Master of Engineering in Energy Technology

Permanent URI for this collectionhttp://192.248.9.226/handle/123/70

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item: Thesis-Abstract
The Impact of climate change on wind energy generation of "Thambapawani" wind power plant
(2023) Senarathna, TMGS; Narayana, M
The Sri Lankan northwestern coast has been identified as having significant wind power potential. Higher electricity generation from wind has been influenced by favorable terrain and geographic location. The government of Sri Lanka is currently encouraging the creation of wind power throughout the nation. The goal of this research is to determine how climate change would affect wind power generation in the Thambapawani wind power facility. Climate change affects wind resource variations. The Coordinated Regional Climate Downscaling Experiment and General Circulation Models (GCM) model can predict wind speed variation trends in the region due to climate change. In this study, wind data were collected in Mannar and predicted wind data based on Cordex and GCM forecasting baseline. The generalized wind climates in the future years for the region were developed considering ground roughness, topography, and elevation details in the area and assumed to remain these conditions unchanged in the predicted period of the study. Commercial wind turbines erected were microsited by applying a generalized wind atlas to specific wind turbine areas with the influence of ground roughness and topology in order to assess the cost to be utilized of wind electricity production in Mannar. By taking into account the features of wind turbines and the anticipated wind capacity of the areas. WAsP was utilized to forecast the production of wind power. Reso, a Danish company, created the software application WAsP to assess the wind energy production of wind farms for micro-sitting. For a specific wind farm architecture, the wake effect is computed in the micro-sitting. This study assesses the utilization of wind electricity production and the impact of climate change on wind yield in Mannar for the next 22 years, taking into account the economically feasible cost of wind electricity' production. Keywords— wind potential: cost of wind electricity' production: climate change: Commercial wind Turbines: Cordex: General Circulation Models (GCM)
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
Energy optimization of fluidized bed drier used in activated carbon processing industry
(2023) Ariyathilaka, PSI; Jayasekara, S
Drying is an essential part of most industrial material processing operations. Similarly, it takes a typically large capital expenses and operating cost. There are various types of dryers used in activated carbon processing industry. Among these active dryers, fluidized bed dryer is extremely popular not only in the activated carbon industry but also in other product drying facilities such as food industry, chemical industry, fertilizer industry and pharmaceutical industry etc. Fluidize Bed dryers are popular in industry because they are simple in design, easiness of operation and maintenance capability. To reduce the overall energy use, it is crucial to determine the ideal drying conditions for activated carbon in fluidized beds dryers. As a result, two parameters of drying temperature and hot air velocity were chosen while the remaining parameters remained fixed. Therefore, in this study, the drying properties of activated carbons were examined by conducting number of tests on a fluidized bed dryer located in an activated carbon manufacturing plant. The trials were conducted at three distinct air speeds of 2 m/s, 3 m/s and 4 m/s at 03 various temperatures of 130 °C, 140 °C and 150 °C. The results of the experiment were fitted using the current drying models. The MS Excel Solver was used to evaluate the model coefficients and constants. The Singh et al. model was discovered as the best fit drying model to dry activated carbon at fluidized bed dryer with lowest Root Means Square Error (RMSE) of 0.005973. Then Minitab software was used to analyse energy consumption data and it was obtained that the overall drying energy reduces when the hot air velocity and drying temperature are raised. And it came to a minimum of 145 °C when the hot air velocity maintained at 3.7 m/s. For drying experiments, computed Effective Moisture Diffusivity values ranged from 0.001315 to 0.00175. Effective Moisture Diffusivity increases with increasing hot air velocity and temperature. Results also revealed that the Activation Energy of activated carbon range in-between 11.28 to 14.10 kJ/mol. In FBD, the maximum value of Ea was determined under high velocity conditions. The aforementioned drying properties are helpful for choosing the appropriate fluidized bed dryer operating point and design a precise drying system. Key words: Fluidized Bed Dryer, Energy optimization, Activated Carbon, Drying Models, Effective Moisture Diffusivity
