Master of Engineering in Mechanical Engineering

Permanent URI for this collectionhttp://192.248.9.226/handle/123/748

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item: Thesis-Full-text
Novel method to measure abrasion of sold tyres
Chathura, BAY; Punchihewa, HKG
Peripheral velocity, load, floor surface and type of rubber compounds are the key determinants considered when selecting solid tyres. These factors also determine the life of the tyres. However, there is no accepted method to measure tyre wear against the factors mentioned above. At present, lifespan of tyres is determined through field tests where the tyres are used in different industries and collecting data on tyre life in terms of running hours. Another method is to use a drum-type apparatus with bonded abrasive paper or abrasive particles between the tyre and the drum. The limitations of these methods include the time requirement and inaccuracies in data to enable accurate analysis of tyre life. As a result, the tyre manufacturers find it difficult to specify the tyre life with adequate degree of certainty to the customers. This gives rise to a need for a standard method to assure the life of tyres, especially solid tyres, for the benefit of the customers and to conduct tests to help improve tyre performance. The proposed apparatus has the facility to change the operating speed, surface and the load. The overall designed length, width and height of the machine are respectively 3000 mm, 1150 mm and 3350 mm. The computer-based simulation results for design evaluation suggest that the stress and stain are within allowable limits under typical loading conditions. Then a scale down prototype was constructed and three samples which were manufactured from three different compounds were tested for measure rubber abrasion and temperature. Results showed high abrasion resistance compound according to DIN 53516 had low wearing and low heat build up compound according to drum testing results had low temperature. Construction and testing of the apparatus are proposed as future work to complete the work.
item: Thesis-Abstract
Development of an operator friendly boiler performance calculator
Delpitiya, C; Perera, KKCK; Manthilaka, I
Saving fuel by optimising the equipment performance has become a goal for almost all global organisations and boilers which contribute to a major share of global recourses consumption was subjected to the present study. This study was conducted to develop a boiler performance evaluation tool. Different performance indicators and methods of evaluating those indicators were studied. Performance calculator was developed based on British Standard, which can estimate performance of steam, hot water boilers and thermal fluid heaters with limited inputs and standard measurements. The calculator was used to estimate direct efficiency, indirect efficiency and evaporation ratio of selected cases using secondary data. Calculated values of respective performance indicators were compared with measured values. Calculated results of indirect efficiencies have 0.897 to 0.950 correlation and the excess air percentages were 99.5% agreed with measured values. This can be developed using advance software including an expanded version of the steam table.
item: Thesis-Abstract
Daylight utilisation in commercial buildings and potential energy savings
(2016-02-13) Korale, CJGM; Attalaga, RA
Energy is one of the most vital contribut ions to sustainable development strategy of Sri Lanka. However, the r ising cost of energy generation, the deplet ion and the unpredictability of availability of energy resources and the adverse impacts of energy generation and its usage on the environment, have been causing much anxiety and great concern from recent t imes. Within this context, buildings have been considered as one of the largest consumers of energy and have therefore been ident ified as one of the target areas for energy conservat ion. Statistics have revealed that the proportion of energy consumed for light ing in buildings is much greater than what is consumed ind ividually for providing thermal comfort or other ancillary services. Therefore adding of daylight for space, architectural designing has become a vital overcomes above problems. Adding adequate sunlight, integration with artificial light ing and reducing the cooling load on HVAC systems are effect ively providing wide energy savings in buildings and houses. The principle object ive in this research is therefore to explore strategies of designing buildings with opt imal utilisation of natural light, efficient application of electrical energy for inter ior light ing and minimising energy usage of HVAC systems. A simulation modelling on daylight implementation was carried out under this research, with different kinds of light ing arrangement against a few different external characteristics within the control of the designer. The computer simulation software DIALUX 4.11 version was used to analyse illuminat ion level inside the building and a n extensive literature survey on maximising ut ilisation of daylight and its effect on HVAC system was also carried out under this research project. As per the research energy savings from daylight design in buildings cannot be realized unless the electric lights are dimmed or switched in response to the amount of available daylight. The analysis results shows , that there is potential for saving 51% of energy consumed for building light ing with daylight implementation for the building. But due to practical limitation, exist ing light ing arrangement is not suitable for daylight implementation and therefor e new light ing arrangement was considered under this research and new light ing arrangement shows that there is potent ial for 50% of energy saving with daylight integration. The analysis was further carried out for new type of luminar ies to find out further energy saving potent ial with implementation of energy saving lights with integration of daylight. This analysis results shows, that there is potent ial for 52% of energy saving with new type of luminaries and its arrangement. Effect on HVAC system due to daylight implementation was also analysed and it is shown that there is 10% increase of building cooling load due to daylight implementation. Also this research presents guide lines for designing of daylight efficient buildings light ing systems to contribute towards energy conservation, environmental protect ion and establishment of sustainable economic system as well. This research can be further extended to analysis for different kind of building with different wall colouring and internal objects arrangement for opt imal energy saving with daylight implementation for commercial buildings.
