into consideration the effect of a vehicle's EOL phase. In particular, the material intensity-space allocation trade-off was identified as a key factor in the realisation of the LCE optimal designs.This coupling existing between optimal use of material and space allocation was further explored by functionally expanding the LCEO methodology's scope to handle aerodynamic functional requirements. This involved the definition of a novel allocation strategy for the energy necessary to overcome aerodynamic drag, as well as the development of a parametrised vehicle body model that ensures that the LCE knock-on effects of aerodynamically motivated design decisions are fully accounted for at the targeted subsystem level.The expanded methodology was subsequently applied to perform the aero-structural life cycle-driven design optimisation of a vehicle subsystem, with the impact of the constitutive material's circularity potential being included through the previously developed EOL model and scenarios. The results demonstrate the significant extent of the coupling existing between a vehicle's fundamental aerodynamic shape, and a vehicle's structural material composition, including its EOL characteristics, within the LCEO context.Beyond the vehicle level implications, the LCEO methodology's position within the broader vehicle-design methodology context was further characterised by comparing its outcomes to those of the purely lightweight and purely aerodynamic approaches. It was found that the LCE optimal designs were distinctly clustered from their mono-disciplinary counterparts. They offered up to 20% energy savings over the lightweight alternatives by being, on average, larger, heavier and more aerodynamics designs; while also being shorter and lighter than the optimal aerodynamic configurations.Subsequently, a mixed integer nonlinear programming formulation of this expanded LCEO methodology was developed to include the effects of battery energy storage systems on the LCE optimal vehicle designs. In particular, the vehicle's battery size and number of such batteries needed over its life cycle were introduced as variables subject to a range and a cycle life constraint. The former is derived from the battery-capacity-to-structural-mass ratio of recent production vehicles, while the second ensures that the batteries' cycle lives are sufficient for the entirety of the vehicle's use phase. Additionally, three battery chemistries with varying characteristics were included: lithium nickel manganese cobalt oxide (NMC), lithium iron phosphate (LFP) and lithium cobalt oxide (LCO); along with an EOL recycling scenario. The results of the coupled aero-structural-battery energy storage LCE-driven design optimisations demonstrate that battery chemistry and recycling potential have a significant impact on the system's design in terms of overall LCE footprint, battery size and number, as well as aerodynamic shape. More specifically, a change in battery composition was found to lead to up to 12.5% variation in drag coefficient, while battery recycling can on average reduce a vehicle's associated LCE by 32%.Finally, elements of robust design and uncertainty quantification were included into the LCEO methodology, in order to evaluate the impact of uncertainty on the resulting LCE optimal designs. Specifically, uncertainty was introduced through the assumption that the material properties of a subset of the optimisation's candidate materials are described by statistical distributions, as opposed to a priori fixed values, thereby changing the nature of the optimisation problem from deterministic to stochastic. This change is handled through a multilevel representation hierarchy for the targeted subsystem's model, and using the Multilevel Monte Carlo (MLMC) approach in the optimisation process to evaluate the expected compliance of a given design with the transport-related functional requirements. the results demonstrate how the robust design configurations both constitute a significant departure from their deterministic counterparts and depend on the EOL scenario considered, while only incurring a marginal LCE premium. Moreover, this work also further illustrated the performance increase associated with the use of the MLMC estimator in lieu of the classical Monte Carlo one within an optimisation under uncertainty framework.Overall, the work presented in this doctoral thesis has contributed to the development of the state-of-the-art of the LCEO methodology to enable the early-stage conceptual design of more sustainable vehicle configurations, and demonstrated how the methodology is at its most effective when leveraging its cross-scalar and cross-disciplinary nature to enable integrative functional vehicle design.
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| 4. |
- Bouchouireb, Hamza, 1991-, et al.
