Kalina Cycle Research Articles

Comparative and optimal study of energy, exergy, and exergoeconomic performance in supercritical CO2 recompression combined cycles with organic rankine, trans-critical CO2, and kalina cycle

The bottom cycle in supercritical carbon dioxide (sCO2) recompression Brayton combined cycle (RCBC) effectively recovers substantial waste heat for electricity generation, enhancing energy utilization. The recovery efficiency is significantly influenced by the bottom cycle configurations and specific working conditions. Besides, implementing these bottom cycles introduces challenges related to increased system dimensions and design complexity. The present study aims to understand and evaluate the characteristics and optimal trade-offs of various bottom cycles, including trans-critical, subcritical, and non-azeotropic mixed working fluids, by establishing 3E (energy, exergy and Exergoeconomic) models for sCO2/tCO2, sCO2/ORC, and sCO2/KC combined cycle systems. To analysis and enhance interpretability, statistical Global Sensitivity Analysis (GSA) alongside unsupervised learning-based Self-Organizing Map (SOM) techniques and parametric analysis are employed. These methods identify key parameters and discern system patterns. Subsequently, the Non-Dominated Sorting Whale Optimization Algorithm (NSWOA) and entropy weight-based Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) are applied to establish a Pareto-optimal decision space and identify compromised ideal design points for each combined cycle. The results quantitatively rank sensitivity for objective variables within the design space in different combined cycles and visually represent system nonlinearity and coupling relationships in 2D weight planes using SOM. The TOPSIS trade-off points based on the Pareto frontier for the three combined cycles are ηth = 45.08 %, cp,tot = 8.5199 $/GJ, ηth = 45.13 %, cp,tot = 8.3739 $/GJ, and ηth = 48.97 %, cp,tot = 8.4783 $/GJ, respectively. Integrating machine learning techniques provides a comprehensive understanding of system patterns, offering valuable insights for decision-makers in the design and optimization of combined cogeneration cycles.

4E analysis of novel waste heat-driven combined cooling and power (CCP) systems based on modified Kalina-ejector refrigeration cycles

Global warming and environmental pollution are becoming increasingly severe problems due to the excessive use of fossil fuels. Recovering and utilizing waste heat from different energy systems can considered a sustainable solution to this destructive trend. This study proposes two modified Kalina cycle structures that use ejector refrigeration for combined cooling and power (CCP) generation in low-temperature waste heat. While to recover energy from a lean ammonia solution uses a two-phase expander. Thermodynamic analysis shows that the modified Kalina cycles E and F operate with a thermal efficiency of 0.3066 and 0.2557, respectively, representing a significant improvement of more than 123% and 86%, respectively, compared to the base cycle. Also, the exergy efficiency of the improved configurations E and F has been calculated as 0.083 and 0.089, respectively, showing an improvement of 53.8% and 64.8%, respectively, compared to the base cycle. The exergoeconomic analysis also revealed that the total capital cost rate for improved cycles E and F is estimated at 2.62 and 2.76 $/h, respectively. In addition, from an environmental perspective, the improved Kalina cycle F has proven to have a more eco-friendly performance with a pollution index of 0.2281 mPts/s. Moreover, a parametric study is conducted to investigate and analyze the effect of changes in significant performance parameters such as ammonia concentration, evaporator temperature, turbine inlet temperature and pressure, and turbine back-pressure for both presented modified cycles.

Investigation of a novel multigeneration system driven by an ammonia-methane Brayton cycle with partial production and utilization of ammonia, methane, and hydrogen: Energy and carbon footprint assessments

In this paper, to address gaps in the development of low-carbon energy systems, an innovative concept of an ammonia-methane Brayton cycle is proposed. This system is interconnected with various subsystems, including the Kalina cycle, high-temperature steam electrolysis, thermoelectric generators, and ammonia and methane synthesis reactors. The primary aim of this system was to reduce dependence on external resources by establishing local sources for water and fuel, thus reducing the environmental impact and enhancing energy sustainability. A thermodynamic model of an energy system was developed via EES codes which leads to a thoughtful perception into the interactions of the proposed system parameters. Also, comprehensive investigations involved the examination of different energy system scenarios. Modeling outputs of the proposed multigeneration system discovered excellent thermal efficiency and power production, with figures of 56.5 % and 17 MW, respectively, while the Brayton system showed the results of 23.7 % and 3.8 MW. This study also highlighted the environmental benefits of the multigeneration system by demonstrating a carbon dioxide emission of 0.058 kg/kWh, representing its significant positive impact on environmental sustainability. Also, the produced ammonia and methane within the system was 0.37 % and 9 %, of fuel in combustion chamber, respectively. Also, the rest of demand fuel was provided from the external resources.

