Browsing by Author "Witharana, S"

Now showing 1 - 19 of 19

item: Conference-Abstract
Adaptive prediction of power fluctuations from a Wind Turbine at Kalpitiya Area in Sri Lanka
Narayana, M; Witharana, S
Hydro power is the major renewable energy contributor to the national grid in Sri Lanka amounting to 48% of the total installed capacity. Further expansion of hydropower however is limited due to environmental and resource constraints. Meanwhile the demand for electricity is estimated to rise at an annual rate of 8% - 10% prompting the need to find alternative power options. The wind energy has been identified as a promising candidate to generate electricity in Sri Lanka. However for a reliable integration of wind energy the volatile nature of wind has to be understood. Wind speedtime series data typically exhibit autocorrelation, which can be defined as the degree of dependence on preceding values. Generally, statistical models and neural network techniques being used for time series analysis. Present study shows how an adaptive digital filter can serve as a modelling, forecasting and monitoring technique, and, how they contribute to a successful integration of wind power into the national grid. The north-western region of Kalpitiya has been identified as one of the potential location for wind power generation in the country. This study also predicts power generation and investigates power fluctuations for grid integrations of a commercially available wind turbine installed in Kalpitiya area by using measured wind speeds and performance of the wind turbine.
item: Article-Full-text
Bolgoda Chat : an interview with Prof. Malik Ranasinghe
(Faculty of Graduate Studies, 2024) Karunathilake, H; Witharana, S
Through this Bolgoda Chat, we meet Professor KAMK (Malik) Ranasinghe, another celebrated former Vice Chancellor of the University of Moratuwa. During his tenure as Dean and as Vice Chancellor, Professor Ranasinghe introduced the semester system to the Faculty of Engineering (FoE), started the process to relocate the NDT program from the Katubedda premises to the Diyagama, encouraged students to participate at international competitions like Google Summer of Code, motivated research among academics, and forged strong and close relationship with industry. Professor Ranasinghe is often cited as the creator of the University of Moratuwa brand. Here is his story, from his own words.
item: Article-Full-text
Bolgoda chat : the first vice chancellor
(2022-09) Karunathilake, H; Witharana, S
A technical collage was being transformed to a university. This is the story of an academic who led the institution in its early years.
item: Article-Full-text
Bolgoda Chat : the founding Dean of Engineering and Architecture
(Faculty of Graduate Studies, 2022-12) Karunathilake, H; Witharana, S
I obtained my B.Sc. degree from the University of Ceylon, and Prof. Kuruppu was my batch mate. There was only one university those days. My career at the University of Moratuwa started when the newly established Ceylon College of Technology (CCT) was started with virtually the university status, and they wanted to hire academic staff members. I was at the University of British Columbia, Canada at that time. Prof. Kuruppu sent me a letter telling that he joined CCT, and asking to join as well. I applied from Canada. Since CCT was a government institution, the Sri Lankan High Commissioner came in person from Ottawa to UBC to interview me. I completed my PhD in Electrical Engineering in 1969, and was selected for the job. Later, the institution became a campus of the University of Sri Lanka. In 1972, I was the first Dean of Engineering and Architecture. Architecture at that time was a mature department operating under the University of Colombo, and they were shifted to Katubedda, and joined with the engineering programme. Later, after my time, the faculties were separated due to growth in different directions.
item: Article-Full-text
Bolgoda chat : the teaching Vice-Chancellor
(2021) Karunathilake, H; Witharana, S
When I think of my early days, there are two experiences that made a profound influence on my future career. My father was an Assistant Station Master, and he taught me all aspects of managing a railway station except telegraphy. Later, as my father become ill, my parents arranged accommodations for me in a house near the Ulapane station and left for our home in Ambalangoda. Occasionally, the station master used to consume alcohol during night shift, and he used to summon me to look after the station.
item: Article-Full-text
Bolgoda chat: the era of transformation
(2023-08) Karunathilake, H; Witharana, S
Mahamendige Wilfred Joseph Gerard Mendis was born in Moratuwa on 7th day of November 1942. Popularly known as “Willie”, did his entire schooling at the St. Peter’s College Bambalapitiya, and excelled in studies, in debating and in leadership. In a school science event, young Willie was happened to meet satellite guru Dr Arthur C Clarke, without a clue that they would become colleagues four decades later at the prestigious University of Moratuwa.
