Master of Science By Research

Permanent URI for this collectionhttp://192.248.9.226/handle/123/11526

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Now showing 1 - 5 of 5

item: Thesis-Abstract
Evaluvating the potenital of adopting clean development mecahanism for implementing renewable energy based projects in Sri Lanka
(2015-07-09) Samarasinghe, JB; Attalage, RA; Perera, KKCK
Sri Lanka has had a hydropower dominated electricity generation for many years with relatively high rainfall mainly in the central hilly region. This factor has led to a greater dependence on hydropower for its power generation. However, at the same time, Sri Lanka is heavily dependent on imported fuel and for energy security it is imperative that we take steps to harness the renewable energy sources. The government is trying to respond to the energy supply issue by relying heavily on fossil fuel based electrical power, which may not be the correct energy option for Sri Lanka. Therefore, the large scale fossil based power plants are not environmentally friendly in comparison to other energy options. This will result in a gradual increase in greenhouse gas (GHG) and other environmental emissions in the power sector and, hence, there has been a lot of opposition from the people, especially environmentalists, civil society and residents in the locations where fossil based plants have been planned. The main intention of this study is to form an internationally consistent view to answer the question as to whether and to what extent the adoption of renewable based combustion technologies in projects could be economic and sustainable in, place of the nonrenewable based combustion dominant projects. The study will consider the appropriateness of existing perspectives and policy imperatives in the above regard also. Special emphasis will be given for the local environmental protection, mitigation of climate change, legislation and quality of service in a context of global competition. It is a fact as well as the general perception that adoption of renewable energy technology based projects and the Clean Development Mechanism (CDM) created under the Kyoto Protocol, are directly linked. The Clean Development Mechanism (CDM) act as a bridge to link the industrialized countries and developing countries. The CDM intends to assist developing countries achieve sustainable development by providing incentives for industrialized countries to invest cost-efficient GHG reduction projects in these countries. The developed countries can receive some credits by investing and implementing GHG emission reduction projects in the developing countries, then use the credits to fulfil their legally binding quantitative obligations laid down in the Kyoto Protocol. Although the Clean Development Mechanism (CDM) does not have an explicit technology transfer mandate, it may contribute to technology transfer by financing emission reduction projects using technologies currently not available in the host countries. The study presented in this thesis first analyse the potential technology possibility under the CDM in power generation. This study is a theoretical study focused on the survey of the current state of art of CDM and related issues. The results show that the potential of CDM opportunities in mini hydro, biomass including dendro power and wind energy , which can be identified as the leading, sustainable, non-conventional forms of renewable energy promoted in Sri Lanka for electricity generation to feed into the thermal grid. Also the main intention of this study is to investigate the technological and regulatory interventions on overall power sector emissions and economic and environmental benefits of such interventions. Based on the analysis it was found that present annual CO2 emission with respect to the thermal power electric generations in Sri Lanka is about 0.75 Million Metric Tons and Wind, mini-hydro and bio mass will be very attractive with CDM funding. Out of the selected CDM options, the Mini Hydro plant that Sri Lanka need to choose is particularly important. Considering that this is the option giving the highest carbon reduction within the planning horizon while having the highest profit. But when considering the local energy tariff structure, the tariff is highest for Biomass.
item: Thesis-Abstract
Heat gains to building interiors through roofs : a study based on selected configurations in Sri Lanka
(7/21/2012) Sirimanna, MPG; Attalage, RA; Perera, KKCK
Roofs of residential buildings play a crucial role in the context of building heat gains and thermal comfort, since they are exposed to a significant portion of insolation during the day. Therefore, it is important to develop a generalized model to evaluate thermal performance of roof structures under local conditions. This modeling becomes complex due to the dynamic nature of the parameters and various configurations, orientations of the roof surfaces in 3-D space. To address this issue a numerical approach was used to determine view factors of roof surfaces of a generic configuration. Consequently, a thermal model was developed to represent roof structures with four roof surfaces and a ceiling. Model is capable of incorporating insolation on roof surfaces, environmental conditions, roof configuration and materials and obtaining thermal responses of roof surfaces. A computational tool was finally developed based on the model. In order to validate the computational tool, an experimental setup was build and readings were recorded for several days. Same system was simulated using the computational tool and the results were compared. Furthermore, a commercial software and the developed computational tool were used to simulate a selected case and the results were compared with each other.
item: Thesis-Abstract
Multi criterion decision making based on techno-economical optimization of stand-alone hybrid energy systems
(2014-08-12) Perera, ATD; Attalage, RA; Perera, KKCK; Dassanayake, VPC
Hybrid Energy System (HES)s areincreasingly becoming popular for standalone electrification due to global concerns on GHG emissions and higher depletion of fossil fuel resources. Simultaneously research work on optimal design of HESs has also made much progess based on progress with numerous optimization techniques while giving special focus to Pareto optimization considering conflicting objectives. This study comes up with a novel evolutionary algorithm to optimize HESs based on ε- dominance technique. Mathematical modeling of energy flows, cash flows, GHG emissions were carried out in order to support the optimization. Pareto analysis was conducted for two different cases where former analyzes a novel design of a HES and latter analyzes a conversion of existing Internal Combustion Generator (ICG) into a HES in the expansion process. The Levelized Energy Cost (LEC), annual fuel consumption and Initial Capital Cost (ICC) were considered to be objective functions in the first analysis. A sensitivity analysis was followed the mathematical optimization in order to evaluate the impact of power supply reliability on the Pareto front. Furthermore, sensitivity of fuel cost and renewable energy component cost on Pareto front was also investigated considering the present dynamic condition of energy market. LEC, power supply reliability and added renewable energy capacity were taken as objectives to be optimized in the second case. Sensitivity of ICG capacity on the Pareto front was also taken into discussion. Pareto analysis clearly elements such as LEC, power supply reliability and fuel consumption are conflicting to each other. Therefore it is essential to perform multi criterion analysis in order to assist decision making. In order to assist decision making, Fuzzy-TOPSIS (a multi criterion decision making technique) was combined with Pareto optimization. For that, multi objective optimization was carried out considering Levelized Energy Cost (LEC), unmet load fraction, Wasted Renewable Energy (WRE) and fuel consumption as elements in the objective functions to generate non-dominant set of alternative solutions. Pareto front obtained from the optimization was ranked using Fuzzy-TOPSIS technique and Level Diagrams were used to support this process