item: Thesis-Full-text
Evaluation of hourly solar radiation models to estimate radiation on inclined surfaces in day zone of Sri Lanka
(2018-02-20) Abeyrarthna, ARMUE; Attalage, RA
An analysis of global, beam and diffuse solar radiation on horizontal and 7° tilt about east west axis and facing due south orientation at Hambanthota was carried out to assess the solar resource potential in dry zone of Sri Lanka. The calculated monthly averaged daily insolation for dry zone was found to be varying between 16.30 MJ/m2/day to 22.75 MJ/m2/day with the annually averaged daily insolation of 20.07 MJ/m2/day. Calculated annually averaged beam horizontal radiation was 10.87 MJ/m2/day and diffuse horizontal radiation was found to be 9.19 MJ/m2/day while 0.56 was the annual average clearness index indicating that partly cloudy sky throughout the year. Horizon brightness coefficients of Perez et al (1990) was modified using diffuse radiation data of Hambanthota. Modified model was used for the estimation of titled radiation on due south faced surfaces. Diffuse tilted daily insolation and global tilted insolation for -45° to +45° inclined surfaces with 1° increments was estimated and monthly and annual optimum tilt angles were derived. The calculated monthly optimum tilt angle varied between -26° to +27° while having annual optimum tilt angle of -2°. Hence, tilting towards due south by same angle as latitude is not the recommended optimum tilt for fixed axis systems. Optimum tilt angle for beam radiation was derived and it was found that annual optimum tilt angle for beam radiation is 6° facing towards the due south. The derived maximum solar resource potential was 2068 kWh/m2 per annum for fixed system at -2° tilt angle and 2169 kWh/m2 per annum for monthly tracking system which is 5% higher than the horizontal potential. It is proposed to assess the solar resource potential for tilted surfaces with different surface azimuth angles by using modified Perez et al (1990) model in future. It is also possible to modify the coefficients of circumsolar brightness components of Perez et al (1990) model for better results.
item: Thesis-Abstract
A Neural network based model for forecasting the power output of a commercial scale photovoltaic power plant
(2022) Manchanayaka MAAP; Nissanka ID
Solar photovoltaic (PV) is penetrating electrical grids with a substantial growth of new additions, as a result of renewable energy policies and plans implemented locally and globally. However, the intermittent nature of the availability of solar energy brings an uncertainty into electrical power systems making it complex for power management and integrating into existing electricity infrastructure. This has been a key issue in promoting renewable energy in developing countries. Accurate solar power forecasts in different time horizons can play a vital role to bring down the uncertainty by a significant margin. In this work, a neural network (NN) model was coupled with a decomposition and transposition (D&T) model to forecast day(s) ahead hourly PV output of a grid connected 1 MW solar PV plant located in Hambantota, Sri Lanka. Historical weather and solar radiation data for last 14 years were collected from two APIs (Application Programming interfaces) for the location of PV plant and variation of global horizontal irradiation (GHI) with percentage cloud cover, rain, temperature, relative humidity, and wind speed were analysed. The selected parameters from the analysis together with day and hour numbers were fed in to the NN model through a scaling layer and trained it using Levenberg–Marquardt backpropagation algorithm. Optimum NN model was selected by changing the hidden layer sizes and calculating the mean squared error. The forecasted GHI values of the optimized NN model were decomposed to diffuse horizontal irradiance (DHI) and direct normal irradiance (DNI) using Erbs correlation, as the first step of D & T model. Then, DHI and DNI components were converted to global tilted irradiance (GTI) using HDKR correlation, in order to calculate solar PV output, including possible plant specific losses. The correlation coefficient (R) between GHI output and target values of the trained NN model for an unseen testing data set was observed to be 0.86. For final model, mean percentage forecasting accuracy was observed to be 86% with 12% standard deviation. The model could be adopted to any commercial or utility scale solar PV plant which is in a tropical climate region.
