Research Papers - Department of Mechanical Engineering

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Author: search.filters.author.Attalage, R. AHas files: Yes

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Now showing 1 - 10 of 29
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    PublicationOpen Access
    Power Management Strategy of a Parallel Hybrid Three-Wheeler for Fuel and Emission Reduction
    (Multidisciplinary Digital Publishing Institute, 2021-01) Maddumage, W; Perera, M; Attalage, R. A; Kelly, P
    Millions of three-wheelers in large cities of Asia and Africa contribute to the already increasing urban air pollutants. An emerging method to reduce adverse effects of the growing three-wheeler fleet is hybrid-electric technology. The overall efficiency of a hybrid electric vehicle heavily depends on the power management strategy used in controlling the main powertrain components of the vehicle. Recent studies highlight the need for a comprehensive report on developing an easy-to-implement and efficient control strategy for hybrid electric three-wheelers. Thus, in the present study, a design methodology for a rule-based supervisory controller of a pre-transmission parallel hybrid three-wheeler based on an optimal control strategy (i.e., dynamic programming) is proposed. The optimal control problem for minimizing fuel, emissions (i.e., HC, CO and NOx) and gear shift frequency are solved using dynamic programming (DP). Numerical issues of DP are analyzed and trade-offs between optimizing objectives are presented. Since DP strategy cannot be implemented as a real-time controller, useful strategies are extracted to develop the proposed rule-based strategy. The developed rule-based strategy show performance within 10% of the DP results on WLTC and UDC-NEDC drive cycles and has the clear advantage of being near-optimal, easy-to-implement and computationally less demanding.
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    PublicationOpen Access
    Making Realistic Predictions on Building Energy Performance through Coupled Energy Simulation and Computational Fluid Dynamics
    (National Energy Symposium, 2015-11-20) Bandara, R. M. P. S; Attalage, R. A; Fernando, W. C. D. K
    Buildings account for nearly 40% of the global energy consumption and hence presently high emphasize is made on improving the energy performance of buildings. Energy Simulation (ES) is the most widely used method in predicting the energy performance of buildings during the conceptual stage. However, it is observed that Energy Simulation tools show certain inherent deficiencies in predicting the energy performance of buildings. The said tools do not have the capacity to model air circulation through the building space explicitly. Energy Simulation tools mainly rely on the simplifying assumption that air within a thermal zone of a building is well-mixed. Furthermore, convective heat transfer coefficients of building surfaces are calculated using set empirical correlations. Hence, ES tools often find it difficult to make realistic predictions on energy performance of buildings. The literature also reveals that most Energy Simulation tools under-predict energy consumption in buildings, especially under sunny conditions. On the other hand, Computational Fluid Dynamics (CFD) tools are capable of predicting the indoor flow field comprehensively. However, CFD simulations need to be provided with the corresponding boundary conditions of the computational domain, which are readily available in the Energy Simulation approach. On this basis, the paper explains how Energy Simulation can be coupled with Computational Fluid Dynamics in predicting the energy performance of an actual building design more accurately through complementary data exchange between the tools. The analysis uses EnergyPlus 8.0 and Ansys Fluent 6.3 as the tools for conducting Energy Simulation and Computational Fluid Dynamics respectively. MATLAB R2012a establishes the coupling platform. The study shows that the coupled scheme predicts considerably higher energy consumption for the building design compared to that given by the conventional Energy Simulation using EnergyPlus.