(författare)
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The inclusion of End-Of-Life modelling in the Life Cycle Energy Optimisation methodology
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In this work, an End-Of-Life (EOL) model is included in the Life Cycle Energy Optimisation (LCEO) methodology to account for the energy burdens and credits stemming from a vehicle’s EOL processing phase and balance them against the vehicle’s functional requirements and production and use phase energies. The substitution with a correction factor allocation method is used to model the contribution of recycling to the EOL phase’s energy. The methodology is illustrated through the optimisation of the design of a simplified vehicle sub-system. For the latter, multiple recycling scenarios with varying levels of assumed recycling induced material property degradation were built, and their impact on the vehicle sub-system’s optimal solutions was compared to that of scenarios based on landfilling and incineration with energy recovery. The results show that the inclusion of EOL modelling in the LCEO methodology can significantly alter material use patterns thereby effecting the life cycle energy of the optimal designs. Indeed, the vehicle sub-system’s optimal designs associated with the recycling scenarios are on average substantially heavier, and less life cycle energy demanding, than their landfilling or incineration with energy recovery-related counterparts.
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| 5. |
- Bouchouireb, Hamza, et al.
(författare)
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The inclusion of end-of-life modelling in the life cycle energy optimisation methodology
- 2021
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Ingår i: Journal of Mechanical Design. - : ASME International. - 1050-0472 .- 1528-9001. ; 143:5
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Tidskriftsartikel (refereegranskat)abstract
- In this work, an End-Of-Life (EOL) model is included in the Life Cycle Energy Optimisation (LCEO) methodology to account for the energy burdens and credits stemming from a vehicle's EOL processing phase and balance them against the vehicle's functional requirements and production and use phase energies. The substitution with a correction factor allocation method is used to model the contribution of recycling to the EOL phase's energy. The methodology is illustrated through the optimisation of the design of a simplified vehicle sub-system. For the latter, multiple recycling scenarios with varying levels of assumed recycling induced material property degradation were built, and their impact on the vehicle sub-system's optimal solutions was compared to that of scenarios based on landfilling and incineration with energy recovery. The results show that the vehicle sub-system's optimal designs are significantly dependent on the EOL scenario considered. In particular, the optimal designs associated with the recycling scenarios are on average substantially heavier, and less life cycle energy demanding, than their landfilling or incineration with energy recovery-related counterparts; thus, demonstrating how the inclusion of EOL modelling in the LCEO methodology can significantly alter material use patterns, thereby effecting the very mechanisms enabling the embodiment of the resulting life cycle energy optimal designs.
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| 6. |
- Bouchouireb, Hamza, et al.
(författare)
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The inclusion of vehicle shape and aerodynamic drag estimations within the life cycle energy optimisation methodology
- 2019
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Ingår i: Procedia CIRP. - : Elsevier. - 2212-8271 .- 2212-8271. ; 84, s. 902-907
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Tidskriftsartikel (refereegranskat)abstract
- The present work describes a widening of the scope of the Life Cycle Energy Optimisation (LCEO) methodology with the addition of shape-related design variables. They describe the curvature of a vehicle which impacts its aerodynamic drag and therewith its operational energy demand. Aerodynamic drag is taken into account through the estimation of the drag coefficient of the vehicle body shape using computational fluid dynamics simulations. Subsequently, the aforementioned coefficient is used to calculate the operational energy demand associated with the vehicle. The methodology is applied to the design of the roof of a simplified 2D vehicle model which is both mechanically and geometrically constrained. The roof is modelled as a sandwich structure with its design variables consisting of the material compositions of the different layers, their thicknesses as well as the shape variables. The efficacy of the LCEO methodology is displayed through its ability to deal with the arising functional conflicts while simultaneously leveraging the design benefits of the underlying functional alignments. On average, the optimisation process resulted in 2.5 times lighter and 4.5 times less life cycle energy-intensive free shape designs. This redesign process has also underlined the necessity of defining an allocation strategy for the energy necessary to overcome drag within the context of vehicle sub-system redesign.
