114 research outputs found
Impact of inlet fogging and fuels on power and efficiency of gas turbine plants
A computational study to assess the performance of different gas turbine
power plant configurations is presented in this paper. The work includes the
effect of humidity, ambient inlet air temperature and types of fuels on gas
turbine plant configurations with and without fogger unit. Investigation also
covers economic analysis and effect of fuels on emissions. GT frames of
various sizes/ratings are being used in gas turbine power plants in Saudi
Arabia. 20 MWe GE 5271RA, 40 MWe GE-6561B and 70 MWe GE-6101FA frames are
selected for the present study. Fogger units with maximum mass flow rate of 2
kg/s are considered for the present analysis. Reverse Osmosis unit of
capacity 4 kg/s supplies required water to the fogger units. GT PRO software
has been used for carrying out the analysis including; net plant output and
net efficiency, break even electricity price and break even fuel LHV price
etc., for a given location of Saudi Arabia. The relative humidity and
temperature have been varied from 30 to 45 % and from 80 to 100° F,
respectively. Fuels considered in the study are natural gas, diesel and heavy
bunker oil. Simulated gas turbine plant output from GT PRO has been validated
against an existing gas turbine plant output. It has been observed that the
simulated plant output is less than the existing gas turbine plant output by
5%. Results show that variation of humidity does not affect the gas turbine
performance appreciably for all types of fuels. For a decrease of inlet air
temperature by 10 °F, net plant output and efficiency have been found to
increase by 5 and 2 %, respectively for all fuels, for GT only situation.
However, for GT with Fogger scenario, for a decrease of inlet air temperature
by 10 °F, net plant output and efficiency have been found to further increase
by 3.2 and 1.2 %, respectively for all fuels. For all GT frames with fogger,
the net plant output and efficiency are relatively higher as compared to GT
only case for all fuels. More specifically, net plant output and efficiency
for natural gas are higher as compare to other fuels for all GT scenarios.
For a given 70 MWe frame with and without fogger, break even fuel price and
electricity price have been found to vary from 2.2 to 2.5 USD/MMBTU and from
0.020 to 0.0239 USD/kWh respectively. It has been noticed that turbines
operating on natural gas emit less carbon relatively as compared to other
fuels
Thermal induced stresses in thin-shell structures
Thin shell structures constructed from stabilised earth were assumed to be fully compressive
structures as the loading conditions applied by the designers indicated this. However, it was
found that these structures were experiencing extremely high tensile stresses and strains.
These tensile stresses and strains are assumed to originate from thermal induced loading. This
thesis investigates the temperature distribution and thermal induced stresses in a typical thin
shell structure.
In order to determine the temperature distribution across a typical thin shell structure, a model
was built and the temperature distribution was then determined. It was found that the
temperature in the model was higher than expected. This temperature distribution was
processed in a finite element model to produce typical magnitudes of the thermal induced
stresses. It was found that thermal induced stresses are not negligible in these types of
structures and a design engineer would need to account for theses stresses. This inspired the
formulation of a design guide for these types of structures so as to adequately design these
structures in the future
Heat transfer in a channel with inclined target surface cooled by single array of centered impinging jets
An experimental investigation has been carried out to study the heat transfer
characteristics in a channel with heated target plate inclined at an angle
cooled by single array of equally spaced centered impinging jets for three
different jet Reynolds numbers (Re=9300, 14400 and 18800). Air ejected from
an array of orifices impinges on the heated target surface The target plate
forms the leading edge of a gas turbine blade cooled by jet impingement
technique. The work includes the effect of jet Reynolds numbers and feed
channel aspect ratios (H/d = 5, 7, 9 where H=2.5, 3.5, 4.5 cm and d=0.5 cm)
on the heat transfer characteristics for a given orifice jet plate
configuration with equally spaced centered holes with outflow exiting in both
directions (with inclined heated target surface). In general, It has been
observed that, H/d=9 gives the maximum heat transfer over the entire length
of the target surface as compared to all feed channel aspect ratios. H/d=9
gives 3% more heat transfer from the target surface as compared to H/d=5 (for
Re=14400). Also, it has been observed that the magnitude of the averaged
