Evaluation of a Novel Quadruple Combined Cycle with the Magnetohydrodynamic Generator based on 6E Analysis

2020 ◽  
pp. 1-28
Author(s):  
Mohammadamin Esmaeilzadehazimi ◽  
Mohammad Hasan Khoshgoftar Manesh ◽  
M. Majidi ◽  
Mohsen Nourpour
Keyword(s):  
High Temperature ◽  
Heat Source ◽  
Electric Power ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Brayton Cycle ◽  
Exergy Performance ◽  
Organic Fluids ◽  
First Time

Abstract The generation of the electric power through magnetohydrodynamic is one of the most advanced high -temperature energy conversions as it directly turns the heat into electricity. In this study, a quadruple cycle with magnetohydrodynamic generator was considered as the upstream cycle and a Brayton cycle was taken as the middle cycle through heating and an organic Rankine cycle and steam cycle were regarded as the downstream cycles using the heat loss of the magnetohydrodynamic generator and gas turbine, respectively. Energy, exergy, exergoeconomic, exergoenvironmental, emergoeconomic, and emergoenvironmental (6E) analyses were done in the proposed system simultaneously for the first time. In addition, advanced exergy, exergoeconomic, and exergoenvironmental analyses were performed for the proposed system to show the effect of irreversibility accurately and deeply. Despite the slight difference between the results of the emergoeconomic and emergoenvironmental sector with the exergoeconomic and exergoenvironmental sector, the obtained qualitative results were very similar showing that the emergoeconomic and emergoenvironmental analyses can be proper alternatives to the conventional exergoeconomic and exergoenvironmental analyses. The temperature of the heat source is one of the most important criteria for fluid selection in the organic Rankin cycles. Five organic fluids were selected and evaluated according to the desired hot source temperature for the Rankin organic cycle (262 °C). The results showed that the R141b with energy and efficiency of 15.25 and 58.05%, respectively had the best thermodynamic and exergy performance with the least amount of total costs using this fluid.

Working Fluid Selection for Organic Rankine Cycles from a Molecular Structural Point of View

2013 ◽  
Vol 805-806 ◽  
pp. 649-653
Author(s):  
Bing Zhang ◽  
Shuang Yang ◽  
Jin Liang Xu ◽  
Guang Lin Liu
Keyword(s):  
Critical Temperature ◽  
Heat Source ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Point Of View ◽  
Operating Conditions ◽  
Working Fluid ◽  
Working Fluids ◽  
Organic Fluids ◽  
Cycle Efficiency

The optimum working conditions of 11 working fluids under different heat source temperatures for an organic Rankine cycle (ORC) were located in our previous work. In the current work, the system irreversibility of each candidate were calculated and compared at their optimal operating conditions. Obvious variation trends of both the cycle efficiency and irreversibility were found for different types of organic fluids. It is suggested, when selecting working fluid for our ORC system, the critical temperature should be as close as possible to the heat source temperature to achieve high cycle efficiency but avoid large irreversibility. The relationships between the structure of the molecules and the critical temperature of the working fluids are investigated qualitatively and potentially meaningful for the rational selection of proper organic fluids for certain ORCs.

Organic Rankine Cycle as Bottoming Cycle to a Combined Brayton and Clausius - Rankine Cycle

2013 ◽  
Vol 597 ◽  
pp. 87-98
Author(s):  
Dariusz Mikielewicz ◽  
Jan Wajs ◽  
Elżbieta Żmuda
Keyword(s):  
Power Plant ◽  
Power Plants ◽  
Large Scale ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Working Fluid ◽  
Preliminary Evaluation ◽  
Organic Fluids ◽  
Steam Cycle

A preliminary evaluation has been made of a possibility of bottoming of a conventional Brayton cycle cooperating with the CHP power plant with the organic Rankine cycle installation. Such solution contributes to the possibility of annual operation of that power plant, except of operation only in periods when there is a demand for the heat. Additional benefit would be the fact that an optimized backpressure steam cycle has the advantage of a smaller pressure ratio and therefore a less complex turbine design with smaller final diameter. In addition, a lower superheating temperature is required compared to a condensing steam cycle with the same evaporation pressure. Bottoming ORCs have previously been considered by Chacartegui et al. for combined cycle power plants [ Their main conclusion was that challenges are for the development of this technology in medium and large scale power generation are the development of reliable axial vapour turbines for organic fluids. Another study was made by Angelino et al. to improve the performance of steam power stations [. This paper presents an enhanced approach, as it will be considered here that the ORC installation could be extra-heated with the bleed steam, a concept presented by the authors in [. In such way the efficiency of the bottoming cycle can be increased and an amount of electricity generated increases. A thermodynamic analysis and a comparative study of the cycle efficiency for a simplified steam cycle cooperating with ORC cycle will be presented. The most commonly used organic fluids will be considered, namely R245fa, R134a, toluene, and 2 silicone oils (MM and MDM). Working fluid selection and its application area is being discussed based on fluid properties. The thermal efficiency is mainly determined by the temperature level of the heat source and the condenser conditions. The influence of several process parameters such as turbine inlet and condenser temperature, turbine isentropic efficiency, vapour quality and pressure, use of a regenerator (ORC) will be presented. Finally, some general and economic considerations related to the choice between a steam cycle and ORC are discussed.

