Sum Unit Cost Of The Product Research Articles

Designing and multi-objective optimization of a novel multigenerational system based on a geothermal energy resource from the perspective of 4E analysis

Over the past few years, a growing emphasis has been placed on providing sustainable energies to reduce carbon emissions and promote energy efficiency. This paper delved into energy, exergy, exergoeconomic, and exergoenvironmental investigation for a system that combines the Kalina cycle, a double-effect absorption chiller with a vapor compression refrigeration system coupled with an air handling unit driven by a geothermal renewable energy resource. This innovative system generated four distinct outputs: electricity, potable water, cooling load, and hot water. Key system performance variables, such as net power output, coefficient of performance, sum unit cost of the product, energy and exergy efficiencies, the temperature of supply air to the cold store, and potable water production in the base mode, are measured at 63.45 kW, 0.83, 56.74 $/GJ, 62.28 %, 45.67 %, 268.7 K and 20.82 lit/h, respectively. This research explored the impact of various parameters on the output variables, the exergy destruction and environmental impact rate of all components, and the net percent value of the proposed system. The multi-objective optimization significantly improved energy and exergy efficiencies by 6.83 % and 1.8 % from its base mode. Exergy and exergoenvironmental analysis revealed that the highest exergy destruction occurs in Re-injection, and the highest environmental impact rate associated with exergy belongs to the HPG component. Moreover, the geothermal section has the largest share of exergy destruction, approximately 58.5 % of the total exergy destruction of the system.

Exergoeconomic Evaluation of a Cogeneration System Driven by a Natural Gas and Biomass Co-Firing Gas Turbine Combined with a Steam Rankine Cycle, Organic Rankine Cycle, and Absorption Chiller

Considering energy conversion efficiency, pollution emissions, and economic benefits, combining biomass with fossil fuels in power generation facilities is a viable approach to address prevailing energy deficits and environmental challenges. This research aimed to investigate the thermodynamic and exergoeconomic performance of a novel power and cooling cogeneration system based on a natural gas–biomass dual fuel gas turbine (DFGT). In this system, a steam Rankine cycle (SRC), a single-effect absorption chiller (SEAC), and an organic Rankine cycle (ORC) are employed as bottoming cycles for the waste heat cascade utilization of the DFGT. The effects of main operating parameters on the performance criteria are examined, and multi-objective optimization is accomplished with a genetic algorithm using exergy efficiency and the sum unit cost of the product (SUCP) as the objective functions. The results demonstrate the higher energy utilization efficiency of the proposed system with the thermal and exergy efficiencies of 75.69% and 41.76%, respectively, while the SUCP is 13.37 $/GJ. The exergy analysis reveals that the combustion chamber takes the largest proportion of the exergy destruction rate. The parametric analysis shows that the thermal and exergy efficiencies, as well as the SUCP, rise with the increase in the gas turbine inlet temperature or with the decrease in the preheated air temperature. Higher exergy efficiency and lower SUCP could be obtained by increasing the SRC turbine inlet pressure or decreasing the SRC condensation temperature. Finally, optimization results indicate that the system with an optimum solution yields 0.3% higher exergy efficiency and 2.8% lower SUCP compared with the base case.

Exergoeconomic appraisement, sensitivity analysis, and multi-objective optimization of a solar-driven generation plant for yielding electricity and cooling load

Solar energy-driven generation units can assist in moderating energy-linked environmental issues. For this target, a new solar heliostat-based generation unit is suggested for electricity generation as the crucial product. A heliostat-based solar unit with a closed Brayton cycle and thermal energy storage unit is coupled with a Kalina cycle and an absorption refrigeration unit through a single-effect absorption chiller as an inimitable series of power plants. Exergy, economic, and energy investigations are carried out to scrutinize the efficiency of the introduced unit, and a thorough parametric evaluation is performed. Multi-aspect optimization is implemented to identify the optimum decision values, regarding four various scenarios, namely exergy performance/ sum unit cost of the product, exergy performance/ coefficient of performance, NPV/exergy performance, and exergy performance/ cooling load. In this regard, The Grey Wolf Optimizer is the multi-objective optimization method, and TOPSIS, LINMAP, and Shannon entropy approaches assist the optimization procedure in acquiring the optimal solution in each scenario. The results indicate that the optimized exergy performance, coefficient of performance, and sum unit cost of the product are computed as 33.48 %, 0.817, and 3.44 $/GJ, respectively.

