Faculty of Engineering, Mechanical Engineering

Permanent URI for this communityhttp://192.248.9.226/handle/123/69

Browse

Now showing 1 - 20 of 222

item: Thesis-Abstract
Analaysis and simulation of a poly bag manufacturing systems
Gopura, RARC; Jayawardene, TSS
The film blowing plays a major role in manufacturing poly bag products that are indispensable in day-to-day life. Film blowing is largely deployed to manufacture poly bags in a continuous flow. As material prices skyrocket to new heights and forecasters see no end to this trend, any positive contribution in the poly bag manufacturing value chain has a great impact on reducing the manufacturing costs. High density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and polypropylene (PP) are basically used as raw materials for the poly bag manufacturing and subsequently undergo some other processes such as cutting, sealing, printing, quality checking, and packing. Due to the variations of parameters in poly bag manufacturing process with different products, a considerable setting time as conceded and substantial amount of raw material is wasted. Material wastage is high as 10% to 12% in figures. Rather high lead-time, improper line balancing, and improper inventory control mimic serious bottlenecks in the system from performance point of view. With the purpose of identifying the productivity and the efficiency problems of the poly bag manufacturing system, as a preliminary study to simulation, risk analysis, bottle neck analysis, and SWOT analysis were carried out in poly bag manufacturing system. Then the possible risk of the selected system was prioritized. In addition, a computer based simulation has been carried out to simulate the system and thereby find the draw backs. The poly bag manufacturing system has been modelled to obtain the optimum production times and throughput time of a given type of bag. Production schedule has been developed for maximum productivity by using the simulated production and throughput times, and customer orders. The effect of changing the parameters of the control process was investigated through simulation trials. A Graphical User Interface (GUI) was developed to present the result of simulation easily and user friendly.
item: Thesis-Full-text
Analysis for optimization of energy efficiency in office buildings in Sri Lanka
(2020) Dilhan MKT; Perera KKCK
Energy consumed in the building sector consists of residential and commercial end users and it accounts for 20.1% of the total delivered energy consumed worldwide [22].Global primary energy demand is projected to increase by annual rate of 1.6% between 2004 and 2030[23]. There are building codes, Standards, Guidelines etc. to regulate and promote energy efficiency in building sector [page 33]. Sri Lanka also had focused on minimising these increasing trends during the past decade. “Code of Practice for Energy Efficient Buildings in Sri Lanka 2008” was introduced as an initiative. Sri Lankan government is carrying out various programmes, seminars and activities to encourage building owners, developers, designers to implement energy saving measures. In this research three commercial buildings in Colombo region having 8, 8 & 10 floors and total floor areas of around 35 000 ft2, 60 000 ft2 & 90 000 ft2 and monthly average energy consumption around 50 000 kWh, 70 000 kWh & 100 000 kWh were selected. The study and analysis were done to find out whether there are none-compliances of the selected buildings with ASHERAE 92.1-2007 standard and Code of Practice for Energy Efficient Buildings in Sri Lanka-2008 which are used by professionals in the subject and to find out whether there are opportunities to improve energy efficiency of already constructed buildings further by modelling those buildings in Trace 700 software by simulating various possible options. None of the three selected buildings fully complied with the standards considered. Major weak points were poor building envelope sealing, insufficiency of usage of automatic controls, improper balancing of systems, poor lighting system efficiency , higher lighting power density and higher Solar Heat Gain Coefficient of vertical glazing. Though Building Automation Systems (BAS) are installed, it was revealed that by adding/upgrading some new features/options to BAS and by eliminating the weaknesses found, there are still more opportunities to increase energy efficiency further significantly.
item: Thesis-Full-text
Analysis of cooling tower performance of world trade center in Colombo
(2020) Wickramasinghe W.A.D.P.; Perera KKCK; Manthilaka MMID
Energy crisis first experienced in the world during 1975, since then it is ever rising phenomenon felt by every human being on earth. This is due to accelerated industrialization of the world and rapid growth of standard of living of people. Therefore, global Energy requirement is increased day by day deficit between energy available is increasing. It is felt that energy preservation is much more important than searching for New Sources. Sustainability has been introduced to building services to reduce waste of energy and provide for future. Green building concept is increasingly popular in terms of reducing fossil fuel usage and introducing alternative energy utilization. Reducing Carbon foot print of a building is the responsibility of the engineer in modern times to support the sustainability goals. Heating, Ventilating & Air conditioning (HVAC) systems in Commercial buildings accounts for 60% to 70% of their total power consumption. This thesis explores the possibilities of improving the configuration of cooling tower and optimization of the chiller plant. A central chiller plant for tall-building was analyzed for the effect of improving efficiency to enhance energy saving with varying cooling tower combinations and fan speed regulation. It was revealed that increasing the combination of cooling towers has a limitation of efficiency rise. However, reducing fan speed with increasing chiller combination prove to be success in the increasing efficiency of the chiller plant.
