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.

Waste Heat Recovery From Closed Brayton Cycle Using Organic Rankine Cycle: Thermodynamic Analysis

2009 ◽  
Author(s):  
Mortaza Yari
Keyword(s):  
Waste Heat ◽  
Pressure Ratio ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Inlet Temperature ◽  
Brayton Cycle ◽  
Exergy Destruction ◽  
Evaporator Temperature ◽  
Destruction Rate

This study examines the performance of a gas-cooled nuclear power plant with closed Brayton cycle (CBC) combined with an organic Rankine cycle (ORC) plant, as well as the irreversibility within the system. Individual models have been developed for each component, through applications of the first and second laws of thermodynamics. The overall system performance is then analyzed by employing individual models and further application of thermodynamic laws for the entire cycle, to evaluate the thermal efficiency and entropy production of the plant. The effects of the turbine inlet temperature, compressor pressure ratio, evaporator temperature, and temperature difference in the evaporator on the combined cycle first-law, second-law efficiency and exergy destruction rate are studied. Finally optimization of the combined cycle in a systematic way has been developed and discussed. It was found that the combined cycle first-law efficiency is about 9.5–10.1% higher than the simple CBC cycle. Also, the exergy destruction rate for the GT-MHR/ORC combined cycle, is about 6.5–8.3% lower than that of the GT-MHR cycle.

Biomass combined cycles based on externally fired gas turbines and organic Rankine expanders

2011 ◽  
Vol 225 (8) ◽  
pp. 1066-1075 ◽  
Author(s):  
C M Invernizzi ◽  
P Iora ◽  
R Sandrini
Keyword(s):  
Gas Turbines ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Economic Feasibility ◽  
Maximum Efficiency ◽  
Working Fluid ◽  
Inlet Temperature ◽  
System A ◽  
Combined Cycles

This article investigates the possibility to enhance the performance of a biomass organic Rankine cycle (ORC) plant by adding an externally fired gas turbine (EFGT), yielding a combined EFGT + ORC system. A typical ORC configuration is first modelled and validated on data available from an existing unit 1.5 MW reference plant. Then, different working fluids belonging to the methyl-substituted benzene series and linear methylpolysiloxanes have been evaluated for the ORC section on the basis of both thermodynamics considerations and design issues of the regenerator and the turbine. Results of the simulations of the combined cycle (CC) referred to a furnace size of about unit 9 MW, assuming a maximum GT inlet temperature of 800 °C, show a maximum efficiency of 23 per cent, obtained in the case where toluene is adopted as a working fluid for the bottoming section. This value is about 4 points per cent higher than the efficiency of the corresponding simple ORC. Finally, to conclude, some preliminary considerations are given regarding the techno-economic feasibility of the combined configuration, suggesting the need of a further investigation on the possible technological solution for the furnace which represents the main uncertainty in the resulting costs of the CC.

Performance Evaluation of a Small Scale High Efficiency Cogeneration System

2006 ◽  
Author(s):  
Mauro Reini
Keyword(s):  
High Efficiency ◽  
Pressure Ratio ◽  
Organic Rankine Cycle ◽  
Thermodynamic Cycle ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Working Fluid ◽  
Small Scale ◽  
Performance Parameters ◽  
Cogeneration System

In recent years, a big effort has been made to improve microturbines thermal efficiency, in order to approach 40%. Two main options may be considered: i) a wide usage of advanced materials for hot ends components, like impeller and recuperator; ii) implementing more complicated thermodynamic cycle, like combined cycle. In the frame of the second option, the paper deals with the hypothesis of bottoming a low pressure ratio, recuperated gas cycle, typically realized in actual microturbines, with an Organic Rankine Cycle (ORC). The object is to evaluate the expected nominal performance parameters of the integrated-combined cycle cogeneration system, taking account of different options for working fluid, vapor pressure and component’s performance parameters. Both options of recuperated and not recuperated bottom cycles are discussed, in relation with ORC working fluid nature and possible stack temperature for microturbine exhaust gases. Finally, some preliminary consideration about the arrangement of the combined cycle unit, and the effects of possible future progress of gas cycle microturbines are presented.