Thermo-Economic Analysis of Innovative Integrated Power Cycles for Low-Temperature Heat Sources Based on Heat Transformer

This paper proposes two novel integrated power cycles as appropriate systems for low-temperature heat sources. The proposed cycles encompass an absorption heat transformer (AHT) system to convert low-temperature heat source to high-temperature source and supply the required heat for driving Kalina cycle (KC) and absorption power cycle (APC) as bottoming cycles. A comprehensive simulation of the system is presented based on the thermo-economic viewpoint. The results show that the AHT/KC has higher energy and exergy efficiencies than the AHT/APC, with 7.69% and 49.03%, respectively. In addition, the sum unit cost of the product (SUCP) for the system is calculated 87.72 $/GJ. According to the results, throttle valve 1 and absorber 1 are the most destructive components of the AHT/KC and AHT/APC, respectively. The net output power in the AHT/KC and the AHT/APC is assessed 60.06 kW and 34.86 kW, respectively. The circulation rate (CR), Coefficient of performance (COP), and exergetic coefficient of performance (ECOP) for both cycles are 3.819, 0.4108, and 0.6107, respectively. The study of key parameters demonstrates that the energetic performance of the proposed power cycles increases and decreases by a rise in the temperature of the generator and condenser, respectively. From the exergetic perspective, rising temperature of the generator improves the efficiency of the cycles, while increasing the ammonia concentration as well as condenser and absorber temperatures reduce the exergy efficiency.

Thermoeconomic analysis and optimization of a geothermal-driven multi-generation system producing power, freshwater, and hydrogen

Global warming and the insufficiency of fossil fuels have elicited in human beings envisaging the optimal employment of energy resources and attention to heat recovery systems. Grounded on this context, in this study, a geothermal-driven multi-generation system cogenerating power, freshwater, and hydrogen is proposed, comprised of multi-effect distillation (MED), organic Rankine cycle (ORC), and proton exchange membrane (PEM) electrolyzer. A comprehensive numerical model, hinged on energy, exergy, and exergoeconomic analyses, is developed as means of assessing the proposed system. Key parameters, namely, ORC inlet and MED first effect temperature, and geothermal water mass flow rate are investigated. Thereafter, using the multi-objective TOPSIS method, these parameters are optimized, based on freshwater production, exergy efficiency, and sum unit cost of the product (SUCP) for five different geothermal mass water flow rates (20 kg/s to 100 kg/s). The study finds that the generation of 2419–4274 tons of CO2 is prevented by using the system instead of fossil fuels, and thereof $ 150,000 to $ 256,000 would be saved in taxes. The system produces freshwater (0.28 kg/s to 1.5 kg/s) and hydrogen (0.0009 kg/s to 0.0045 kg/s), at a cost rate of 175 $/h to 587.5 $/h in the optimal state with various mass flow rate of geothermal.

Energy, exergy, and exergoeconomic analyses and optimization of a novel thermal and compressed air energy storage integrated with a dual-pressure organic Rankine cycle and ejector refrigeration cycle

The current work analyzes an innovative thermal and compressed air energy storage cycle integrated with a dual-pressure organic Rankine cycle combined with an ejector refrigeration cycle for power and cooling cogeneration. The bottoming cycle employs zeotropic mixtures, including Pentane (0.5)/Butane (0.5) and Pentane (0.5)/Trans-2-butene (0.5), as working fluids for performance improvement. The system assessment includes three crucial viewpoints: energy, exergy, and exergoeconomic. A parametric study is performed to examine the effects of some key parameters on the performance of the devised system. Also, a multi-objective optimization program based on the MOPSO algorithm is conducted to find an optimal trade-off between thermodynamic performance and economic attractiveness of the system considering two decision-making techniques of TOPSIS and LINMAP. The results showed that the sum unit cost of the product has less value for Pentane (0.5)/Trans-2-butene (0.5). Also, it is found that the performance of Pentane (0.5)/Trans-2-butene (0.5) as the zeotropic working fluid is better. Therefore, this fluid is considered as the working fluid for the optimization procedure. Besides, based on the achieved results, the optimum round trip efficiency and sum unit cost of the product are 54.25% and 13.51 $.GJ−1, respectively.