item: Thesis-Abstract
Investigation of the performance of back-pressure steam turbines combined with thermo-compressors
(2016-02-13) Wickramasinghe, WPJK; Attalage, RA
Steam is highly used in most of the industries. There are many occasions where low pressure steam is used. Most of the times, relatively higher pressure is generated, transported and finally the pressure is reduced before use. Throttling devices are used for reducing pressure. Throttling valves or pressure reducing valves have been used for this work in most of the instances. There is a huge potential of utilizing this energy by introducing back pressure steam turbines. If the turbine exhaust pressure can be further dropped, power generation through the steam turbine can be increased. This research project was created to cover these areas. There is no literature which can be used to calculate the power output of a turbine with known flow rates and input and output conditions. This project is aimed to give the information how much power is generated under the given conditions. This can be used for selecting a suitable back pressure turbine for the particular requirement. Giving the capital investment for such project also was an objective. It can be decided whether the selected project on retrofitting pressure reducing valves with the steam turbines is viable. There is no sufficient information on performance of thermo-compressors which can be used for increasing steam pressure. There is an objective of finding out the motive flow required for the known suction flow at known input and output conditions. As the title of the research shows, ultimate objective of this study was to see whether combining thermo-compressors to reduce back pressures is feasible or not. This research project was done for five input steam conditions and six output steam conditions of the turbines. For a selected turbine, performance at known pressures was calculated. This information was graphically represented to give a clear picture. Similarly performance of thermo-compressors was calculated for known input and conditions. This information also was graphically represented. Finally the performance of the back pressure turbines were calculated when the back pressure dropped further by introducing thermo-compressors. Calculated values were graphically represented to check whether this was a viable option. As per the outcome of this project, guide lines were made for back pressure steam turbines with different input and output conditions. As the input, superheated steam varying from 10barg at 350 deg. C up to 50 barg at 450 deg.C have been considered. Turbine exhaust pressures varying from 1 bara to 6 bara also have been considered. Guide lines were extended to show the cost of investment to retrofit pressure reducing valves with back pressure turbines. Guide lines were made on the amount of motive pressure consumed to increase the pressure of steam at different input and output conditions. These guidelines also were extended to show the capital investment of the installing thermo-compressors. Process steam pressures varying from 2 bara to 6 bara have been discussed against turbine exhaust pressures varying from 1 bara to 6 bara under the study of the behavior of the back pressure steam turbines combined with thermo-compressors. Further study was done to ensure whether there is any effect of the isentropic efficiency and the generator efficiency on this behavior. Finally, it was proved that there was no benefit of operating the back pressure steam turbines at lower exhaust pressure by introducing thermocompressors and increasing the pressure before giving to the process for the pressure and temperature ranges covered in this study. Retrofitting of PRV with steam turbines seems to be an attractive option. This study discussed only the application of superheated steam. Further studies can be extended to saturated steam to use single stage steam turbines. Introducing of thermo-compressors for specific industries also can be done as a further study. However, further study of introducing thermo-compressors to enhance performance of back pressure turbine will not be done as it seems not viable.
