Papers by Dr Chamil Abeykoon
World Congress on Mechanical, Chemical, and Material Engineering, 2017
The demand for renewable energy sources such as hydro, solar and wind has been rapidly growing ov... more The demand for renewable energy sources such as hydro, solar and wind has been rapidly growing over the last few decades due to the increasing environmental issues and the predicted scarcity of fossil fuels. Among the renewable energy sources, hydropower generation is one of the primary sources which date back to 1770s. Hydropower turbines are in two types as impulse and reaction where Kaplan turbine is a reaction type which was invented in 1913. The efficiency of a turbine is highly influenced by its runner wheel and this work aims to study the design of a Kaplan turbine runner wheel. First, a theoretical design was performed for determining the main characteristics where it showed an efficiency of 94%. Usually, theoretical equations are generalized and simplified and also they assumed constants of experienced data and hence a theoretical design will only be an approximate. This was confirmed as the same theoretical design showed only 59.98% of efficiency with a computational fluids dynamics (CFD) evaluation. Then, the theoretically proposed design was further analysed where pressure distribution and inlet/outlet tangential velocities of the blades were analysed and corrected with CFD to improve the efficiency of power generation. The original design could be improved to achieve an efficiency of 93.01%. In general, the blades' inlet/outlet angles showed a significant influence on the turbine's power output. Finally, a comparison of the optimised and theoretical design is presented.
Cleaner Engineering and Technology, 2021
International Conference on Fluid Flow and Thermal Science, 2020
For the manufacturing industry, process monitoring is a key to observe the product quality, opera... more For the manufacturing industry, process monitoring is a key to observe the product quality, operational health, safety, and also for achieving good/satisfactory process control performance. For some industrial processes, the level of control of the process operational quality is vastly dependent upon the performance of the process monitoring techniques as it is quite difficult to observe the inside of the processing chambers during the process operation. Currently, a number of physical sensing devices/techniques are widely available for industrial applications for monitoring of parameters, such as temperature, pressure, speed, product dimensions, and so on, in real-time. However, there may be some limitations in using physical sensors in some of the practical process measurements due to several constraints such as their access requirements, disruptive effects to the process/product, fragility, complexity, and so on. Therefore, soft sensing techniques should be highly useful for improved process monitoring and modelling, and hence for advanced process control as well. In the context of current industrial process control, the majority of the industrial processes are equipped with PID controllers. However, these controllers may not be capable of gathering knowledge from the processes to make control decisions. Hence, artificial intelligence (AI) approaches such as fuzzy logic, neural networks and machine learning are becoming popular due to their ability of making control decisions incorporating real-time processing behaviour. Given the situation, soft sensing techniques and AI based control techniques should be really invaluable for the future development of the processing/manufacturing industry.
Proceedings of the 7th World Congress on Mechanical, Chemical, and Material Engineering, 2021
This study aims to evaluate potential methodologies for improving the performance of polypropylen... more This study aims to evaluate potential methodologies for improving the performance of polypropylene (PP) matrix composites by the addition of carbon fibre and kaolin fillers, processed using a twin screw extruder, and compare them with neat PP. The effect of filler types and loading was investigated on mechanical properties such as the tensile modulus, flexural modulus, and impact strength, evaluated by using universal testing systems. Of the two types of composites, carbon fibre reinforced composites gave the best performance. The results showed that the addition of 30 wt% of short carbon fibre to neat PP raised the tensile modulus and flexural modulus by 219% and 280%, respectively, compared to neat PP itself. Also, the elongation at break was reduced by 87-96% compared to neat PP, which is attributed to such fillers restricting the chain mobility of polymer molecules. Addition of kaolin has also resulted in improved tensile and flexural modulus up to 42% and 41%, respectively, fro...