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.

Fluid dynamics in the Kalina cycle: Optimizing heat recovery for sustainable energy solutions

The Kalina cycle is well-known for its innovative energy conversion optimization, utilizing various working fluids such as butane, freon, isobutane, and pentane to evaluate efficiency and performance. This research explores the interaction of fluids in the Kalina cycle to enhance heat recovery by utilizing heat from road infrastructure. Our research focuses on analyzing thermodynamic intricacies and fluid dynamics to provide insights for improving sustainable energy technologies and enhancing heat utilization in various industrial applications. The performance of working fluids in the Kalina cycle has a notable impact on power generation or consumption, which can differ depending on the equipment configurations. One interesting observation is that certain cycles showed a net energy gain at the turbine, particularly the ammonia cycle running at 75 % working fluid, which generated a total net power of −1030.6048 kW. Two freon cycles were compared in terms of net power output: the pure freon cycle produced −125.493 kW, whereas the freon cycle with 90 % freon generated −375.1616 kW. Finally, the pentane cycle with a 50 % efficiency yielded a net power output of −137.6613 kW. This study offers a thorough understanding of how working fluids perform in the Kalina cycle, which can help improve energy conversion processes and promote sustainable energy solutions.

Development and Assessment of the Performance of a Novel Parabolic Trough Solar Collector-Driven Three-Stage Cooling Cycle

Abstract A gaseous flow is employed as heat transfer fluid (HTF) in a parabolic trough solar collector (PTSC) for simultaneous production of cooling at three different levels of temperature to meet the demands of air conditioning, refrigeration, and ultra-low-temperature refrigeration required to ensure the efficacy of some special vaccines. The combined system consists of five subsystems including PTSC, Kalina cycle (KC), ejector refrigeration cycle (ERC), cascaded refrigeration cycle (CRC), and absorption refrigeration cycle (ARC). A simulation through an engineering equation solver (EES) is conducted to assess the impact of internal tube diameter of absorber and solar irradiation on rise of HTF temperature and mass flowrate of Kalina cycle fluid. It is determined that for given solar irradiation, the temperature of HTF goes down when internal diameter of absorber tube is enlarged. The influence of weather conditions; solar irradiation and ambient temperature, type of HTF, and concentration of ammonia–water basic solution on thermal and exergy efficiencies of three-stage cooling cycle (TSC) are examined. The TSC with helium-operated PTSC delivers better results than air and CO2. Exergy analysis shows that solar collector (30.26%) dissipates the highest exergy, followed by the ejector (12.5%) and vapor generator subsystem (7.61%). The type of CRC fluid pair affects TSC cycle refrigeration capacity and cooling exergy efficiency. The promotion of solar irradiation from 850 to 1200 W/m2 increases the cooling exergy efficiency of the three-stage cycle from 6.72% to 9.52% when the evaporator temperature is set at −45 °C and CRC employs NH3-propylene.

Renewable energy-water nexus: Optimal design of an integrated system including a single flash geothermal plant, Kalina cycle, and seawater desalination units

This paper concerns the optimization of a dual-purpose desalination system based on a geothermal flash cycle, a Kalina cycle, and a desalination process. A non-linear mathematical programming (NLP) optimization is developed and implemented in GAMS –General Algebraic Modelling System– a high-level modeling environment widely used in process systems engineering (PSE). CONOPT, a NLP derivative-based optimization algorithm, is employed. Furthermore, dynamic link libraries (DLLs) are developed and implemented in C programming code to calculate the thermodynamic properties of all process streams. The DLLs are systematically called from the GAMS environment. Additionally, a solution strategy has been devised to facilitate model convergence. In this strategy, several models are solved sequentially, commencing with the simplest model and progressing to solve the most complex model. This approach enables the optimal sizing and operating conditions of all process units to be obtained simultaneously. Two process configurations, differing in the type of seawater desalination system (reverse osmosis and multi-stage flash desalination systems), are optimized. The proposed mathematical models are effective decision-making tools for the design and synthesis of integrated geothermal power and seawater desalination processes. They can be used as either simulators or optimizers, depending on the number of degrees of freedom specified by the user.