item: Thesis-Abstract
Experimental investigation on black pepper drying in a hot air cabinet dryer for optimized energy performance
(2022) Virantha EAI; Wijewardane MA
Open sun drying is the widely used passive method for black pepper drying, but due to its limitations such as unavailability on rainy days, lack of controllability, degradation of food quality, loss of volatile oil, and improper drying, the active dryers have become more popular than the open sun drying method. Among these active dryers, tray dryers are extremely popular in medium and small-scale black pepper processing industries because they are small in size, simple in design and lower capital cost comparative to other dryers. It is extremely important to identify the optimum drying temperature and the hot air velocity for black pepper drying process on a convective tray dryer to minimize the total energy while improving the quality of the black pepper. The drying properties of black pepper were examined in a convective thermal tray dryer during this investigation. In house built experimental setup was used to understand the variations of moisture ratio (MR) during the drying. The experiments were carried out in different temperatures of 50 °C, 55 °C and 60 °C and, for three different air speeds of 0.4ms , 0.8 ms -1 and 1.2 ms -1 . The observed experimental results were fitted with the existing drying models. Model coefficients and constants were evaluated by using the MS Excel software. The Logarithmic model was discovered as the best drying model to explore the black pepper drying on a convective hot air tray dryer with an average RMSD (root mean square deviation) of 0.0140. The total amount of time required to decrease the moisture content (MC) to 12% (minimum secure storage MC) in dry basis under various drying settings were computed using the logarithmic model equation. The total drying energy required to dry 1 kg of raw black pepper for different drying conditions was calculated and, a surface plot of total drying energy against temperature and air speed was generated. Based on the contours of the surface plot, the drying conditions which minimize the total drying energy were determined.
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-Abstract
Numerical study of microchannel heat transfer with nanofluid based two - phase slug flow
(2022) Siriwardana SSGC; Bandara PMT; Ranasinghe RACP
Microfluidics has recently gained research attention for its high-end thermal applications, including micro heat exchangers, Lab on a Chip, micro reactors, and MEMS. It has been proven that the addition of suitable nanoparticles to a fluid can enhance the heat transfer efficiency in microchannels, both in single phase and liquid-liquid two-phase flow. In general, slug flow is said to be the most efficient in heat transfer. However, the investigation performed on liquid-liquid slug flow with added nanoparticles was found to be very limited. Hence, this study numerically investigates the heat transfer characteristics in microchannels with liquid-liquid two- phase fluid flow (water and light mineral oil) with added nano particles (AI2O3). The VOF method and phase field equations were solved using ANSYS Fluent and COMSOL Multiphysics to capture two-phase flow interfaces. Adaptive mesh refinement techniques were employed to reduce computational power while maintaining sharp interfaces between fluid phases. The Eulerian mixture model was used to solve the cases containing nanoparticles. Numerical results were validated against published experimental data reported by [1] and [2]. Simulations were conducted for a 3000 micron long microchannel with a diameter of 100 microns for fluid velocity, ranging from 0.1 m/s to 0.5 m/s. First, 1 kW/cm2 of heat flux is introduced to the channel wall after 1000 microns to mimic the microchip heat generation, also allowing flow to be developed. Results have shown that using nanoparticles in either phase significantly increases heat transmission. This can be amplified even more when used in the secondary phase, by 58 percent compared with liquid-liquid two phase slug flow. This was accomplished with a nanoparticle fraction of 0.05 v/v in the secondary fluid phase. The addition of nanoparticles to the primary fluid increased heat transfer by 34%. The findings of this study can be used to improve MEMS and micro-to-macro systems that move heat.
item: Thesis-Abstract
Minimization of start-up time of sojitz kelanitissa combined cycle power plant
(2021) Manickasivam P; Jayasekara S
There are only three combined cycle power plants in Sri Lanka. Ceylon Electricity Board owns one power plant, and private companies own the other two. Combined cycle power plants start-ups can be divided into three categories such as hot, warm and cold. Most of the start-ups are hot start-ups due to varying demand in the Sri Lankan’s grid system. During start-up, power plant run at part load, which is inefficient. Because a portion of the steam generated is directed to the atmosphere during boiler warming up, it is essential to reduce the combined cycle power plants' start-up time. This thesis focuses on optimising hot start-up time without compromising equipment reliability. The thesis is carried out on a combined cycle power plant in Sri Lanka. Parameters during hot start-ups between 2019 and 2021 were collected in a minute interval. After analysing the start-ups in 2019 and 2020, several experiments were carried out during 2020 and 2021 hot start-ups. For this purpose, the start-up operation was divided into sub-operations, and four critical operations which have a significant impact on start-up time were identified. Operations such as G.T. Loading, High Pressure (H.P.) start-up vent operation, High Pressure (H.P.) steam bypass valve operation and new vent system operation were analysed, and the best optimum operation pattern was identified.