Energies, 2020
Thermophotovoltaic (TPV) systems generate electricity without the limitations of radiation interm... more Thermophotovoltaic (TPV) systems generate electricity without the limitations of radiation intermittency, which is the case in solar photovoltaic systems. As energy demands steadily increase, there is a need to improve the conversion dynamics of TPV systems. Consequently, this study proposes a novel radiation-thermodynamic model to gain insights into the thermodynamics of TPV systems. After validating the model, parametric studies were performed to study the dependence of power generation attributes on the radiator and PV cell temperatures. Our results indicated that a silicon-based photovoltaic (PV) module could produce a power density output, thermal losses, and maximum voltage of 115.68 W cm−2, 18.14 W cm−2, and 36 V, respectively, at a radiator and PV cell temperature of 1800 K and 300 K. Power density output increased when the radiator temperature increased; however, the open circuit voltage degraded when the temperature of the TPV cells increased. Overall, for an 80 W PV modul...
Mathematics, 2021
A system of transcendental equations (SoTE) is a set of simultaneous equations containing at leas... more A system of transcendental equations (SoTE) is a set of simultaneous equations containing at least a transcendental function. Solutions involving transcendental equations are often problematic, particularly in the form of a system of equations. This challenge has limited the number of equations, with inter-related multi-functions and multi-variables, often included in the mathematical modelling of physical systems during problem formulation. Here, we presented detailed steps for using a code-based modelling approach for solving SoTEs that may be encountered in science and engineering problems. A SoTE comprising six functions, including Sine-Gordon wave functions, was used to illustrate the steps. Parametric studies were performed to visualize how a change in the variables affected the superposition of the waves as the independent variable varies from x1 = 1:0.0005:100 to x1 = 1:5:100. The application of the proposed approach in modelling and simulation of photovoltaic and thermophot...
Cleaner Engineering and Technology, 2021
Materials & Design, 2020
A novel generic model to simulate the temperature evolution and crystal growth rate during materi... more A novel generic model to simulate the temperature evolution and crystal growth rate during material extrusion was proposed. • Effects of major process parameters during material extrusion additive manufacturing are considered in the proposed model. • The proposed novel model can predict the temperature evolution precisely and the relative prediction error is less than 2%. • The proposed method should be useful for setting-up and optimizing of additive manufacturing and polymer extrusion processes.
Renewable and Sustainable Energy Reviews, 2021
Kha (2021) Energy efficiency in extrusionrelated polymer processing: a review of state of the art... more Kha (2021) Energy efficiency in extrusionrelated polymer processing: a review of state of the art and potential efficiency improvements. Renewable and Sustainable Energy Reviews, 147. a111219.
International Journal of Heat and Mass Transfer, 2020
Heat transfer is one of the key aspects of machineries, devices and industrial processes for main... more Heat transfer is one of the key aspects of machineries, devices and industrial processes for maintaining their functionality and also for achieving better product quality. Hence, heat exchangers of different types and sizes are used in these applications with the purpose of removing the extra process/device heat to maintain the desirable working temperatures. However, the size of a heat exchanger is a major consideration for any type of process/device as it decides the space requirements (i.e., the size) of the machine/device or the processing plant. At first, this study aims to investigate the design procedure of a heat exchanger theoretically and then its performance will be analyzed and optimized using computational fluid dynamics. For the design purposes, a counter flow heat exchanger was considered and its length was theoretically calculated with the LMTD method while the pressure drop and energy consumption were also calculated with the Kern method. Afterwards, a computational model of the same heat exchanger was implemented with ANSYS and then this model was extended to six different models by altering its key design parameters for the optimization purposes. Eventually, these models were used to analyze the heat transfer behavior, mass flow rates, pressures drops, flow velocities and vortices of shell and tube flows inside the heat exchanger. Theoretical and CFD results showed only a 1.05% difference in terms of the cooling performance of the hot fluid. The axial pressure drops showed positive correlations with both the overall heat transfer coefficient and pumping power demand. Overall, the results of this study confirms that CFD modeling can be promising for design and optimization of heat exchangers and it allows testing of numerous design options without fabricating physical prototypes.