item: Thesis-Abstract
The Effect of centrifugal pump performance due to water level variation of the source
(2015-08-27) Munasinghe, RM; Manthilaka, MMID; Sugathapala, AGT
At present, there is very few published literature for energy cost of water supply. National Water Supply and Drainage Board(NW&SDB) is the prime organization responsible for providing drinking water to public in the country. Therefore the NWS&DB has the vested interest to optimize the energy of operation and maintenance for the water supply schemes in order to give more benefits to the public. Hence it was decided to carry out this research work and to utilize the outcome of the research for the NWS&DB. The effect of water level variation to energy wastage in the water supply intake on Kelani River for Ambatale water supply scheme was selected as this is the most common type of intake of water supply schemes in NWS&DB. The main focus of this research is to identify and evaluate the energy conservation potential for the water supply scheme. The research was based on the available data of past records of water supply intake at Ambatale. Such as annual water level variations of the Kelani River at the intake, annual water production, annual electricity consumption, actual pumps performances and system performance data. Data was analyzed to obtain power consumption and intake water level variation, operation condition of pumps and the system was modeled using Water CAD computer model to obtain actual status of the operational condition of pumps and the system. Analyses were carried out for scenarios during drought where highest water level fluctuation is occurred and the normal situation and the flooding situation. Analyses showed that flow variations in drought were 6,600 m3/day and 5,016m3/day for old and new intakes respectively for single pump operation, resulting total energy loss of 286,413.9 kWh and 1,066.8 kWh per month for old and new intakes respectively and raw water pumping energy variation is about 34%.The highest water level variation the intake was 2.2m. The specific energy consumption for the treatment plant was found to vary between 0.307 kWh/m3 and to 0.479 kWh/m3. Therefore any effort on energy conservation should concentrate more on reducing energy consumption of raw water and distribution pumping. The research identified raw water pumping energy consumption varies according to the water level of the intake. It is recommended to maintain constant water level in the intake. Otherwise an additional pump to be used with variable speed drive in drought season for pumping water to the treatment plant with separate pipe line.
item: Thesis-Abstract
Passive techniques to improve thermal comfort in factory buildings in Sri Lanka
(2014-08-01) Wijewardane, SP; Jayasinghe, MTR; Attalage, RA
Recent past the electricity prices have boosted to a certain height as to be identified by the industries, a key factor that hindered their competitiveness in international market. As a result, ways of reducing the energy consumption are called for within every segment of manufacturing. This new trend places the active techniques such as air conditioning a less feasible option for achieving thermal comfort within factories involving large workforces. Consequently, there occurs a rising preference for naturally ventilated factory buildings with passive techniques that enhanced the thermal comfort over HVAC controlled buildings as fit to the scenario. This array of researches was a consequence of above circumstances, which aimed to find the thermal comfort preferences of factory workers and to study and develop passive techniques that reduce or totally eliminate the active means of achieving thermal comfort in factory buildings at the low altitude of the country. The thermal comfort survey formulated accordance with the "adaptive hypothesis" primarily illustrate the comparability of thermal comfort range of Sri Lankan factory workers and ambient temperature span of typical out door conditions at low altitudes. Therefore signify the possibility of adopting the methodology of creating the favorable outdoor thermal environment within the built environment thus show the opportunity to become independent from costly active means such as air conditioning. Further the results were used to compare the validity of various adaptive models and formulas published recently for tropical warm climatic conditions. On the basis that there are abundant benefits to be gained from an improved understanding of the influence of adaptation on thermal comfort in the built environment, few novel experiments were designed and conducted to understand how workers behave and interact with different intensities of solar radiation and with different air velocities. The experiment that aimed to compare the effects of direct solar radiation on various parts of the body shows that 70% of the participants were uncomfortable when direct radiation fall on the back of their body than front of their body. Other 30% did not notice any significant difference So for existing factories, which are unable to stop the direct solar radiation inside the building, can change their production lines if possible so that the unavoidable direct sunlight fall front side of the body rather than backside of the body. Another experiment showed that 80% of the workers thermal comfort improves when walking, than staying in one place. It is believed that the augmentation of the relative velocity (0.6-0.8 ms"1) when walking makes this difference even the metabolic rate is slightly higher when having a leisurely walk. Further it was noticed that the level of thermal comfort starts to reduce when the walking speed exceeds 0.8 ms"1 . Moreover, the questionnaire survey shows that about 50% factory workers have the option to have a short walk around, about after 20-25 minutes time period. This may be a good technique for workers to improve the thermal comfort of themselves. Finally A simple and basic, but pragmatic factory model is presented by integrating the results of both field surveys and questionnaire surveys. The orientations and sizes of the openings with respect to walls and the techniques that uses vegetation as a cooling potential is considered here to give practical guidelines to a factory designer. Computer simulations using programs DEROB-LTH and AIOLOS were used to compare the model that with a common type. Results show the significant improvement with respect to ACH (Air Changes per Hour) in newly designed model.
