The working medium for the megawatt class utilization heat and power complex based on Organic Rankine Cycle

Abstract The article presents the results of the analysis of energy conversion cycles making use of thermal energy of oceans. The objects of analysis were two cases of closed Organic Rankine Cycle (ORC) power plants, which were: the cycle in which the vapour of the working medium was produced by warm oceanic water in the circum-equatorial zone, and the so-called “arctic” cycle in which this vapour was produced by non-frozen water in the circumpolar zone. Between ten and twenty low-boiling media were examined for which operating parameters were optimised to obtain the highest cycle efficiency. A preliminary design of an ORC turbine which was obtained by optimising basic design parameters is included. It has been proved that realisation of the Ocean Thermal Energy Conversion (OTEC) cycle is possible both in the warm and permanently frozen regions. The results of the calculations have also revealed that the efficiency of the OTEC cycle is higher in the circumpolar zone. Selecting a low-boiling medium and designing a highly efficient turbine operating in both abovementioned regimes is technically realisable.

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Parametric Optimization of Organic Rankine Cycle by Genetic Algorithm

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.672-674.741 ◽

2014 ◽

Vol 672-674 ◽

pp. 741-745

Author(s):

Shuang Bian ◽

Teng Wu ◽

Jin Fu Yang

Keyword(s):

Genetic Algorithm ◽

Parametric Optimization ◽

Parametric Design ◽

Waste Heat ◽

Lower Boundary ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Pinch Point ◽

Working Medium ◽

Net Power Output

Organic Rankine Cycle (ORC) is widely used in the field of low temperature waste heat recovery, including solar, biomass and geothermal energy, among others. Based on the thermodynamic model of ORC system built up in Matlab, this study employ Genetic Algorithm (GA) on ORC system for parametric optimization and select a ratio of heat transfer area to total net power output as the performance evaluation criterion to predict the economy of system. R11, R113, R123 and isopentane are choosed as the working medium. The results show that the ORC system with isopentane has the minimum objective function value of 0.429m2/kw. The corresponding condensing temperature and degree of supercooling are generally located at lower boundary over their parametric design ranges, and the corresponding pinch point temperature difference are located at upper boundary. For different working fluids, there exist an optimum evaporating temperature and degree of superheat.

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Advances in Working Medium for Organic Rankine Cycle

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.860-863.1362 ◽

2013 ◽

Vol 860-863 ◽

pp. 1362-1365

Author(s):

Han Lv ◽

Wei Ting Jiang ◽

Qun Zhi Zhu

Keyword(s):

Organic Rankine Cycle ◽

Rankine Cycle ◽

Research Direction ◽

Heat Energy ◽

Low Grade ◽

Existing Problems ◽

Working Medium ◽

The Future ◽

Working Principle ◽

Low Grade Heat

Organic Rankine cycle is an effective way to recover low-grade heat energy, working medium is an important part of the cycle, it is one of the important factors that affects its performance. This paper introduces the working principle of organic Rankine cycle, composition, and it analyzes the excellent characteristics of medium, and the current research advances at home and abroad. Finally, aiming at existing problems, it puts forward the research direction and the key of development in the future.

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Advanced Turbine Cycles with Organic Media

Energies ◽

10.3390/en13061327 ◽

2020 ◽

Vol 13 (6) ◽

pp. 1327

Author(s):

Marian Piwowarski ◽

Krzysztof Kosowski

Keyword(s):

Power Plants ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Thermodynamic Cycles ◽