Integration of biomass gasification with a supercritical CO2 and Kalina cycles in a combined heating and power system: A thermodynamic and exergoeconomic analysis

A novel cogeneration system based on a combination of a gas turbine cycle, a supercritical CO2 cycle, and a Kalina cycle is devised for heating and power generation. Energy, exergy, and exergoeconomic analysis are performed to assess the system’s performance and feasibility. According to the findings, the energy and exergy efficiencies of the system are obtained by 78.15% and 40.97%, respectively. In addition, heating capacity enhanced with the increment of air preheater’s terminal temperature difference (ΔTAP), air compressor’s pressure ratio (r1p), and pressure ratio of S–CO2 compressor (r2p). The system’s sum unit cost of the product (SUCP) decreased with the increment of ΔTAP and with the decrement of ammonia concentration. Besides, the minimum value of SUCP is obtained at the air compressor pressure ratio of r1p=13.24 and r2p=2.63. The maximum value of exergy efficiency is evaluated at ΔTAP=262K, r1p=14.5, and r2p=4.21. Moreover, the maximum net output power is obtained where the design parameters are set as ΔTAP=262K, r1p=14.5, and r2p=3.5. Furthermore, the economic analysis revealed that the payback period and net present value are evaluated to be 6.9 years and 5.374×10+6 $, respectively, for the electricity price of 0.07 $/kWh and fuel cost of 2 $/GJ.

Optimal working conditions of various city gate stations for power and hydrogen production based on energy and eco-exergy analysis

In this study, the feasibility of producing power and hydrogen from the waste heat of different City Gate Stations (CGSs) is investigated to select the optimal working conditions. A thermodynamic model is developed for a proposed system combined of the CGS station, the Rankin cycle and the extended hydrogen production cycle. Initially, six CGS stations are simulated based on energy, exergy-economic and environmental analysis and then a comparative study is conducted between different stations. The results of numerical modeling show that the Mashhad-old station with 5315 kW and 31.062 ton/year has the highest amount of power and hydrogen production among other stations, respectively. It is also observed that, it is more economic to increase the input gas pressure in order to increase the production rate. In addition, optimal working conditions are determined based on the two important optimization factors of the hydrogen production rate and SUCP (sum unit cost of the product) using genetic algorithm optimization technique. The results of multi-objective optimization indicate that Gonbad, Gorgan and Mashhad-old stations, where the inlet gas mass flow rate is in the range of 8–9 kg/s, are the optimum stations.

A novel cooling and power cycle based on the absorption power cycle and booster-assisted ejector refrigeration cycle driven by a low-grade heat source: Energy, exergy and exergoeconomic analysis