item: Conference-Full-text
Bottom-up cost modeling of lithium-ion battery cells for electric vehicle applications
(IEEE, 2022-07) Hewawasam, D; Subasinghe, L; Karunathilake, H; Witharana, S; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Lithium-ion Batteries (LIBs) have come a long way with various improvements to make them more efficient, compact, and safe while simultaneously enhancing the energy density and cycle life. If it is possible to improve the technicalities to lower the cell cost by indicating some potential solutions, the economic issues in LIBs automotive applications can be addressed. This study intends to approach a bottleneck solution for pure Electric Vehicle (EV) cost reduction. The BatPaC 5.0 modeling tool is used to examine different cell chemistries (NMC811-Graphite(Gr), NCA-Gr, LFP-Gr, LMO-Gr, and 50%/50%NMC532/LMO-Gr) and determine the accuracy of the hypothesis made on the effect of positive electrode coating thickness of LIBs, on the cell cost, gravimetric energy density and volumetric energy density in high volume production. Using the above assumption, it is obtained that doubling the coating thickness of the positive electrode from 60 to 120 μm, reduces the cost in all cell types. But the highest by ~20% in LFP-Gr. And it emerges that increasing the positive electrode coating thickness of LIBs, lowers the cell cost whilst improving the gravimetric energy density and volumetric energy density. Therefore, the positive electrode coating thickness can be considered a crucial parameter in cell cost reduction.
item: Conference-Abstract
Comparison of the embedded energy in two distinct walltile manufacturing processes in Sri Lanka
(2006) Divakara, S; Witharana, S; Attalage, RA
The ceramic industry is a highly energy intensive industry in Sri Lanka. In meeting its daily rated out put of nearly 34,000m2 which is growing at a steady rate, the ceramic factories consume a sizable chunk from the total industrial energy, both thermal and electrical, in this country. Their energy bills account for one third of the total production cost. In comparison to other ceramic manufacturing countries such as India, Indonesia, Malaysia and Italy, out cost of energy is excessively high. The unfortunate consequence is that the Sri Lankan ceramic products find it very difficult to compete in price, both in local and foreign markets.
item: Conference-Extended-Abstract
Design, fabrication and testing of a down draft stove for small scale industrial applications
(2006) Wickramasooriya, IPTS; Witharana, S; Wickramanayake, ABAT; Sugathapala, AGT
Biomass represents the largest share of primary energy supply in Sri Lanka. For household cooking as well as large industry applications, there have been a growing trend in the development of high efficiency technologies. However, the small scale industrial sector is yet to find efficient combustion solutions
item: Thesis-Abstract
Development of solar powered pumping for the integration of rainwater harvested in multistory houses
(7/16/2011) Sendanayake, S; Jayasinghe, MTR; Witharana, S
Rain water Harvesting (RWH) is an ancient civil practice for more than 4000 years, drawing attention among scientists in recent decades in the light of potable water shortages and water based natural disasters such as draughts and flash floods. It is observed that the domestic service water (SW) usage patterns are uniform for a given scenario, where over 30% of drinking quality water being consumed for non potable uses such as we flushing, for which harvested rain water (RW) could be used. Roof Top Rain Water Harvesting Systems (RTRWHS) suitable for domestic situations are not being widely used due to non-optimizing of the system's highest cost component, the storage facility or the tank. Extensive research has produced a set of generic curves for Water Saving Efficiency (WSE) of a RTRWHS, enabling the selection of an optimum tank size for a given demand. Validation of this for Sri Lanka could provide a valuable design tool. This was undertaken using a prototype where the daily rainfall data was used with selected usages to create a substantial number of data points, which satisfy the generic curves. These data has indicated that the generic curves can be used in Sri Lanka with generally used roof types such as cement fibre and calicut tiles. In multi-story situations energy is needed for pumping collected rain water to end user points. A strategy should be developed to provide an alternative energy solution to mitigate the strain of extra energy consumption to the national power grid and the resultant Green House Gas (GHG) emissions for RWH to be a true component of sustainable development. Sri Lanka being a tropical country, solar power option is pursued as the most desirable alternative energy source. Since solar power also has high capital cost, minimization of energy used while relying on gravity systems also have been actively pursued. Identifying the suitability of positive displacement pumps over centrifugal pumps when connected to photo voltaic power source, a viable and cost effective solar pumping system is proposed to be used as an integrated draw-off device for a potential RWH system to be used in domestic situations
item: Thesis-Abstract
Energy conservation on a central chiller plant
Ramanayake, VS; Udawatta, L; Witharana, S
Air-conditioning is no more treated as a luxury but a day to day requirement essential for the human comfort and productivity. When compared among different sub systems of a building, air-conditioning subsystem is responsible for the largest proportion of the energy consumption especially in a tropical climate like Sri Lanka. Central air-conditioning that comprise of a chiller plant is the most common means of air-conditioning in large commercial buildings. Hence successful energy optimizations that are implemented on a central chiller plant will definitely result with large financial savings. Even though it is a known fact that all individual components that comprise a central chiller plant are now optimized in terms of energy efficiency, the overall behavior of the entire system once these pieces are put together is something that has to be separately worked out. This research proposes and implements energy optimizations on top of a central chiller plant. It evaluates the amount of saving from each optimization and presents a practical model to follow in a similar plant. Energy optimizations proposed in this research were implemented in conjunction with the capabilities of the central chiller plant control system that is already available at the site for the purpose of real time monitoring and controlling of the central chiller plant. Results of energy saved was quantified using the run hour reading gathered prior and after the implementation of the optimizations. A saving of 15.8% from COW pumps, 23.8% from CHW pumps and 32.8% from CTs were achieved as a result of those optimizations. Outcomes of this research can be made use by different parties including investors and decision makers of buildings to promote similar energy saving projects in their organizations.
