Performance Of Organic Rankine Cycle Research Articles

Disruptions and Malfunction Control in ORC using Spiral Predictive Model

This paper provides a critical and analytical assay in the process vicinity of an Organic Rankine Cycle (ORC) resulting in a representation of a controlling model named as Spiral Model as the best approach to implement for an efficient Plant Management (PM) and Risk Mitigation Planning (RMP), focusing on the robust and elegant energy production. There have been so many predictive and sensing process models presented for a gist and substantial control of the ORC plant in recent years but the proposed Spiral Predictive Model (SPM), eliminating all the limitation of all previously implemented models, provides the robustness by performing all the roles in increments; e.g. in the changing controllers, complex time-frequency characteristics, fault detectors for turbines against disruptions and the multi-switching techniques needs to be cascaded ahead of time with predictive and detective techniques. The proposed model optimizes the performance of ORC by response tracking and recursive correction which relegates the errors and sudden disturbance in the process flow. Fast response and recursive correction nicely handles Demand Response (DR) and parameters variations at different working modules which ultimately provide the dynamic performance capability. This study will be elaborating efficient model design and implementation to conjure up a well-designed working flow in an ORC plant.

Exergy Analysis of Organic Rankine Cycle with Internal Heat Exchanger

 Abstract—In recent years Organic Rankine Cycle (ORC) has become a field of intense research and appears a promising technology for conversion of heat into useful work or electricity. In this work thermodynamic performance of ORC with internal heat exchanger is comparatively assessed for various working fluids based on the second law of thermodynamics. Special attention is paid to the effect of turbine inlet pressure on the exergy destructions (anergies) at various system components and the exergy efficiency of system. Results show that for a given source the component at which the greatest anergy occurs differs with working fluid. As turbine inlet pressure increases, exergy efficiency increases for working fluid such as ammonia or R22, but decreases for working fluid with low critical pressure such as iso-pentane or n-pentane.

Biomass Exploitation in Efficient ORC Systems

The research intends to investigate the energetic performances of Organic Rankine Cycles (ORCs) for the exploitation of the biomass resulting from agricultural residues. To this purpose, a parametric analysis has been carried out. Saturated and superheated conditions at the turbine inlet have been imposed and the effect of the internal regeneration on plant performances has been studied. The results highlight that ORC plants represent an interesting and sustainable solution for small-scale and decentralised power production. Moreover, the analysis shows the significant impact of the temperature and internal regeneration technique on the performances of the biomass power plants.

Exergetic Evaluation of an Organic Rankine Cycle Using Medium-Grade Waste Heat

This article presents an exergetic analysis for an organic Rankine cycle that converts waste energy to power from medium-grade heat sources (503 to 923 K). In addition, the effect of the waste heat temperature, the evaporator pressure, and the pinch point temperature difference on the thermal and exergetic performance of the system is studied. Several organic working fluids were selected to investigate the effect of the fluid's critical temperature on the performance of organic Rankine cycles. The working fluids under investigation are R245fa, R123, R142b, Isobutane, R113, and R141b with critical temperatures in the range of 407.7 to 524.9 K.

Influence of coupled pinch point temperature difference and evaporation temperature on performance of organic Rankine cycle

This paper presented the analysis on the influence of the pinch point temperature difference (PPTD) and the evaporation temperature on the performance of organic Rankine cycle (ORC) in recovering the low temperature waste heat of the flue gas. Both the net power output and the heat transfer area of the evaporator and condenser were evaluated for dry and isentropic working fluids. When the heat and cold source conditions were given, the maximum net power output and the heat transfer area were obtained. The results show that some organic working fluids cannot reach the maximum net power output to avoid the low temperature corrosion. With the increase of the PPTD of the evaporator at a given total temperature difference, the total heat transfer area decreases first and then increases, while the corresponding cost-effective performance (ratio of the net power output to total heat transfer area) displays almost the opposite variation tendency. The PPTD of the evaporator for the optimization cost-effective performance is approximately the same for different organic working fluids. Meanwhile, the isentropic working fluids show better cost-effective performance than dry working fluids.