Optimizing trigeneration energy systems: Biogas-centric methanol production via direct CO2 hydrogenation with advanced integration of PEM electrolyzer and LNG cold technology

Biogas, a sustainable alternative to fossil fuels, addresses issues of non-renewability and accessibility. Its structural similarity to fossil fuels makes it a potent option for energy systems. With this in mind, this paper discusses a novel trigeneration system that utilizes biogas and Liquefied natural gas cooling to produce methanol, electricity, cold water, hot water, oxygen, and natural gas. The system integrates various components such as a biogas burner, Kalina cycle, organic Rankine cycle, liquefied natural gas liquid gasification cycle, proton exchange membrane electrolyzer, and methanol synthesis unit. Simulation via Aspen HYSYS software includes an analysis of energy, exergy, economic, and environmental aspects. Efficiency assessment in single generation, cogeneration, trigeneration, and chemical trigeneration modes concludes chemical trigeneration as most efficient, with the proton exchange membrane electrolyzer being the most efficient subsystem. Key variables like Kalina cycle evaporator temperature, gas flow rate to the methanol reactor, and organic Rankine cycle working fluid pressure are assessed. Predictions on thermodynamic, environmental, and economic behaviors, along with their fluctuations, are made. Using a thermoeconomic approach, the economic analysis determines an exergy unit cost of 59.79 $/GJ and a total cost rate of 2764 $/h. Overall, this work presents a novel and efficient chemical trigeneration system that utilizes biogas and LNG cooling to produce multiple products.

Thermo-enviro-economic analyses of a landfill biogas-fed polygeneration process combined with a liquefied natural gas cold energy utilization unit

Landfill biogas offers a promising opportunity to supply society’s energy requirements, following the waste-to-energy approach, which issuitable for sustainable production. However, structural modification for its utilization is the main gap, requiring additional research efforts. Considering this issue, the current study aims to design an eco-friendly polygeneration method for landfill biogas utilization for a cutting-edge heat recovery system that integrates a cold energy recovery and utilization unit for liquefied natural gas. The liquefied natural gas recovery section, the organic Rankine cycle with a zeotropic mixture, and the Kalina cycle are all started using the flue gas from the combustion of biogas in a cascade process. In addition, the waste heat of the Kalina cycle is recovered by a single-effect desalination cycle and liquefied natural gas recovery section. Also, a water electrolysis process is integrated into the whole system. As a result, the products include hydrogen, electricity, natural gas, hot and cold water, and freshwater. The Aspen HYSYS software is utilized to design the system and investigate its thermodynamic, environmental, and economic aspects. The results demonstrate an energy efficiency of 57.54 % and an exergy efficiency of 18.78 %. Also, the carbon dioxide footprint associated with the system equals 0.34 kg/kWh, and the specific cost of products is 73.96 $/GJ. An optimal exergy efficiency of 25.8 % and a specific cost of products of 69.7 $/GJ are obtained by means of an intelligent optimization approach that ultimately makes use of non-dominated sorting genetic algorithm-II and artificial neural networks.

Development and modeling of power, hydrogen and freshwater production based on a novel double-flash geothermal power plant

In this article, a novel geothermal energy-assisted multigeneration plant is proposed and analyzed from the thermodynamic, economic, and environmental perspectives. In the design of the geothermal power system, a transcritical Rankine cycle, which employs CO2 as the working fluid (tCO2-RC), a Kalina cycle (KC), a hydrogen generation sub-plant, and a desalination unit are considered. The reverse osmosis (RO) desalination process is used for freshwater production, while the proton exchanger membrane (PEM) electrolyzer is utilized for hydrogen generation. In addition, parametric analyses are conducted to ascertain the impacts of the temperature of the geothermal source, mass flow rate, and flash chamber pressure on system performance. According to the results, the plant's overall energetic and exergetic efficiencies are determined to be 8.6 % and 34.9 %, respectively where the net power production is calculated as 3317.94 kW, and the system's total irreversibility is found to be 5852.88 kW. Furthermore, the hourly H2, O2, and freshwater generation amounts are 8.5 kg, 49.1 kg, and 9.3 m3, respectively. Finally, the levelized energy cost (LEC) and sustainability index of the system are found to be 0.128 USD/kWh and 0.215.