item: Thesis-Full-text
Analysis of energy embodied in cement produced in Sri Lanka
(3/25/2011) Namal, DDA; Attalage, RA; Perera, KKCK
Analysis of the embodied energy in cement produced in Sri Lanka was carried out considering national boundaries. National energy input to the cement manufacturing was the main focus or this study and therefore any energy involvement outside Sri Lanka was not taken in to consideration in this analysis. The total embodied energy content was analyzed in three levels. In level I. direct energy consumption in manufacturing of cement at Puttalam cement factory was analyzed and energy consumption for ancillary inputs was considered in the level 2. Energy consumption for raw material extraction and transportation with in the country was analyzed in level 3.// The direct delivered energy consumption was assessed by carrying out an energy survey at Puttalam cement factory. Then this direct energy was referred to primary energy by considering the national energy mix in electricity generation together with transmission and distribution losses in electricity distribution. power plant efficiencies. and energy consumption in refining petroleum fuels.// The total national energy requirement to produce one ton of cement in Sri Lanka was found to be 4896 MJ based on the present energy mix of electricity generation. This varies between4982 MJ/MT and 4732 MJ/MT according to the future energy mix of the electricity generation and the transmission loss reduction plan of Sri Lanka.// The outcome of this study can be used to select the best material for building construction from cement based products and in the formulation of energy conservation policies like the Building Code. In addition the outcome of the study can be used as inputs for further research relevant to energy content of materials.
item: Thesis-Full-text
Analysis of energy performance of domestic refrigerators
(2019) Costa GSR; Manthilake MMID
One of the most common appliances in today’s households is the refrigerator, for cooling and preserving food. Continuous maintenance of correct compartment temperature is the key factor which contributes to food quality at preservation, though it results in high energy utilization. It is estimated that refrigerator consumes one third of total electricity demand from a typical household. If energy efficient refrigerators could be identified from different models in the market, it would contribute towards individual and national level benefits. SLS 1230:2003 is the refrigerator testing standard in Sri Lanka for energy labeling of domestic refrigerators which has the key responsibility to illustrate energy efficient refrigerator models in the market. Further inverter-based refrigerators are the new tendency today, and there is limited number of studies comparing performance of inverter and non-inverter refrigerators and SLS 1230:2003 does not consider loading and temperature stabilization connected with energy performance of refrigerators are the limitations that motivated for carrying out this research. The aim of this research is to study the temperature stabilization rate along with energy consumption of inverter and non-inverter types of domestic refrigerators, after loading a given mass, and to apply the results to make necessary amendments to present refrigerators testing methodology in SLS 1230:2003. Experiments were accompanied with pairs of inverter and non-inverter refrigerators with unique capacity, manufacturer and brand, incorporated with door-opening, loading and cooling. Tests were carried out at Refrigerators Testing Laboratory at, National Engineering Research and Development Centre. As per results, inverter refrigerators consumed 22% less energy than non-inverter refrigerators but the models with inverters had low cooling rate and consumed 3 more hours to cool down 3kg of test load than non-inverter refrigerators. This result is beneficial to refrigerator consumers, manufacturers, dealers as well as policy makers when making decisions on energy efficient refrigerators.
item: Thesis-Abstract
Analysis of ERP implementation issues and evaluation of critical success factors in Sri Lankan apparel sector
(2014-07-11) Karunarathna, RMNSK; Perera, HSC; Naeem, ACM
An ERP system is a business support system that maintains in a single database for data needed to a variety of business functions such as Manufacturing, Supply Chain Management, Financials, Projects, Human Resources and Customer Relationship Management. Organizations adapt ERP systems in order to achieve competitive advantage through integration of information, with improved visibility throughout the system. ERP systems promise benefits such as facilitating improvement in quality, reduce WIP, reduce inventory cost, reducing time to market, to deliver right thing to the right place at right time commensurate in continuous improvement of the business. ERP implementation has not always been a success. If the implementation took place without a much consideration of the business process and other infrastructure, quite a lot of money invested on it would be in vain and successful integration of information would never be achieved. Referring to the literature several Critical Success Factors and crucial Implementation Issues were identified when implementing ERP systems. Critical success factors were categorized under four groups as Organizational, Project related, Technical and Economical where Implementation difficulties were categorized as Organizational, Social, Technical and Economical factors. Separate questionnaires were designed and distributed among ERP users and ERP Experts to examine their experience on the above factors across the life cycle of ERP implementation. Responses from both parties were compared in order to get a clear picture on how separate parties experience ERP implementation. According to the analyzed data from responsible parties it could be seen that there are differences in how both parties feel the importance of each factor displayed in the Questionnaire and the views of both patties become visible.