local Nusselt number increases with an increase in the jet Reynolds number
for all the feed channel aspect ratios studied
Optimization of a stand - alone renewable energy system for a small load requirement
Optimization of a stand-alone Renewable Energy (RE) system involves selecting the best RE resources and components, and sizing the system accordingly to get the most efficient and cost-effective solution. Design and optimization of an RE power system to serve the lighting in a University of the South Pacific car park was carried out using HOMER software and compared to manual calculations. Resource analysis showed that on average the site received 3.8 kWh m−2 day−1 of solar energy, with 1,387 full sun hours annually. Monthly average wind speed of 3.88 m s−1 at 10 m above ground level extrapolated to 15 m (the hub height of the wind turbine) resulted in an average wind speed of 4 m s−1, with power density of 70 Wm−2. With this wind resource, a Whisper 100 wind turbine would be in operation for approximately 50 % of the time in the year. The complementary nature of solar and wind resources showed good potential for a solar-wind hybrid system. In this study three possible systems—a PV system, a wind power system, and a hybrid power system (PV-wind)—were analyzed. It was found that a hybrid system is the best and most cost-effective option, as it is able to provide reliable power whilst minimizing the need for battery storage compared to a single RE power system. The optimum system comprised 0.270 kWp PV combined with a 900 W Whisper wind turbine with total battery storage capacity of 440 Ah at 12 V. Manual calculations yielded results similar to the HOMER simulations
Wind power resource assessment for Rafha, Saudi Arabia
Abstract This paper, presents the analysis of wind speed data and available energy in Rafha area using wind machines of 600, 1000 and 1500kW sizes from three manufacturers. The long-term annual mean values of wind speeds were found to vary between a minimum of 2.5 m/s in the year 2002 and a maximum of 4.9 m/s in 1990. The frequency distribution showed that wind remained silent for 7% of the time on an average during 24 years of data period and 35% between 0 and 3.5 m/s. Wind speed remained above 3.5 m/s for 65% of the time and only 20% of the times above 6.5 m/s. The annual wind energy production and plant capacity factors, obtained using different methods and wind machines of three sizes and from three manufacturers are also discussed and compared. r 2006 Elsevier Ltd. All rights reserved. Keywords: Wind speed; Wind power; Plant capacity factor; Wind machin
Wind power resource assessment for Rafha, Saudi Arabia
Abstract This paper, presents the analysis of wind speed data and available energy in Rafha area using wind machines of 600, 1000 and 1500kW sizes from three manufacturers. The long-term annual mean values of wind speeds were found to vary between a minimum of 2.5 m/s in the year 2002 and a maximum of 4.9 m/s in 1990. The frequency distribution showed that wind remained silent for 7% of the time on an average during 24 years of data period and 35% between 0 and 3.5 m/s. Wind speed remained above 3.5 m/s for 65% of the time and only 20% of the times above 6.5 m/s. The annual wind energy production and plant capacity factors, obtained using different methods and wind machines of three sizes and from three manufacturers are also discussed and compared. r 2006 Elsevier Ltd. All rights reserved. Keywords: Wind speed; Wind power; Plant capacity factor; Wind machin
Feasibility study of hybrid retrofits to an isolated off-grid diesel power plant
Abstract The green sources of energy are being encouraged to reduce the environmental pollution and combat the global warming of the planet. A target of 12% usage of wind energy only has been agreed by the UNO country members to achieve by 2020. So, the power of the wind is being used to generate electricity both as grid connected and isolated wind-diesel hybrid power plants. This paper performed a pre-feasibility of wind penetration into an existing diesel plant of a village in north eastern part of Saudi Arabia. For simulation purpose, wind speed data from a near by airport and the load data from the village have been used. The hybrid system design tool HOMER has been used to perform the feasibility study. In the present scenario, for wind speed less than 6.0 m/s the, the existing diesel power plant is the only feasible solution over the range of fuel prices used in the simulation. The wind diesel hybrid system becomes feasible at a wind speed of 6.0 m/s or more and a fuel price of 0.1 - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.rser.2005.05.003 Corresponding author. Tel.: +9663 860 3802; fax: +966 3 860 3996. E-mail address: [email protected] (S. Rehman). 1Home page: http://staff.kfupm.edu.sa/ri/srehman
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