Nowadays, different renewable sources and energy systems are attracting world attention due to the significant concerns about excessive emissions and the global energy crisis. To achieve both power and cooling supply for users, a new combined cooling and power system is proposed to utilizing low-grade heat sources, such as industrial waste heat, solar energy, and geothermal energy. In this paper, to enhance the efficiency of the traditional power and cooling combined system, a novel system based on the absorption power cycle (APC) and booster-assisted ejector refrigeration system is designed. In the proposed combined power and ejector refrigeration (CPER) cycle, a booster compressor is devised between the ejector and evaporator to enhance the output cooling. The system operates using the low-grade heat source (LGHS). The thermodynamic and thermoeconomics models are developed to analyze the proposed combined power and cooling system, after which, considering the mathematical analysis, the parametric investigation is employed to evaluate the impact of the design parameters on the main performance criteria. The results showed that the proposed system assisted with booster compressor has higher energy efficiency than the traditional APC cycle. The modeling results revealed that the proposed system could provide a cooling capacity of 23.89kW and the net output power of 18.52kW by receiving 195.5kW energy from the low-grade heat source. Also, the first-law efficiency, second-law efficiency, and the total SUCP (Sum unit cost of the product) of the proposed plant are obtained by 21.7%, 52.22%, and 93.52$/GJ, respectively. From the exergy analysis, it can be inferred that the maximum rate of exergy destruction among all the constitutes of the system belongs to the ejector which constitutes around 27.05% of the overall exergy destruction of system. Besides, the vapor generator 2 is responsible for the 24.31% of total exergy destruction rate. And, the highest cost of exergy destruction corresponds to the condenser followed by ejector. The parametric analysis revealed some valuable results such as a drop in the total SUCP by decreasing vapor generator 1 hot PPTD (Pinch point temperature difference), final absorption temperature, turbine inlet pressure, and LiBr mass fraction. The cooling output capacity is increasing by the increment of vapor generator 1 hot PPTD, turbine inlet pressure, and LiBr mass fraction.

Thermodynamic and thermoeconomic analysis of innovative integration of Kalina and absorption refrigeration cycles for simultaneously cooling and power generation

The energy consumption and the emission of greenhouse gases have been motivated researchers toward using renewable energy sources for the development of a sustainable society. Low-temperature heat sources like geothermal sources can be a desirable option to produce the demanded power, cooling, heating, and other byproducts. In the present literature, a novel combined cooling and power generation system is presented which is an internal integration of the Kalina Cycle and the absorption refrigeration cycle. The system operates using the low-temperature heat source. The thermodynamic and thermoeconomics analysis is carried out using Engineering Equation Solver software. Besides, considering the mathematical modeling, the parametric investigation is implemented to evaluate the effect of the key parameters on the sum unit cost of the products. Based on the obtained results, the cooling and power generation system can provide the net output power of 158.3kW and the cooling capacity of 1084kW. The results indicate that the system is most appropriate for cooling provision rather than for power generation aims. The energy and the exergy efficiencies and the net power of the combined cycle obtained 41.33%, 27.47%, and 158.3kW respectively. The sum unit cost of the product cooling, power, and total system are respectively evaluated 148.5$/GJ, 97.16$/GJ, and 19.44$/GJ. The minimum and maximum values for the rate of exergy destruction cost belong to the pump and absorber, respectively. The parametric analysis delivered some valuable results such as a drop in the sum unit cost of the net power, cooling output, and overall system by increasing the generator hot pinch point temperature difference, an increase in the overall system sum unit cost of the products with increment in the low-temperature heat source inlet temperature, and rising in the sum unit cost of the net power, cooling output, and the overall system with an increase in the evaporator temperature.

Thermodynamic and thermoeconomic analysis of a 21 MW binary type air-cooled geothermal power plant and determination of the effect of ambient temperature variation on the plant performance

Abstract The thermodynamic and thermoeconomic performances of a 21 MW geothermal power plant with air-cooled two level binary type organic Rankine cycle was numerically investigated based on its design and operating data. The investigated plant is the Sinem Geothermal Power Plant in Germencik, Aydin, Turkey. The paper provides a detailed comparison of the exergetic performance of this plant with other eight similar type of plant units, which make use of geothermal resources with similar specific exergies. Results indicate that the exergetic efficiency of the Sinem Geothermal Power Plant is the highest with 48.2% and the others vary between 9.6% and 42.7%. This result is mainly related to the exergy losses due to suppression of heat transfer in this plant, via low temperature brine reinjection, small temperature difference in the heat exchangers and high efficiencies of the individual components. First and second law efficiencies, as well as the exergy losses and improvement potentials of each component in the plant are also calculated. In air-cooled geothermal power plants, since ambient temperature is a critical parameter for the plant performance, both thermal and economic analysis of the plant is performed based on variation in ambient air temperature. Specifically, thermoeconomic analysis of the plant is evaluated to determine the exergoeconomic factor, the relative cost difference and the sum unit cost of the product (SUCP) of the plant. The effect of ambient temperature on the SUCP of the power plant, power generation, energy and exergy efficiencies are also examined in the present study. The results showed that; when the ambient temperature increases from 5 °C to 35 °C the reduction in power generation is 6.8 MW, energy efficiency decreases from 13.7% to 9.2% while exergy efficiency decreases from 54.9% to 36.7 and SUCP of the plant increases from nearly 230 $/GJ to 330 $/GJ.