Performance Assessments of Organic Rankine Cycle With Internal Heat Exchanger Based on Exergetic Approach

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
Nurettin Yamankaradeniz ◽  
Ali Husnu Bademlioglu ◽  
Omer Kaynakli
Keyword(s):  
Heat Exchanger ◽  
Organic Rankine Cycle ◽  
Internal Heat ◽  
Rankine Cycle ◽  
Performance Assessments ◽  
Evaporator Temperature ◽  
Pinch Point ◽  
Internal Heat Exchanger ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis

This study makes energy and exergy analysis of a sample organic Rankine cycle (ORC) with a heat exchanger which produces energy via a geothermal source with a temperature of 140 °C. R600a is preferred as refrigerant to be used in the cycle. The changes in exergy destructions (of irreversibility) and exergy efficiencies in each cycle element are calculated in the analyses made based on the effectiveness of heat exchanger used in cycle and evaporator temperature changing between 60 and 120 °C for fixed pinch point temperature differences in evaporator and condenser. Parameters showing system performance are assessed via second law approach. Effectiveness of heat exchanger and temperature of evaporator are taken into consideration within the scope of this study, and energy and exergy efficiencies of cycle are enhanced maximum 6.87% and 6.21% respectively. Similarly, exergy efficiencies of evaporator, heat exchanger, and condenser are increased 4%, 82%, and 1.57%, respectively, depending on the effectiveness of heat exchanger and temperature of evaporator.

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.

Energy and Exergy Performance Comparative Analysis of Solar Driven Organic Rankine Cycle Using Different Organic Fluids

2021 ◽  
pp. 1-38
Author(s):  
Md. Tareq Chowdhury ◽  
Esmail M. A. Mokheimer
Keyword(s):  
Energy Efficiency ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Exergy Efficiency ◽  
Optimum Operating ◽  
Inlet Temperature ◽  
Turbine Inlet Temperature ◽  
Turbine Inlet ◽  
Energy And Exergy ◽  
Organic Fluids

Abstract In this study, the performance of Parabolic Trough Collector (PTC) integrated with Organic Rankine Cycle (ORC) is investigated to find the optimum operating scenarios and to assess the exergy destruction at different components of the system. Commercial PTC LS-2 model with Therminol VP-1 as heat transfer fluid was integrated with an organic Rankine cycle that was examined for its thermal and exergetic performance using different organic fluids. It was found that every fluid has an optimum pressure and temperature level at which it works better than other fluids. R134a (Tetrafluoroethane, CH2FCF3) showed the best performance for the turbine inlet temperature range from 340 K — 440 K regarding the achieved energy and exergy efficiencies. At a temperature of 362.8 K and a pressure of 2750 kPa, R134a showed the highest energy efficiency of 8.55% and exergy efficiency of 21.84% with the lowest mass flow rate required in ORC. Energy efficiency of other fluids namely, R245fa (Pentafluoropropane, CF3CH2CHF2), n-pentane and Toluene were less than 5%. On the other hand, Toluene exhibited thermal efficiency of 23.5 % at turbine inlet temperature of 550 K and pressure of 2500 kPa, while the exergy efficiency was 62.89 % at solar irradiation of 1 kW/m2.

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.

scholarly journals Exergoeconomic and Environmental Analysis and Multi-Objective Optimization of a New Regenerative Gas Turbine Combined Cycle

2021 ◽  
Vol 11 (23) ◽  
pp. 11554
Author(s):  
Ali Baghernejad ◽  
Amjad Anvari-Moghaddam
Keyword(s):  
Gas Turbine ◽  
Pressure Ratio ◽  
Unit Cost ◽  
Environmental Parameters ◽  
Rankine Cycle ◽  
Exergy Efficiency ◽  
Combined Cycle ◽  
Inlet Temperature ◽  
Cost Rate ◽  
Cycle Systems

Combined cycle systems have an important role in power generation. In the present study, three different configurations of combined Brayton and Rankine cycle system are studied from the perspective of energy, exergy, exergoeconomic and environmental perspectives. Results indicate that it depends on the preferences and criteria of each decision maker to select the best configuration among the three proposed configurations as the final configuration. For the purpose of parametric analysis, the effect of changing various parameters such as compressor pressure ratio, gas turbine inlet temperature on the output work, exergy efficiency, exergy-economic and environmental parameters is studied. In addition, an attempt is made to optimize the performance of combined cycle systems considering three objective functions of exergy efficiency, total cost rate and exergy unit cost of produced electricity.

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.

An overview on subcritical organic rankine cycle configurations with pure organic fluids

2021 ◽  
Author(s):  
Jun Fen Li ◽  
Hang Guo ◽  
Biao Lei ◽  
Yu Ting Wu ◽  
Fang Ye ◽  
...  
Keyword(s):  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Organic Fluids
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