Energy and exergy optimization of Kalina Cycle System-34 with detailed analysis of cycle parameters

This study proposes a novel methodology for optimizing the Kalina Cycle System-34, providing new insights into the existing literature on the cycle. The research highlights the cycle's key variables and identifies the most critical parameters that require improvement while proposing a practical and effective optimization method. The effects of parameters on thermal and exergy efficiency were quantified using Taguchi and ANOVA methods. The study focuses on critical parameters such as evaporator outlet temperature, turbine inlet pressure, ammonia concentration, turbine efficiency, and pump efficiency. The optimal values of these parameters were determined within specified ranges. Furthermore, the study employed the L25 orthogonal array to create case scenarios that reduced the computational cost of the Kalina cycle. The best-case scenario was not included in the 25 cases in the orthogonal array, which significantly reduced computational costs. The results showed that the system's thermal efficiency increased to 16.2 %, and exergy efficiency increased to 27.8 %, with the case conditions for the best case being an evaporator outlet temperature of 120 °C, ammonia concentration of 0.9, turbine inlet pressure of 40 bar, turbine efficiency of 0.9, and pump efficiency of 0.8.

Exergo-economic analyzes of a combined CPVT solar dish/Kalina Cycle/HDH desalination system; intelligent forecasting using artificial neural network (ANN) and improved particle swarm optimization (IPSO)

Power and freshwater are two energy-intensive products, which consume a huge amount of fossil fuels. It is important to supply the aforementioned products using renewable energy sources due to the depletion of fossil fuel resources and environmental issues. This paper investigates the exergy and exergy-economic analysis of water and power production using a small-scale combined cycle encompasses the concentrated photovoltaic thermal (CPVT) solar collectors, a Kalina cycle (KC), and a humidification-dehumidification (HDH) desalination unit. An exergo-economic parametric analysis was first investigated to determine the influence of some pertinent parameters on the exergy efficiency, and specific unit cost of the products. In the second stage, two intelligent forecasting approaches based on the artificial neural network (ANN) and improved particle swarm optimization (PSO) algorithms were utilized for predicting the performance metrics of the studied system. The system was supposed to work at half of the year's hour. The results demonstrated that the shares of CPVT, generator, humidifier, dehumidifier, and condenser in exergy destruction are 84 %, 6 %, 3 %, 2.5 %, and 2 %, respectively. Moreover, the exergy efficiency, and specific unit cost of the products, unit cost of electricity, and unit cost of the fresh water at the design condition were obtained as 23.23 %, 0.0806 $/kWh, 5.44 $/m3, and 31.15 $/GJ, respectively. Besides, the most effective parameter on the exergy efficiency and the specific unit cost of the products was the solar beam radiation, the increment in which from 300 W/m2 to 1000 W/m2 improved the exergy efficiency by 15.21 % and reduced the specific unit cost of the products by 63.16 %. In addition, the increase in the condenser pressure from 15 bar to 22 bar and the generator pinch point temperature difference from 5 °C to 15 °C reduced the exergy efficiency by 8.13 % and 4.03 %, respectively, leading to increasing the specific unit cost of the products by 1.30 % and 4.30 %. The results of modeling showed that hybrid ANN-IPSO models provide the most accurate prediction, highest tendency, and agreement to observation as compared to ANN in terms of (R2| exergy efficiency = 0.9903 and R2| specific unit cost of products = 0.9948) and (RMSE| exergy efficiency = 0.0010 and RMSE| specific unit cost of products = 0.9684).

Waste heat recovery from a green ammonia production plant by Kalina and vapour absorption refrigeration cycles: A comparative energy, exergy, environmental and economic analysis

The production of green ammonia involves significant energy penalties due to heat losses. Recovering this heat can enhance the sustainability of ammonia production. However, this area remains largely unexplored, making it unclear which approach to waste heat recovery is best suited. Therefore, this paper investigates two methods of waste heat recovery in a green ammonia production plant: the Kalina Cycle (KC) and the Vapour Absorption Refrigeration Cycle (VARC). The underlying processes are simulated, and an analysis is conducted covering energy, exergy, environmental, and economic aspects. The results show that integrating the system with KC yields a marginal energy efficiency improvement of about 1%. However, when the conventional ammonia production system is integrated with VARC, the improvement in energy efficiency reaches 8%, while exergy efficiency improves by 11%. An environmental assessment estimates the greenhouse gas emissions saved by each heat recovery method, revealing that VARC achieves almost four times the emission savings compared to KC. Economically, integrating KC increases the levelized cost of ammonia (LCOA) by over 18%, whereas adding VARC has almost no impact on the LCOA. Overall, the co-production of refrigeration using VARC is identified as a superior heat recovery technique for green ammonia plants.

