1,720,967 research outputs found
Integration of refinery flare gas system with fuel gas network for power generation
No full textThe high price of crude oil, strict environmental regulations and increasing demand for energy have made refineries adopt a more holistic approach to integrating energy, economics and environment in their design and operation. In this situation gas flaring can be considered as a major course for wasting energy in oil and gas refineries. It can be modified and use it for power generation and in-house heat generation. In this study a novel methodology is introduced to utilize the flare gas generated in a refinery through utilizing the pressure energy generated within the process. The proposed methodology uses pressure stages to regulate the pressures in predefined values and use either natural gas or LPG to makeup the gas requirement other than the gases from the process and flare system. Especial attention was given to regulate the existing FGN operation and to recover steady flow out for power generation. According to the cases analyzed with different input parameters, there was no observed variations in the vessel pressures and desired gas output flows. The gas flow from the plant values was set to vary up to 1574 g/s and the flare gas flow is varied up to 422 g/s. The profitability of using the flare gas recovered has been analyzed in 6 cases. Accordingly the total profit gain depends on the excess gases generated within the refinery, total gasses used in the process furnaces, total electricity demand and the makeup gas price. Considering LPG as a makeup gas and with the low LPG prices, there is maximum profit gain of 7,141,943 LKR in the situation where the power is generated using flare gas in the peak hours only
Energy analysis of mini hydro schemes using plant performance data
No full textIn this research project, characteristics of mini hydro power schemes which affect to
the performance of the scheme were analyzed. The main objective of the project was
to develop an analytical criterion to estimate the variations of the energy associated
with small hydropower schemes which plays a major role in feasibility of the mini
hydro scheme while fulfilling the other objectives of defining site specific efficiency
factors associated with each mini hydro power scheme. For the present model of
forecasting annual energy variations, the factors being used for computing
anticipated energy losses in and during the sections of weir entrance, head race canal,
forebay tank, penstock line, hydraulic turbines and electricity generator are not sitespecific
and technology specific. Therefore an experimental approach was used in
combination with statistical data analysis to develop a relationship between stream
flows with scheme characteristics. Electrical power generation, rainfall of the nearby
meteorological data measuring stations, plant maintenance records were analyzed
and several catchment runoff calculation methods were studied. Four consecutive
operational mini hydro schemes were selected and relationships among their
operational characteristics were studied during the analysis.
The results of the study show that performance data of adjacent operational power
schemes can be used to predict energy potential of a downstream scheme which is
situated within 5 km distance from the operational plant. By the proposed model
energy potential of a selected mini hydro scheme can be estimated very accurately
for the first five months of the year with a slight deviation varies in the range 2% to
11%. But this model cannot be recommended to estimate energy potentials of
upstream to the considered operational scheme. This can be used as a simple
hydrological resource as this model can forecast energy potentials without using
current hydrological data as it associates only performance data of mini hydro power
plants
Potential of organic rankine cycle based heat recovery systems for power generation
No full textDue to intense fuel dependency on energy production in the world, cost of energy has a
greater bearing on the prices of fossil fuels. Most of the countries in the world are
suffering due to this and Sri Lanka is no exception. It is in this context promotion of
optimize the usage of thermal power generation, is so vital to the country. Even though
fossil fuel base power generation plays a greater role as a source of primary energy in
the country, major portion wasted to environment. WHR systems have been already
introduced, but most of them are not performing effectively and efficiently. On other
hand, novel systems and technologies required to investigate, to recovery most of the
wasted heat of thermal plant while increasing the system efficiency and reducing the
fuel cost. Conceptual thermodynamic cycles such as Trilateral Flash cycle, Organic
Rankine cycle, Kalian cycle and Gaswami cycle, can be successfully incorporate for
WHR applications. Hence, purpose of this research was to assess the amount of waste
heat generated by thermal plants in the country while discussing the possible
technologies that can be introduce for heat recovery. Further, discuss about selection of
most suitable option and carryout thermo-economic analysis as a case study.
Fluid selection and system optimisation based on heat source temperature are two most
critical aspect of Organic Rankine Cycle. Eleven fluids were investigated to optimize
the work output by varying the evaporator temperature and varying the expander
pressure ratio with theoretical model. In evaporator analysis, Heptane, Pentane and
Decane shows favourable results in terms of work outputs while, in terms of efficiency,
Decane and Heptane are better. Further it is recommended to use fluid Pentane, when
source temperatures of WHR lies between 45 – 190 oC, while fluid Heptane is
recommended when source temperature between 190 – 260 oC. Fluid Decane is
recommended when temperature between 260 – 340 oC. Respective monographs were
developed where one point on the graph can denote approximate work output,
efficiency, pressure, temperature, etc. Based on expander analysis, Decane, Heptane
and Toluene fluids have shown higher work outputs while, in terms of efficiency,
Decane is better. In expander selection, when inlet/outlet pressure ratios are less than
10, fluid Decane is recommended. Further, when ratios are in between 10 – 13 and 13
– 20, fluid Heptane and fluid Toluene are recommended respectively. Refer to these 03
fluids, monographs were developed accordingly.
