Browsing by Author "De silva, N"

Now showing 1 - 5 of 5

item: Conference-Full-text
Developing a Maintenance strategy plan to improve energy efficiency of HVAC system
(Ceylon Institute of Builders, 2013-06) Dahanayake, KWDKC; De silva, N; Fernando, SS; Sandanayake, YG; Fernando, NG
In managing energy in buildings, a greater focus has been given to the HVAC system as it generally consumes more than 50% of total energy usage in buildings. Proper maintenance Had been identified as a significant factor to improve energy efficiency of HVAC systems. For instance a proper maintenance plan can save 5% -20% of energy bills without a significant capital investment. Thus, the research aims to develop a maintenance strategic plan to improve energy efficiency of HVAC systems. Survey technique was adapted to collect data on HVAC system failures, impact of failures, frequency o each failure, significance of causes for failures, and HVAC maintenance requirement to ensure efficiency. A statistical analysis was carried out to develop a maintenance a strategy plan. Maintenance strategic is proposed by using the preventive and predictive maintenance strategy. This proposed plan may be useful for building managers to manage energy by adopting efficient maintenance strategies.
item: Thesis-Abstract
Economic loss optimization technique for distribution transformer sizing
(2014-07-31) Thushara, RMHL; De silva, N; Wijayapala, WDAS
The Distribution system is a dynamic system which requires frequent system augmentation to ensure customer satisfaction and optimum system operation. Planning of such a system needs to consider many variables and alternative solutions in a complex process to select the system components at their economical size combination. Since distribution transformer is the major cost contributor in the secondary distribution network, correct sizing should be achieved via economical optimization in avoiding under utilization. Adoption of a global design methodology is preferred in this case. This research was intended to implement a model based secondary distribution planning strategy which will be capable enough to provide final solution in a minimum time with economic evaluation. The application of geometry to represent distribution transformer service area is helpful in the system analysis and it simplifies greatly the complexity of the system while allowing comparison of alternative arrangements in a faster manner. Several options are analyzed during this study in comparing actual system data of large number of distribution transformers in Lanka Electricity Company's (LECO) l lk V/400V system. It is concluded that the model of hexagonal geometric service cell area with trapezoidal separation per feeder is the best fit model to represent a secondary distribution transformer service area. This selection is based on voltage oriented. This includes three main feeders originating from the distribution transformer located at the center of the hexagon. Set of application charts for commonly available distribution transformers are developed in the research. This gives faster method of investigation about voltage drop and power loss for a particular distribution transformer in various configurations. The computer program is finally implemented in MATLAB to generate final solution for the optimum transformer capacity. Existing network expansion or reinforcement is investigated in this program. Economic optimization is implemented in both cases where Genetic Algorithm is used as an optimizing technique for the first option which achieves converged to the global optimum point in a few seconds. A detail case study is done with actual system data to verify the final results.
item: Conference-Full-text
Impact of maintenance management procedures on energy efficiency of chillers
(Ceylon Institute of Builders, 2013-06) De silva, N; Siriwardana, MR; Nawarathna, RAG; Sandanayake, YG; Fernando, NG
The most important element of the central air conditioning system, the chiller, accounts for about 40% of annual total energy consumption of commercial and industrial buildings. As a result, many approaches have been proposed to increase energy efficiency of chillers with the intention of managing the annual total energy consumption of facilities. Among them, it was revealed that the approach of proper chiller maintenance procedures lead towards the energy efficiency of chillers. Therefore, the research was focused on identifying the impact of maintenance management procedures on energy efficiency of chillers. The data was collected through a pilot survey and a main survey which were followed by a questionnaire along with observations and interviews with experienced industry practitioners. It was identified that the maintenance procedures has a great impact towards the energy efficiency of chillers. Perform condenser water quality test, Monitoring refrigerant pressure and temperature, Monitoring water flows, cleaning of condenser bundle and cooling tower cleaning and water treatment were identified as the most significant maintenance activities which assist to meet the standard energy efficiency level of chillers. Eventually, a multiple linear regression model was developed with the intention of deriving relationship between performance deviation of above maintenance activities and energy efficiency drop of chillers.
item: Conference-Full-text
Relationally integrated value networks for sustainable procurement
(Ceylon Institute of Builders, 2013-06) Weerapperuma, S; De silva, N; Kumaraswamy, M; Ranasinghe, M; Sandanayake, YG; Fernando, NG
Relationally integrated value networks (RIVANS) aim to boost collaboration in built infrastructure supply chains, thereby improving both efficiencies and value creation. However, in widely practiced traditional procurement modes, transactional forces are still complex and short-sighted, resulting in weak collaborative supply chain networks, while potentially beneficial relational forces remain untapped and/or fragmented, lacking well-defined common goals among stakeholders. RIVANS have been proposed to provide a holistic conceptual framework for relational integration towards the concept to all stakeholders in the built asset lifecycle, by engaging them in cross linked value networks. The ultimate goal is for sustainable procurement through RIVANS, by developing collaborating practices and overall value focus across the entire network and through the whole built asset life cycle. A questionnaire survey was carried out to elicit relevant opinions from industry professionals. The survey led to identifying eight potential synergies/better values by linking supply chains in Infrastructure Project Management (IPM) with Infrastructure Asset Management (IAM). Functional and relational integration were identified as an appropriate mechanism to achieving value through integration. The degree of importance of eleven common goals was identified in achieving ‘better value'. The key stakeholders of D&C and O&M value networks were also identified.
item: Thesis-Abstract
Voltage stability analysis of a grid connected wind farm
(2014-08-21) Nagodavithana, RD; De silva, N; Karunadasa, JP
Voltage instability is one of the problems that can cause a wind farm to shut down without any warning. The resulting sudden drop or generation can lead to large power system faults. The voltage instability issue mainly plagues one type of wind farm. The squirrel cage induction generator fed wind farms. This is due to the lack of reactive power support in this type of generators. To assess the stability of such wind farms a dynamic model of wind farm has been developed by accumulating the following models. 1. Squirrel cage induction machine 2. Wind turbine 3. Transmission line 4. Transformer 5. Capacitor bank Model parameters were calculated and simulations were performed for a wind farm consisting of eight wind turbine generators each with a capacity of 1805kVA. Stability was assed for normal 33kV national grid level network voltage variations of +10% of rated Voltage. The wind farm is shown to be stable for this variation and operated within normal parameters. The wind farm was also checked for LVRT capability and found to be within CEB specifications.