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    PublicationEmbargo
    Co-production of fucoxanthin, docosahexaenoic acid (DHA) and bioethanol from the marine microalga Tisochrysis lutea
    (Elsevier, 2021-12-01) Premaratne, M; Liyanaarachchi, V. C; Nimarshana, P. H. V; Ariyadasa, T. U; Malik, A; Attalage, R. A
    The marine microalga Tisochrysis lutea is renowned for its ability to synthesize fucoxanthin and docosahexaenoic acid (DHA), which are nutritionally valuable high-value compounds. Although numerous studies in literature have assessed fucoxanthin and DHA production by T. lutea, very few studies have evaluated the feasibility of comprehensively utilizing biomass for co-production of these metabolites within the framework of biorefineries. To this end, the current study focused on the synthesis of fucoxanthin and DHA by cultivation of T. lutea under two different initial nitrate concentrations (1x: 882 µM, 3x: 2,646 µM) and three different light intensities (LL: 50 µmol/m2/s; ML: 100 µmol/m2/s; HL: 150 µmol/m2/s). The maximum fucoxanthin yield of 8.80 ± 0.30 mg/L (14.43 ± 0.52 mg/g) and DHA yield of 7.08 ± 0.02 mg/L (11.90 ± 0.14 mg/g) were achieved in the 3x HL culture at the end of 16 days of cultivation. Thereafter, a novel process of biphasic solvent extraction using ethanol/n-hexane/water (10:9:1 v/v/v) was utilized for co-extraction 97.96 ± 0.54% fucoxanthin and 74.11 ± 1.49% DHA from 3x HL biomass, and products were separated into two fractions. Fermentation of the residual biomass obtained from co-extraction resulted in a bioethanol yield of 48.49 ± 0.58 mg/g. Accordingly, the current study demonstrated the potential of T. lutea as a feedstock for biorefineries.
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    PublicationEmbargo
    A techno-economic analysis for an integrated solar PV/T system for building applications
    (IEEE, 2016-12-16) Jayasuriya, W. J. A; Athukorala, A. U. C. D; Perera, A. T. D; Sirimanna, M. P. G; Attalage, R. A
    This study presents a techno-economic assessment about an integrated energy system based on hybrid Photovoltaic/Thermal (PV/T) panels to cater the energy demand for an apparel manufacturing application. The energy system consists of PV/T panels, H2 storage, electrolyzer, fuel cell and a latent heat thermal storage. A computational model (energy flow model combined with an economic model) is developed to assess the performance of the system. The computational model is simulated on hourly basis for a selected set of representative days of the year. The responses of energy storage and local grid according to demand variations of the application are evaluated subsequently considering the economic aspects. A novel dispatch strategy is introduced to charge and discharge energy storage based on the real time pricing of the grid. The response of local grid with the changes in system configuration is analyzed in the study. The potential of harvesting energy from integrated PV/T systems is emphasized by comparing the grid interaction with the in different climatic conditions is through case studies for different geographic locations. Results obtained from the study demonstrate the feasibility of integrated energy systems based on PV/T.
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    Development of multi-sensory feedback system for building automation systems
    (IEEE, 2017-10) Basnayake, B. A. D. J. C. K; Amarasinghe, Y. W. R; Attalage, R. A; Jayasekara, A. G. B. P; Devinda, M. G. K
    Under this research, the multi-sensory feedback system has been developed utilizing commercially available MEMS based and miniaturized sensors for building automation systems. This system consist of non-contact infrared thermal array sensor based occupancy identification / localization system and self-floor locations categorization system with an environmental monitoring system. Further, it has smart realtime energy monitoring system which capable to identify the load devices and their status while operation. The entire system is capable of obtaining quantitative values of this sensory information and applied for the development of more convenient and energy efficient automation in building premises. The implemented system was tested and validated using fuzzy logic based building automation controller via the wireless network.
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    A model for analyzing the thermal performance of roof configurations with flat inclined surfaces
    (Elsevier, 2016-03-15) Sirimanna, M. P. G; Attalage, R. A
    The development of a thermal model, followed by a generalized computational tool that analyses thermal performance of roofs with four inclined surfaces and a ceiling by considering dynamic environmental and operating conditions, changes of roof geometry and materials is presented here. Roof elements are analyzed based on finite-volume method with implicit formulation. View factors of roof enclosures are calculated numerically. Experimental results, obtained for six actual building roofs under tropical climatic conditions of Sri Lanka, indicated that the thermal model is capable of replicating the actual temperature profiles with an average accuracy of 1.1 °C. Ceiling temperature of common roofs were found to be 10 °C above the ambient temperature, which could even rise up to15 °C in hot days. The model was successfully used to compare roofs and quantify the thermal effects of different parameters. For instance, changes in geometrical parameters led ceiling temperature to change by 5 °C, highlighting the importance of roof geometry. Out of the widely used three roofing materials in Sri Lanka, clay tile roofing has showed the best thermal performance. Compared to clay tiles, asbestos and steel roofing can have a maximum ceiling temperature rise of 4 °C and 6 °C, respectively.
