Research Papers - Department of Materials Engineering

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Start date: 2012End date: 2019

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Now showing 1 - 6 of 6
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    PublicationOpen Access
    Comparative assessment on the extraction of carotenoids from microalgal sources: Astaxanthin from H. pluvialis and β-carotene from D. salina
    (Elsevier, 2019-03-20) Rammuni, M N; Ariyadasa, Thilini U; Nimarshana, P. H. V; Attalage, R. A
    Astaxanthin and β-carotene are important carotenoids used in numerous pharmaceutical and nutraceutical applications, owing to their vigorous antioxidant properties. The microalgal strains Haematococcus pluvialis and Dunaliella salina accumulate the highest quantities of astaxanthin and β-carotene (up to 7% and 13% dry weight respectively) and are therefore considered as sustainable feedstock for the commercial production of carotenoids. Thus, from an economical perspective, it becomes desirable to optimize recovery of carotenoids from microalgal cells. To this end, here, we have summarized the conventional and modern extraction techniques generally used for the recovery of astaxanthin from Haematococcus pluvialis and β-carotene from Dunaliella salina. Furthermore, we have also discussed the optimum process conditions employed for numerous extraction protocols including solvent extraction, ultrasonic-assisted extraction (UAE), microwave-assisted extraction (MAE) and supercritical fluid extraction (SFE). Overall, our study highlights the sustainability of integrated co-production of biofuels and carotenoids in a biorefinery framework.
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    PublicationOpen Access
    Designing standalone hybrid energy systems minimizing initial investment, life cycle cost and pollutant emission
    (Pergamon, 2013-06-01) Perera, A. T. D; Attalage, R. A; Perera, K. K. C. K; Dassanayake, V. P. C
    HES (hybrid energy system)s are becoming energy systems of choice for standalone applications due to ever increasing fuel costs and global concern on GHG (Green House Gas) emissions. However, it is difficult to justify the higher ICC (Initial Capital Cost) of renewable energy components, especially for rural electrification projects in developing countries. This paper illustrates the modeling and simulation of HESs, and multi-objective optimization carried out in order to support decision-making in such instances. LEC (Levelized Energy Cost), ICC and GHG emission were taken as objective functions in the optimization and the sensitivity of market prices and power supply reliability was further evaluated. Results depict that Pareto front of LEC, ICC and GHG emission can be simplified as a combination of ICC–LEC and LEC–GHG emission Pareto fronts making the decision-making process simpler. Gradual integration of renewable energy sources in a number of design stages is proposed for instances where it is difficult to bear the higher ICC. Finally, importance of planning integration of renewable energy sources at early design stages of the project is highlighted in order to overcome the difficulties that need to be faced when coming up with the optimum design.
  • Thumbnail Image
    PublicationOpen Access
    Comparative assessment on the extraction of carotenoids from microalgal sources: Astaxanthin from H. pluvialis and β-carotene from D. salina
    (Elsevier, 2019-03-30) Rammuni, M N; Ariyadasa, Thilini U; Nimarshana, P H V; Attalage, R.A
    Astaxanthin and β-carotene are important carotenoids used in numerous pharmaceutical and nutraceutical applications, owing to their vigorous antioxidant properties. The microalgal strains Haematococcus pluvialis and Dunaliella salina accumulate the highest quantities of astaxanthin and β-carotene (up to 7% and 13% dry weight respectively) and are therefore considered as sustainable feedstock for the commercial production of carotenoids. Thus, from an economical perspective, it becomes desirable to optimize recovery of carotenoids from microalgal cells. To this end, here, we have summarized the conventional and modern extraction techniques generally used for the recovery of astaxanthin from Haematococcus pluvialis and β-carotene from Dunaliella salina. Furthermore, we have also discussed the optimum process conditions employed for numerous extraction protocols including solvent extraction, ultrasonic-assisted extraction (UAE), microwave-assisted extraction (MAE) and supercritical fluid extraction (SFE). Overall, our study highlights the sustainability of integrated co-production of biofuels and carotenoids in a biorefinery framework.