item: Thesis-Abstract
Effect of IPP electrical energy tarif to the economy of Sri Lanka
(2014-08-01) Harischandra, HMB; Wijayatunga, PDC; Attalage, R
I have written this report for the requirement of M.ENG. of second year and the research problem being analyzed is Effect of IPP Electrical Energy Tariff to the Economy of Sri Lanka. I have being involved more than ten years in the filed of thermal power generation activities including operation, maintenance, design, construction, testing and commissioning activities in foreign country as well. Further, I carried out Power Purchase Agreement administration on behalf of the power purchaser of four major IPP projects established in Sri Lanka to the value of 225 Million Dollars, since the effective date right up to the commercial operation date. Therefore, I believe that the topic is well in line with my career and look forward to carry out a comprehensive analysis of the topic. I emphasize the fact that this topic generated in my mind because of carrier involvement of the subject for a long time. The title describes the meaning and understanding of the dilemma if exists and shall try to elaborate repercussion of it and how it would be affected or not affected to the economy of Sri Lanka. For the special study of the 3r d term of the project, I have touched the problem in a different style and I hope to augment and analyze the topic in more details by identifying the factors that are contributed. In Chapter 1, I elaborated the background of economy of Sri Lanka and highlighting up and downs of various key economic performance indicators in certain occasions since the independence. I believe that the understanding of the economic status of the country is required before touching the subject matter. At the end of Chapter 1 a brief introduction has been done to the power generation situation in the country and immerges of thermal power generation to the system. -The Chapter 2 begins the story Electricity Industry of the country outlining the components contributing to the demand of electricity. It further illustrates the history of capacity augmentation and the exact time line of the introduction of IPP generation to the system and visualizes the future trend in mathematical formula for determination of the values at any potential year. §00 University of Moratuwa 87890 87890 I tried to cover the whole Independent Power concept in Chapter 3 and believe that it will be useful to the understanding of various stages of the IPP and elaborated the each stage and agreements in detail. Chapter 4 is completely devoted to the analysis of all IPP plants established up to date and each plant is considered separately highlighting their own features. Even though this chapter looks like short and much time has been spent to mold out the final effect as a result of involvement of thousands and thousand of data and many months at the computer table. All the data being used here are factual and I have faced great obstacle while establishing the diesel fuel price for power generation due to the very volatile market price and involvement of many tax components of the final product. The relevant data always presented in Chart format for better visualization and which was more enthusiasms and for instant understanding. By dividing the Chapters in the above manner, it may be seen that the work has been organized to form a continuous logical manner. Finally, I anticipate that the result of this comprehensive analysis would be useful to the accurate decision makers of the country.
item: Thesis-Abstract
Removal of heavy metals from waste water using locally derived chitosan
(2014-06-05) Sewvandi, GA; Adikary, SU
In this research work natural bio polymer “chitosan” was synthesized using locally available shrimp shells and adsorption of chromium by chitosan was studied. Synthesize of chitosan involved four main stages as preconditioning, demineralization, deprotenisation and deacetylation. “Preconditioning” process is a new step introduced in this research, to remove loosely bound protein. In the preconditioning, the skeletal matrix structure is first weakened which makes easier to remove soluble protein by washing with water. Therefore during deproteination process less alkali concentration can be used. Effect of deacetylation conditions such as alkali concentration, number of times of deacetylation performed and reaction temperature was investigated. Chitosan was characterized using Fourier Transform Infrared Spectroscopy (FTIR), Differential Thermal analysis (DTA), Thermal Gravimetric Analysis (TGA) and X-ray diffraction (XRD). These characterization techniques confirm the existence of chitosan. Degree of deacetylation was calculated using FTIR spectra. This value was highly depending on reaction temperature, reaction time, alkali concentration and number of times of deacetylation. Both characterization techniques confirm the existence of chitosan. The affinity of chitosan for chromium was studied using K2Cr2O7 solution as the heavy metal solution containing Cr (VI) ions. Adsorption of chromium ions by chitosan was investigated under different conditions. The effect of reaction temperature, particle size of chitosan and pH of solution were studied. Amount of chromium absorbed under different conditions was evaluated using atomic absorption spectroscopy.