item: Conference-Extended-Abstract
Experimetal investigation of the influence of moisturecontent of firewood on the performance of a direct fired boiler
(2006) Witharana, S; Jayasekera, JGAS
item: Thesis-Full-text
Optimal allocation of air conditioning services : a case study for a hotel in Sri Lanka
Perera, LAAN; Udawatta, L; Witharana, S; Rajaratne, R
Tourism industry is one of the key players in Sri Lankan economy. With the long run internal conflict, Sri Lankan tourism industry had a negative growth in the last few decades. Not only that, but also due to global economic meltdown, almost all the industries all over the world are facing an extremely hard time. The increase of global warming, with its effects on North Pole glaziers, which have started to-meltdown, the entire world has started to be concerned on the concept of the "green house effect". With global economic crisis and the "go green" concept most of the industries have started to practice cost reduction and energy saving methods in order to make their industries profitable. The situation in Sri Lanka's industry has no difference from that and especially the tourism industry has started to implement such methods. In this thesis a case study has been carried out at one of the five star category resort type hotels in down south, Heritance Ahungalla, to analyze the pattern of energy consumption in that hotel in order to implement a method to reduce their production cost, as energy is one of the heights components in the hotel's expenses. The chilled water distribution system has been studied and the hotel was divided to five section based on that. Cooling load requirement is correlated with the number of occupied rooms hence the energy could be saved by introducing wing operation to the hotel room allocation system. A practical evaluation on wing operation was carried out only based on the energy consumption and a theoretical evaluation was also carried out based on both the energy consumption and the profit. Results showed the energy could be saved by introducing "wing operation" to the system of allocation of rooms in the hotel. With the wing operation, it is required to implement automatic operation of chiller plant as well as isolation of each wing from the hotel main system as the wing operation is highly cost effective. That could be achieved with introduction of building management system to the hotel.
item: Conference-Extended-Abstract
Performance improvement and energy saving potential of internal combustion engines in large-scale power generation
(2006) Kariyawasam, S; Witharana, S
Thermal power stations supply the majority of electricity demand in Sri Lanka. According to eEB's statistics for year 2004, more than 63% of the total annual energy demand was supplied by thermal plants, which amounted to 5,080GWh. By that year, the total installed capacity of Thermal power plants was 1,073MW, with the internal combustion (IC) engines having a share of 543MW. In terms of the number of operating hours, the Ie engines are preferred to Gas turbines due to fuel economy. In total, eEB had spent nearly 20 billion rupees to fuel its thermal power plants during the year 2004. Today the fuel costs are even higher. A 1% improvement in efficiency of all thermal power plants in Sri Lanka would return a saving of approximately 500milion rupees a year.
item: Conference-Full-text
Selection of phase change materials for high temperature latent heat thermal energy storage for concentrated solar power plants
(IEEE, 2022-07) Jayathunga, D; Karunathilake, H; Narayana, M; Witharana, S; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Concentrated Solar Power (CSP) is one of the most promising options among emerging renewable energy technologies. Thermal energy storage can be incorporated into CSP plants to improve dispatchability. Thus, the development of high-temperature Thermal Energy Storage (TES) materials is essential to enhance the performance of CSP plants. Phase Change Materials (PCM) show favourable characteristics to be used as the working material in this application. This paper addresses the selection of appropriate storage materials that have desirable properties for thermal energy storage in CSP applications, considering the cost and volume per unit of thermal energy storage. A three-stage screening process based on melting temperature, latent heat of fusion, cost, thermal conductivity and storage volume criteria was used to select the most economical and thermo-physically feasible materials from a list of 25 materials. Accordingly, Na2CO 3 +Li 2 CO 3 (56:44), Li 2 CO3+K2CO 3 (2S:72), Li 2 CO3+K2CO 3 (35:65), NaF+KF+K2CO 3 (17:21:62), LiCO 3 +Na2CO3+K2CO 3 (20:60:20), Li 2 CO 3 +Na2CO3+K2CO 3 (22:16:62), K 2 CO 3 +Na2CO 3 (51:49) S PCMs were selected as the best materials to develop high temperature TES for CSP plants. Using these PCMs as storage materials, cost-effective TES can be developed to deliver technical and economic benefits.