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    PublicationEmbargo
    Designing standalone hybrid energy systems minimizing initial investment, life cycle cost and pollutant emission
    (Pergamon, 2013-06-01) Perera, A. T. D; Attalage, R. A; Perera, K. K. C. K; Dassanayake, V. P. C
    HES (hybrid energy system)s are becoming energy systems of choice for standalone applications due to ever increasing fuel costs and global concern on GHG (Green House Gas) emissions. However, it is difficult to justify the higher ICC (Initial Capital Cost) of renewable energy components, especially for rural electrification projects in developing countries. This paper illustrates the modeling and simulation of HESs, and multi-objective optimization carried out in order to support decision-making in such instances. LEC (Levelized Energy Cost), ICC and GHG emission were taken as objective functions in the optimization and the sensitivity of market prices and power supply reliability was further evaluated. Results depict that Pareto front of LEC, ICC and GHG emission can be simplified as a combination of ICC–LEC and LEC–GHG emission Pareto fronts making the decision-making process simpler. Gradual integration of renewable energy sources in a number of design stages is proposed for instances where it is difficult to bear the higher ICC. Finally, importance of planning integration of renewable energy sources at early design stages of the project is highlighted in order to overcome the difficulties that need to be faced when coming up with the optimum design.
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    PublicationEmbargo
    A hybrid tool to combine multi-objective optimization and multi-criterion decision making in designing standalone hybrid energy systems
    (Elsevier, 2013-07-01) Amarasinghage, T; Perera, D; Attalage, R. A; Perera, K. K. C. K; Dassanayake, Vishwanath P C
    Hybrid energy systems (HESs) are becoming popular for standalone applications due to global concern regarding green house gas (GHG) emissions and depletion of fossil fuel resources. Research in the optimal design of HESs is ongoing, with numerous optimization techniques giving special emphasis to Pareto optimization, incorporating conflicting objectives. The subsequent decision-making process including the non-dominant set of solutions has yet to be addressed. This work focuses on combining multi-objective optimization with a multi-criterion decision making (MCDM) technique to support decision makers in the process of designing HESs. Four different objectives, i.e., levelized energy cost (LEC), unmet load fraction, wasted renewable energy (WRE) and fuel consumption are used to obtain the Pareto front. A decision support tool based on Fuzzy TOPSIS and level diagrams is proposed to analyze the Pareto front and support the subsequent decision-making activity. A case study is used to illustrate the applicability of the proposed method. The study shows that the novel method is useful when determining the relative weights of objectives, providing a detailed picture of the objective space to the designer when coming up with the optimum system. The technique proposed in this study can be further extended to analyze similar problems in energy system design where MCDM is necessary after multi-objective optimization.
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    PublicationOpen Access
    Modeling of microstructural evolution in an MCrAlY overlay coating on different superalloy substrates
    (Springer US, 2012-02-01) Karunaratne, M. S. A; Martino, Irene Di; Ogden, Sarah L; Oates, David L; Thomson, R C
    A multicomponent, one-dimensional diffusion model that was developed for simulating microstructure evolution in coated gas turbine blade systems has been used to compare the phase structures of three MCrAlY coated superalloy systems. The model is based on finite differences and incorporates oxidation and equilibrium thermodynamic computations. The superalloy substrates considered were the nickel-based superalloy CMSX-4, a high-Cr singlecrystal superalloy, and a cobalt-based MAR-M509, and these were all coated with an MCrAlY bond coat of similar composition. The results predicted by the model have been compared with similar experimental systems. The model can predict many features observed experimentally and therefore can be expected to be a useful tool in lifetime prediction and microstructural assessment of turbine blade systems based on superalloys. The work also highlighted the fact that for a given coating, the phase evolution within system is dependent on the substrate material.