scholarly journals Exergy performance of a new ORC configuration of a solar cogeneration system using a gas ejector

2020 ◽  
Vol 330 ◽  
pp. 01025
Author(s):  
Larbi Afif ◽  
Nahla Bouaziz
Keyword(s):  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Coefficient Of Performance ◽  
Thermal Source ◽  
Subcritical Regime ◽  
Energy And Exergy ◽  
Cogeneration System ◽  
Exergy Performance ◽  
Organic Fluids ◽  
System Operating

In the context of sustainable development and more particularly the conversion of heat into electricity, the present work proposes a new system of cogeneration operating at low energy value. It’s an organic Rankine cycle, associated with a gas ejector and operating with different organic fluids. It should be noted that the development of the ORC technology is partly a well-adapted response to problems of energy saving and ecosystem preservation. Accordingly, this paper presents a new configuration of a cogeneration system operating at low temperature and ensuring the simultaneous production of electricity and refrigeration. The proposed system is operating under transcritical and subcritical regime using solar energy as thermal source. On the other hand, an energy and exergy study has been developed by choosing the refrigerants R124, R236fa, R1234yf and R1234ze as working fluids according to their low environmental impact and thermodynamic properties. The results of the numerical simulation carried out as part of this study have also shown the importance of integrating the ejector into the proposed machine. Indeed, we investigated the effect of the thermodynamic parameters of the ejector on the coefficient of performance and the exergy efficiency of the cogeneration system.

High-Efficiency Solar Dynamic Space Power Generation System

1991 ◽  
Vol 113 (3) ◽  
pp. 131-137 ◽  
Author(s):  
Aristide Massardo
Keyword(s):  
Power Generation ◽  
Power Systems ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Generation System ◽  
Dynamic Power ◽  
Power Generation System

Space power technologies have undergone significant advances over the past few years, and great emphasis is being placed on the development of dynamic power systems at this time. A design study has been conducted to evaluate the applicability of a combined cycle concept—closed Brayton cycle and organic Rankine cycle coupling—for solar dynamic space power generation systems. In the concept presented here (solar dynamic combined cycle), the waste heat rejected by the closed Brayton cycle working fluid is utilized to heat the organic working fluid of an organic Rankine cycle system. This allows the solar dynamic combined cycle efficiency to be increased compared to the efficiencies of two subsystems (closed Brayton cycle and organic fluid cycle). Also, for small-size space power systems (up to 50 kW), the efficiency of the solar dynamic combined cycle can be comparable with Stirling engine performance. The closed Brayton cycle and organic Rankine cycle designs are based on a great deal of maturity assessed in much previous work on terrestrial and solar dynamic power systems. This is not yet true for the Stirling cycles. The purpose of this paper is to analyze the performance of the new space power generation system (solar dynamic combined cycle). The significant benefits of the solar dynamic combined cycle concept such as efficiency increase, mass reduction, specific area—collector and radiator—reduction, are presented and discussed for a low earth orbit space station application.

A Supercritical CO2 Brayton Cycle Micro Turbine for Waste Heat Conversion: Optimization Layout in Cogenerative Applications

2021 ◽  
Author(s):  
Fabrizio Reale ◽  
Raniero Sannino ◽  
Raffaele Tuccillo
Keyword(s):  
Gas Turbines ◽  
Supercritical Co2 ◽  
Waste Heat ◽  
Mechanical Energy ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Thermal Source ◽  
Brayton Cycle ◽  
Micro Turbine