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| 7. |
- Bouchouireb, Hamza, 1991-, et al.
(författare)
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Towards holistic energy-efficient vehicle product system design: The case for a penalized continuous end-of-life model in the life cycle energy optimisation methodology
- 2019
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Ingår i: Proceedings of the International Conference on Engineering Design. - : Cambridge University Press. - 2220-4334 .- 2220-4342. ; 1, s. 2901-2910
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Tidskriftsartikel (refereegranskat)abstract
- The Life Cycle Energy Optimisation (LCEO) methodology aims at finding a design solution that uses a minimum amount of cumulative energy demand over the different phases of the vehicle's life cycle, while complying with a set of functional constraints. This effectively balances trade-offs, and therewith avoids sub-optimal shifting between the energy demand for the cradle-to-production of materials, operation of the vehicle, and end-of-life phases. The present work describes the extension of the LCEO methodology to perform holistic product system optimisation. The constrained design of an automotive component and the design of a subset of the processes which are applied to it during its life cycle are simultaneously optimised to achieve a minimal product system life cycle energy. A subset of the processes of the end-of-life phase of a vehicle’s roof are modelled through a continuous formulation. The roof is modelled as a sandwich structure with its design variables being the material compositions and the thicknesses of the different layers. The results show the applicability of the LCEO methodology to product system design and the use of penalisation to ensure solution feasibility.
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| 8. |
- Bouchouireb, Hamza, 1991-, et al.
(författare)
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Vehicle aerodynamic shape significantly impacted by vehicle material composition and material circularity potential in life cycle energy optimal vehicle design
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- This paper explores how the systemic-level energy consumption of light-duty vehicles could be reduced through integrative design. To this end, the Life Cycle Energy Optimisation (LCEO) methodology is used to achieve the coupled optimal use of materials (including their circularity potential) and vehicle aerodynamic shape to reduce the overall Life Cycle Energy (LCE) footprint of light-duty vehicles, with the results being compared to the lightweight and aerodynamic alternatives. Initially, the methodology is functionally expanded to handle aerodynamic functional requirements through the definition of a novel allocation strategy for the aerodynamic energy, and a parametrised simple vehicle body model that ensures that the LCE knock-on effects of aerodynamically-motivated design decisions are fully accounted for. Subsequently, the methodology is used to perform the first, to the knowledge of the authors, aero-structural LCE-driven design optimisation of a vehicle subsystem, with the impact of the materials’ circularity potential being taken into account through various end-of-life (EOL) processing scenarios, including recycling. The results show that the environmental footprint of light-duty vehicles could significantly be reduced through integrative early-stage design. Specifically, it shows that a life cycle energy optimal vehicle's aerodynamic shape is significantly impacted by the vehicle's material composition and the latter's EOL characteristics — particularly recycling potential. Furthermore, LCE optimal vehicles have been found to be on average longer, heavier and more aerodynamic than their lightweight counterparts, as well as offering up to 20% energy savings per vehicle; while also being shorter and lighter than optimal aerodynamic configurations.
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| 9. |
- Brito de Figueirêdo, M. C., et al.
(författare)
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Environmental assessment of tropical perennial crops : The case of the Brazilian cashew
- 2015
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Ingår i: Journal of Cleaner Production. - : Elsevier. - 0959-6526 .- 1879-1786.
