Exergy Analysis of Carryover Leakage Irreversibilities of a Power Plant Regenerative Air Heater

2002 ◽  
Author(s):  
Rahim K. Jassim ◽  
Badr A. Habeebullah ◽  
Abdulraof S. Habeebullah
Keyword(s):  
Power Plant ◽  
Exergy Analysis ◽  
Process Efficiency ◽  
Design Parameters ◽  
Mixing Processes ◽  
Substantial Impact ◽  
Conservation Of Energy ◽  
Pressure Losses ◽  
Total Process ◽  
Chemical Exergy

Energy recovery devices can have substantial impact on process efficiency and their relevance to the problem of conservation of energy resources is generally recognised to be beyond dispute. One type of such a device, which is commonly used in fossil fired and air conditioning systems, is the rotary regenerator in which a stream of hot waste gas exchanges heat with fresh atmospheric air through the intermediate agency of a rotating matrix. As there are gas streams involved in the heat transfer and mixing processes, then there are irreversibilities, or exergy destruction, due to chemical reaction, pressure losses I˙ΔP and due to temperature gradients I˙ΔT . These principle components of total process irreversibility are not independent and there is a trade-off between them. Therefore the purpose of this research paper is to demonstrate the importance of the use of exergy analysis in the minimisation of carryover leakage irreversibilities of a symmetric balanced rotary regenerator. The chemical exergy E˙o and physical exergy E˙ph are calculated and the ratio of chemical and physical irreversibilities has been evaluated for a rotary regenerator used for air preheating in a coal-fired power plant. A numerical finite difference technique has been used to calculate the fluid and matrix temperature distributions effect on the regenerator performance. The effects of variation of the principal design parameters on the irreversibilities and on the regenerator effectiveness are examined and recommendations are made for the selection of the most appropriate parameters.

scholarly journals Energy and Exergy Analysis of a Coal Fired Power Plant

2018 ◽  
Vol 37 (4) ◽  
pp. 611-624 ◽  
Author(s):  
Sumit Kumar ◽  
Dileep Kumar ◽  
Rizwan Ahmed Memon ◽  
Majid Ali Wassan ◽  
Sikandar Ali Mir
Keyword(s):  
Power Plant ◽  
Energy Loss ◽  
Parametric Study ◽  
Exergy Analysis ◽  
Absolute Error ◽  
Steam Pressure ◽  
Design Parameters ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis ◽  
Main Steam

In this paper, energy and exergy analysis has been conducted on a subcritical coal fired power plant of Wisconsin Power and Light Company, USA to investigate the steam cycle energy and exergy efficiency. The cycle is analyzed by developing a mathematical model using its operating and design parameters. The analysis is performed using EES (Engineering Equation Solver). The energy analysis shows that major share of energy loss occurs in condenser i.e. 72% of total cycle energy loss, whereas, exergy analysis shows that 83.09% total exergy destruction of cycle occurs in boiler.Furthermore, the simulation results are compared with actual with an absolute error of 3.1%. Additionally, the parametric study is performed to examine the effects of various operating parameters such as main steam pressure and temperature, condenser pressure, terminal and drain cooler temperature difference on net power output, energy andexergy efficiency of cycle. The parametric study shows that the plant has maximum energy and exergy efficiencies at steam pressure of 2500psi, condenser pressure of 1.0psi and main steam temperature of 1100oF. Furthermore, these parameters do not seem to change energy and exergy efficiencies significantly.

Thermal performance of gas turbine power plant based on exergy analysis

2017 ◽  
Vol 115 ◽  
pp. 977-985 ◽  
Author(s):  
Thamir K. Ibrahim ◽  
Firdaus Basrawi ◽  
Omar I. Awad ◽  
Ahmed N. Abdullah ◽  
G. Najafi ◽  
...  
Keyword(s):  
Power Plant ◽  
Gas Turbine ◽  
Thermal Performance ◽  
Exergy Analysis ◽  
Gas Turbine Power Plant

scholarly journals Mixing Uncertainties in Low-Metallicity AGB Stars: The Impact on Stellar Structure and Nucleosynthesis

Universe ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 25
Author(s):  
Umberto Battino ◽  
Claudia Lederer-Woods ◽  
Borbála Cseh ◽  
Pavel Denissenkov ◽  
Falk Herwig
Keyword(s):  
Stellar Structure ◽  
Process Efficiency ◽  
Agb Stars ◽  
Mixing Processes ◽  
Data Set ◽  
Convective Envelope ◽  
Capture Process ◽  
Low Metallicity ◽  
Low Mass ◽  
The Impact