item: Thesis-Abstract
Analysis of flash butt welding cracks in rim manufacturing
Hewage, SPK; Munasinghe, N
Flash butt welding is a well established economical process for solid state butt welding. It consists indirect electrical heating of the ends of the work pieces to be welded and forging them together. While heating, a thermal distribution characterized by a steep temperature gradient is established along the axial length of the pieces. Flash butt welding is widely used for steel band welding m wheel industry. Major advantages are economical in operation, suitable for mass production and high in joint strength. Loadstar (pvt) Ltd has six flash butt machines in different production lines for rim and band manufacturing. The major problem is considerably high amount of scrap percentage due to welding cracks. This problem severely affects the lines which have severe forming or stretching operations in latter stages. For this investigation the line 05 was selected which has high scrap percentage. The main aim of this study is to analyze the flash butt welding cracks in rim manufacturing and to find out the main reasons for the defects. The analysis of flash butt welding cracks in nm manufacturing is done m five stages. In the first stage, attention is paid to literature survey, in which the present stage of the researches carried out in the industry regarding the flash butt welding is discussed. Only few literature sources are available although there are many wheel manufacturing companies-.. in the world. Certainly there might be a lot of researches carried out under this topic in the history,' but due to high competitiveness among the companies the research outcomes might be kept as company secrets. In this project, the analysis of flash butt welding cracks in wheel manufacturing will be discussed in detail. The second stage is process description. .and principles of flash butt welding. Third stage is problem identification and the fourth stage is methodology to solve the problem. In methodology it has stated that the identified process' variables that affect the welding quality and how further testing are carried out. Experimental work and results are reviewed under the fifth stage. In this chapter, the testing done for research is discussed in detail and final conclusion is on how the increasing advance velocity of the movable jaw of flash butt machine while keeping the same voltage will give better results in weld joints for SS 400 material.
item: Thesis-Abstract
Analysis of impact on greenhouse gas emissions of commercial buildings by implementing energy efficient building codes in Sri Lanka
(2023) Perera, UKDP; Manthilake, MMID
Global warming and climate change, a result of abundant anthropogenic GHG emissions, is the fundamental human development obstacle in the 21st century. In Sri Lanka, buildings and services account for roughly 29.72% of total CO2 emissions. Energy Efficient Building Codes are one of the key initiatives proposed to reduce emissions in buildings. Sri Lanka is in the process of preparing a mandatory EEBC, and a draft ‘Building Code of Sri Lanka 2020’ has been released. But its potential impact on energy and GHG emissions reduction has not been properly investigated. The study presents an analysis of a prototype commercial building in Colombo, comparing the energy and GHG emissions impact of EEBC requirements from different codes, namely, Code of Practice for Energy Efficient Buildings in Sri Lanka – 2008 (SLBC 2008), Draft Energy Efficiency Building Code of Sri Lanka – 2020 (SLBC 2020), ASHRAE 90.1 – 2022 and NCC Section J - 2022. The analysis was conducted using a calibrated whole-building energy model of the prototype building created using the DesignBuilder and EnergyPlus software. The results indicate that the draft SLBC 2020 can reduce overall energy use and GHG emissions by 8% compared to a BAU scenario with SLBC 2008, with the biggest improvement in lighting energy. The draft SLBC 2020 can also reduce the HVAC design load by 14.1% compared to a standard design thermal envelope. However, compared to leading EEBCs such as ASHRAE 2022 and NCC 2022, the draft SLBC 2020 lags by 2.5% and 15.6%, respectively. The energy and GHG emissions reduction potential of the draft SLBC 2020 could provide massive energy, foreign currency and GHG emissions savings to Sri Lanka over the coming years. Therefore, implementing the draft SLBC 2020 is seen as a timely solution to achieving the GHG emissions reduction targets of Sri Lanka and addressing the deep economic and energy crisis. Further, the draft SLBC 2020 has the potential for further improvements compared to some of the leading EEBCs, and the implementation of the first mandatory EEBC in Sri Lanka can be challenging. Keywords: Building Energy Efficiency, Energy Efficient Building Codes, Energy Modelling, GHG emissions
item: Thesis-Abstract
The Analysis of suitable frame (structure) for a pedal car
(3/28/2011) Molligoda, MLCY; Fernando, MARV