item: Thesis-Full-text
Economic feasibility of a hybrid energy system for Kalpitiya peninsula from selected technologies
(2020) Atapattu KR; Attalage RA
Economic feasibility of having a grid connected hybrid energy system, consist of wind, solar, biomass (rice husk) & municipal solid waste (MSW) technologies for Kalpitiya peninsula was studied. Four (04) different microgrid configurations were simulated in HOMER Pro(Hybrid Optimization of Multiple Electric Renewables) for a project life time of 20 years and the economics of each case was compared with the base case, where Kalpitiya peninsula is fed from fossil fuel based (i.e.: diesel) power transmitted through main utility grid. Electricity demand data of Kalpitiya peninsula in every 30 minute interval throughout a day were obtained for the days in calendar year (2018) from Puttalam grid substation (feeder 03) to derive averaged hourly load profile and to study the daily, monthly variation. Average electricity demand in April was found to be the highest of all months in the year and average load in a typical day was 125056.52 kWh with a daily maximum of 8320.5 kW. Considering the recent global market costs trends of installation, operation and maintenance of renewable energy resources as well as the availability of resources, in Sri Lankan context four (04) different configurations of microgrids were simulated in HOMER Pro with the motive of ensuring 100% power supply throughout the project lifetime of 20 years. Most economical option in a private investors’ perspective was a microgrid with wind, solar, biomass (rice husk) & municipal solid waste (MSW) in the system which has a discounted payback period of 2.68 years. However, in the perspective of Ceylon Electricity Board, the most economical microgrid consist of wind, solar & biomass (rice husk), where annual cost saving against the base case of LKR 350.5 Mn equivalent to ‘stop running’ a 1 MW diesel generator for 353 days per year. Sensitivity analysis was performed limiting the grid sales for each microgrid configuration proved that net energy purchase was lowest when the grid sale capacity was 10000 kW. Any of microgrid combinations was not possible to operate in island mode due to the intermittency of renewable resources. However, it was evident that none of the configurations considered solar energy is significant due to the high dominance in wind, biomass & MSW resources.
item: Thesis-Full-text
Dynamic cooling load analysis on indoor thermal comfort state in passenger trains
(2020) Kodituwakku TP; Manthilake, MMID
Increasing passenger density makes indoor state of train compartments not thermally comfortable. Air conditioned train compartments have been introduced to provide comfortable pleasant interior environment to the passengers. However the trains consume in a high share of electricity for thermal comfort purposes thereby reducing their fuel economy and increasing emissions. Before adopting more air conditioned train compartments to the railway system, it is necessary to understand indoor thermal comfort state expected by passengers and the energy saving potential. This study discusses the acceptable indoor thermal comfort conditions and the variation in cooling load due to fluctuation of outdoor ambient conditions in moving train compartments. It was based on the Fangers thermal comfort model and a mathematical model was built to simulate this dynamic cooling load. Indoor thermal comfort parameters were examined by surveying of passengers travelled in air conditioned trains. The survey was conducted in trains run through the Colombo-Badulla main line and the northern line in Sri Lanka by interviewing 186 numbers of passengers using standard questionnaire. As independent variables, it was considered three main indoor thermal comfort parameters: temperature, relative humidity and air velocity. Analyzing the survey data using descriptive method, a comfort zone on psychometric chart was defined and accordingly indoor temperature and relative humidity of 26˚C & 55%RH were obtained as appropriate indoor thermal comfort parameters for railway passengers in Sri Lanka. On the other hand, energy saving potential was estimated through simulating dynamic cooling load values for the selected stations in both railway lines considered. Significant differences in dynamic cooling loads of train compartment were found between different stations and between different periods of time. The steady cooling load calculated according to the usual standard method was comparatively higher than the dynamic cooling load. Application of actual maximum dynamic cooling loads of a moving train compartment has been shown 10.9 kW & 5.9 kW of power reduction in train air condition system for mainline & northern line respectively. Thus the application of dynamic cooling load with reference to the time and space can lead to a significant energy saving in passenger trains.
