Thermodynamic and thermo-economic analysis of dual-pressure and single pressure evaporation organic Rankine cycles

Wang, Mingtao; Chen, Yi-Guang; Liu, Qiyi; Zhao, Yuanyuan

doi:10.1016/j.enconman.2018.10.017

Cited by 47 publications

(18 citation statements)

References 33 publications

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“…There are some assumptions to simplify the model and its calculations based on References [ 11 , 66 , 67 ]: The flow in the plate condenser is a stable state and homogeneous for flow direction. The working fluid is a two-phase state at the inlet of the plate condenser.…”

Section: Plate Condenser and Its Performancementioning

confidence: 99%

Performance Optimization of a Condenser in Ocean Thermal Energy Conversion (OTEC) System Based on Constructal Theory and a Multi-Objective Genetic Algorithm

Feng

Chen

et al. 2020

Entropy

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Constructal optimization of a plate condenser with fixed heat transfer rate and effective volume in ocean thermal energy conversion (OTEC) system is performed based on constructal theory. Optimizations of entropy generation rate ( S ˙ g ) in heat transfer process and total pumping power ( P sum ) due to friction loss are two conflicting objectives for a plate condenser. With the conventional optimization method, the plate condenser is designed by taking a composite function (CF) considering both S ˙ g and P sum as optimization objectives, and employing effective length, width, and effective number of heat transfer plates as design variables. Effects of structural parameters of the plate condenser and weighting coefficient of CF on design results are investigated. With a multi-objective genetic algorithm, the plate condenser is designed by simultaneously optimizing S ˙ g and P sum , and the Pareto optimal set is obtained. The results demonstrate that CFs after primary and twice-constructal optimizations are respectively reduced by 7.8% and 9.9% compared with the initial CF, and the effective volume of the plate condenser has a positive impact on the twice minimum CF. Furthermore, the Pareto optimal set can provide better selections for performance optimizations of plate condensers.

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Section: Plate Condenser and Its Performancementioning

confidence: 99%

Performance Optimization of a Condenser in Ocean Thermal Energy Conversion (OTEC) System Based on Constructal Theory and a Multi-Objective Genetic Algorithm

Feng

Chen

et al. 2020

Entropy

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“…The reason behind the selection of a scroll expander is the higher characteristic efficiency, with respect to sliding vane technology, at the low mass flowrates that usually characterize low temperature waste heat recovery scenarios. Moreover, scroll expanders are robust towards the quality of the working fluid at inlet, resulting in less constraints on the selection of the superheating degree and eventually in a higher flexibility in thermal profiles matching at the evaporator: as extensively discussed in [34][35][36] this reflects on a lower loss for irreversibility at the heat exchanger and on a 1-to-3 percentage points gain on the overall energy efficiency of the system. Such an efficiency gain is extremely appealing in small scale systems, where a high back-work ratio (i.e.…”

Section: Combined Heat and Power System Modelingmentioning

confidence: 99%

“…Consequently, only little leverage on the performance enhancement is available from the optimum selection of fluid type, operating temperatures and pressures. A number of attempts can be retrieved in the scientific literature, ranging from the mainstream approaches -relying on the selection of highly performing fluids [28][29][30] and proper rotary equipment [31][32][33] -to more pioneering techniques, such as the enhancement of the heat exchanging sections, particularly in low-temperature small-scale plants with only few kW electricity production [34][35][36]: a common feature is the high additional cost required by those improvements and the fact that most of the time it is hardly offset by the gain on the power generation it assures.…”