Design and evaluation of a geothermal power plant integrated with Mg(OH)₂/MgO thermochemical energy storage system: A dynamic simulation for assessing flexibility in power generation, energy, and economics

This study proposes a Carnot battery system that integrates MgO/Mg(OH)2-thermochemical energy storage (TCES) in a fluidized bed reactor (FBR) with Kalina cycle of a geothermal power plant. In the charge mode, surplus electricity from variable renewable energy is converted into heat and stored through the dehydration of Mg(OH)2. In the discharge mode, the hydration of MgO occurs in the FBR, and the reaction heat is converted into electricity through the Kalina cycle. Dynamic simulations of the charge and discharge modes were conducted using a non-steady state fluidized bed model. Results show the energy storage efficiency and capital cost were 76.4% and 68 USD/MJth for the base case, respectively. Round-trip efficiency and levelized cost of storage were 8.62% and 0.291–0.769 USD/kWhe, respectively, when the charging electricity cost was 0–0.042 USD/kWhe. A cost-competitive Carnot battery system using MgO/Mg(OH)2-TCES with high energy storage density and an easy-to-operate FBR has been developed.

Multi-criteria study and optimization of an innovative combined scheme utilizing compressed air energy storage for a modified solid oxide fuel cell-driven gas turbine power plant fueled by biomass feedstock

This paper explores the potential of a combined solid oxide fuel cell and gas turbine technology for medium- to large-scale power generation, emphasizing its applicability and sustainability, particularly with biomass feedstock. An innovative heat integration process is developed for a modified solid oxide fuel cell and gas turbine power plant, incorporating a steam power cycle, compressed air energy storage, a Kalina cycle, and a domestic hot water production subsystem. The system utilizes biomass through a downdraft gasifier, enabling a comprehensive evaluation of thermodynamic, economic, and environmental performance during both charging and discharging phases. A detailed parametric sensitivity analysis is performed to investigate two operational modes. Subsequently, five multi-objective optimization scenarios are formulated and optimized using the cuckoo search algorithm and two decision-making approaches. The results indicate that the optimization scenario focusing on exergetic round-trip efficiency and the unit cost of products during the discharging phase achieves superior thermodynamic and environmental performance. Specifically, the system exhibits energetic and exergetic round-trip efficiencies of 59.20 % and 51.06 %, respectively, with a levelized total emission of 0.64 kg/MWh. Furthermore, when considering the objectives of exergetic round-trip efficiency and net present value, the optimal economic performance is achieved with a payback period of 1.54 years and a net present value of $7.44 million.

Comparative analysis of Kalina and ORC cycles in renewable energy systems: exergo-environmental assessment and cost calculations with carbon emissions

Comparative analysis of Kalina and ORC cycles in renewable energy systems: exergo-environmental assessment and cost calculations with carbon emissions

Proposing an innovative polygeneration process based on biogas fuel: A comprehensive thermo-enviro-economic (4E) analysis

The utilization of biogas as a renewable fuel is feasible due to its high energy density, allowing for the development of polygonation structures in a cascade configuration. However, the high initial cost associated with biogas-based high-temperature applications is the central gap considered in this study. This paper introduces a novel heat integration model that employs a novel multi-stage cascade heat recovery and cost-effective operational approach. A biogas burner, an organic Rankine cycle, a Kalina cycle, an absorption chiller cycle, a heat supplier unit, and a proton exchange membrane electrolyzer-based hydrogen generating process are all part of the proposed system. Following the structure's modeling with the Aspen HYSYS program, thermodynamic, environmental, and economic evaluations are carried out along with a thorough parametric assessment. The simulation results indicate that the system has the capability to generate 2993 kW of electricity, 23350 kg/h of hot water at 80 °C, 68120 kg/h of chilled water at 10 °C, and generate 40.32 kg/h of hydrogen. This structure's energy, exergy, and electrical efficiencies are measured at 40 %, 23.71 %, and 16.68 %, respectively. Moreover, the exergy analysis indicated that the biogas burner and ORC evaporator account for 75.1 % of the total irreversibility (13800 kW).

