MESII - 2023

Permanent URI for this collectionhttp://192.248.9.226/handle/123/21214

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Browsing MESII - 2023 by Author "Attygalle, D"

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    item: Conference-Abstract
    Development of engine oil quality analyzer based on optical metrological techniques
    (Department of Materials Science and Engineering, University of Moratuwa., 2023-07-28) Ishan, RLP; Heshan, MPN; Attygalle, D; Sivahar, V
    With an annual global consumption of 36.3 million tons of engine oil and concerns about premature disposal, we propose an optical metrological approach to accurately assess engine oil quality. A side polished optical fiber in touch with oil, photo diode and a photo detector were used to build the sensor unit. To avoid damage to the core, cladding removal was performed meticulously, while minimizing wire bending reduced optical power loss. Utilizing a side-polished optical fiber, the refractive index changes in engine oil were measured, allowing real-time assessment. This method offers non-destructive, precise, and straightforward measurements. Theoretical validation was done by utilizing Fresnel's equations. Further a correlation between theoretical values and refractive indices of oils with mileage was established. For the oil type 10W-30, which is used as the engine oil for petrol engines, a change of refractive index of 1.4651 to 1.4689 was observed over a milage of 3140 km. the detector voltage ratio for that range was 0.5928 to 0.6748, which is well within the range the sensor can detect. Similarly, an experiment conducted for oil type 15W-40, which is an engine oil used in diesel engine showed a refractive index variation of 1.5966 to1.6015 over a milage of 3721 km, which corresponds to a change of sensor voltage ratio 0.5427 to 0.4571 was obtained. Both experimental data and theoretical predictions confirmed that the sensor is effective and sensitive to subtle change in oil quality. This research successfully developed optical metrology, offering potential for online oil quality monitors, and addressing environmental concerns linked to premature oil disposal.
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    item: Conference-Abstract
    Numerical optimization of band gap gradient cigs solar cells
    (Department of Materials Science and Engineering, University of Moratuwa., 2023-07-28) Sewwandi, HMDU; Amanda, WN; Attygalle, D; Sivahar, V
    Thin-film chalcopyrite Cu(In1-x, Gax)Se2 (CIGS) Solar cells have become more promising for commercial applications due to recent laboratory advancements, achieving an efficiency of approximately 22%, which surpasses efficiencies most other thin-film solar cells. This study of numerical device simulations has proposed methods to improve the efficiency of thin film CIGS solar cells and analyze the composition gradient shift due to In, Ga diffusion under solar cell fabrication conditions. In CIGS solar cells, the Cu(In1-xGax)Se absorber layer is the most critical layer that influences the solar cell performance. In this simulation study, several band gap gradients were created by varying compositional ratio of Ga to In in the absorber layer. The band gap gradient optimization was done by using numerical device simulator SCAPS software. The optimum bandgap gradient slope of 0.61 eVμm-1 was obtained with the improved efficiency of 32% and a fill factor of 88.5. The diffusion of In and Ga under fabrication conditions were simulated by COMSOL MULTIPHYSICS software. Taking account of compositional variation of the absorber due to diffusion, the optimum conversion efficiency has dropped to 25%. The simulation results obtained for solar cell performances and elemental gradients reported for high efficiency solar cells shows a good agreement. Considering the effect of diffusion at elevated temperatures during fabrication, this study proposes an optimum elemental flux to be used fabrication of graded band gap CIGS layer.