Refer to optimum working regions of temperature analysis; fluids were selected for
economic evaluation. Waste heat recovery opportunities were selected from existing
thermal plants for the case study and electric outputs were obtained for each plant,
based upon selected fluids from theoretical model. Then maximum work out of each
opportunity was selected for further economic evaluation under 07 different scenarios.
Possible future economic situations of the country were predicted under those
scenarios and carryout NPV calculations for each, to evaluate the investment feasibility.
Scenario 2, 3 and 7 are the most possible situations of the country in future and for
those conditions, WH opportunities at Supugaskanda, Lakvijaya, Keravalapitiya and
Kelanithissa are most feasible to recover waste heat with ORC system
Application of Zimont's turbulent flame speed closure for combustion modeling of a single cylinder spark ignition engine
No full textIncreasing need to get the maximum power out from fuels while maintaining less amount of toxic emissions has created the requirement of making an optimum IC engine. Numerical simulations play a vital part in determining those design and operating parameters which make that idea of an optimum engine a reality. In the present work applicability of two well-known turbulent flame speed models: Namely Peters and Zimont in premixed charge gasoline spark ignition (SI) engines were evaluated. Their ability to predict the characteristics of premixed turbulent combustion process of an SI engine in the RANS context was first assessed and based on those results Zimont model was used to evaluate the applicability of Smagorinsky-Lilly Large eddy simulation (LES) model in engine simulations. Several simulations were done to identify and implement required modifications to get correct solutions from the LES model.
Combustion of the Ricardo E6 single cylinder test engine was modeled with the above two turbulent flame speed closure models implemented to a commercial computational fluid dynamics (CFD) code. Full cycle simulations, covering all four strokes including the valve motion, spark discharge, flame kernel development and fully developed combustion, were performed using different engine operating conditions. Engine was fueled with gasoline. Obtained results were compared with experimental values obtained using the same operating conditions of the E6 engine to evaluate the prediction ability of the different models. Accordingly, In-cylinder pressure variation and the combustion heat release rate versus crank angle were compared with measured values. In general, predictions, of both models were found to be in reasonable agreement with experiment values, but significant discrepancies could be observed in certain operating conditions
Computational investigation of free surface vortex formation at horizontal power intake of Samanala Hydro Power Station
No full textAnalysis 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
Potential for energy conservation in nwsdb water supply schemes
No full textThis research was aimed to study the potentials for conservation of energy in main schemes of NWSDB in Southern Province. The results are usable on benchmarking energy usage on water supply schemes those operating under NWSDB. From the history of operation of NWSDB over 40 years, energy audits for the resent past were studied for water supply schemes. Specific energy consumption is used to benchmark the energy consumption of each category of operations which leads to identify the potentials for energy conservation. An energy audit was carried out in Southern Province, region-vise Matara, Galle and Hambantota to evaluate the energy conservation potentials.
In electrical energy form, kinetic energy around 25 % of the total consumed is used for pumping raw water. Other 75% is used for major components including water treatments, treated water pumping and distribution networks. Apart from the energy usage on water treatment and pumping, component from total energy as high as 12% was identified as loss on non-revenue water, an area to work on reduction of energy usage.
The main area identified as need for improvements was pumping and transmission equipment and their unit operations where around 14% energy could be targeted for energy saving.
It is worth to improve water sources for free from algae, impurities, pollution and contamination through community awareness, national policy planning and programmed long term vision to meet huge energy conservation in future and to harvesting healthy generation out in danger with numerous diseases.
Direct distribution of water to consuming terminals with continuous pumping is better option to focus to save energy in vigorous amounts instead of distribution through elevated towers yet not ready to be implemented with prevailing electricity pattern in the country
Numerical evaluation of energy labeling test setups of ceiling fans
No full textCeiling fans are widely used as a means of providing thermal comfort to occupants in an indoor environment all around the world and it contributes to a significant portion of annual energy consumption throughout the world. A number of standards for efficiency analysis of ceiling fans are employed by many countries, with the intention of making ceiling fans more efficient. In these test standards, different test setups have been utilised. Work performed on analysis of the effect of these setups on performance evaluation of ceiling fans is currently unavailable. Further, there is a scarcity of research work performed on analysis of flow characteristics around a rotating ceiling fan. Understanding the proper flow around a rotating ceiling fan can lead to designing more efficient fan blades, which can lead to significant energy savings. Therefore, this study is split into two sections. In section one, a systematic investigation of the different test standards available for performance analysis of ceiling fans is performed, namely standards considered are ANSI/AMCA 230 standard, IEC 60879: 1986 standard, SLS 1600:2011 standard and Energy Star v1.2 standard for performance testing of ceiling fans. In section two, a flow physics analysis around a ceiling fan is carried out. For these, a CFD model was developed and it was validated using experimental results. The analysis of test standards was carried out by using a RANS method whereas the analysis of flow physics was carried out by using LES method. The numerical results obtained shows that the test cylinder present in some of the standards mentioned above, does not have a significant impact on the measured performance of the tested ceiling fan (variation is less than 2%), therefore having a test cylinder at an extra cost have no benefit on the measured results of ceiling fan testing. On the other hand, maintaining test cylinders for every fan size would impart a significant cost on the testing process and having a cylinder which is not correctly aligned can lead to inaccurate readings. From the flow results of the LES simulations, creation of two major vorticial structures is seen arising from the tip and the root of the blade. As these vorticial structures move further downward, more vortices were formed due to the action of these and the number of vortices keep growing with flow time, resulting the flow to become turbulent with the flow time. Furthermore, it was seen that the flow transition from laminar to turbulent occurred at the mid chord section, starting from the deflected section of the blad
Applicability of Kalina cycle for waste heat recovery in themal power stations in Sri Lanaka
No full textEnergy Crisis is the critical problem faced by the modern world. Day by day the impact is
becoming severe with decaying of fossil fuels. Therefore, whole world has paid their attention on Non Conventional Renewable Energy sources. Industrial Waste Heat Recovery is one of them. The main focus of this thesis is to identify the best suited method for recovering lowgrade energy from thermal power stations in Sri Lanka. Among few methods, Kalina Cycle System is selected by concerning its viability for usage.
