Performance analysis and multi-objective optimization of a novel solid oxide fuel cell-based poly-generation and condensation dehumidification system

An innovative polygeneration system is proposed to generate power, heat, hydrogen, and oxygen simultaneously. The system integrates a solar central tower system and the heliostat field, a gas turbine cycle, a supercritical carbon dioxide cycle, an Organic Rankine Cycle with a cyclopentane working fluid, and a Rankine steam cycle, and a Proton Exchange Membrane electrolyzer. In this study, to reduce the gas cycle fuel consumption, the solar tower system is integrated with the gas cycle. In the studied system, a Supercritical Carbon Dioxide cycle and an Organic Rankine Cycle have been used to heat recovery of the exhaust gases of the gas turbine. In addition, Energy, Exergy, Exergoeconomic, Exergoenvironmental, Emergoeconomic, and Emergoenvironmental analyses have been performed for this system hour by hour. A computer code was developed in MATLAB for these analyses, and the results are validated by simulation in Thermoflex software and primary references with high accuracy. A systematic approach based on thermodynamic analysis and a combination of Genetic Programming and Artificial Neural Networks is proposed for optimal design. Multi‐Objective Genetic Optimization has been employed to find optimum design parameters. Due to the reduction of computation time of optimization, the integration of Genetic Programming and Artificial Neural networks have been employed to generate correlations for objective functions based on the decision variables. By adding the solar system, the mass flow rate of natural gas consumption in the gas cycle decreases by about 9% and reaches 1.53 kg/s. Utilizing solar energy and the Rankine steam cycle, the production capacity of the considered cycle increases from 43 to 66 MW. Also, the performance analysis of the Proton Exchange Membrane electrolyzer and the primary cycle shows that this equipment can produce 0.01 g/s of hydrogen from 5 g/s of water entering the equipment per second by consuming 2.33 kW of power. The results show that when the decision variables are considered at the optimal performance point, the exergy efficiency, the total cost, the rate of destruction related to environmental impacts, cost based on emergy, and the rate of destruction environmental effects based on energy improve. The highest percentage of improvement among the objective functions compared to the initial state is related to the exergy efficiency with 46%, and then the environmental impact rate based on emergy with an improvement of 36%.

Comparison of different optimized heat driven power-cycle configurations of a gas engine

Techno-economic-environmental analysis and optimization of biomass-based SOFC poly-generation system

Techno-economic-environmental evaluation of a combined cooling heating and power system for gas turbine waste heat recovery

Risk and 4E analyses and optimization of a novel solar-natural gas-driven polygeneration system based on Integration of Gas Turbine–SCO2–ORC-solar PV-PEM electrolyzer

Techno-economic-environmental performance of multi-stage evaporation based poly-generation system under multiple energy supply scenarios

Feasibility study of green ammonia and electricity production via an innovative wind-solar-biomass polygeneration system

Thermodynamic assessment of integrated biogas-based micro-power generation system

In the present study, we investigated a multiple energy generation system based on the use of solar, wind and ocean thermal energy for the study area with high renewable energy potential. In this study, all existing capacities in coastal areas (wind, sun, ocean temperature difference) are used to design a renewable system. The present system consists of subsystems including organic Rankin cycle (ORC), wind turbine, thermoelectric, heat exchanger and flat panel solar collector. EES thermodynamic software has been used to model the system and obtain thermodynamic results. The system designed for the city of Bushehr, which has good ocean thermal energy, wind energy and solar radiation potential, has been studied. The most important effective and practical parameters in the proposed system are collector area, solar radiation, and wind turbine speed. The results of the investigation of the system in Bushehr City showed that the production power of the system is 4,840,913.8 and 1,138,957.02 kWh compared to the climate changes. Also, the amount of freshwater produced by the system is 103,495.99 and 429,080.51 m3/h compared to the climate changes. Finally, in order to optimize the designed system, the response level multi-objective optimization method has been used to find the best set of objective functions and decision variables. The two objective functions of this optimization included the exergy efficiency of the whole system and the system cost rate. The most optimal value of exergy efficiency was 13.25% and the cost rate was 72.17 $/hour.

Thermoeconomic optimization of a solar-assisted supercritical CO2 Brayton cycle, organic Rankine cycle and multi-effect distillation system

Performance analysis of a feasible technology for power and high-purity hydrogen production driven by methane fuel