Electricity Cogeneration Potential in Minas Gerais Cement Industry with Thermodynamic Cycles

To assess the electricity cogeneration potential in the Minas Gerais cement industry with thermodynamic cycles is the main purpose of this study. The potential was estimated based on Minas Gerais cement sector data. The Kalina cycle, the organic Rankine cycle, and the conventional Rankine cycle were technically and economically assessed. The technical evaluation considered the thermodynamic modeling with optimization including the mass, energy, entropy, and exergy balances and the heat transfer calculations for heat exchangers. The economic evaluation considered the economic modeling including the calculation of electric power generated specific cost, the total investment, cash flow, and payback. The result shows that the greatest irreversibilities are concentrated in the turbines and evaporators. The Kalina cycle confirmed more generated power and exergetic efficiency, but in terms of thermal efficiency, the values were very similar between the cycles. The three cycles can cover more than 35% of the energy demand, which means a considerable reduction in cement manufacturing costs. All cycles reveal a payback value lower than 3 years, a considerable value of cash flow, and high competitiveness in the current tariff scenario. The electricity cogeneration potential in the Minas Gerais cement industry is near 100 MW, and it is in the south-central region of Minas Gerais, where there is a greater population and energy demand concentration. This potential could save emissions of around 282,913 tCO2/year.

Optimization and 4E analysis of integration of waste heat recovery and exhaust gas recirculation for a marine diesel engine to reduce NOx emissions and improve efficiency

This paper proposes an integration of waste heat recovery system and exhaust gas recirculation system to break the inherent trade-offs between NOx and carbon emissions of marine low-speed diesel engine. It is significant important to break these trade-offs, because Energy Efficiency Existing Ship Index may not be met, though Energy Efficiency Design Index and Tier III can be already achieved for old ships. The waste heat recovery system consists of supercritical carbon dioxide Brayton cycle and Kalina cycle, where the integration of supercritical carbon dioxide Brayton cycle and Kalina cycle is achieved in the parallel style. This paper uses the classical thermodynamics in terms of engineering approach to carry out the parameter analysis of combined system first. The optimization is conducted in terms of efficiency, energy density and techno-economy with the introduction of global optimal policy. The results showed that the highest efficiency of 52.32% at Tier III mode can be achieved, at which the net power, exergy efficiency, area per unit power output and levelized energy cost can be achieved by 1568.57 kW, 45.75%, 0.589 m2/kW and 0.114$/kWh at main engine load of 85%. Further, the net power output of waste heat recovery system can reach 1085.76 kW and 2043 kW at Tier II mode and Tier III mode, while the recovering rate of waste heat recovery system can reach over 5% at Tier III mode. Finally, the Energy Efficiency Existing Ship Index of a container ship equipping with such combined system can be reduced from 9.50 to 9.05.

Proposal of a geothermal-driven multigeneration system for power, cooling, and fresh water: Thermoeconomic assessment and optimization

The depletion of fossil fuel reserves and environmental challenges have prompted the exploration of alternative energy sources. Geothermal energy, extractable from within the Earth's crust, emerges as a reliable renewable option throughout the mentioned shift. In this regard, the presented study introduces a geothermal-powered multigeneration system designed to generate power, manage cooling loads, and produce fresh water. This comprehensive system incorporates an organic flash cycle, a half-effect absorption refrigeration unit, a Kalina cycle, and a humidification-dehumidification desalination unit. Evaluating the system's thermoeconomic performance involves considering input parameters and simplifying assumptions to determine the performance profitability of the presented system. Furthermore, a parametric examination is conducted which is followed by the employment of an optimization analysis across three diverse scenarios to identify the most favorable operating conditions. The results of the presented research reveal that the suggested system can deliver power, cooling capacity, and freshwater production at rates of 342.3 kW, 301.7 kW, and 0.233 kg/s, respectively. Additionally, the system demonstrates an exergy efficiency of 31.52 % and achieves a payback period of 5.85 years.