item: Conference-Abstract
Simulation of ancient wind-driven iron smelting furnaces of Sri Lanka
Kumbalathara, AAK; Liyanage, DD; Witharana, S; Rajika, JKAT; Narayana, M; Fernando, KCN
Metal processing industry in Sri Lanka began around 3000BC. Ancient chronicles like Mahavansaya, Thupavansa and Pujavaliya proved the Sri Lanka’s history of metal industry. Archaeometallurgical surveys of Sri Lanka have revealed a non-conventional wind-driven iron smelting furnace for the first time in the world. Some of them dated back to third century BC. Replications of iron smelting process have shown the ability of those furnaces to operate and produce high carbon Steel. CFD modeling and simulation is a popular tool to further understand the fluid flow patterns within and surrounding a furnace. This paper discusses the initial steps of modeling and simulation of the total process of iron smelting in the west-facing furnaces situated in Samanalawewa area of Sri Lanka. Main focus of the paper is to analyze the cold flow at 2D and 3D steady state conditions by using the open source OpenFOAM CFD software with over 9million cells for 3D simulation in finite volume method. The results have been compared with a validated simulation on the same furnace using the commercial CFD code Fluent.
item: Conference-Full-text
Study of moisture transport in rice cooking
(IEEE, 2021-07) Jayamini, HPA; Weliwita, JA; Narayana, M; Witharana, S; Hettiarachchi, NK; Adhikariwatte, W; Rathnayake, M; Hemachandra, K
In an era where the conservation of energy is paramount, one cannot overlook the substantial amount of energy consumed by domestic cooking processes. Rice cooking is one of them, in the East in particular, where rice is a staple food. In this work, pre-soaking and boiling processes of white raw rice were investigated through experimentation followed by CFD simulation. Temperature profiles while boiling and the moisture gain during cooking were obtained. The findings reconfirmed the two underlying mechanisms, i.e., gelatinization-driven cooking at lower temperatures, and, diffusion-driven cooking at elevated temperatures. Moreover it was revealed that by fine-tuning the rice cooking process, the cooking duration could be reduced by nearly 15%, saving the cooking energy as much. Finally the moisture diffusion coefficient was accurately modeled using the OpenFoam software.
item: Conference-Extended-Abstract
Thermal comfort performance monitoring for stationary vehicles under tropical climate
(2006) Wickramasooriya, IPTS; Witharana, S; Wickramaratne, C; Perera, ULIU
The thermal comfort in an automobile is provided by the air conditioning system. Generally, in city running, an automobile air conditioner consumes nearly 10% of the fuel burnt by the engine. With the use of shading devices and by parking the vehicle under shades, the heat gain into the vehicle can be minimised. Especially in warm tropical climates, the minimisation of heat gain is of paramount importance as excessive heat gain will result in high interior temperatures, which in turn will demand higher load on the air conditioner while the life of the vehicle interior gets shorter.
item: Article-Full-text
Towards commercializing the “made in Sri Lanka” Lithium-ion batteries
(Faculty of Graduate Studies, 2022-12) Hewawasam, D; Karunathilake, H; Subasinghe, L; Witharana, S
Energy plays a crucial role in the human civilization. Today, the whole world is facing an energy crisis with the rising energy demand, fluctuating prices, supply constraints, and environmental concerns. While renewable energy resources can alleviate some of the global energy security challenges, their intermittency and non-dispatchability can cause problems. Therefore, robust energy storage systems (ESSs) are also important in the sustainable energy transition. Among the many ESS technologies, battery energy storage system (BESS) is one of the most popular methods, as they can be easily adapted to distributed applications and quickly deployed. The Lithium-ion battery (LIB) has significant benefits over other batteries. They have a longer life cycle, higher energy density, faster charge and discharge cycles, quick manufacturing and deploying processes, and lower maintenance requirements. LIB technology is one of the best candidates for a BESS, and its market share and R&D efforts are growing fast [1], [2]. Over the last 30 years, the LIB has come a long way with various improvements to make it more compact and safe while simultaneously enhancing the energy density and cycle life.