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Thermodynamic, economic and environmental analyses of a combined CO 2 capturing system, including, geothermal driven dual fluid organic Rankine cycle (ORC), proton exchange membrane electrolyzer (PEME), S-Graz cycle and methanol synthesis unit (MSU) were carried out. The presented zero emission system was designed based on the oxy-fuel combustion carbon capturing to produce power, hydrogen and methanol, while released CO 2 can be captured. Generated renewable power by the ORC was utilized by the PEME to produce renewable hydrogen. Part of the produced hydrogen is fed to the MSU, while the rest was stored in hydrogen tanks. In fact, CO 2 hydrogenation to produce methanol suggested via direct methanol synthesis in order to utilize the captured CO 2 from the S-Graz cycle. Exergy efficiency of the system defined to analyze the system thermodynamically, while SPECO method utilized to evaluate system economically. Results revealed that the most important part of the system is the S-Graz cycle, from the viewpoint of capital investment. Also, the average product unit cost of 24.88 $/GJ obtained for the whole system. • A zero emission system producing power, hydrogen and methanol is proposed. • A proposal to hydrogenate the captured CO 2 from S-Graz cycle is suggested. • Exergoeconomic and environmental analysis of the system is done. [ABSTRACT FROM AUTHOR]

A comprehensive exergoeconomic comparison of the absorption power and cooling cogeneration cycles based on Kalina is investigated in this study. After thermodynamic and exergoeconomic simulation of the double effect absorption refrigeration/Kalina as well as the first and second configurations of simple absorption refrigeration/Kalina cogeneration cycles, in this part, a widespread parametric study is done and the effects of the simultaneous variations of all studied cogeneration cycles operating parameters are examined on the thermodynamic and exergoeconomic performance of the cogeneration cycles. Also, for a better comparison of the considered cycles, the optimization is done and the considered cogeneration cycles are comprised regarding to five objective functions including the minimum unit cost of products, maximum energy and exergy efficiencies, minimum unit cost of produced exergy and minimum the sum of exergy destruction and capital investment cost rates. Finally, the payback period of the studied cogeneration cycles is calculated in all optimum states. The results show that the minimum unit cost of products for the first configuration of SAR/Kalina cycle is 16.46% and 9.27% less than the corresponding values for the DEAR/Kalina cycle and the second configuration of SAR/Kalina cycle, respectively. Also, the value of C ̇ D + Z ̇ parameter for the first configuration of SAR/Kalina cogeneration cycle is 28.32% and 33.12% less than the corresponding values for the second configuration of SAR/Kalina cycle and DEAR/Kalina cycle, respectively. Also, in all optimum states except for the minimum unit cost of produced exergy, the first configuration of SAR/Kalina cycle has the lowest amount of payback period. [ABSTRACT FROM AUTHOR]

In this study, ammonia-water double effect absorption refrigeration/Kalina cogeneration cycle and two different configurations of ammonia-water absorption refrigeration/Kalina cogeneration cycles are considered for heat recovery from the high temperature heat source. In this type of cogeneration cycles, power generation and refrigeration cycles have become a single cycle that power and cooling are produced simultaneously in a common loop. After applying the first and second laws of thermodynamics on the components of the considered cycles and the validation of them, by developing SPECO approach on the considered cogeneration cycles, the cycles are simulated from the exergoeconomic viewpoint. For this purpose, the unit cost and cost rate of all streams of the cycles as well as the important thermodynamic and thermoeconomic parameters of each component and the considered cogeneration cycles are calculated. The simulation results indicate that although the thermodynamic efficiency of the double effect absorption refrigeration/Kalina cogeneration cycle is much higher than thermodynamic efficiency of other considered cycles, the economic performance of this cycle is not very desirable. Among the considered cogeneration cycles, the best thermoeconomic performance belongs to the first configuration absorption refrigeration/Kalina cycle. Also, in all cases, the boiler and the low pressure absorber have the highest sum of exergy destruction and capital investment cost rates and should be taken into consideration from exergoeconomic viewpoint for better performance of the cogeneration cycles. The most critical components from the exergy viewpoint are also included boiler, the low pressure absorber and rectifier. [ABSTRACT FROM AUTHOR]

In this paper LiBr–H 2 O and NH 3 –H 2 O absorption power cycles and Rankine cycle which produce 1 MW electrical power in same conditions of heat sources are compared from exergoeconomic point of view. Exergoeconomic analysis is performed using the specific exergy costing (SPECO) method. The results show that among these cycles, although the LiBr–H 2 O cycle has the highest first law efficiency, but unit cost of electricity produced by turbine for LiBr–H 2 O cycle is more than that for Rankine cycle. This value is lowest for the NH 3 –H 2 O cycle. Moreover, the NH 3 –H 2 O cycle has the highest and the LiBr–H 2 O cycle has the lowest exergy destruction cost rate. The generator, the absorber and the boiler in all considered cycles have the maximum value of sum of cost rate associated with capital investment, operating and maintenance, exergy destruction and exergy losses. Therefore, these components should be taken into consideration from exergoeconomic viewpoint. In parametric study, it is observed that in the constant generator temperature, as the generator pressure increases, unit cost of power produced by turbine for LiBr–H 2 O and Rankine cycles decreases. This value for Rankine cycle is lower than for LiBr–H 2 O cycle whereas Rankine cycle efficiency is less than the efficiency of LiBr–H 2 O cycle. Also, in LiBr–H 2 O cycle, at constant temperature of the generator, the value of exergy destruction cost rate is minimized and exergoeconomic factor is maximized at particular values of generator pressure and the more absorber pressure results the minimum value of total exergy destruction cost rate. [ABSTRACT FROM AUTHOR]

A novel solar based combined system is proposed to produce hydrogen and cooling. The presented cogeneration system is analyzed in detail from the viewpoints of exergy and exergoeconomic (exergy based economic analysis). The proposed system includes a concentrated PVT (CPVT), a single effect LiBr-H 2 O absorption chiller and proton exchange membrane electrolyzer (PEM). Produced electrical power is consumed in the PEM electrolyzer to split water into oxygen and pure hydrogen while heat removal from the CPVT is done by the absorption chiller to guarantee its better performance. Second law analysis showed that, among the three different parts of the system, the most part of exergy destruction refers to the CPVT followed by absorption chiller unit and PEM electrolyzer. Also, it is observed that, among the absorption units' components, the highest percent of exergy destruction belongs to the generator which absorbs the heat from the CPVT. Moreover, exergoeconomic analysis revealed that the most important unit from the viewpoint of economic is the CPVT with the capital investment cost of 0.08946 $/h and an exergoeconomic factor of 28.82%. [ABSTRACT FROM AUTHOR]

Exergy and exergoeconomic analysis are performed for an electrically separated two-stage thermoelectric cooler (STTEC). Exergetic efficiency and cost of cooling power are considered as the main target of exergy and exergoeconomic analysis, respectively. The effects of important design variables on the STTEC exergy and economic performance are investigated. These variables are applied currents to the stages, geometric characteristics, i.e. electrodes length and cross section area ratios between the stages and first and second stages electrode numbers. Also, effects of applied currents on the optimum values of geometric characteristics to obtain the minimum cooling cost have been analyzed. For achieving maximum exergy efficiency and minimum cooling cost, applied current of hotter (second) stage would stand at a higher level than that of colder (first) stage. The higher the ranges of applied currents, the lower the accessible cooling cost in comparison to exergy efficiency. [ABSTRACT FROM AUTHOR]