Exergoeconomic analysis and optimization of innovative cascade bi-evaporator electricity/cooling cycles with two adjustable cooling temperatures

This article works with performance improvement of the conventional combined cooling/power (CCP) cycles to augment energy and exergy efficiencies of the previous systems. For this target, a conceptual configuration of cascade ejector refrigeration system (CERS) is proposed and is joined with organic Rankine cycle (ORC) to generate power and cooling outputs. The introduced CCP system can generate cooling load at two various temperatures for freezing and air-conditioning usages. For power sub-cycle, basic ORC and recuperative ORC with turbine bleeding are selected as topping cycles. Thermodynamic and exergoeconomic assessments of the cycles are done, leading to provision of the working criteria of the systems. Also, an extensive parametric evaluation and single- and multi-criteria optimizations are conducted. With this regard, the optimum air-conditioning load, freezing load, net electricity, energy efficiency, exergy efficiency, and total sum unit cost of the product (SUCP) for the modified system are obtained 44.18 kW, 35.33 kW, 64.03 kW, 48.32%, 65.3%, and 404 $/GJ, respectively. More consequentially, the generator is clarified as the premier portion of destruction, followed by ejectors. Moreover, it is exhibited that the system’s SUCP can be decreased as generator pressure, heat source temperature, and condenser temperature increase, or evaporators superheated temperature and evaporators pressure decrease.

Comparative study of two novel micro-CCHP systems based on organic Rankine cycle and Kalina cycle

With regard to the significant role of combined cooling, heating, and power (CCHP) systems in performance enhancement of power plants, two novel micro-CCHP systems are presented which are based on organic Rankine cycle (ORC) and Kalina cycle (KC) as topping cycles. Additionally, ejector refrigeration cycle (ERC) and vapor compression heat pump cycle (VCHPC) are utilized as the bottoming cycle of the power systems. To demonstrate feasibility of the recommended micro-CCHP systems, an exhaustive thermodynamic modeling and exergoeconomic analysis are employed as the most effective tools for performance evaluation of the systems. Also, to get better performance of the systems, single- and multi-criteria optimizations are carried out, using genetic algorithm. It is figured out that the KC-based micro-CCHP system has higher optimum thermal efficiency and total sum unit cost of the product (SUCP) than the ORC-based micro-CCHP system, while it had lower exergy efficiency. Regarding that, the optimum thermal efficiency for the ORC- and KC-based micro-CCHP systems are computed by 76.54% and 77.32%, respectively, whilst the optimum exergy efficiency for the ORC- and KC-based micro-CCHP systems are calculated by 48.37% and 31.2%, respectively. In addition, generator had the major exergy destruction rate among all components for both systems. Furthermore, the results of parametric study proved that higher thermal (energy) efficiency can be computed with increasing the heat source temperature, heater temperature, evaporation temperature, and terminal temperature difference of the recovery heat exchangers.