item: Thesis-Full-text
Numerical modeling of the flow field for indoor thermal comfort of a building under stack effect
(2015-11-27) Nimarshana, PHV; Attalage, RA; Perera, KKCK
In recent years natural ventilation is widely recognised as excellent contributing towards in design low energy buildings. The main challenge in natural ventilation is identified as lack of knowledge in providing acceptable thermal comfort in an occupied space to meet the internal requirements against the prevailing climatic conditions variations. Numerical investigations of the indoor thermal comfort condition in a simple office space governed by the solar chimney stack effect have been undertaken using CFD techniques. A mathematical model was developed based on the relevant analytical framework governing the phenomena to simulate the velocity flow field and temperature distribution on the designated plane within the indoor space. Boussinesq approximation was incorporated to numerical scheme with realistic boundary conditions for flow simulation. The model was enriched by incorporating a sufficient fluid volume to represent environment surrounding the space and thereby eliminating the entry effect to the flow. Hexahedral cells were used in a non-uniform grid distribution to minimise numerical diffusion. A fine mesh is used near the walls to enhance the resolution and accuracy resolving the problems under the turbulent flow conditions. Grid independence analysis was carried out to ensure the accuracy of the numerical results. Under-relaxation factors 0.3, 1, 2, 0.8, 0.8, 1, 0.9 for pressure, density, momentum, turbulence kinetic energy, turbulence dissipation rate, turbulent viscosity, energy respectively were used. The model outputs were compared with the available experimental measurements taken under the same condition to calibrate the numerical scheme. A parametric study was carried out using the calibrated model to assess the distribution of thermal comfort index against the changes in geometrical and solar radiation parameters. The values of activity, metabolic rate for seated activity and clothing insulation were selected as 0, 60 W/m2 and 0.5 Clo respectively for thermal performance analysis. The effect of each input parameter was investigated in terms of mean value and standard deviation corresponding to the flow velocity and the PPDNV value. It can be concluded that the present model is capable of predicting the indoor thermal performance of a building under stack effect.
item: Thesis-Abstract
Performance evaluation of an innovative tea dryer using mathematical modeling
(7/25/2012) Shantha, KYHD; Attalage, RA
This entire research work is focused for the performance evaluation of an Innovative tea dryer using a technique of mathematical modeling. The innovative tea dryer was designed and fabricated targeting the group of farmers who cultivate bio tea /organic tea in few acres amidst of lot of constraints. Main challenge for the production of tea at small scale is consistent drying. Since drying is a key factor affecting the quality of the ultimate product of tea, the simulation results of the mathematical model explain the drying performance and how the physical model or the prototype could be scaled. The tea sector has always been a vital component of Sri Lanka’s economy. Sri Lanka as the third biggest tea producing country globally, has a production share of 9% in the international sphere, and one of the world's leading exporters with a share of around 19% of the global demand. The total extent of land under tea cultivation has been assessed at approximately 187,309 hectares. Much of the growth boost in low grown tea production is attributed to the rise of the tea smallholders who are concentrated in the low-country. It is estimated that the smallholders occupy about 65 to 70% of the tea extent in the country and their contribution to overall production has also now risen to around 65 to 70%. Since the organic tea has an increasing demand and a good overseas market the tea cultivators of small holders are encouraged to produce organic tea. In the traditional or 'orthodox' procedure, the process used to make loose tea, the leaves must go through a process of Withering, Rolling, Oxidation /fermentation and Drying. Among these processes, withering and fermentation are taken place as a result of environmental conditions except rolling and drying. Rolling could be done manually on a serrated timber plank as the quantity is small. Dholes followed by the above three processes are fed into the innovative dryer for the making of tea. This dryer was completed as two stages with two cylinders having concentric perforated cylinders inside. Two hot air generators are being used to supply the hot air where saw dust is burnt for the supply of thermal energy for the first stage drying and the electricity is used in second stage drying, The cylinders are rotating at the same speed of about 12 rpm, and screw feeder is used for the feeding of material into rotating inner cylinder at a constant rate without the material being clogged at the entrance. Analyzing the direction of material and hot air flow inside the cylinder the dryer is said to be the type of cross-flow co-current. The two drums and the material feeder are powered by a single motor of ½ hp with a gearing ratio of 1:30. As the heat transfer is direct from the heat transfer medium to product the dryer is also called direct or adiabatic dryer. The adiabatic dryer is more closely related to the humidification process than is the indirect one. As per the raw material and other drying parameters, the dryer type for the innovative dryer has been selected as cross flow, co current rotary type considering physical properties of the drying materials. Testing of this innovative dryer under real conditions and its results are further illustrated in the report. Based on the physical and thermodynamic parameters of the design and experimental data, a mathematical model has been developed studying various drying models and simulation methods using experimental figures in the report in details. The mathematical model and simulated results using Matlab show how far the model relate with the actual performance. The accuracy of simulation results of the mathematical model is highly depend upon the accuracy of the experiments carried out at various situations for finding out the dryer constant and the characteristic constants using physical models.

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Browsing Master of Science By Research by Author "Attalage, RA"