Abstract Waste heat recovery (WHR) can represent a good solution to increase overall performance of energy systems, even more in case of small systems. The exhaust gas at the outlet of micro gas turbines (MGTs) has still a large amount of thermal energy that can be converted into mechanical energy, because of its satisfactory temperature levels, even though the typical MGT layouts perform a recuperated cycle. In recent studies, supercritical CO2 Brayton Cycle (sCO2 GT) turbines were studied as WHR systems whose thermal source was the exhausts from gas turbines. In particular, subject of this study is the 100 kW MGT Turbec T100. In this paper, the authors analyze innovative layouts, with comparison in terms of performance variations and cogenerative indices. The study was carried out through the adoption of a commercial software, Thermoflex, for the thermodynamic analysis of the layouts. The MGT model was validated in previous papers while the characteristic parameters of the bottoming sCO2 GT were taken from the literature. The combined cycle layouts include simple and recompression sCO2 bottoming cycles and different fuel energy sources like conventional natural gas and syngases derived by biomasses gasification. A further option of bottoming cycle was also considered, namely an organic Rankine cycle (ORC) system for the final conversion of waste heat from sCO2 cycle into additional mechanical energy. Finally, the proposed plants have been compared, and the improvement in terms of flexibility and operating range have been highlighted.

Investigation of the Performance of a Three Stage Combined Power Cycle for Electric Power Plants

2019 ◽  
Author(s):  
Pereddy Nageswara Reddy ◽  
J. S. Rao
Keyword(s):  
Power Plant ◽  
Electric Power ◽  
Steam Turbine ◽  
Gas Turbine ◽  
Pressure Ratio ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Brayton Cycle ◽  
Atmospheric Air ◽  
Power Cycle

Abstract A three stage combined power cycle with a Brayton cycle as the topping cycle, a Rankine cycle as the middling cycle and an Organic Rankine Cycle (ORC) as the bottoming cycle is proposed in the present investigation. A two-stage Gas Turbine Power Plant (GTPP) with inter-cooling, reheating and regeneration based on the Brayton cycle, a single-stage Steam Turbine Power Plant (STPP) based on the Rankine cycle, and a two-stage ORC power plant with reheating based on ORC with atmospheric air as the coolant is considered in the present study. This arrangement enables the proposed plant to utilize the waste heat to the maximum extent possible and convert it into electric power. As the plant can now operate at low sink temperatures depending on atmospheric air, the efficiency of the combined cycle power plant increases dramatically. Further, Steam Turbine Exhaust Pressure (STEP) is positive resulting in smaller size units and a lower installation cost. A simulation code is developed in MATLAB to investigate the performance of a three stage combined power cycle at different source and sink temperatures with varying pressure in heat recovery steam boiler and condenser-boiler. Performance results are plotted with Gas Turbine Inlet Temperature (GTIT) of 1200 to 1500 °C, Coolant Air Temperature (CAT) of −15 to +25 °C, and pressure ratio of GTPP as 6.25, 9.0 and 12.25 for different organic substances and NH3 as working fluids in the bottoming ORC. Simulation results show that the efficiency of the three stage combined power cycle will go up to 64 to 69% depending on the pressure ratio of GTPP, GTIT, and CAT. It is also observed that the variation in the efficiency of the three stage combined power cycle is small with respect to the type of working fluid used in the ORC. Among the organic working fluids R134a, R12, R22, and R123, R134a gives a higher combined cycle efficiency.

scholarly journals Experimental Investigation of a 300 kW Organic Rankine Cycle Unit with Radial Turbine for Low-Grade Waste Heat Recovery

Entropy ◽  
2019 ◽  
Vol 21 (6) ◽  
pp. 619 ◽  
Author(s):  
Ruijie Wang ◽  
Guohua Kuang ◽  
Lei Zhu ◽  
Shucheng Wang ◽  
Jingquan Zhao
Keyword(s):  
Heat Source ◽  
Electric Power ◽  
Power Output ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Volume Flow Rate ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Low Grade ◽  
Electric Power Output

The performance of a 300 kW organic Rankine cycle (ORC) prototype was experimentally investigated for low-grade waste heat recovery in industry. The prototype employed a specially developed single-stage radial turbine that was integrated with a semi-hermetic three-phase asynchronous generator. R245fa was selected as the working fluid and hot water was adopted to imitate the low-grade waste heat source. Under approximately constant cooling source operating conditions, variations of the ORC performance with diverse operating parameters of the heat source (including temperature and volume flow rate) were evaluated. Results revealed that the gross generating efficiency and electric power output could be improved by using a higher heat source temperature and volume flow rate. In the present experimental research, the maximum electric power output of 301 kW was achieved when the heat source temperature was 121 °C. The corresponding turbine isentropic efficiency and gross generating efficiency were up to 88.6% and 9.4%, respectively. Furthermore, the gross generating efficiency accounted for 40% of the ideal Carnot efficiency. The maximum electric power output yielded the optimum gross generating efficiency.