Section: Introductionmentioning

confidence: 99%

Multi-Variable Control and Optimization Strategy for Domestic Solar-ORC Combined Heat and Power Generation System

et al. 2020

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The feasibility of a solar-ORC system for domestic combined heat and power generation (CHP) is deeply affected by both the time-varying ambient conditions (e.g. solar irradiance, temperature, wind speed) and the thermal and electrical load profiles variability of the final application. The definition of a proper control strategy is proven to be a major design-challenge for successful operation of solar-ORC systems, with the main goal of assuring that the thermal power demand for space heating and Domestic Hot Water (DHW) production and the electricity needs are simultaneously satisfied. The rising demand for energy-autonomous systems also calls for the inclusion of a storage system within the base-layout, that could assure the electricity demand is properly matched after sunset or in very-low irradiance conditions, such as cloudy days. A comprehensive model accounts for the dynamic of the plant-integrated unit, featuring an ORC-based plant that bottoms a flat plate solar thermal collector: a parametric study is presented, and an off-design analysis is performed to properly assess the energy performance of the system. The heat availability to the ORC heat exchanger is evaluated, based on solar availability, thermal losses in the pipes and plant requirements, in terms of operating temperature and pressures and organic fluid mass flowrate. R245fa is selected as working fluid in the ORC-section. Sliding vanes machines expander and pump – are considered as rotary equipment. Flat plate heat exchangers complete the base layout, the analysis accounts for. Due to the need for DHW production, a storage unit for hot water is present, upstream the recovery branch: dependently on the ability the fluid at the collector outlet has to meet the ORC requirements for proper operation (about 110°C), the ORC evaporator is fed and the recovery section enabled. Both continuous and unsteady operation underwent an in-depth analysis, as well as the benefits associated with different discharge times for the storage unit. A dedicated control strategy is defined, dependently on whether the electrical output or the thermal one need to be maximized, and accounts for either a flash or a progressive tank discharge. A virtual platform allowed the setting-up of a pilot plant, for direct performance assessment, in presence of different amounts of tank discharges per day and different lower temperatures at the storage tank.

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“…In the past few decades, an enormous amount of researches have been carried out on ORC, focusing on working fluid selection [6][7], expander design [7][8], cycle configuration modification [9][10], optimum design of heat exchanger [11][12], system optimization [13][14], and experimental research on ORC system [15][16], etc. Regarding to optimization researches on ORC, there are single-objective and multi-objective optimizations based on different evaluation criteria.…”

Section: Introductionmentioning

confidence: 99%

“…Regarding to optimization researches on ORC, there are single-objective and multi-objective optimizations based on different evaluation criteria. Generally, the evaluation criteria could be categorized into three classes which are thermodynamic indicators including net power output, thermal efficiency, exergy efficiency [17]; economic indicators including electricity production cost (EPC) [9,[18][19][20], levelized energy cost (LEC) [20], specific investment cost (SIC) [21], net present value (NPV), depreciated payback period (DPBP) [22]; and environmental impact through life cycle assessment (LCA) [23][24].…”

Section: Introductionmentioning

confidence: 99%

Multi-Objective Optimization of Organic Rankine Cycle for Low-Grade Waste Heat Recovery

et al. 2019

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The organic Rankine cycle (ORC) is considered as one of the most viable technology to recover low-grade waste heat. A multi-objective optimization model is established to simultaneously derive the maximum exergy efficiency and the minimum electricity production cost (EPC) of a specific ORC system by employing the genetic algorithm (GA). Evaporation temperature and condensation temperature are selected as decision variables. At first, variations of exergy efficiency and EPC with evaporation temperature and condensation temperature are investigated respectively using R245fa, R245ca, R600, R600a, R601 and R601a as working fluids. Subsequently, a multi-objective optimization is performed and the Pareto frontiers for various working fluids are obtained. Results indicate that performance of the specific ORC system with R245fa as working fluid is better that with other working fluids.

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Thermodynamic and thermo-economic analysis of dual-pressure and single pressure evaporation organic Rankine cycles

Cited by 47 publications

References 33 publications

Performance Optimization of a Condenser in Ocean Thermal Energy Conversion (OTEC) System Based on Constructal Theory and a Multi-Objective Genetic Algorithm

Performance Optimization of a Condenser in Ocean Thermal Energy Conversion (OTEC) System Based on Constructal Theory and a Multi-Objective Genetic Algorithm

Multi-Variable Control and Optimization Strategy for Domestic Solar-ORC Combined Heat and Power Generation System

Multi-Objective Optimization of Organic Rankine Cycle for Low-Grade Waste Heat Recovery

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