On the exergy balance equation and the exergy destruction

Energy ◽  
2016 ◽  
Vol 116 ◽  
pp. 824-835 ◽  
Author(s):  
V.A.F. Costa
Keyword(s):  
Balance Equation ◽  
Exergy Destruction ◽  
Exergy Balance

Exergy Analysis for a Gas Turbine Cogeneration System

1996 ◽  
Vol 118 (4) ◽  
pp. 782-791 ◽  
Author(s):  
Si-Doek Oh ◽  
Hyo-Sun Pang ◽  
Si-Moon Kim ◽  
Ho-Young Kwak
Keyword(s):  
Gas Turbine ◽  
Balance Equation ◽  
Exergy Analysis ◽  
Production Costs ◽  
Actual Performance ◽  
Exhaust Gases ◽  
Cogeneration System ◽  
Predicted Values ◽  
Exergoeconomic Analysis ◽  
Exergy Balance

A general exergy balance equation that is applicable to any component of thermal systems has been formulated in this study. One of distinct features of this formulation is that the exergy involved in the component of any thermal system can be decomposed into exergy flows, entropy production flows, and the appropriate exergy rate terms such as fuel and available work. The exergy analysis based on this equation permits one to predict the thermal efficiency of the system, the exergy destruction in each component as well as the mass flow rate, the composition, and the temperature of the exhaust gases. We have examined the performance of a 1000 kW gas turbine cogeneration system when it is operated at part and full-load conditions through this analysis. We have also tested the effect of the inlet air temperature and the relative humidity of the inlet air on the performance of the system. The predicted values of the performances for the system have been compared with the actual performance data provided by the gas turbine manufacturer. It has been found that the measured data of net power and the properties of exhaust gases are in good agreement with calculation ones, differing by less than 3 percent. The exergy balance equation may be utilized in the exergoeconomic analysis to estimate the production costs depending on various input costs in a gas turbine cogeneration system.

A Fundamental Equation for Exergy Balance on Solar Collectors

1988 ◽  
Vol 110 (2) ◽  
pp. 102-106 ◽  
Author(s):  
Akio Suzuki
Keyword(s):  
Flat Plate ◽  
Balance Equation ◽  
Solar Collector ◽  
Fundamental Equation ◽  
Thermal Design ◽  
Optimum Operating ◽  
Solar Collectors ◽  
Optimum Operating Condition ◽  
Flat Plate Collector ◽  
Exergy Balance

This paper presents the exergy balance equation on a solar collector which acts as the fundamental and principal expression for the solar thermal design. The equation fully explains the exergy loss processes and can be used to derive the approximate optimum operating condition for solar collectors. Furthermore, using the equation, it can be shown that two different collectors, an evacuated tubular collector and a flat-plate collector, have both nearly equal capabilities in exergy gain despite large differences in technological efforts and expenses to produce them. In addition, ways for improvement for a solar collector are also discussed here briefly.

scholarly journals Thermal performance of a gas turbine based on an exergy analysis

2019 ◽  
Vol 128 ◽  
pp. 01027
Author(s):  
Abdallah Haouam ◽  
Chaima Derbal ◽  
Hocine Mzad
Keyword(s):  
Energy Balance ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Thermal Performance ◽  
Exergy Analysis ◽  
Exergy Destruction ◽  
Equilibrium Equations ◽  
Air Compressor ◽  
Exergy Balance ◽  
Thermodynamic Processes

This work concerns the calculation and the analysis of the thermal performance of the components ofan MS 7001 type gas turbine with a nominal power of 87 MW using the concept of exergy. The exergy balance is used in addition to the energy balance to estimate the irreversibility of the air compressor, the combustion chamber and the turbine. The exergy analysis is carried out by applying the equilibrium equations obtained from the general definitions of the irreversibility of the thermodynamic processes and the data provided by the manufacturer. The results show that the exergy destruction of the gas turbine depends on the variation of the thermodynamic parameters: ambient temperature, compression ratio, air–fuel ratio. The combustion chamber has the highest exergy destruction estimated at 36.34 MW. The air compressor has an exergy efficiency of 84.19% that of the combustion chamber is 75.91% whilethat of the turbine expansion is 92.58%. The total exergy destruction of the gas turbine is 53.51 MW and itsefficiency is 32.44%. Improving the performance of the gas turbine requires decreasing the temperatureof the intake air.