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    Multi Objective Optimization of Lifecycle Cost, Unmet Load, and Renewable Energy Capacity for an Expansion of Existing Standalone Internal Combustion Generator (ICG) Systems
    (Elsevier, 2011-01-01) Perera, A. T. D; Attalage, R. A
    This paper presents, for the first time, the application of the strength Pareto evolutionary algorithm to the multi-objective design of isolated hybrid systems, minimising both the total cost throughout the useful life of the installation and the unmet load. For this task, a multi-objective evolutionary algorithm (MOEA) and a genetic algorithm (GA) have been used in order to find the best combinations of components for the hybrid system and control strategy. Also, a novel control strategy has been developed and it will be expounded in this article. As an example of application, a PV–wind–diesel system has been designed, obtaining a set of possible solutions (Pareto set) from which the designer can choose those which he/she prefers considering the costs and unmet load of each. The results obtained demonstrate the practical utility of the design method used.
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    Occupancy identification based energy efficient Illuminance controller with improved visual comfort in buildings
    (IEEE, 2017-05-29) Basnayake, B. A. D. J. C. K; Amarasinghe, Y. W. R; Attalage, R. A; Jayasekara, A. G. B. P
    Under this research Smart energy efficient and visual comfort lighting system has been developed based on the presence of occupancy and occupancy localization information. The developed system consist of non-contact occupancy identification system, wireless sensor network, and wireless light intensity control device. The controller is constructed on a fuzzy logic based closed loop controller developed on a single board computer powered by 900MHz quad-core ARM Cortex-A7 CPU. Lighting is an important factor in maintaining the visual comfort in a living premise. According to literature, the lighting consumes about 40% of total electricity consumption in a building. Since lighting energy requirement contains a larger share of energy demand any saving from that demand will result in a reduction in areas of energy wastage, negative impact to the environment and the cost to the consumers and so on. The results of the experiment indicate that the improvement of visual comfort and enhanced energy performance by avoiding of unwanted visual comfort level in a living premise.
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    PublicationEmbargo
    Smart solar tracking and on-site photovoltic efficiency measurement system
    (IEEE, 2016-04-05) Basnayake, B. A. D. J. C. K; Jayathilaka, W. A. D. M; Amarasinghe, Y. W. R; Attalage, R. A; Jayasekara, A. G. B. P
    On-site photovoltaic efficiency data is a valuable asset during a process of predicting photovoltaic potential. Not just the solar power output, but also the ambient conditions and panel temperature should be measured for a better and convinced results. Due to the unavailability of on-site data, erroneous conclusions have been made after various prediction methods. Smart solar tracking and on-site photovoltaic measurement system is proposed as a novel tool to be used in solar potential predictions which can measure and log on-site solar data. This device is capable of measuring and logging available solar power together with ambient measurements such as light intensity level, ambient temperature and humidity level and panel temperature. Measured data will then be stored in an internal memory card and will be available at any moment. Integrated wireless communication module will enable remote log-in and control of the device. Computer based Graphical User Interface (GUI) software application enables the remote access to the gathered data and optimization of its operation.
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    PublicationOpen Access
    Optimization Methodologies for Building Performance Modelling and Optimization
    (FACULTY OF ENGINEERING, UNIVERSITY OF MORATUWA, 2013) Bandara, R. M. P. S; Attalage, R. A
    Buildings account for approximately 40% of the global energy consumption and 36% of total carbon dioxide emissions. At present, high emphasis is given on the reduction of energy consumption and carbon footprint by optimizing the performance and resource utilization of buildings to achieve sustainable development. Building performance is analyzed in terms of energy performance, indoor environment for human comfort & health, environmental degradation and economic aspects. As for the energy performance analysis, this can be best modeled and optimized by a whole building energy simulation tool coupled with an appropriate optimization algorithm. Building performance optimization problems are inherently multivariate and multi-criteria. Optimization methodologies with different characteristics that are broadly classified as Adaptive, Non-adaptive and Pareto Algorithms can be applied in this regard. The paper discusses the applicability of the aforementioned optimization methodologies in building performance optimization for achieving realistic results.