item: Thesis-Full-text
Evaluating the heat recovery options from the generated oily sludge in thermal power plants
(2020) Charithananda SPM; Manthilake MMID
Oily sludge is a process waste of thermal power plants that use heavy fuel oil for power generation. At present, the oily sludge is sold or incinerated from the power stations belonging to Ceylon Electricity Board. Since the waste heat generated from the incineration process is disposed to the environment without harnessing for effective work, the operation and maintenance cost of incineration is not cost-effective. In this study, the waste heat recovery options were considered based on the sludge treatment methods used in thermal power stations. The possibility of using the sludge as fuel for micropower generation, hot water generation, and waste heat recovery from the oily sludge incineration was investigated. The study was carried out to determine the potential of recovering the waste heat of the oily sludge incineration process and to investigate the design parameters for a suitable heat recovery steam generator. Furthermore, the calorific value and the constituents in the sludge sample were investigated. As a result of this study, Heat Recovery Steam Generator was found as the most suitable heat recovery method. The proposed HRSG was modeled, simulated, and optimized using the Engineers Equation Solver (EES) software. From the trial runs, the maximum power output that could be recovered from HRSG is 96.04 kW of energy at a rate of 222.1 kg/h sludge incinerating. Considering the steam mass flow rate for commercially available steam turbines, implementing a micropower generation plant with a capacity of 93.63kW is a feasible project with a payback period of 2.70 years to recover the cost of the investment. Furthermore, the feasibility of the sludge using as a fuel to a sludge fired boiler for power generation and hot water generation were investigated. 107.0 kW of power could be harnessed by burning of sludge at a rate of 204.48 kg/h and 13.36 kg/h of hot water could be generated by burning sludge at a rate of 1kg/h.
item: Thesis-Full-text
Optimization of soot blowing operation for Lakvijaya coal power plant in Sri Lanka
(2020) Sarathkumara SCM; Attalage RA
An optimization of soot blowing operation was carried out for Unit No.3 for Lakvijaya Power Plant in Sri Lanka. Average coal flow rate and flue gas temperature are the key indicators of boiler performance with soot blowing process. In accordance with ASMI PTC 4-1998, a mathematical modeling tool was developed to determine the boiler efficiency in present condition and different frequencies of soot blowing. The maximum efficiency of the boiler was determined as 79.76% at soot free condition. An equation was derived to express the relationship between input fuel consumption and soot blowing frequency. Maximum fuel cost saving can be achieved in between the frequency of 24 hours and 34 hours with respect to the normal operation of routing of soot blowing. Same frequency range gives the maximum cost saving in terms of effective cost. Considering the practical applicability daily soot blowing schedule is recommended.
item: Thesis-Full-text
Low grade thermal energy harvesting from thermo-acoustic generator
Rathnayake, RKA; Manthilaka, MMID; Wijewardane, MA
A thermoacoustic generator is an energy conversion device. It converts thermal energy into acoustic energy by using the stack. That is porous medium that contains a large number of channels. The acoustic energy can be converted into electric energy by the alternator. The condenser mics, speakers and piezoelectric materials can use as alternators. The atmospheric air is used as a working fluid. Generally, Helium, Neon, Argon and their proper mixtures are preferred as the working fluid. That has a high sound speed and high mean pressure. That types of working fluids yield high acoustic power density. prime mover. Thermoacoustic generator is an environmental friendly. Its biggest advantage is that they do not use harmful gas as a working fluid. It uses helium which is noncombustible, nonpoisonous inert gas having zero global warming effect. The generator length is quarter wave length that is equal to the length of a resonator tube. The alternator and the stack are fixed inside the resonator tube. The solar thermal energy, waste heat from internal engine and heat from industrial waste are used as a hot heat exchanger (heat source). The cold heat exchanger (sink) is water or atmospheric air. The thermoacoustic generator has two heat exchangers they produce temperature difference across the stack. Now acoustic pressure wave creates and it propagates through a resonator tube. The pressure wave can work on the alternator. That does not contain any moving parts (no lubricant) and decrease the maintenance cost. The only disadvantage of this thermoacoustic engine is low efficiency. Lots of researches are developing on the stack and resonator design. It is based on linear thermoacoustic theory combined with numerical simulations in the thermoacoustic design soft wares. The 612 mm long thermo-acoustic generator was design, built and tested. That device generates sound at 84.2℃ -275.7℃ temperature difference across the stack. Approximately, device produced acoustic power and internal efficiencies of the acoustic generator are 0.90-19.20 W and 0.05-0.06 % respectively.
