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

scholarly journals Energy, exergy, and environmental assessment of a small-scale solar organic Rankine cycle using different organic fluids

Heliyon ◽  
2021 ◽  
Vol 7 (9) ◽  
pp. e07947
Author(s):  
Geanette Polanco Piñerez ◽  
Guillermo Valencia Ochoa ◽  
Jorge Duarte-Forero
Keyword(s):  
Environmental Assessment ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Small Scale ◽  
Organic Fluids

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.

Influence of Supersonic Nozzle Design Parameters on the Unsteady Stator-Rotor Interaction in Radial-Inflow Turbines for Organic Rankine Cycles

2021 ◽  
Author(s):  
Alessandro Cappiello ◽  
Raffaele Tuccillo
Keyword(s):  
Power Plants ◽  
Supersonic Nozzle ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Expansion Ratio ◽  
Design Parameters ◽  
Large Expansion ◽  
Downstream Flow ◽  
Organic Fluids ◽  
Stator Design

Abstract Organic Rankine Cycle (ORC) technology represents an interesting option for improving the efficiency of existing power plants and industrial processes as well as exploiting renewable and renewable-equivalent energy sources. The use of Radial-Inflow Turbine (RIT) for ORC plant sizes below 100 kW is promising, although the application remains challenging. In fact, the single stage arrangement imposed by economic constraints and hence the large expansion ratio, together with the large molecular weight, which characterizes organic fluids, usually result in highly supersonic flows, so making the use of transonic stators often mandatory. Particularly, the influence of RIT stator design parameters on losses and the level of unsteadiness seen by the subsequent rotor is still scarcely addressed in published literature. Previous work by the authors investigated the effect of some stator design parameters on stator loss and downstream circumferential uniformity. The present work investigates the effect of the convergent-divergent stators design parameters and the resulting downstream flow field non-uniformity on the unsteady stator-rotor interaction and loss generation in ORC Radial-Inflow Turbines. To this end, two stator and rotor configurations which differ by the stator design parameters (i.e., discharge metal angle and number of vanes) have been tested by means of 3D unsteady CFD calculations accounting for real-gas properties. The results show that larger stator-rotor interaction is present for the case featuring higher vane count and lower outlet metal, which also features the largest fluctuations of power output and pressure force on blade, together with a substantially lower average total-to-static efficiency.

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.

Performance Predictions of Axial Turbines for Organic Rankine Cycle (ORC) Applications Based on Measurements of the Flow Through Two-Dimensional Cascades of Blades

2014 ◽  
Author(s):  
Karsten Hasselmann ◽  
Felix Reinker ◽  
Stefan aus der Wiesche ◽  
Eugeny Y. Kenig ◽  
Frithjof Dubberke ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Low Temperature ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Two Dimensional ◽  
Real Gas ◽  
Specific Loss ◽  
Performance Predictions ◽  
Flow Through ◽  
Organic Fluids

The Organic-Rankine-Cycle (ORC) offers a great potential for waste heat recovery and use of low-temperature sources for power generation. However, the ORC thermal efficiency is limited by the relatively low temperature level, and it is, therefore, of major importance to design ORC components with high efficiencies and minimized losses. The use of organic fluids creates new challenges for turbine design, due to real-gas behavior and low speed of sound. The design and performance predictions for steam and gas turbines have been mainly based on measurements and numerical simulations of flow through two-dimensional cascades of blades. In case of ORC turbines and related fluids, such an approach requires the use of specially designed closed cascade wind tunnels. In this contribution, the specific loss mechanisms caused by the organic fluids are reviewed. The concept and design of an ORC cascade wind tunnel are presented. This closed wind tunnel can operate at higher pressure and temperature levels, and this allows for an investigation of typical organic fluids and their real-gas behavior. The choice of suitable test fluids is discussed based on the specific loss mechanisms in ORC turbine cascades. In future work, we are going to exploit large-eddy-simulation (LES) techniques for calculating flow separation and losses. For the validation of this approach and benchmarking different sub-grid models, experimental data of blade cascade tests are crucial. The testing facility is part of a large research project aiming at obtaining loss correlations for performance predictions of ORC turbines and processes, and it is supported by the German Ministry for Education and Research (BMBF).

scholarly journals Parametric Study of an Organic Rankine Cycle Using Different Fluids

2020 ◽  
Vol 4 (2) ◽  
pp. 122-128 ◽  
Author(s):  
Rabah Touaibi ◽  
Hasan Koten ◽  
Ozlem Boydak
Keyword(s):  
Mechanical Energy ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Cycle Performance ◽  
Heat Sources ◽  
Molecular Weights ◽  
Volatile Organic ◽  
Organic Fluids ◽  
Selection Of

This work is an energy study of an organic Rankine cycle (ORC) for the recovery of thermal energy by comparing three organic fluids. This cycle is considered to be a promising cycle for the conversion of heat into mechanical energy suitable for low temperature heat sources; it uses more volatile organic fluids than water, which generally has high molecular weights, thus allowing operating pressures at temperatures lower than those of the traditional Rankine cycle. A thermodynamic model was developed using the Engineering Equation Solver (EES) software to determine its performance using different working fluids (toluene, R245fa and R123) under the same operating conditions, taking into account the effect of certain operating parameters and the selection of organic fluids on cycle performance. The results obtained show that the toluene organic fluid has the best thermal efficiency of the cycle compared to the other fluids; 14.38% for toluene, 13.68% for R123 and 13.19 for R245fa.

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.

Exergetical Performance Assessment of Organic Rankine Cycle with Superheating

2012 ◽  
Vol 234 ◽  
pp. 69-73 ◽  
Author(s):  
Kyoung Hoon Kim ◽  
Hyung Jong Ko
Keyword(s):  
Performance Assessment ◽  
Fossil Fuel ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Exergy Efficiency ◽  
Energy Sources ◽  
Low Grade ◽  
System Components ◽  
Organic Fluids ◽  
Peak Value

Organic Rankine Cycle (ORC) has attracted much attention in recent years, since it has potential of reducing fossil fuel consumption and many favorable characteristics to exploit low-grade energy sources. This work carries out an exergetical performance assessment of ORC with superheating comparatively for various organic fluids. Special attention is paid to the effect of evaporating temperature on the exergy destructions (anergies) at various system components and the exergy efficiency of system. Results show that for a given source both the anergies at the components and exergy efficiency may have a peak value or monotonically increase with evaporating temperature.

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