Modeling and Analyzing of Simple Combined Cycle of Modular High Temperature Gas Cooled Reactor

2016 ◽  
Author(s):  
Xinhe Qu ◽  
Xiaoyong Yang ◽  
Jie Wang
Keyword(s):  
High Temperature ◽  
High Efficiency ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Inlet Temperature ◽  
Outlet Temperature ◽  
Brayton Cycle ◽  
Reactor Outlet ◽  
Cycle Efficiency ◽  
High Temperature Gas

High temperature gas cooled reactor (HTGR) which is one of generation IV reactor has been widely given attention in many countries since the sixties of the last century because of its inherent safety and high efficiency. Currently, the HTGR commonly uses regenerative Brayton cycle. However, as reactor outlet temperature (ROT) rising, regenerative Brayton cycle has a higher reactor inlet temperature (RIT) than 500°C and is limited by reactor materials. Combined cycle of HTGR not only can solve the problem of high RIT, but also can get a higher cycle efficiency than 50%. In this paper an accurate model of combined cycle consisting of topping Brayton cycle, bottoming Rankine cycle and heat recovery steam generator (HRSG) was established. In terms of new model of combined cycle, this paper analyzed the main properties of simple combined cycle. And put forward two optimization schemes improving the cycle efficiency of combined cycle.

The Features of Closed Brayton Cycle and Sub-Critical Combined Cycles Coupled With (Very) High Temperature Gas-Cooled Reactor

2018 ◽  
Author(s):  
Xinhe Qu ◽  
Xiaoyong Yang ◽  
Gang Zhao ◽  
Jie Wang
Keyword(s):  
High Temperature ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Fourth Generation ◽  
Outlet Temperature ◽  
Brayton Cycle ◽  
Reactor Outlet ◽  
Combined Cycles ◽  
Very High ◽  
High Temperature Gas

High Temperature Gas-cooled Reactor (HTR) and Very High Temperature Gas-cooled Reactor (VHTR), are the most promising and achievable fourth-generation nuclear reactor for its inherent safety. In this paper, the performance of Closed Brayton Cycle (CBC) and two sub-critical combined cycles were investigated and compared. The CBC is a recuperated and inter-cooling closed Brayton cycle. Two combined cycles include the sub-critical Rankine cycle without steam reheating (Simple Combined Cycle, SCC) and a sub-critical reheated Rankine cycle (Reheated Combined Cycle, RCC). The topping cycles of SCC and RCC are both a simple Brayton cycle, and connect with the bottoming cycles by a sub-critical heat recovery steam generator (HRSG). Physical and mathematical models of three different thermodynamic cycles were established. Within the temperature range of the HTR and VHTR, the effects and mechanism of key parameters, such as reactor outlet temperature, steam temperature and pressure, on features of three different cycles were investigated. The results showed the elevated reactor outlet temperature could obviously enhance efficiency of three cycles. The results showed that RCC had the highest efficiency while SCC had the lowest efficiency, and the efficiency of CBC is slightly lower than that of RCC. The results could be helpful to understand and develop the power conversion system coupled with (V)HTR in the future.

Thermodynanic Analysis of a Combined Micro Turbine With a Micro ORC

2008 ◽  
Author(s):  
Mortaza Yari
Keyword(s):  
Pressure Ratio ◽  
Organic Rankine Cycle ◽  
Internal Heat ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Inlet Temperature ◽  
Evaporator Temperature ◽  
Combined Cycles ◽  
Micro Turbine ◽  
Organic Fluids

In the last years, a big effort has been undergone to improve micro turbines thermal efficiency, actually rated at about 30%. A value of 40% is often regarded as a possible target. Such a result could be achieved implementing more complicated thermodynamic cycles, like combined cycles. This paper deals with the hypothesis of bottoming a low pressure ratio, recuperated gas cycle, typically realized in actual micro turbines, with an Organic Rankine Cycle (ORC) with internal heat exchanger (IHE), obtaining a micro-combined-cycle. The results are presented and the influence of the several parameters: Turbine inlet temperature of the micro turbine, compressor pressure ratio, evaporation temperature and evaporator temperature difference are discussed. Both simple ORC and ORC with IHE bottom cycle options are discussed. The dry organic fluids in this study are Isopentane, n-Pentane, n-Heptane, n-Octane, n-Hexane, R113, R123 and Toluene.

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