Two Algorithms for the Reliable Estimation of Organic Rankine Cycle Performance

As the demand grows for low-temperature waste heat recovery systems, organic Rankine cycles (ORCs), and other alternatives to traditional steam, Rankine cycles are becoming more common in industry. Although analytical tools exist that can predict the performance of a steam cycle in a given waste-heat application, the development of a similar tool for ORCs has been hampered by the large choice of possible working fluids. In this paper, two methods are presented with the aim of providing an estimate of the best performance possible for any ORC in a given industrial application. The first is a purely analytical approach assuming an idealized fluid, and the second compares real fluids through cycle simulations to select the most appropriate parameters for the application. The analytical approach provides a rough baseline for performance, while the simulation method refines the estimate to give predictions that are more consistent with the documented performance of ORC plants currently in operation. Together, the two approaches represent a robust means of quickly estimating the capability of an ORC plant and to allow quick comparisons with other technologies.

Energetic and exergetic investigation of an organic Rankine cycle at different heat source temperatures

The energetic and exergetic performance of an updated ORC (organic Rankine cycle) is investigated. The thermal efficiencies of the ORC at different heat source temperatures of about 100, 90, 80, and 70 °C are explored. The thermodynamic irreversibility that takes place in the evaporator, condenser, turbine, pump, and separator is revealed. The ORC feasibility for low-temperature applications is demonstrated. With a hot side temperature of around 80 °C, a thermal efficiency of 7.4% and a turbine isentropic efficiency of 0.68 can be achieved. The present research further indicates that exergy destruction caused by heat transfer through an appreciable temperature difference in the evaporator is the largest in the energy conversion process, followed by that in the condenser. The exergy destroyed in the heat exchangers amounts to 74% of the overall exergy loss. The total system exergy efficiency is approximately 40%; thus, ways to improve exergy efficiency are required. HCFC-123, a dry fluid, is experimentally confirmed to be highly superheated after expansion in this study. A regenerator should be used to preheat HCFC-123 prior to entering the evaporator. Meanwhile the heat-transfer configuration with two oil cycles can be a good solution to overcome the thermodynamic disadvantage of a one-stage evaporator.

Performance analysis of ORC power generation system with low-temperature waste heat of aluminum reduction cell

Performance of organic Rankine cycle (ORC) system to recover low-temperature waste heat from aluminum reduction cell was analyzed. The temperature of waste heat is 80°C-200°C and the flow rate is 3×105m3/h. The pinch temperature difference between waste heat and working fluids is 10°C. The results show that there is optimal evaporating temperature for maximum net power under the same pinch point. For heat source temperature range of 80°C-140°C and 150°C-170°C, the working fluid given biggest net power is R227ea and R236fa, respectively. When the temperature is higher than 180°C, R236ea generates the biggest net power. The variation of heat source temperature has important effect on net power. When the temperature decreases 10%, the net power will deviate 30% from the maximum value.

Comparative energetic analysis of high-temperature subcritical and transcritical Organic Rankine Cycle (ORC). A biomass application in the Sibari district

Abstract The present work aims to analyse the energetic performances of Organic Rankine Cycles (ORCs) for small-scale applications. To this purpose, a parametric energy analysis has been performed to define the proper system configurations for a biomass power plant. Saturated and superheated conditions at the turbine inlet have been imposed and subcritical and transcritical cycles have been investigated. Furthermore, the effect of operating conditions and the impact of internal regeneration on system performances have been analysed. Finally, the possible exploitation of the biomass resulting from the pruning residues of peach trees in the Sibari district (Southern Italy) has been evaluated for the ORC configurations optimised during the energetic analysis. The analysis shows that ORCs represent a very interesting solution for small-scale and decentralised power production. Moreover, the results highlight the large influence of the maximum temperature and the significant impact of the internal regeneration on the power plant performances.

On the role of working fluid properties in Organic Rankine Cycle performance

Abstract The performance of ORC systems strongly depends on working fluid properties. We explore the relationships between working fluid properties and ORC common economic and thermodynamic performance criteria from a theoretical and an analytical point of view. The mapping of individual properties and performance criteria presented in this paper will provide a basis for the development of efficient and systematic strategies and approaches for ORC working fluid selection in future.