This study is mainly focused on to determine a suitable structure for the pedal car by considering following areas. 1.To determine the number of wheels for the pedal car/ 2.Driven drive (whether front or rear) 3.Number of wheels for steering "Tadpole car" is the final designed of the research because it is comparatively easy to fabricate and, there are so many advantages when fixing power transmission and steering mechanisms./ Here the steering mechanism couples with front wheels of the "tadpole" structure. It governs by standard bicycle handle. End of the handle, by using two steel rods, couples with pin joint to the front wheels. Suspensions arc necessary to maintain comfort-ability of the car. Therefore front wheels are assembled with two springs. And Rear wheel later part was assembled with pin joint and upper joint introduced with coil spring. This combination helps to maintain Constancy distance between flywheel and the rear wheel./ Brake must be with the vehicle to safe operation of it. Here all three wheels are controlled at the same time by jamming one liver. It is important for the stability of the vehicle while stopping. Steel Conduits are used for the fabrication of first embodiment. But after Cosmos analysis, it reveals that maximum stress occurred on the structure is 27 N/mm2. For Cosmos analysis, numbers of possible load combinations were applied on seat and paddles. Seat load considered as distributed load and pedal load took as point load/ Further this research can turn to another area of "law weight structures". Herein maximum efficiency can be achieved by reducing the body weight of the car. And it will help to popularize the car. Because generally riders like easy- handling vehicles. This goal would be achieved by replacing steel parts with Aluminum alloy or Timber/Structures wherever possible.
item: Thesis-Full-text
Analysis of the possibility of minimising the warpage in injection moulding
Premarathna, GAR; Fernando, MARV
This thesis focuses on the research “to investigate and analyse the warpage in a product and reduce the warpage using optimum parameters”. Factors affecting for warpage are discussed and categorized their relative position of affecting. An article subjected to warpage is selected and factors affected for the warpage are detailed analysed one by one. The research carried out on the basis of selected major factors. Part geometry, gate location, runner system, filling and packing/ holding pressures, filling and packing/ holding times and cooling layout are analysed and changed to determine optimum parameters and minimize the warpage factor. Modified mould design was done by utilizing Computer Aided Design and analysed the mould to ensure the success of the design. The CAD Software used for design is Unigraphics NX and two software packages used for analysis of warpage are Auto Desk Moldflow Advisor and Solid Works Plastics. Finally with the justification of changed parameters the existing mould is modified to meet the required quality of product. In this context, all above details are comprehensively discussed and summarized in the body of this report accompanied by necessary drawings, data tables and analysis results etc.
item: Thesis-Full-text
Analysis of the status of the rubber product manufacturing industry in Sri Lanka :
(2018) Dissanayake, MNCP; Punchihewa, HKG
The Sri Lankan rubber industry is currently experiencing burning problems. Mainly rubber industries are facing issues such as, low production, lack of cultivation area, low productivity, reduction of re-planting area and new planting area, decline trend of rubber prices, increase of cost of production, reduction of export of raw rubber, increase of domestic consumption and declined trend of exports earnings, lack of skilled labour. However no one has identified which factors are affecting to create these problems and also hardly to find any solution to the most important problems which are presently available in rubber industry. Therefore, this research is aiming to find most important barriers of rubber product industry and find out what they are and how to avoid or minimize those barriers. Objective of this survey was to gather information related to the present status of the rubber product industry in Sri Lanka and analyse the gathered information to propose the way forward in terms of barriers in the rubber products manufacturing sector. Survey was carried out by using questionnaires to find out the present situation, barriers, difficulties, issues, and solutions for rubber products industry. Large and medium scale rubber industries were targeted, and questionnaires were distributed according to the annual export performance (turnover) in each rubber products sectors. Gathered information from questionnaire was analysed by using PESTLE with Cobweb diagram, quantitative analysis, statistical analysis with linear correlation and qualitative analysis. During this survey, three major factors were identified which affect the rubber products industry, and they are Economic, Legal and Technological factors. Under above factors, identified several key barriers are Impact of globalization on market share, Effect of Health and Safety issues, Insufficient facilities for the development of technology in the organization, Lack of Research and Development activities compared to the Competitors, Lack of proper techniques to absorb international technology. Proposed several solutions are Free trade agreement with developed countries, Promote to follow (Occupational Safety and Health Standards) OSHS for rubber industry, Need free technology Alliance with developed countries, Need to increase budget allocation for R&D activities, Govt should provide facilities for Reverse Engineering. Extension of this survey to the small scale rubber industry is proposed as future work.