item: Thesis-Full-text
Feasibility assessment of the applicability of tri-generation systems in the apparel industry in Sri Lanka : a case study
Abeynayake, AMNS; Jayasekara, JGAS
In this study, the technical and financial performances of the first tri-generation plant installed in Sri Lanka were evaluated. This plant was installed at Tee Jay Lanka PLC; a leading knit fabric manufacturer in the local context. In this tri-generation design, the thermal demand of the process was matched and the technology used was the Rankine cycle with a back-pressure turbine. The overall efficiency, heat to power ratio and the net electrical power were the technical parameters evaluated for the technical feasibility. The net cash flow was evaluated for the financial performance. The evaluation indicates that the TG plant operates below the technical performance of a TG system, which uses the same technology. The failure to operate the steam turbine was identified as the main factor for the underperformance. However, the financial feasibility was observed for the year 2016, indicating a positive cash flow throughout the year. The detailed study reveals that the process steam flow variation caused the back-pressure variation and therefore, the tripping of the turbine. It was proposed to alter the turbine control mode from load command mode to the back-pressure mode. However, the turbine startups failed due to high vibration. After the dismantling of the turbine, it was found that the rotor had corroded and the turbine blades were loose. It was sent for repairs. Afterwards, the turbine is to be started under back pressure mode. If the operation is successful, the technical parameters which measure the performance will reach nominal levels. The political factors affecting the performance were also reviewed in brief. The energy efficiency policies of the government are to be strengthened to encourage investment in energy efficiency projects. The policy of importing coal has to be reviewed again to assure a seamless supply chain especially for the small and medium scale users.
item: Thesis-Full-text
Comparison of biomass cookstoves in Sri Lanka
Chandrasena, RIK; Ranasinghe, C
Biomass plays an important role in Sri Lanka Energy Sector. The consumption of biomass in the commercial and household sector is declining due the popularity of fossil fuels. Consumption of biomass is getting less popular due to various reasons. Handling difficulties due to various sizes, combustion difficulties due to various calorific values, low combustion efficiency due to high moisture content transportation cost due to bulk size and moisture. To evaluate the performance ofselected biomass cookstoves thermal efficiency together with other performance parameters were tested by Shell Foundation Version 4.3.2 Water Boiling Test. The tested stoves are Semi-enclosed firewood cookstove, popular Anagi-2 firewood stove, Turbo charcoal stove, Desha Shakthi saw dust pellet stove and Spectra saw dust pellet stove. Desha Shakthi stove shows the highest efficiency of 0.59 at high power operation while Spectra shows 0.43 and fallen in to the tier 4 of IWA matrix. Turbo charcoal stove categorized in to tire 2 as it is having thermal efficiency of 0.26. Anagi-2 and semi-enclosed stoves can be categorized in to tire 1 since they are having efficiencies of 0.17 and 0.15 respectively. Anagi- 2 stove shows the lowest time to boil while DeshShakthi stove takes highest time to boil water. Desha Shakthi stove shows lowest burning rate which is 5 g/min while Anagi -2 shows the highest burning rate of 28.65g/min. Specific fuel consumption of Desha Shakthi is the lowest as 0.05 kg of fuel per kg of water while semi-enclosed stoves shows the highest as 0.16. and high storage and Overall average specific energy consumption of Desha Shakthi stove is the lowest as 1.10 kJ/kg of water and highest of Anagi-2 as it is 5.27 kJ/kg of water. The highest fire power of 8712.71 W is shown by Anagi-2 while Desha Shakthi has the lowest fire power as 1279.58 W. To categories stove emissions and safety under IWA performance matrix, the emission tests also should be done during the WBT. When comparing the designs ofstoves there is a possibility of improving the performance of Spectra stove by introducing design modifications.