저온 열원으로부터 최대 동력을 생산하기 위한 유기랭킨사이클(ORC)에 관한 연구

ORC(organic Rankine cycle) has potential of reducing consumption of fossil fuels and has many favorable characteristics to exploit low-temperature heat sources. This work analyzes performance of ORC with superheating using low-temperature energy sources in the form of sensible energy. Maximum mass flow rate of a working fluid relative to that of a source fluid is considerd to extract maximum power from the sources. Working fluids of R134a, and , and source temperatures of , and are considered in this work. Results show that for a fixed source temperature thermal efficiency increases with evaporating temperaure, however net work per unit mass of source fluid has a maximum with respect to the evaporating temperature in the range of low source temperature. Results also show that the maximum power extraction is possible with R134a for the source temperature of , with for , and with for .

Effects of Superheating on Thermodynamic Performance of Organic Rankine Cycles

Effects of Superheating on Thermodynamic Performance of Organic Rankine Cycles

Parametric optimization and comparative study of organic Rankine cycle (ORC) for low grade waste heat recovery

Organic Rankine cycles for low grade waste heat recovery are described with different working fluids. The effects of the thermodynamic parameters on the ORC performance are examined, and the thermodynamic parameters of the ORC for each working fluid are optimized with exergy efficiency as an objective function by means of the genetic algorithm. The optimum performance of cycles with different working fluids was compared and analyzed under the same waste heat condition. The results show that the cycles with organic working fluids are much better than the cycle with water in converting low grade waste heat to useful work. The cycle with R236EA has the highest exergy efficiency, and adding an internal heat exchanger into the ORC system could not improve the performance under the given waste heat condition. In addition, for the working fluids with non-positive saturation vapor curve slope, the cycle has the best performance property with saturated vapor at the turbine inlet.

An examination of exergy destruction in organic Rankine cycles

The exergy topological method is used to present a quantitative estimation of the exergy destroyed in an organic Rankine cycle (ORC) operating on R113. A detailed roadmap of exergy flow is presented using an exergy wheel, and this visual representation clearly depicts the exergy accounting associated with each thermodynamic process. The analysis indicates that the evaporator accounts for maximum exergy destroyed in the ORC and the process responsible for this is the heat transfer across a finite temperature difference. In addition, the results confirm the thermodynamic superiority of the regenerative ORC over the basic ORC since regenerative heating helps offset a significant amount of exergy destroyed in the evaporator, thereby resulting in a thermodynamically more efficient process. Parameters such as thermodynamic influence coefficient and degree of thermodynamic perfection are identified as useful design metrics to assist exergy-based design of devices. This paper also examines the impact of operating parameters such as evaporator pressure and inlet temperature of the hot gases entering the evaporator on ORC performance. It is shown that exergy destruction decreases with increasing evaporator pressure and decreasing turbine inlet temperatures. Finally, the analysis reveals the potential of the exergy topological methodology as a robust technique to identify the magnitude of irreversibilities associated with real thermodynamic processes in practical thermal systems. Copyright © 2008 John Wiley & Sons, Ltd.

Performance analysis of different working fluids for use in organic Rankine cycles

This article presents a second-law analysis for the use of organic Rankine cycle (ORC) to convert waste energy to power from low-grade heat sources. The organic working fluids were selected to investigate the effect of the fluid boiling point temperature on the performance of ORCs. The working fluids under investigation are R134a, R113, R245ca, R245fa, R123, isobutane, and propane, with boiling points between 243 and 48 °C. The results are compared with those of water under similar conditions. A combined first- and second-law analysis is performed by varying some system operating parameters at various reference temperatures. Some of the results demonstrate that ORC using R113 shows the maximum efficiency among the evaluated organic fluids for temperatures >430 K; R123, R245ca, and R245fa show the best efficiencies for temperatures between 380 and 430 K; and for temperatures <380 K, isobutane shows the best efficiency. Also, it is shown that the organic-fluid boiling point has a strong influence on the system thermal efficiency.