item: Thesis-Full-text
Analysis of weld shrinkage to obtain compensation factors for ship hull construction
Karunarathna, TA; Punchihewa, HKG
Modern manufacturing faces two main challenges: more quality at lower prices and the need for the productivity improvement. In ship building industry, companies need to respond to market requirements efficiently, keeping their products competitive while reducing the cost. When considering complicated ship production processes up to final hull block erection, the productivity of each work station for hull assembly mainly depends on the dimensional quality of hull blocks. Poor dimensional accuracy leads to reworks such as re cutting, mechanical or thermal correction against misalignment, excessive welding for wide gap and thermal straightening and this will subsequently increases the total production cost. One of the major dimensional accuracy control activities is the shrinkage margin design, which means that the optimal excess of plate is calculated and assigned into ship production drawings in order to compensate for the accumulated welding shrinkage through block assembly phases. In Sri Lankan context the most common practise to compensate for shrinkage has been to add excess material, usually 50-100 mm on one or two sides of a block that would be trimmed at the erection stage. Normally, this added material would be adequate to compensate for any weld shrinkage incurred during block assembly. It is however, a commitment to rework. This has been adopted due to the lack of accurate and reliable weld shrinkage and distortion allowance data. Even though there are some research findings on shrinkage factors it can’t be directly apply for the Sri Lankan industry as shrinkage factors may vary from shipyard to shipyard due to facilities, welding equipment, joint design, welding sequence, ambient temperature, and type of material. This research project provides a comprehensive weld shrinkage factor identification that enables neat construction capabilities for the shipbuilding industry in Sri Lanka. A key component of the research is a predictive weld shrinkage factor based on current ship designs, materials, and construction practices. Through this study, the shrinkage factors will be identified by a statistical analysis of data. It will be done from the development of check sheets, establishing of checking procedures, data gathering, and finally the statistical analysis of data. Since variety of variables can affect the determination of a shrinkage factor, it has to be decided the most crucial factors for particular production process and consider only those factors as the variables. Even though there are three major processes (panel fabrication, block construction, block assembly) in ship building the data was analysed only for data collected from panel fabrication and sample testing. Finally two equations were derived for sample testing and panel fabrication separately by providing dedicated factor for each and every considered variable. The obtained results were validated again by means of another sample testing and the deviation is less than 0.2 mm. The other processes were not considered due to complexity of the structures and data collection difficulty with in limited time frame. The block construction and assembly processes can be considered for the next step of this research and it can be done with the involvement of modelling software. From the modelling software the differences in each of complex blocks can be identified easily and measured values can be analysed against those differences. Then a comprehensive welding shrinkage compensation factor can be identified and it can be entered to the modelling software at the time of modelling the vessel.
item: Thesis-Abstract
Analysis of yarn parameters influencing the knittability of thermoplastic polyurethane yarns
(2021) Atapattu DM; Manthilake I; Punchihewa H
Knittability specially in synthetic yarns such as polyester and nylon is an essential index of the performance in ensuring the proper conversion of yarn to a knitted fabric. This can be affected by various conditions of the yarn manufacturing, yarn storage, knitting machine, knitting pattern and the environment. In footwear knitting industry, Thermoplastic Polyurethane synthetic yarn is being used due to its higher heat resistance and colour fastness properties compared to normal melt spun yarns. One of the major concerns in the process of knitting is the continuous yarn burst, which occurred significantly in thermoplastic polyurethane yarn. Occurrence of this burst appeared to be random and emerged in every yarn knitted areas. This research aimed to identify the critical factors affecting the yarn burst. After identifying the most critical factors through literature review, temporary and permanent countermeasures were developed. Initially, Prisma approach was applied to extract the relevant information from literature. Then, parameters were categorized into three based on factors related to: yarn compound, storage environment, and machine and knitting pattern. Under each category the critical parameters relevant to each factor was identified after analyzing the significance of each quantitatively and qualitatively. In terms of yarn aging, previous literature explains three types of tests namely natural exposure, field aging and artificial acceleration. According to literature, the strength of Thermoplastic Polyurethane yarn deteriorates once it is subjected to extreme conditions. In this study, the relationship between the Thermoplastic Polyurethane polymer manufactured date, the yarn lot manufactured date and the yarn burst was experimentally tested. The correlation with knittability and the yarn manufacturing dates were found to be not significant. In terms of yarn compound related factors, yarn unevenness was identified as the most critical parameter. An experimental set up was developed to measure the unevenness of black and white colourway samples. These colourways were selected as the defect rate of white colour was the highest while the black colour was the lowest. Through the statistical analysis of “t” distribution, it was identified that the statistical variance of the data set was high between the two colourways. This proves that the factor of yarn unevenness is directly correlated with defect rates. Related to machine and method related factors, the programming structures were less researched in the literature. According to the relevant footwear application, initial all needle knit structure is changed to 1*1, 1*2, and 2*2 structures. All 1*1, 1*2 and 2*2 structures prove better knittability compared to initial all needle structure. Depending on the aesthetic factors, 1*1 structure is considered as the optimum one for the relevant application. This study was limited to few parameters and the dependence of other parameters such as temperature, time and moisture absorption has to be further investigated in future works. Further, the needle knit structure is also an interesting avenue for further research.