Proposal and assessment of a new geothermal-based multigeneration system for cooling, heating, power, and hydrogen production, using LNG cold energy recovery

Multigeneration systems (MGSs) driven by renewable sources are proved as cutting-edge technologies for multiple productions purposes to curb greenhouse gas emissions. With this regard, a novel geothermal-based MGS is proposed to produce multiple commodities of cooling, heating, power, and hydrogen, simultaneously, using liquefied natural gas (LNG) as cold energy recovery. The system is composed of an organic Rankine cycle (ORC), an ejector refrigeration cycle (ERC), an LNG power generation system, and a proton exchange membrane (PEM) electrolyzer system. To demonstrate the feasibility of the proposed MGS, energy, exergy, and exergoeconomic analysis are employed as the most effective tools for the performance assessment of the system. It is found that the proposed MGS can produce cooling capacity, heating capacity, net output power, and hydrogen of 1020 kW, 334.8 kW, 1060 kW, and 5.43 kg/h, respectively. In this case, the thermal efficiency, exergy efficiency and total SUCP (sum unit cost of the product) of the MGS are calculated 38.33%, 28.91%, and 347.9 $/GJ, respectively. Furthermore, condenser 2 is introduced as the main source of irreversibility of the proposed MGS by exergy destruction ratio of 58.98%. Moreover, a comprehensive parametric study is carried out and it is concluded that the SUCP of the system can be optimized based on the geothermal inlet temperature. In addition, it is demonstrated that a higher thermal efficiency can be obtained by increasing the turbine 2 expansion ratio, evaporator temperature, and geothermal temperature or decreasing of the generator terminal temperature difference, turbine 1 expansion ratio, pump 3 pressure ratio, and condenser temperature. In the same vein, a higher exergy efficiency can be attained at high turbine 1 expansion ratio, turbine 2 expansion ratio, evaporator temperature, and pump 3 pressure ratio or low generator terminal temperature difference, geothermal inlet temperature, and condenser temperature.

Exergoeconomic optimization of a novel multigeneration system driven by geothermal heat source and liquefied natural gas cold energy recovery

Multigeneration systems driven by renewable sources are proved as cutting-edge technologies for multiple productions purposes to curb greenhouse gas emissions. With this regard, a novel geothermal-based multigeneration system is proposed to produce multiple commodities of cooling, heating, power, and hydrogen, simultaneously, using liquefied natural gas as cold energy recovery. To demonstrate the feasibility of the proposed multigeneration system, energy, exergy, and exergoeconomic analysis are employed as the most effective tools for performance assessment of the proposed system. Also, to enhance the performance of the system, single- and multi-objective optimizations are carried out, using genetic algorithm. It is found that the proposed multigeneration system can be run with the optimum basic ammonia concentration of 0.42, geothermal inlet temperature of 160.5°C, evaporator temperature of 7.76°C, vapor generator pressure of 33 bar, mass extraction ratio of 0.2, condenser temperature of 29.01°C, separator 2 pressure of 4.99 bar, vapor generator terminal temperature difference of 7°C, and turbine 2 inlet pressure of 22.11 bar. In this case, the optimum thermal efficiency, exergy efficiency, and total SUCP (sum unit cost of the product) of the system are calculated 62.74%, 33.82%, and 125.4 $/GJ, respectively. Moreover, a comprehensive parametric study is carried out and it is shown that a higher thermal efficiency can be obtained by increasing the vapor generator pressure and evaporator temperature, or decreasing the mass extraction ratio, separator 2 pressure, turbine 2 inlet pressure, geothermal inlet temperature, vapor generator terminal temperature difference, and basic ammonia concentration.

Thermodynamic and thermoeconomic analysis of a novel combined cooling and power (CCP) cycle

A new combined cooling and power (CCP) cycle is proposed by a novel combination of the Kalina cycle (KC) and ejector refrigeration cycle (ERC) to produce simultaneous power output and cooling output. The exhaust of the turbine is fed to the ejector as a primary flow to draw the secondary flow (outlet of the evaporator) into the ejector. Energy, exergy, and exergoeconomic analysis of the proposed cycle are carried out leading to determine the first-law-efficiency, the second-law-efficiency, the sum unit cost of the product (SUCP) of the system, and the main source of the irreversibility. The thermal efficiency, exergy efficiency, overall exergy destruction rate, SUCP of the system, net produced power, and cooling capacity of the cycle are calculated 33.65%, 10.78%, 348.4 kW, 256.1 $/GJ, 33.65 kW, and 160.6 kW, respectively. Moreover, the parametric study of some key parameters (i.e., vapor generator pressure, evaporator temperature, condenser 2 pinch point temperature, ammonia concentration, turbine expansion ratio, and heat source temperature) on the main thermodynamic performance criteria is conducted. Based on this study it is found that increasing ammonia concentration and heat source temperature decreases the thermal efficiency, exergy efficiency, and SUCP of the system. Moreover, an increase in the turbine expansion ratio decreases the thermal efficiency and the SUCP of the system, while increases the exergy efficiency.