item: Thesis-Abstract
CAD/CAM applications : a developmental strategy for the potential footwear industry in Sri Lanka
(7/22/2011) Mutunayake, APK; Kahangamage, UP; Punchihewa, HKG
The Sri Lankan Small and Medium scale Enterprise (SME) footwear industry is at crossroads. In order for the SME sector to survive and thrive in this competitive market, advanced technology needs to be introduced among other incentives. Developmental strategies for this industry are vital given the economic condition of these organisations and the global context of the footwear industry. The overall objective of this research is to identify the present state of technology usage in the SME footwear industry and to recommend pragmatic solutions to develop it. Data was collected from the random sample (nx=14) from the target population (Sx;:::40). Semi-structured interviews were conducted with the participants during the "Footwear and leather fair in 2007", which was jointly organized by the lOB and the Sri Lanka Footwear Association held at Bandaranaike Memorial International Conference Hall (BMICH) on 24th and 25th of November 2007. Further, unstructured interviews were conducted to collect data from the sample of experts (ny=4) selected from industry to obtain the experts' view about the industry to set benchmarks for the Common Resource Centre (CRC) and to validate the information collected from semi-structured interviews. Comprehensive analysis of the data elicited through the semi-structured and unstructured interviews was carried out. The main outcome of this study is a proposal with recommendations based on stakeholder and expert views for a CRC, which is to provide services to the footwear industry. Since the large-scale manufacturers may be able to maintain their own Computer Aided Design and Computer Aided Manufacturing (CAD/CAM) facilities, the proposed centre is to provide services especially to the potential SMEs. This CRC mainly will consist of CAD/CAM division, testing and laboratory services division, education, training and skills development division, research development (R&D) division, and administration and customer care division to provide services to the industry. The facts gathered suggest the immediate need of the establishment of CRC to uplift the potential SME footwear industry.
item: Thesis-Abstract
Critical evaluation of container trailer failures and improvements in their manufacture
(6/17/2011) Mugunthan, S; Fernando, MARV
Container trailer manufacturing is a growing industry in Sri Lanka. Only two organizations are involved in this business and the monthly production was recorded as100 to 125 trailers. Like other manufacturing industries, trailer industry also faces problems due to trailer failures and difficulties to improve the trade. Failures are mainly due to lack of design stage analysis of the product. The primary objective of my research project is to analyze trailer failure problems and suggest solutions to improve the trailer industry in Sri Lanka. The methodology of this research is a combination of research training programme ,questionnaire based study and a finite element analysis of the trailer solid model. Research training programme was arranged in a leading manufacturing and servicing organization in Sri Lanka by the Department of Mechanical Engineering, University of Moratuwa. It was very useful to understand the trailer manufacturing concepts, designs ,trailer failures and the general problems faced by the trailer industry. Questionnaires are produced to two different categories of industries such as Trailer manufacturers and Trailer users. Questionnaires for trailer manufacturers are oriented to wards identifying the techniques used by manufacturers to control the failurese specially in design stage and identifying their problems and limitations in manufacturing trailers. Questionnaires for trailer users are oriented towards identifying trailer failures. A finite element analysis was carried out to study the present design of a particular type of trailer to identify the efficiency in design and to present any solutions if needed. Further, there were several rounds of semi-structured interviews with technical specialists, designers, supervisors and welders who were involved in trailer manufacturing. By the combination of all the efforts, it is found that trailer failures are mainly due to the problems due to design, fabrication, materials and parts selection, human resource and trailer misuse. Suggestions to present trailer problems and future improvements in trailer manufacture are produced.

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