Energetic and exergetic analysis of cogeneration power combined cycle and ME-TVC-MED water desalination plant: Part-1 operation and performance

Energetic and exergetic analyses are conducted using operating data for Sabiya, a combined cycle power plant (CCPP) with an advanced triple pressure reheat heat recovery steam generator (HRSG). Furthermore, a sensitivity analysis is carried out on the HRSG using a recent approach to differentiate between the sources of irreversibility. The proposed system was modelled using the IPSEpro software and further validated by the manufacturer’s data. The performance of the Sabiya CCPP was examined for different climatic conditions, pressure ratios, pinch point temperatures, high-pressure steam, and condenser pressure values. The results confirmed that 60.9% of the total exergy destruction occurs in the combustion chamber, which constitutes the main source of irreversibilities within a system. The exergy destruction was significantly affected by both the pressure ratio and the high-pressure steam, where the relation between them was seen to be inversely proportional. The high-pressure stage contributes about 50% of the exergy destruction within the HRSG compared to other stages and the reheat system, due to the high temperature difference between the streams and the large number of components, which leads to high energy loss to the surroundings. Numerous possibilities for improving the CCPP’s performance are introduced, based on the obtained results.

A novel hybrid system coupled liquid dehumidification with absorption refrigeration driven by solar energy is proposed. Traditional and advanced exergy and exergoeconomic analyses of the system are conducted to ascertain the degree of irreversibility and potential improvement for each component. Based on the advanced exergy and exergoeconomic analyses, the effects of air humidity, segment temperature, and refrigeration temperature on the total exergy destruction and cost rates of the system are obtained. The total avoidable exergy destruction rate, avoidable exergy destruction cost rate, and avoidable investment cost rate of the system are selected as objective functions and optimized by using nondominated sort genetic algorithm-II. The results show that the total exergy destruction rate and the total exergy destruction cost rate reach 262.39 kW and 8.563 $/h, respectively. The generator and regenerator have higher cost rates of the irreversibility overall system, achieving the values 3.536 and 2.430 $/h, respectively. The absorber has the highest investment cost rate in the whole system. The endogenous parts of the exergy destruction and cost rates are much higher than the exogenous parts in the system. Multiobjective optimization results show that optimal values for the total avoidable exergy destruction rate and the exergy destruction cost rate are 50.99 kW and 1.60 $/h, which are 4.15 and 9.14% lower than those calculated by single-objective optimization, respectively. This study provides a potential way to utilize solar energy for dehumidification and refrigeration.

Parametric study and multi-criteria optimization of total exergetic and cost rates improvement potentials of a new geothermal based quadruple energy system

Advanced exergy and environmental analyses and multi objective optimization of a real combined cycle power plant with supplementary firing using evolutionary algorithm

Energy demand is increasing exponentially in the last decade. To meet such demand there is an urgent need to enhance the power generation capacity of the electrical power generation system worldwide. A combined- cycle gas turbines power plant is an alternative to replace the existing steam/gas electric power plants. The present study is an attempt to investigate the effect of different parameters to optimize the performance of the combined cycle power plant. The input physical parameters such as pressure ratio, air fuel ratio and a fraction of combustible product to heat recovery heat exchanger via gas turbine were varied to determine the work output, thermal efficiency, and exergy destruction. The result of the present study shows that for maximum work output, thermal efficiency as well as total exergy destruction, extraction of combustible gases from the passage of the combustion chamber and gas turbine for heat recovery steam generator is not favorable. Work output and thermal efficiency increase with an increase in pressure ratio and decrease in air fuel ratio but for minimum total exergy destruction, the pressure ratio should be minimum and air fuel ratio should be maximum.

Exergetic evaluation of gas-turbine based combined cycle system with vapor absorption inlet cooling

Exergy analysis of a combined power and cooling cycle

Advanced exergoenvironmental analysis of the oil shale retorting process with SJ-type rectangular retort

Parametric analysis and performance prediction of an ultra-low temperature cascade refrigeration freezer based on an artificial neural network

Exergy destruction of heat transfer and turbulent convective fluid flow through spiral passage subjected to constant wall temperature is analyzed. Constant and temperature dependent thermo physical properties models of process fluid have been adopted. Heat transfer characteristics and both thermal as well viscous fluid friction exergy destruction are investigated. The local variation of total (thermal and viscous dissipation) exergy destruction was studied along the spiral passage. Some of second law of thermodynamic dimensionless parameters, such as Bejan (Be) and entropy generation (Ngen) numbers were considered. It is found that De (Dean Number) with its magnitude is a measure of the secondary flow, and has opposite influence on these two numbers along the passage. The study concluded that total exergy destruction was dominated by thermal effects due to temperature difference. But the influence of irreversibility due to pressure drop was found less significant. This effect is of a particular interest in the heat transfer and fluid flow in spiral passages where secondary flow phenomenon plays an important role in thermal mixing and conversion of viscous dissipation into thermal energy through narrowing passage.

One of the roles of Exergoeconomics is to provide energy system designers and operators with the information, necessary for the improvement of energy systems. It employs both economic principles and exergy concepts particularly taking into account the values of individual components’ exergy destruction: the thermodynamic loss due to irreversibilities within a system’s component. The total exergy destruction occurring in a component is not only due exclusively to the component (endogenous exergy destruction) but is also caused by the inefficiencies of the remaining system components (exogenous exergy destruction). Hence care must be taken in using the total exergy destruction of a component when making decisions to optimize the overall energy system. The understanding of Exogenous and Endogenous Exergy Destruction for any given component can further assist the engineer in deciding whether a subsystem or a structural adjustment is required in the optimization of the entire energy system. With emphasis placed on process performance (i.e. the mutual interdependencies of the components within the system) as oppose to the final output, exogenous and endogenous exergy destruction analysis guarantees that the quality of the output is improved without compromising the performance of individual components. Additionally, only a part of the exergy destruction in a component can be avoided (avoidable exergy destruction) since a system component is also imposed by a number of constraints including physical, technological and economical. Knowledge of the Exogenous and Endogenous exergy destruction together with an understanding of the (unavoidable and avoidable exergy destruction) can provide a realistic measure of the potential for optimising any energy system. The thesis deals with the development of a concept for splitting the exergy destruction and the costs associated with the system components. This concept is then applied to improve three energy conversion plants: a simple gas turbine process, a cogeneration and an externally-fired combined cycle power system and the results compared to the improvement of these said plants using a conventional exergoeconomic analysis.

The purpose of this study is to analyse the proposed liquid desiccant absorber with low solution flow rate compared with the conventional packbed-type absorber. The total exergy destruction and exergy efficiency were estimated to assess the system performance. To determine the total exergy destruction and exergy efficiency, it was predicted that the specific thermal and chemical exergy in the inlet and outlet both air and solution side of the absorber. The results indicated that the average total thermal and chemical exergy destruction is 0.054 kW and 0.080 kW in the proposed system while it is 0.292 kW and 0.093 kW in the conventional absorber. The exergy efficiency is 0.573 and 0.114 on average in the proposed and conventional absorber, respectively.

Analysis of vapor compression refrigeration cycle using advanced exergetic approach with Taguchi and ANOVA optimization and refrigerant selection with enviroeconomic concerns by TOPSIS analysis

Advanced exergy analysis of a combined Brayton/Brayton power cycle

Advanced exergy and advanced exergoeconomic analyses of biomass and natural gas fired combined cycles with hydrogen production