item: Thesis-Full-text
Effect of roofing on the thermal comfort in domestic buildings in Sri Lanka
Abeysinghe, AMJ; Attalage, RA
This study aimed to investigate the indoor thermal performance of different roofing and ceiling alternatives and their configurations used for residential buildings in Sri Lanka. In this regard, a basic residential building was selected as the reference case. Five roofing and two ceiling materials were used and combinations of roofing/ceiling types were obtained to investigate the relative effect on the indoor temperature fluctuations and energy use. Both 2-pitched and 4-pitched roof designs were selected and the buildings were aligned for two orientations; east-west and north-south. The two-pitched bare roof (noceiling) constructed with a commonly used old cement fiber sheet (asbestos) material was selected as the reference case. The computer software tool, DEROB-LTH (version 99.02) was used to model the building and evaluate the cooling energy use and the indoor air temperatures. These parameters were evaluated hourly, daily and monthly basis for three different months ofthe year 2011. The simulation results have shown that there is a noticeable difference in cooling energy use and indoor air temperature with the changes in roofing and ceiling materials as well as with different roof configurations. The results suggest a positive conclusion towards the feasibility of using burnt clay calicut tiles with wooden plank flat suspended ceiling, it was further shown that the common roofing material used in the Sri Lankan residential building industry. Asbestos sheet is not feasible in terms of energy cost and indoor thermal performance. Finally, an economic analysis / cost-benefit analysis was performed in order to investigate the economic viability of applying different roofing/ceiling combinations and the results indicate that most of the designs are feasible in terms of the cooling energy use and additional expenditure incurred. Simple pay back periods were less than 4 years in most cases. The results also elaborated that even though new calicut tile roof design is expensive, it is worth paying for considering the climate of Sri Lanka. It is suggested that through experimental validation and modeling, these results could be further validated to enhance the accuracy ofthe output obtained from DROB-LTH.
item: Thesis-Abstract
A Detailed analysis of CDM potential in the thermal power generation sector of SriLanka
Hemashantha, HMB; Attalage, RA; Wijayathunga, PDC
The objective ofthis study is to analyse potential technology possibility under the CDM in power generation sector. This study is a theoretical study focused on the survey ofthe current state ofthe art ofCDM and related issues. The climate and energy policy, the energy market and the status of energy technology in Sri Lanka. The results show that the potential ofCDM opportunities in thermal power sector of Sri Lanka, and ten methodological areas are recommended as areas of potential CDM projects origins. In order to further investigate the opportunities for implementation ofCDM in thermal power sector in Sri Lanka and to identify the potential problems, two case studies were conducted. First case study is the construction and operation of 600 MW super critical coal fired grid power plant (CoP: 0.065 USD/kWh). Electricity generated by the project activity will supply to Sri Lanka national grid replacing sub-critical coal power plant what would have been implemented in the absence ofthe project activity since sub-critical coal power plant (CoP: 0.063 USD/kWh) is more economically attractive than the project activity. The emission reduction ofthe first case study is 160,000 tC02/annum. There are some barriers associated with installation ofsuper-critical coal power plants such as investment barriers (high investment compared to the investment what would have been made to a sub-critical coal power plant), prevailing practice barriers (the project activity is the first supercritical coal power plant in Sri Lanka, there are no super-critical coal power plants implemented at the time ofthe investment decision) and technological barriers (there are no super-critical coal power plants in Sri Lanka which leads to have lack ofskilled labour). Second case study is the construction and operation of new natural gas fired power plant (CoP: 0.263 USD/kWh). Electricity generated by the project activity will supply to Sri Lanka national grid replacing sub-critical coal power plant what would have been implemented in the absence ofthe project activity since sub-critical coal power plant (CoP: 0.063 USD/kWh) is more economically attractive than the project activity. The emission reduction ofthe first case study is 82,200 tC02/annuam. There are some barriers associated with installation of natural gas based power plants such as investment barriers (high investment compared to the investment what would have been made to a sub-critical coal power plant), prevailing practice barriers (the project activity is only one natural gas project in Sri Lanka, which has been developed by the government) and technological barriers (natural gas based power plants are not common in Sri Lanka, which leads to have lack ofskilled labour, further there is no proper natural gas pipe line constructed in the country to distribute the natural gas). However there are some barriers to be resolved in order to achieve the CDM status. IV It is concluded that Sri Lanka not only can achieve credits to earn some extra revenue, but also can maintain its leading position in international cooperation and competence on the climate change issues, moreover, Sri Lankan expert can involve in international climate change process. Further, the CDM projects can help Sri Lanka to realize sustainable development, while reducing its GHGs emissions, which could be a great contribution in addressing climate change..