The transition towards a more affordable, reliable, and sustainable energy provision paradigm is one of the main 21st century challenges that humanity must overcome to protect the planet from the harmful effect caused by climate change. The concentration of CO2 in the atmosphere has been dramatically increasing since the pre-industrial era. If the increase of green-house gasses emissions continues unabated, this will bring dramatic consequences for planet Earth, compromising eventually the existence of many species, including the human race. To avoid a climate change catastrophe, the share of primary energy coming from renewable energy resources must increase from around 15% in 2015 to 65% in 2050. This energy transition can not rely solely on few successful technologies (i.e., solar photovoltaic, and wind energy), but it must count on a larger variety of technical solutions that are suitable for a wider range of renewable sources and diversity of circumstances. For instance, renewable thermal energy sources for power generation (i.e., geothermal reservoir, biomass fuel, and concentrated solar radiation), can provide a large portion of the world electricity demand in the future. However, the exploitation of a good portion of these sources strongly depends on the market success of technologies such as the Organic Rankine Cycle (ORC) power system. One of the key aspects to make ORC systems economically competitive, especially at the smaller sizes (⇡ 1 − 50 kW), is the realization of highly efficient turbomachinery components. The fluid-dynamic design of ORC turbomachinery significantly differs from the design of traditional machines (i.e., steam and gas turbines), and this is mainly due to the different thermo-physical properties and gas dynamic behavior of the organic working fluids. This means that design methods devised for standard steam and gas turbomachinery can not be used for turbomachinery operating in the Non-ideal compressible fluid dynamics (NICFD) region. Furthermore, no experimental campaigns have ever been carried out to create a body of empirical knowledge to support the design highly efficient ORC turbomachinery. As a consequence, the entire design process of ORC turbomachinery relies only on the use of advanced CFD software. The current trend is to couple CFD tools with numerical optimization techniques in order to automatically obtain optimal flow passage geometries. In particular, adjoint-based methods have clearly demonstrated to be the only optimization technique capable of tackling the multi-stage turbomachinery design problem, in which thousands of design variable must be concurrently optimized. Therefore, the research documented in this PhD dissertation aimed at extending the adjoint method in order to perform the fully-turbulent fluid-dynamic shape optimization of 3D multi-stage ORC turbomachinery. This document contains an extensive introduction, three main chapters, each documenting a building block towards the accomplishment of the main goal of this PhD project, and a final concluding chapter that summarizes all the research outcomes of this work and proposes future steps for research in this field. The first part of the thesis describes the extension of the RANS equations, the convective numerical schemes, and the viscous numerical schemes to the use of complex thermo-physical laws, so to simulate turbulent flows of components working in the NICFD thermodynamic region. The second part documents the derivation of the adjoint solver in order to resolve shape-optimization design problems for 2D single row of ORC turbomachinery. Finally, the last part reports the extension of the adjoint method to 3D multi-stage turbomachinery design.

The organic Rankine cycle (ORC) is a promising power generation cycle to fully utilize the cold energy of liquid natural gas (LNG). ORC is usually operated under variable working conditions, and the operation performance is significantly worse than under design conditions. In this paper, a novel composition-tunable zeotropic ORC using LNG cold energy-based liquid-separation condenser is proposed and a thermodynamic optimization model is formulated. A case study is then conducted to validate the superiority of the proposed ORC and analyze the important operation parameters to explore the reasons for the performance advantages of the novel system. The results show that the novel ORC has a higher evaporation temperature, lower condensation temperature, lower condensation pressure, and lower pinch point temperature difference than the basic ORC. The exergy loss of the condenser is reduced, and the exergy efficiency is improved. The novel ORC features 2.86% higher annual average net power output, 2.47% higher annual average thermal efficiency, 2.85% higher annual utilization efficiency of cold energy, and 2.76% higher annual exergy efficiency of cold energy recovery than the basic ORC.

This review examines Organic Rankine Cycle (ORC) technology, which generates electricity using organic fluids at low temperature ranges. To enhance the efficiency of basic ORC systems, they are often adapted into Regenerative Organic Rankine Cycle (R-ORC) systems. The review highlights the dimensions of economic, energy, and exergy efficiency, which are critical for practical application. Factors like the choice of working fluid, heat source temperature, and heat exchanger efficiency significantly affect economic feasibility; suboptimal choices can reduce returns and hinder project viability. Strategic decisions can improve economic outcomes and make ORC technology more appealing, as improved efficiency often leads to better economic performance through increased energy output and reduced operational costs. ORC and R-ORC systems promote sustainable energy production by enhancing energy efficiency in various applications, including geothermal power plants, industrial waste heat recovery, biomass energy production, and solar power plants. By enabling electricity generation even at low temperatures, these systems efficiently utilize existing energy sources, reduce dependence on fossil fuels, and minimize environmental impacts, thus providing both economic and ecological benefits. Additionally, when the studies conducted are examined, R-ORC exhibits higher performance than basic ORC. R-ORC is significantly superior to ORC in terms of both energy and exergy efficiency. Specifically, in terms of energy efficiency, R-ORC has been found to be 1.83 %–25.5 % more efficient. Regarding exergy efficiency, R-ORC demonstrates approximately 7.69 % better performance. Furthermore, due to these increases in efficiency, it has been determined that R-ORC also provides a more positive economic contribution compared to ORC. Thus, comparisons between ORC and R-ORC systems play a significant role in sustainable energy production and offer valuable guidance for future research. The limitations of ORC and R-ORC systems include limited efficiency due to low temperature differentials, the environmental impact of the organic fluids used, and high costs.

Performance assessment and optimization of a novel integrated multigeneration system for residential buildings