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Tidskriftsartikel (refereegranskat)abstract
- This study is an original environmental assessment of the Brazilian cashew, a perennial tree cultivated in 30 tropical countries that yields four products: nuts, apples, gum and wood. While economic and agronomic data regarding cashew are available worldwide, the environmental issues related to the main production systems and products commercialized by Brazilian farms have not been discussed consistently. This environmental assessment is important to guide the efforts of researchers and farmers for improving the environmental performance of cashew cropping systems and products. Life cycle assessment is applied to assess the environmental impacts of cashew systems and products, considering multi-cropping systems, agriculture functions and allocation procedures. Two cashew cropping systems are compared: (i) a high-input system, or reference system, developed through 20 years of research, and (ii) a low input system, as defined by a sample of farms practicing multi-cropping systems. Aspects and impacts of these systems are reported via the following production stages: nursery, establishment, and low and full production. Two agriculture functions are adopted to analyze the cropping systems: land management (impacts per hectare) and financial (impact per US$ from total sales receipts). The impacts of cashew products are evaluated using the crop production function (per kilogram of product). The impacts of products are measured using both mass and economic allocation. This study shows that the low and full production stages account for the majority of impact in both cropping systems, but land transformation for the establishment of cashew orchards is the main contributor of climate change. The analysis of multiple agriculture function shows different results for the study of cashew production systems and products. Considering the land management function (impacts per hectare), the low-input system causes less significant environmental impact, when compared to the high-input system, in all categories but toxicity. When the financial function is analyzed (impacts per US$ from total sales receipts from one ha), the low-input system achieves better performance for only eutrophication and water depletion impact categories. The analysis of the crop production function (impacts per kilogram of product) shows that the choice of allocation procedure also affects the results when comparing the impact values of products from different cropping systems. If the choice is for mass allocation, products from the low-input system achieve better environmental performance, but if economic allocation is chosen, products from the high-input system perform equal or better than when produced in the low-input system. From the joint analysis of agriculture functions, the conclusion is that the best option to improve the environmental performance of the Brazilian cashew production is to adjust the high-input system with modifications regarding fertilization and pest management. From this case study, the benefits of considering multi-agriculture functions and accounting for all production stages in the study of perennial crops are highlighted. The importance of developing emission and characterization factors to reduce uncertainty when estimating pollutant loads and evaluating impacts of perennial crops cultivated in tropical regions is also discussed. This study advances the knowledge base on the environmental assessment of perennial crops in general, and on cashew crops specifically.
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| 10. |
- Brito de Figueiredo, Maria Clea, et al.
(författare)
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Reducing the impact of irrigated crops on freshwater availability : the case of Brazilian yellow melons
- 2014
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Ingår i: The International Journal of Life Cycle Assessment. - : Springer Science and Business Media LLC. - 0948-3349 .- 1614-7502. ; 19:2, s. 437-448
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Tidskriftsartikel (refereegranskat)abstract
- This study quantifies freshwater consumption throughout the life cycle of Brazilian exported yellow melons and assesses the resulting impact on freshwater availability. Results are used to identify improvement options. Moreover, the study explores the further impact of variations in irrigation volume, yield, and production location. The product system boundary encompasses production of seeds, seedlings, and melon plants; melon packing; disposal of solid farm waste; and farm input and melon transportation to European ports. The primary data in the study were collected from farmers in order to quantify freshwater consumption related to packing and to production of seeds, seedlings, and melons. Open-field melon irrigation was also estimated, considering the region's climate and soil characteristics. Estimated and current water consumptions were compared in order to identify impact reduction opportunities. Sensitivity analysis was used to evaluate variations in the impact because of changes in melon field irrigation, yield, and farm location. This study shows that the average impact on freshwater availability of 1 kg of exported Brazilian yellow melons is 135 l H2O-e, with a range from 17 to 224 l H2O-e depending on the growing season's production period. Irrigation during plant production accounts for 98 % of this impact. Current melon field water consumption in the Low Jaguaribe and A double dagger u region is at least 39 % higher than necessary, which affects the quality of fruits and yield. The impact of melon production in other world regions on freshwater availability may range from 0.3 l H2O-e/kg in Costa Rica to 466 l H2O-e/kg in the USA. The impact of temporary crops, such as melons, on water availability should be presented in ranges, instead of as an average, since regional consumptive water and water stress variations occur in different growing season periods. Current and estimated water consumption for irrigation may also be compared in order to identify opportunities to achieve optimization and reduce water availability impact.
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