Thermal Science and Engineering Progress, 2019
Nigeria is the most populous country and the largest economy in the African continent; but its po... more Nigeria is the most populous country and the largest economy in the African continent; but its power sector is currently underdeveloped. Remarkably, its economic and energy security depend on dwindling fossil fuel reserves. Yet, the Nigerian landscape experiences an average daily solar intensity of 20.1 MJ/m 2 /day; and the wind speed across the states ranges from 1.5 to 4.1 ms-1 ; with potential for harnessing energy from biomass, geothermal and water. With a projected population of 300 million by 2050, the current 7,566.2 MW electricity generation capacity would continue to impede socioeconomic development of the nation. Presently, few studies have reported on the suitable renewable energy technologies (RETs) for Nigeria. This study, therefore, updates the current and emerging RETs for harnessing the abundant renewable energy resources in Nigeria. Furthermore, a critical discussion is made on the application of RETs in achieving sustainable development in the imminent hydrogen economy. Eventually, some recommendations are made; and, it can be stated that the RETs, particularly distributed hybrid/integrated power systems, should be promoted in Nigeria based on the availability of diverse renewable sources. Undoubtedly, it is timely for the Nigerian government to investigate the possible applications of the RETs to improve the nation's power generation capacity.
IEEE Sensors Journal, 2018
In manufacturing industry, process monitoring is a key to observe the product quality, operationa... more In manufacturing industry, process monitoring is a key to observe the product quality, operational health, safety and also for achieving good/satisfactory process control performance. In polymer processing, the level of control of the process operational quality is vastly dependent upon the performance of the process monitoring techniques as it is quite difficult to observe the inside of an extruder barrel (or processing chamber) during the process operation. Currently, a number of physical sensing devices/techniques are widely available for industrial applications for monitoring of parameters such as melt temperature, melt pressure, screw/processing speed, product dimensions, etc in real-time. However, there may be some limitations in using physical sensors in piratical process measurements (such as melt viscosity and melt temperature profile) due to several constraints such as their access requirements, disruptive effects to the melt flow, fragility, complexity, etc. Therefore, soft sensing techniques should be highly useful for improved process monitoring and modelling, and hence for advanced process control. In this work, a general description is presented on the state-of-the-art of soft sensor design. Then, a comprehensive review is made on the use of soft sensing techniques in polymer processing applications while identifying their capabilities and limitations. Eventually, the importance of developing of such soft sensing techniques (together with some sort of built-on intelligence) for the advancement of process monitoring is discussed while indicating some of the possible directions for future industry.
2015 Internet Technologies and Applications (ITA), 2015
Due to the predicted scarcity of the fossil fuels and their adverse effects to the environment, c... more Due to the predicted scarcity of the fossil fuels and their adverse effects to the environment, currently renewable energy generation is a major focus of the power and energy sector. Wind energy is one of the potential and rapidly growing sources of green energy. This is particularly due to the cost of the wind energy production has reduced by a factor of more than five over the last two decades. Moreover, wind turbines can cover a wide range of power outputs from 50 W to 5 MW and beyond compared to other green energy sources. This study is aimed to model a horizontal axis wind power turbine theoretically and computationally. Initially, theoretical calculations were carried out by considering a few specific case studies with different power outputs. Then, the same case studies were considered for a computational fluid dynamics (CFD) analysis. Theoretical results show that the modelled wind turbine reaches a power output of 4.4 MW. Moreover, the theoretically calculated thrust and torque show a good agreement with the values obtained from CFD with a deviation of 2.9% only which confirms the accuracy of results. Therefore, the findings of this work should be useful in investigating ways to improve the performance of horizontal axis wind turbines.