Several attempts were made to assess the available heat energy from thermal power stations in Sri Lanka. The first objective of this research is to assess the thermal energy wasted from thermal power stations operating in Sri Lanka. The next objective was to identify the best suited configuration of Kalina Cycle System for extracting low-grade heat energy. The final objective was to use the said system for harnessing the energy, and quantify them. Simultaneously an economic analysis was carried out to assess its economic feasibility. A literature review was done to identify possibilities of harnessing the energy from flue gas of thermal power stations and to find out the suitable method for extracting energy.Lakvijaya Power Station and Kelanitissa Combined Cycle Power Station, which have emissions below 200oC, has the ability of generating electricity using the Kalina Cycle.However, as per the analysis, they are not economically feasible. However, with these results,it is suggested to continue the same exercise to other thermal power stations, which has high temperature flue gases. As the next step, it is proposed to identify the best suited Kalina Cycle System for the rest of thermal power stations and expand this exercise throughout CEB owned and private owned thermal power stations, using other suitable configurations of Kalina Cycle System
Assessment of spallart almaras turbulence model for numerical evaluation of ceiling fan performance
No full textCeiling fans are a popular means of providing
thermal comfort to occupants in an indoor environment,
mainly in tropical countries and it contributes to a significant
portion of annual energy consumption throughout the world.
It is proven that using ceiling fans in conjunction with air
conditioners in an air-conditioned environment can lead to
higher thermal comfort at a lower cost of energy which will in
turn increase the popularity of the ceiling fans in near future.
Understanding the proper flow field around a rotating ceiling
fan can lead to design more efficient fan blades, which can
lead to significant energy savings. Analyzing these using
experimental methods is both a tedious and a costly task. By
using numerical methods, this can be achieved at a significant
lower cost and effort. For such analyses, CFD methods using
RANS equations are widely used for both indoor and outdoor
conditions. For this purpose, numerous turbulence models are
available, each of which would more accurately predict some
cases than others. Therefore, Standard KE, Standard KW,
RNG KE and Spalart Allmaras model is evaluated for a case
of efficiency assessment of ceiling fans and SA model was
found as the most accurate model with just 1.9% NRMSD
with experimentally calculated values
Performance of solid fuel burners in Sri Lanka
No full textThe energy has been one of the main crises in the world; hence, it is essential to save and utilize it in its optimized form. One of the major fuels available in the world is fossil fuel. When harnessing energy from fossil fuel, burning process is used with the help of burners and boilers. The efficiency of these systems is very important to get the maximum energy conversion. Therefore, the performance of the burner and the boiler affect the fuel consumption. The old burners in industries will have to be evaluated for performance to decide whether they can be improved or weather to rehabilitate the burner unit. The performances vary with different factors which need to be found out in this thesis. Then the solutions can be introduced for the inefficiency in burner to get the optimum operation.
Burners use different types of firing technologies to harness the energy from the fuel. Its’ technology, type of fuel used and size of the burner need to be identified in order to evaluate the performance of the burner. There are two methods used to evaluate the performances of burners. This research is focused on performance of solid fuel burners used in Sri Lanka. The existing burners can then be improved using performance results which is the focus in this research. Many burners used in country are conventional burners and they use basic technology for burning. Reduction of fuel wastage, improvement of safety and reduction of environmental pollution are some of the improvements from the performance evaluation.
The significant parameters that effect the performance of burner are identified using the indirect method. Those are moisture content of solid fuel, ambient temperature, carbon content of fuel, exhaust temperature and excess air supplied. Some of the parameters identified, can be optimized to improve the performance of burner as described. The direct method results and indirect method results are compared and it is evident that the indirect method interprets much descriptive results. The results are depend on specific heat capacity of flue gas but it won't depend on specific heat capacity of steam generated. Burners and boilers in other countries show more variations of efficiency with moisture content compared to the Sri Lanka's
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