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Evaluation of hourly solar radiation models to estimate radiation on inclined surfaces in day zone of Sri Lanka
Abeyrathna, ARMUE; Attalage, RA
An analysis of global, beam and diffuse solar radiation on horizontal and 7° tilt about east west axis and facing due south orientation at Hambanthota was carried out to assess the solar resource potential in dry zone of Sri Lanka. The calculated monthly averaged daily insolation for dry zone was found to be varying between 16.30 MJ/m2/day to 22.75 MJ/m2/day with the annually averaged daily insolation of 20.07 MJ/m2/day. Calculated annually averaged beam horizontal radiation was 10.87 MJ/m2/day and diffuse horizontal radiation was found to be 9.19 MJ/m2/day while 0.56 was the annual average clearness index indicating that partly cloudy sky throughout the year. Horizon brightness coefficients of Perez et al (1990) was modified using diffuse radiation data of Hambanthota. Modified model was used for the estimation of titled radiation on due south faced surfaces. Diffuse tilted daily insolation and global tilted insolation for -45° to +45° inclined surfaces with 1° increments was estimated and monthly and annual optimum tilt angles were derived. The calculated monthly optimum tilt angle varied between -26° to +27° while having annual optimum tilt angle of -2°. Hence, tilting towards due south by same angle as latitude is not the recommended optimum tilt for fixed axis systems. Optimum tilt angle for beam radiation was derived and it was found that annual optimum tilt angle for beam radiation is 6° facing towards the due south. The derived maximum solar resource potential was 2068 kWh/m2 per annum for fixed system at -2° tilt angle and 2169 kWh/m2 per annum for monthly tracking system which is 5% higher than the horizontal potential. It is proposed to assess the solar resource potential for tilted surfaces with different surface azimuth angles by using modified Perez et al (1990) model in future. It is also possible to modify the coefficients of circumsolar brightness components of Perez et al (1990) model for better results.
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Computational investigation of free surface vortex formation at horizontal power intake of Samanala Hydro Power Station
(2019) Fernando NT; Ranasinghe RACP
Analysis of free surface vortices formation in a horizontal type water intake structure of Samanala Power Station has in this study been carried out with the help of “Flow-3D” Computational Fluid Dynamic software. A numerical model was validated by using a physical model with horizontal protruded intake which is similar to the construction of Intake of the Samanala Power Station. The numerical model successfully captured the free surface vortex position during the validation process. The surface depression was not captured, however the tangential velocity distribution along the radial distance through the center line of the vortex, which was formed during the physical experiment, was in a good agreement with the tangential velocity distribution of Rankine Compound Vortex, where the middle of the vortex has a rotational flow field (forced vortex) and outside of the vortex it has an irrotational flow field (free vortex). After that, the model has been used to investigate the free surface vortex formation of the Samanala Intake. The intake was modeled by using “Solidworks” software. Due to unavailability of actual terrain data of the pond, I have considered the following: distance from the Dam, the depth of the pond and the intake side abutment angle, as the major parameters to be modeled during the pond modeling. Simulations were carried out to identify the formation of free surface vortices and their properties and characteristics by varying the submergence and fixing the flow rate to the maximum flow of the intake.