06/01918 Experiences on pollution level measurement in Mexico: Montoya-Tena, G. et al. Electric Power Systems Research, 2005, 76, (1–3), 58–66

This paper presents thermodynamic modelling and simulation study of a small scale saturated solar organic Rankine cycle (ORC) which consists of a stationary, flat plate solar energy collector that is utilised as a vapour generator, a vane expander, a water-cooled condenser and a pump. Simulations are conducted under constant condensing temperature/pressure and various cycle pressure ratios (PR) for 24 organic thermofluids including Hydrocarbons (HCs), Hydrofluorocarbons (HFCs), Perfluorocarbons (PFCs), Hydrofluoroethers (HFEs) and Hydrofluoroolefins (HFOs). Special attention is given to the influence of PR and fluids’ physical properties on the solar ORC performance as well as fluids’ environmental and safety impacts including global warming potential (GWP), flammability and toxicity. The simulation results indicate that when the same fluid is considered, pressure ratio of the cycle leads to various operating conditions such as collector (evaporating) pressure which results in various collector, expander and cycle efficiency. For instance, increasing the pressure ratio of the cycle enhances the net work output and the thermal efficiency of the cycle, whereas it decreases the flat plate collector efficiency. The results also indicate that the proposed system produces the maximum net work output of 210.45 W with a thermal efficiency of 9.64% by using 1-butene. Furthermore, trans-2-butene, cis-2-butene, R600, R600a, R601, R601a and neopentane (HC), R227ea and R236fa (HFC), RC318 (PFC) and R1234ze (HFO) show promising solar ORC thermal performances. However, the flammability problem of HCs and global warming potential issue of HFCs and PFCs limit their applications, owing to the safety and environmental concerns.On the other hand, in terms of the environmental impact, thermofluids such as RE347mcc, RE245fa2 (HFEs) and R1234ze, R1233zd (HFOs) offer an attractive alternative, yet they were neither the most efficient, nor generated the highest amount of net work output. This paper provides thermofluids’ selection guidelines to achieve maximum efficiency within solar thermal energy technologies while keeping environmental impacts into considerations.

Effect of working fluids on organic Rankine cycle for waste heat recovery

This study presents an analysis of the performance of organic Rankine cycle (ORC) subjected to the influence of working fluids. The effects of various working fluids on the thermal efficiency and on the total heat-recovery efficiency have been investigated. It is found that the presence of hydrogen bond in certain molecules such as water, ammonia, and ethanol may result in wet fluid conditions due to larger vaporizing enthalpy, and is regarded as inappropriate for ORC systems. The calculated results reveal that the thermal efficiency for various working fluids is a weak function of the critical temperature. The maximum value of the total heat-recovery efficiency occurs at the appropriate evaporating temperature between the inlet temperature of waste heat and the condensing temperature. In addition, the maximum value of total heat-recovery efficiency increases with the increase of the inlet temperature of the waste heat source and decreases it by using working fluids having lower critical temperature. Analytical results using a constant waste heat temperature or based on thermal efficiency may result in considerable deviation of system design relative to the varying temperature conditions of the actual waste heat recovery and is regarded as inappropriate.

00/01172 World energy prospects to 2020

Increasing energy-demand and environmental concerns are leading to a growing interest in alternative and sustainable energy solutions. Low-grade waste heat recovery through ORC systems is considered to be one of the most feasible eco-friendly energy conversion technologies.In this paper, a comprehensive model of an organic Rankine cycle (ORC) system for micro-CHP applications is presented in order to compare the behavior under part-load conditions of two types of positive displacement expanders, a single-screw expander and a scroll expander. The ORC model is implemented in the AMESim® environment, which allows system modeling both for steady-state and transient analysis. Typical residential electrical and heating loads are considered to study the performances of a suitable small-scale system.By means of a detailed quasi-1D model for a single-screw expander and a Reverse Engineering (RE)-Computational Fluid Dynamics (CFD) approach for a scroll expander, the performance characteristic maps of both expansion machines, in terms of isentropic efficiency as function of expansion ratio and rotational speed, have been determined and implemented in the AMESim® model.A comparison between the selected expanders is presented to address the influence of different positive displacement-type expanders on the overall ORC performances at off-design conditions. The capability of the system to meet the requested loads is also discussed.