item: Thesis-Abstract
Analysis on the effect of trench geometry on film cooling effectiveness of shaped holes using rans simulation
(2022) Sanjeeva KPP; Ranasinghe RACP
Diffused shaped holes have shown superior cooling performance over the other shapes of holes in many situations. In the present study, numerical simulation using realizable k-ε model with enhanced wall treatments as implemented in Ansys Fluent solver was performed to study the effect of trench geometry made at 7-7-7 shaped hole exit on cooling effectiveness. The predictions were generated at different depth ratios of the trench geometry. Three different blowing ratios of M = 1.5, 3, and 5 were employed with different depth ratios of h/D = 0.25, 0.5, and 1. Altogether nine cases were run to generate predictions and three cases without trench, h/D = 0, at different blowing ratios of M = 1.5, 3, and 5 were run as the baseline. All cases were maintained at density ratio of DR = 1.5 and turbulence intensity or Tu = 0.5%. Based on the error analyses and the comparisons performed to flow field patterns and cooling effectiveness variations during the validation, the realizable k-ε model with enhanced wall treatment was selected among standard k-ω, SST k-ω and realizable kε for predictions. When compared to the baseline, not only the modified geometry presents better cooling effectiveness according to the laterally averaged effectiveness, but superior lateral spreading of coolant can also be observed at higher depth ratio of trench. Maintaining higher blowing ratios at lower slot depth ratio such as h/D = 0.25 is only a waste of coolant without improvements to cooling effectiveness while higher cooling effectiveness can be obtained by higher blowing ratios at higher trench depth ratios. Based on the laterally averaged effectiveness, the cooling effectiveness is improved by increasing the trench depth at all blowing ratios investigated. Based on the lateral effectiveness variations, the coolant jet has shown a skewness at higher blowing ratios and lower trench depth ratios while the skewness becomes invisible at lower blowing ratios and lower trench depths. A steeper decay can be observed in laterally averaged effectiveness at high blowing ratios (M = 5) and low slot depth ratios (h/D = 0.25) due to the jet penetration into mainstream thereby degrading the cooling performance.
item: Thesis-Full-text
Applicability of Kalina cycle for waste heat recovery in themal power stations in Sri Lanaka
Dematapitiya, DRAK; Perera, KKCK; Ranasinghe, RACP
Energy Crisis is the critical problem faced by the modern world. Day by day the impact is becoming severe with decaying of fossil fuels. Therefore, whole world has paid their attention on Non Conventional Renewable Energy sources. Industrial Waste Heat Recovery is one of them. The main focus of this thesis is to identify the best suited method for recovering lowgrade energy from thermal power stations in Sri Lanka. Among few methods, Kalina Cycle System is selected by concerning its viability for usage. Several attempts were made to assess the available heat energy from thermal power stations in Sri Lanka. The first objective of this research is to assess the thermal energy wasted from thermal power stations operating in Sri Lanka. The next objective was to identify the best suited configuration of Kalina Cycle System for extracting low-grade heat energy. The final objective was to use the said system for harnessing the energy, and quantify them. Simultaneously an economic analysis was carried out to assess its economic feasibility. A literature review was done to identify possibilities of harnessing the energy from flue gas of thermal power stations and to find out the suitable method for extracting energy.Lakvijaya Power Station and Kelanitissa Combined Cycle Power Station, which have emissions below 200oC, has the ability of generating electricity using the Kalina Cycle.However, as per the analysis, they are not economically feasible. However, with these results,it is suggested to continue the same exercise to other thermal power stations, which has high temperature flue gases. As the next step, it is proposed to identify the best suited Kalina Cycle System for the rest of thermal power stations and expand this exercise throughout CEB owned and private owned thermal power stations, using other suitable configurations of Kalina Cycle System.