The slow neutron-capture process (s-process) efficiency in low-mass AGB stars (1.5 < M/M⊙ < 3) critically depends on how mixing processes in stellar interiors are handled, which is still affected by considerable uncertainties. In this work, we compute the evolution and nucleosynthesis of low-mass AGB stars at low metallicities using the MESA stellar evolution code. The combined data set includes models with initial masses Mini/M⊙=2 and 3 for initial metallicities Z=0.001 and 0.002. The nucleosynthesis was calculated for all relevant isotopes by post-processing with the NuGrid mppnp code. Using these models, we show the impact of the uncertainties affecting the main mixing processes on heavy element nucleosynthesis, such as convection and mixing at convective boundaries. We finally compare our theoretical predictions with observed surface abundances on low-metallicity stars. We find that mixing at the interface between the He-intershell and the CO-core has a critical impact on the s-process at low metallicities, and its importance is comparable to convective boundary mixing processes under the convective envelope, which determine the formation and size of the 13C-pocket. Additionally, our results indicate that models with very low to no mixing below the He-intershell during thermal pulses, and with a 13C-pocket size of at least ∼3 × 10−4 M⊙, are strongly favored in reproducing observations. Online access to complete yield data tables is also provided.

Research on Additional Specific Consumption Distribution of Biomass Direct Combustion Power Plant

2011 ◽  
Vol 347-353 ◽  
pp. 631-634
Author(s):  
Qin Liang Tan ◽  
Cai Juan Zhang ◽  
Xiao Ying Hu ◽  
Li Gang Wang ◽  
Qiang Lu ◽  
...  
Keyword(s):  
Power Plant ◽  
Energy Saving ◽  
Second Law Of Thermodynamics ◽  
Operating Conditions ◽  
Specific Consumption ◽  
Pollutant Emissions ◽  
Design Parameters ◽  
Direct Combustion ◽  
Analysis Theory ◽  
Biomass Power Plant

Biomass direct combustion power generation is the most simple but effective way in dealing with environmental issues and energy crisis. A comprehensive diagnosis with accurate evaluation of energy saving potential of a given biomass power plant is of great importance in lowing the cost of generating electricity, reducing the consumption of energy and pollutant emissions [1]. This paper throws light upon an innovative energy consumption diagnosis method-the specific consumption analysis theory, which is based on the First and Second law of thermodynamics [2,3]. Taking a given biomass power plant of National Energy Group as an example, mathematical models are made based on all the components and processes. The specific consumption analysis theory is employed to calculate the specific consumption within the biomass power plant using design parameters under design operating conditions, thus demonstrating the specific consumption distribution in the power plant, which provides theoretical basis for energy-saving and optimization in biomass power plant.

Correlation Between Pressure Recovery of Highly Loaded Annular Diffusers and Integral Stage Design Parameters

2017 ◽  
Author(s):  
Dajan Mimic ◽  
Bastian Drechsel ◽  
Florian Herbst
Keyword(s):  
Boundary Layer ◽  
Dynamic Pressure ◽  
Boundary Layer Separation ◽  
Flow Coefficient ◽  
Tip Vortex ◽  
Pressure Recovery ◽  
Design Parameters ◽  
Steam Turbines ◽  
Pressure Losses ◽  
Induced Velocity

Exhaust diffusers significantly enhance the available power output and efficiency of gas and steam turbines by allowing for lower turbine exit pressures. The residual dynamic pressure of the turbine outflow is converted into static pressure, which is referred to as pressure recovery. Since total pressure losses as well as construction costs increase drastically with diffuser length, it is more than favourable to design shorter diffusers with rather steep opening angles. However, those designs are more susceptible to boundary layer separation. In this paper, the stabilising properties of tip leakage vortices generated in the last rotor row and their effect on the boundary layer characteristics are examined. Based on analytical considerations, for the first time a correlation between the pressure recovery of the diffuser and integral rotor parameters of the last stage, namely the loading coefficient, flow coefficient and reduced frequency, is established. Both, experimental data and scale resolving simulations, carried out with the SST-SAS method, show excellent agreement with the correlation. Blade tip vortex strength predominantly depends on the amount of work performed in the rotor, which in turn is described by the non-dimensional loading coefficient. The flow coefficient influences mainly the orientation of the vortex, which affects the interaction between vortex and boundary layer. The induced velocity field accelerates the boundary layer, essentially reducing the thickness of the separated layer or even locally preventing separation.

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