2015 Internet Technologies and Applications (ITA), 2015
Gas turbines are one of the most important internal combustion engines in the modern world's tran... more Gas turbines are one of the most important internal combustion engines in the modern world's transportation. Any possible improvements of the performance of the gas turbine engines would help to minimize the world's annual fossil fuel consumption and hence the emissions of the adverse greenhouse gases. Therefore, modelling and simulation of gas turbines have been a major focus of many fields in aviation to improve their performance. In this work, it is aimed to model a turbojet gas turbine engine theoretically and computationally. On this basis, the pre-established equations were implemented in MATLAB Simulink to create a model of a turbojet engine. The influence of atmospheric conditions was also taken into account in creating the model. Furthermore, GasTurb was used to study the turbojet engines and provided useful results to explore the engine performance. The theoretical and Simulink models were in a good agreement within reasonable limits which verifies the correctness of the Simulink model established in this paper. Therefore, the proposed model can be used in investigating the performance of various types of turbojet engines without performing time taking theoretical calculations.
A thermocouple mesh technique measured melt temperature radially across polymer flows, precisely ... more A thermocouple mesh technique measured melt temperature radially across polymer flows, precisely profiling the relationship between melt behavior and processing parameters in polymer extrusion.
Thermal stability is of major importance in polymer extrusion, where product quality is dependent... more Thermal stability is of major importance in polymer extrusion, where product quality is dependent upon the level of melt homogeneity achieved by the extruder screw. Extrusion is an energy intensive process and optimisation of process energy usage while maintaining melt stability is necessary in order to produce good quality product at low unit cost. Optimisation of process energy usage is timely as world energy prices have increased rapidly over the last few years. In this study, an attempt was made to explore correlations between melt thermal stability and energy demand in polymer extrusion under different process settings and screw geometries. A commodity grade of polystyrene was extruded using a highly instrumented single screw extruder, equipped with energy consumption and melt temperature field measurement. Results showed that specific energy demand of the extruder (i.e. energy per unit mass of melt output) decreased with increasing throughput whilst fluctuation in energy demand also reduced. However, the relationship between melt temperature and extruder throughput was found to be complex, with temperature varying with radial position across the melt flow. Moreover, the melt thermal stability deteriorated as throughput was increased, meaning that a greater efficiency was achieved at the detriment of melt consistency. Extruder screw design also had a significant effect on the relationship between energy consumption and melt consistency. Overall, the relationship between the process energy demand and thermal stability was shown to be highly complex in nature, but the level of process understanding achieved here can help to inform selection of equipment and setting of operating conditions to optimise both energy and thermal efficiencies in parallel.
Delivery of a melt which is homogenous in composition and temperature is paramount for achieving ... more Delivery of a melt which is homogenous in composition and temperature is paramount for achieving high quality extruded products. However, melting stability can be difficult to determine via typical melt pressure and thermocouple instrumentation. This can result in inefficient operation through non-optimized operating conditions or extruder screw geometry. In this work, melt temperature homogeneity in a single screw extruder is investigated experimentally using a thermocouple mesh technique. The effect of barrel temperature settings and screw speed on die melt temperature homogeneity is investigated. Inferential methods of determining melting stability in-process are investigated with the aim of developing modeling and control techniques to improve process quality and efficiency.
Lecture Notes in Computer Science, 2010
Extrusion is one of the most important production methods in the plastics industry and is involve... more Extrusion is one of the most important production methods in the plastics industry and is involved in the production of a large number of plastics commodities. Being an energy intensive production method, process energy efficiency is of major concern and selection of the most energy efficient processing conditions is a key aim to reduce operating costs. Extruders consume energy through motor operation (i.e. drive to screw), the barrel heaters and also for cooling fans, cooling water pumps, gear pumps, screen pack changing devices etc. Typically the drive motor consumes more than one third of the total machine energy consumption. This study investigates the motor power consumption based on motor electrical variables (only for direct current (DC) motors) and new models are developed to predict the motor power consumption from easily measurable process settings for a particular machine geometry. Developed models are in good agreement with training and unseen data by representing the actual conditions with more than 95% accuracy. These models will help to determine the effects of individual process settings on the drive motor energy consumption and optimal motor energy efficient settings for single screw extruders.
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Papers by Dr Chamil Abeykoon