item: Thesis-Full-text
Application of Zimont's turbulent flame speed closure for combustion modeling of a single cylinder spark ignition engine
(2018) Eranga, JKL; Ranasinghe, RACP
Increasing need to get the maximum power out from fuels while maintaining less amount of toxic emissions has created the requirement of making an optimum IC engine. Numerical simulations play a vital part in determining those design and operating parameters which make that idea of an optimum engine a reality. In the present work applicability of two well-known turbulent flame speed models: Namely Peters and Zimont in premixed charge gasoline spark ignition (SI) engines were evaluated. Their ability to predict the characteristics of premixed turbulent combustion process of an SI engine in the RANS context was first assessed and based on those results Zimont model was used to evaluate the applicability of Smagorinsky-Lilly Large eddy simulation (LES) model in engine simulations. Several simulations were done to identify and implement required modifications to get correct solutions from the LES model. Combustion of the Ricardo E6 single cylinder test engine was modeled with the above two turbulent flame speed closure models implemented to a commercial computational fluid dynamics (CFD) code. Full cycle simulations, covering all four strokes including the valve motion, spark discharge, flame kernel development and fully developed combustion, were performed using different engine operating conditions. Engine was fueled with gasoline. Obtained results were compared with experimental values obtained using the same operating conditions of the E6 engine to evaluate the prediction ability of the different models. Accordingly, In-cylinder pressure variation and the combustion heat release rate versus crank angle were compared with measured values. In general, predictions, of both models were found to be in reasonable agreement with experiment values, but significant discrepancies could be observed in certain operating conditions.
item: Thesis-Abstract
Assessment of embedded energy in manufacturing wall tiles using two different firing technologies in Sri Lanka
(3/28/2011) Divakara, SA; Attalage, RA; Sugathapala, T
Energy productivity is a critical factor for the Sri Lankan manufacturing industries which is a critical issue that affects the cost of production. Efficiency in consumption of energy and its conservation would be one of the most important means of energy cost reduction and also for meeting future energy demand. The ceramic industry is one of energy intensive industry in Sri Lanka which uses massive quantity of thermal energy as well as electrical energy for the manufacturing processes. An analysis was carried out to asses the energy consumption of two industrial processes in manufacturing ceramic wall tiles using technologies of conventional and fast firing. Conventional firing technology is the oldest technology and fast firing technology is the latest technology that are being used to fire ceramic products./ The main objective of the study was to analyze the energy efficiency of technologies in a broad view and as secondary to study the energy conservation techniques used and can be used in order to reduce the energy consumption. The method of embedded energy analysis was used to analyze the energy of two processes under certain boundary conditions. Analysis of embedded energy was calculated in three levels such as level I direct energy supplied by the fuels and electricity, level 2 all ancillary energy inputs and level 3, energy in raw materials. The calculated embedded energy of wall tiles manufactured with the technology of conventional firing is 16 GJ/ MT and similarly the embedded energy of wall tiles manufactured with the technology of fast firing is 9 GJ / MT. The energy consumption in each levels, level 1, level 2 and level 3 of conventional firing technology is 96.7%, 2.4 %, and 0.9% respectively and in fast firing technology is 96.5%, 2.4%, 1.1% respectively./ 1'he latest technology of fast firing technology has been developed highly considering of energy efficiency productivity and product quality. The fast firing technology consist of many kinds energy saving technologies such as waste heat recovery, high thermal efficient kiln furniture and refractory, high efficient burners, efficient tile transportation methods. Out of two technologies of fast firing and conventional firing the most energy efficient technology is the fast firing technology which is 12% more efficient than the conventional tiring with compared to the result of the study. Further the implementation of energy conservation techniques to the existing plants will be incorporated to reduce energy consumption by 5 to 10 percent on electrical and 2 to 5 percent on thermal.