Evaluation of human brain hyperthermia using exergy balance equation

2020 ◽  
Vol 93 ◽  
pp. 102723
Author(s):  
Imran Mahmood ◽  
Ali Raza ◽  
Aamir Mehmood ◽  
Nasir Ahmad ◽  
Khalid Arif
Keyword(s):  
Human Brain ◽  
Balance Equation ◽  
Exergy Balance ◽  
Brain Hyperthermia

Study of pumping effect in flow-through electrolysers

1983 ◽  
Vol 48 (8) ◽  
pp. 2232-2248 ◽  
Author(s):  
Ivo Roušar ◽  
Michal Provazník ◽  
Pavel Stuhl
Keyword(s):  
Natural Convection ◽  
Balance Equation ◽  
Volume Fraction ◽  
Industrial Applications ◽  
Pumping Effect ◽  
Flow Through ◽  
The Mean ◽  
The Difference

In electrolysers with recirculation, where a gas is evolved, the pumping of electrolyte from a lower to a higher level can be effected by natural convection due to the difference between the densities of the inlet electrolyte and the gaseous emulsion at the outlet. An accurate balance equation for calculation of the rate of flow of the pumped liquid is derived. An equation for the calculation of the mean volume fraction of bubbles in the space between the electrodes is proposed and verified experimentally on a pilot electrolyser. Two examples of industrial applications are presented.

Second-Law Analysis in a Steam Power Plant for Minimization of Avoidable Exergy Destruction

2010 ◽  
Author(s):  
Tapan K. Ray ◽  
Pankaj Ekbote ◽  
Ranjan Ganguly ◽  
Amitava Gupta
Keyword(s):  
Work Performance ◽  
Operating Conditions ◽  
Performance Criteria ◽  
Second Law ◽  
Feed Water ◽  
Exergy Destruction ◽  
Actual Performance ◽  
Time Operation ◽  
Major Equipment ◽  
Cycle Efficiency

Performance analysis of a 500 MWe steam turbine cycle is performed combining the thermodynamic first and second-law constraints to identify the potential avenues for significant enhancement in efficiency. The efficiency of certain plant components, e.g. condenser, feed water heaters etc., is not readily defined in the gamut of the first law, since their output do not involve any thermodynamic work. Performance criteria for such components are defined in a way which can easily be translated to the overall influence of the cycle input and output, and can be used to assess performances under different operating conditions. A performance calculation software has been developed that computes the energy and exergy flows using thermodynamic property values with the real time operation parameters at the terminal points of each system/equipment and evaluates the relevant rational performance parameters for them. Exergy-based analysis of the turbine cycle under different strategic conditions with different degrees of superheat and reheat sprays exhibit the extent of performance deterioration of the major equipment and its impact to the overall cycle efficiency. For example, during a unit operation with attemperation flow, a traditional energy analysis alone would wrongly indicate an improved thermal performance of HP heater 5, since the feed water temperature rise across it increases. However, the actual performance degradation is reflected as an exergy analysis indicates an increased exergy destruction within the HP heater 5 under reheat spray. These results corroborate to the deterioration of overall cycle efficiency and rightly assist operational optimization. The exergy-based analysis is found to offer a more direct tool for evaluating the commercial implication of the off-design operation of an individual component of a turbine cycle. The exergy destruction is also translated in terms of its environmental impact, since the irretrievable loss of useful work eventually leads to thermal pollution. The technique can be effectively used by practicing engineers in order to improve efficiency by reducing the avoidable exergy destruction, directly assisting the saving of energy resources and decreasing environmental pollution.

scholarly journals Analysis of Selected Methods Use for Calculation of the Coefficients of Adsorption Isotherms and Simplified Equations of Adsorption Dynamics with the Use of IZO Application

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4192
Author(s):  
Jacek Piekarski ◽  
Katarzyna Ignatowicz ◽  
Tomasz Dąbrowski
Keyword(s):  
Linear System ◽  
Adsorption Isotherms ◽  
Balance Equation ◽  
Laboratory Tests ◽  
Adsorption Process ◽  
Estimation Method ◽  
Linearization Method ◽  
Sufficient Accuracy ◽  
Mass Balance Equation ◽  
Adsorption Dynamics

The purpose of this paper is to present the IZO application that calculates and visualizes coefficients of adsorption isotherms according to Freundlich, Langmuir, and BET in a classic and linear system, in a simple communicative way. The application also calculates the working time of the adsorption bed based on the transformation of the mass balance equation, and according to the Zuchowicki, Zabieziński, Tichonow, and the Bohart-Adams equations. The laboratory tests of the adsorption process of leachate from a municipal landfill on selected active coals ORGANOSORB 10, DESOTEK, and BA-10, were conducted to check the program for accuracy. Results of tests confirm that the linearization method of the calculation of adsorption isotherms coefficients, used in the IZO application, gives sufficient accuracy and may be used as an alternative of, e.g., the nonlinear estimation method.

Sign in / Sign up

Export Citation Format

Share Document