Thermodynamic and thermoeconomic analysis and optimization of a novel dual-loop power/refrigeration cycle

Exploration of the ejector refrigeration cycle (ERC) in the combination with well-known power cycles to produce cooling output as well as power output is highlighted in recent decades. Since organic Rankine cycle (ORC) is practically usable than other power cycles, a combination of the ORC/ERC in a novel form is presented. Power and refrigeration sub-cycles are combined by a common condenser in separate loops to form dual-loop power/refrigeration cycle. The exhaust of the turbine is mixed with the outlet flow of the ejector, and then the mixed flow is fed into the condenser. Thermodynamic and thermoeconomic analysis of the proposed cycle are carried out with different working fluids (i.e., isobutane, isobutene, butene, cis-2-butene, n-butane, R236fa, and R245fa) showing that among all working fluids isobutane is the best one from thermodynamic, thermoeconomic, and environmental viewpoints. The results of exergy analysis showed that among all components generator accounts for the biggest exergy destruction rate followed by the heater for all selected working fluids. In addition, multi-objective optimization of the proposed cycle is carried out by considering of generator pressure, heater pressure, evaporator temperature, and condenser temperature as decision variables, using the genetic algorithm (GA). The results of the optimization demonstrated that the proposed cycle performs in an optimum state based on the selected objective functions when generator pressure, heater pressure, evaporator temperature, and condenser temperature work at 3 MPa, 1 MPa, 280 K, and 299.8 K, respectively, as isobutane is used. In this case, the optimum net output power, cooling output, thermal efficiency, exergy efficiency, total SUCP (sum unit cost of the product) of the system are calculated 15.22 kW, 61.99 kW, 39.02%, 25.09%, and 86.04 $/GJ, respectively. To better understand the effect of various parameters on system performance, a comprehensive parametric study of some key parameters on performance criteria is carried out. It is shown that the net output power, exergy efficiency, and total SUCP of the system can be optimized based on the generator pressure. In addition, the total SUCP of the system can be minimized by evaporator temperature, too. Also, it is shown that higher cooling output, net output power, thermal efficiency, and exergy efficiency can be obtained at lower heater pressures as well as condenser temperatures. Moreover, at higher generator pressures and evaporator temperatures, a higher cooling output and thermal efficiency can also result.

Performance assessment and optimization of a novel multi-generation system from thermodynamic and thermoeconomic viewpoints

Multi-generation systems are promising technologies for multiple production applications to reduce the waste heat of the basic system. For this purpose, a novel multi-generation system using geothermal heat source is proposed which produces different commodities of cooling, heating, power and freshwater, simultaneously. The system comprises of a Kalina cycle, an absorption refrigeration cycle, a humidification-dehumidification desalination system, and a domestic water heater unit system. Exergoeconomic optimization of the proposed system is conducted, showing that the optimum thermal efficiency, exergy efficiency and total SUCP (sum unit cost of the product) can be obtained 94.84%, 47.89%, and 89.95 $/GJ, respectively. Moreover, a comprehensive parametric study showed that the Gained-Output-Ratio, freshwater, thermal efficiency and exergy efficiency can be optimized based on the desalination mass flow rate ratio. In addition, it is demonstrated that a higher thermal efficiency can be obtained by increasing vapour generator pinch point temperature difference, turbine inlet pressure, and evaporator temperature or decreasing condenser temperature, absorber temperature, basic ammonia concentration, desalination top temperature, desalination bottom temperature, and heater terminal temperature difference. Whereas, a higher exergy efficiency can be attained at high evaporator temperature, basic ammonia concentration, and desalination bottom temperature or low vapour generator pinch point temperature difference, turbine inlet pressure, condenser temperature, absorber temperature, desalination top temperature, and heater terminal temperature difference.