item: Thesis-Abstract
Assessment of environmental performance of milling machining
(2022) Priyankara KPM; Gamage JR
The manufacturing industry largely contributes to the economy of a country. Thus, manufacturing by material removal processes leaves a significant environmental footprint. This is caused by the influence of process energy, resources, and releases. Due to that, increased attention on sustainable means of machining operations can be seen today. Thus, environmental sustainability assessments and preventive measures are being researched for promoting green manufacturing. In conventional machining, milling is a widely used machining method in the production and manufacturing industries. Thus, the purpose of this study is to assess the environmental performance of milling machining in an industrial setup. A literature review is conducted to understand the requirement of empirical assessment on sustainable milling and to identify the factors contributing to environmental damage while identifying sustainable machining practices. To conduct the empirical assessments, an industrial milling operation is monitored. At the experiment stage, different consumables and releases are identified and monitored such as power consumption, workpiece material usage, tool material, and coolant while controlling the machining parameters and the tool path. Design of Experiments were used to efficiently manage the controllable machining parameters relevant to environmental performance. The contribution to the environmental damage is analysed and quantified according to the ReCiPe endpoint impact assessment method using SimaPro® (Version 8) life cycle assessment (LCA) software following the guidelines of ISO 14044. The review revealed several factors that are significantly contributing to the environmental impact. Further, a number of operational level improvements were identified to improve the environmental performance. The results identified the electrical energy consumption and workpiece material usage as the most influencing contributing factors to the adverse environmental impact. Further, an operator‟s guide was also developed to harness the operational level savings to ensure the better environmental performance of milling.
item: Thesis-Full-text
Assessment of the geothermal potential for energy generation in Sri Lanka
Arachchi, GSM; Punchihewa, H
Geothermal energy is the heat extracted from the subsurface of the earth. The heat loss of the earth is higher at plate boundaries compared in the tectonic plates. The global heat loss is about 44TW where volcanic eruptions in the range 2.4 – 4.0 TW. Sri Lanka has not located geologically favor conditions for geothermal energy development it has nine hot water springs in the eastern and southern region of the country. Out of nine 7 were located in the Vijayan complex. Geochemical analysis of geothermal water of 6 selected hot water springs and the resistivity depth cross sections for few magnetotelluric tested traverses were used for the assessment of geothermal potential in southern and eastern regions of Sri Lanka. Geothermal energy potential for 1 km3 reservoir near the six hot springs in southern and eastern of Sri Lanka can be calculated around 5.76 MW in Mahapelessa to 34.86 MW in Marangala. Based on the geochemical analysis, average temperatures of the geothermal reservoirs are around 120-160°C for MP, KI, KP and NW and for Marangala, Maha Oya 390 and 230°C respectively. Also the water from Kapurella, Nelum wewa, Maha Oya has representing the characteristics of volcanic water and Marangala as steam heated water. Available potentials according to the magnetotelluric studies were well beyond the economical depth of exploration so located deep in the available magnetotelluric cross sections. However according to the chemical analysing the presence of intermediate reservoirs in between the traverse can be expected in shallower. Night time infrared photography can be used to explore the surface hot water accumulations hence can explore new hot springs. Other than the chemical concentrations, isotopes characterization is useful to detect the origin of the geothermal water. To identify the exact dimensions of the reservoirs three dimensional magnetotelluric testing should be done near the hot springs.
item: Thesis-Abstract
Benchmarking water demand of low-income housing apartment complexes in Colombo, Sri Lanka
(2024) Gallage, SL; Ranasinghe, C; Jayasundara, R; Wijewardane, A
Along the main roads, Sri Lanka's coastline regions are fast urbanizing and expanding. The progress of these development works increased the population inside the urban areas, which created new social and economic issues. The high-density apartment complexes as high-rise apartment buildings are introduced to mitigate these social and economic issues. To maintain sustainable development in these urban areas, providing essential facilities for these apartment buildings is important. 70,000 low-cost housing units were scheduled for construction as part of the Urban Regeneration program and Sri Lanka's National Physical Plan (2011-2030). These plan to relocate the people currently residing in underserved areas of Colombo city. Providing the essential facilities for these apartments does not assure the sustainability of the development. Overuse and waste are also required to be minimized, and optimum usage of these facilities is also to be assured. As a result, efficient buildings that preserve the environment are necessary for sustainable development, and these services need to be standardized. There are building rating systems like LEED, BREEAM, and Green Star that are well recognized in this context. In Sri Lanka, the Green Building Rating system, UDA Green, is recognized to describe a building's efficiency. Energy efficiency is what these rating systems are primarily concerned with. Concerns about water efficiency are also significant in this context because Sri Lankan water demand benchmarks are not established, which makes it difficult for construction designers to create effective solutions for these structures and monitor the efficiency of the existing apartment buildings. The study of establishing a benchmark for the water demand of low-income housing apartments requires studying of socio-economic behaviour of this community. A survey questionnaire was used to collect the information required for this study from 500 randomly chosen sample residents spread over 18 low-income apartment complexes in the Colombo area. A benchmark for the water demand in apartment buildings for low-income housing was developed after the survey's results were analysed. The benchmark water demand values for low-income housing are 170.16 litres per person per day and 850 litres per apartment per day. Keywords: Water demand benchmarking, Low-Income housing apartments, socio-economic behaviour, Survey questionnaire