A novel trigeneration system using geothermal heat source and liquefied natural gas cold energy recovery: Energy, exergy and exergoeconomic analysis

This paper deals with the energy, exergy, and exergoeconomic analysis of a novel trigeneration system working with geothermal heat source and liquefied natural gas (LNG) cold energy recovery as thermal sink. The proposed trigeneration system is constructed based on the absorption refrigeration cycle (ARC). Due to the high ammonia concentration at condenser outlet of ARC, a heat pump system is employed for heating production, while LNG cold energy is used for recovering the latent heat of the basic solution from the condenser as heat source as well as for producing power output. A comprehensive thermodynamic modeling of the proposed system is presented and the performance of the system is investigated based on the following performance criteria: net power output, cooling output, heating output, thermal efficiency, exergy efficiency and sum unit cost of the product (SUCP) of the system. In this respect, the simulation revealed that the net power output, cooling output, heating capacity, thermal efficiency, exergy efficiency and total SUCP of the system can be calculated 405.1 kW, 1109 kW, 35.3 kW, 85.92%, 18.52%, and 68.76 $/GJ, respectively, under the proposed constrain variables. In addition, the irreversibility of each component and overall system are presented showing that condenser accounts for the highest exergy destruction among all components which constitutes around 55.51% of the overall exergy destruction rate of the system. Moreover, a comprehensive parametric study is conducted to investigate the effects of some key parameters on the main performance criteria. It is observed that one can obtain a higher thermal efficiency at high evaporator temperature or at low condenser temperature, heating unit temperature and absorber temperature; while a higher exergy efficiency can be obtained at high evaporator temperature or at low absorber and condenser temperatures. In addition, a lower total cost of product of the system can be obtained at high heating unit and evaporator temperatures or low absorber and condenser temperatures. Moreover, it is found that the overall performance of system can be optimized based on the generator hot pinch point temperature difference as well as geothermal inlet temperature.

Thermodynamic and thermoeconomic analysis and optimization of a novel combined cooling and power (CCP) cycle by integrating of ejector refrigeration and Kalina cycles

In the present work, a novel combined power and ejector refrigeration cycle is proposed by an appropriate combination of a Kalina cycle (KC) and an ejector refrigeration cycle (ERC) to produce power output and cooling output, simultaneously. The exhaust of the turbine is fed to the ejector as a primary flow to draw the secondary flow into the ejector. Energy, exergy, and exergoeconomic analysis of the proposed cycle are carried out using Engineering Equation Solver (EES) software. In addition, considering the thermal efficiency, exergy efficiency, and sum unit cost of the product (SUCP) of the system as objective functions, single- and multi-objective optimizations are carried out by genetic algorithm (GA) leading to determination the optimum design variables including the vapor generator pressure, evaporator temperature, condenser pinch point temperature, heat source temperature, ammonia concentration, and expander ratio. The results of the optimization demonstrated that the proposed cycle performs in an optimum state based on the selected objective functions when vapor generator pressure, evaporator temperature, condenser pinch point temperature, heat source temperature, ammonia concentration, and expander ratio work at 17.5 bar, 285 K, 8 K, 473 K, 15%, and 2.5, respectively. In this case, the optimum thermal efficiency, exergy efficiency, SUCP of the system are calculated 20.4%, 16.69%, and 2466.36 $/MWh, respectively. Moreover, it is demonstrated that the thermal efficiency can be maximized for the proposed cycle with respect to the vapor generator pressure, vapor generator temperature, and heat source temperature. Furthermore, it is shown that ejector has the main contribution in the exergy losses which is followed by the condenser. At the end, the effect of some key parameters on the main thermodynamic performance criteria are examined. It is shown that one can obtain a higher thermal and exergy efficiencies at lower ammonia concentration and condenser pinch point temperature as well as at higher evaporator temperature.