Working Medium ◽

Micro Power ◽

Higher Temperature ◽

Materials Used ◽

Cycle Efficiency ◽

Plant Efficiency

Organic Rankine Cycle (ORC) power plants have become very popular and have found their applications in systems with renewable sources of energy. So far their overall efficiencies are not very impressive and only for the upper temperature of about 300 °C do they exceed 20%. A drawback of these cycles is the limitation of the cycle upper temperature due to the heat exchanger technology and the materials used. However, it is possible to overcome these difficulties by certain modifications of the thermodynamic cycles, a proper choice of the working medium and the optimization of cycle parameters. In the paper the problems of choosing the working medium and the question of higher temperature at the turbine inlet have been discussed. Different modifications of the schemas of the thermodynamic cycles have also been taken into account. The variants of power plants with regenerators, reheaters and heat exchangers have been considered. The proposed increase in temperature (in some cases up to 600 °C or higher) and innovative modifications of the thermodynamic cycles allow to obtain the power plant efficiency of above 50%. The modified cycles have been described in detail in the paper. The proposed cycles equipped with regenerators and reheaters can have the efficiency even slightly higher than classical steam turbine plants with a reheater and regenerators. Appropriate cycle and turbine calculations have been performed for the micro power plants of turbine output in the range of 10 kW–300 kW (up to several MW in some cases). The best arrangements achieved very high values of the overall cycle efficiency.

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Numerical Analysis of the Rotor of a 30 kW ORC Microturbine Considering Properties of Aerodynamic Gas Bearings

Mechanics and Mechanical Engineering ◽

10.2478/mme-2018-0034 ◽

2020 ◽

Vol 22 (2) ◽

pp. 425-436

Author(s):

Łukasz Breńkacz ◽

Grzegorz Żywica ◽

Małgorzata Bogulicz

Keyword(s):

Rotational Speed ◽

Dynamic Properties ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Geometrical Parameters ◽

Gas Bearings ◽

Lubricating Film ◽

Working Medium ◽

Optimal Dynamic ◽

Free Machine

AbstractThe paper focuses on the analysis of a 30 kW microturbine operating in the organic Rankine cycle (ORC) with a low-boiling working medium. The nominal speed of the rotor is 40,000 rpm. The investigated microturbine is an oil-free machine, which means that its bearings use the ORC working medium as a lubricant. We created a numerical model, which was used to assess the dynamic properties of the newly designed microturbine. The conducted analyses covered, inter alia, the optimization of some geometrical parameters of each bearing in order to cause the lubricating film to be created at a correspondingly low rotational speed as well as to obtain optimal dynamic properties of the system. The article provides a full dynamic picture of the rotor supported by two aerodynamic gas bearings. The included graphs demonstrate the vibration amplitude of the shaft as a function of the rotational speed as well as the results of the modal analysis in the form of natural vibration modes of the system and their corresponding natural frequencies.

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CORRECT SELECTION OF THE ORC SYSTEM PARAMETERS FOR THE EXHAUST GASES HEAT SOURCE

The 11th International Conference ENVIRONMENTAL ENGINEERING 11th ICEE SELECTED PAPERS ◽

10.3846/enviro.2020.706 ◽

2020 ◽

Author(s):

Andrzej Grzebielec ◽

Artur Rusowicz ◽

Tomasz Ziąbka

Keyword(s):

Heat Source ◽

Electrical Power ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Correct Selection ◽

Maximum Efficiency ◽

Source Power ◽

System Parameters ◽

Working Medium ◽

Cycle Systems

Contrary to appearances, ORC (Organic Rankine Cycle) systems should not be selected for the highest available temperature of the upper heat source. This approach allows, of course, to achieve the highest energy efficiency, but this happens at the expense of the electrical power obtained. This solution would be good for an infinite heat source. In practice, there is always a finite heat source power. Therefore, the analysis should take into account other aspects than just maximum efficiency. The article presents a method of selecting ORC system parameters for a heat source in the form of waste gases, enabling the highest electrical power to be obtained. The analysis shows that even a significant reduction in the evaporation temperature of the working medium in the ORC system compared to the source temperature is beneficial for the profitability of investing in an ORC system. The analysis showed that for flue gases with temperatures of 300, 400, 500 and 600 °C, the best evaporating temperatures of the working medium in the ORC system are 145 °C, 185 °C, 214 °C and 250 °C, respectively. The highest level of generated electricity is obtained for these temperatures.

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The Method of the Working Fluid Selection for Organic Rankine Cycle (ORC) Systems Employing Volumetric Expanders

Energies ◽

10.3390/en13030573 ◽

2020 ◽

Vol 13 (3) ◽

pp. 573 ◽

Cited By ~ 4

Author(s):

Piotr Kolasiński

Keyword(s):

Organic Rankine Cycle ◽

Rankine Cycle ◽

Expansion Ratio ◽

Thermal Capacity ◽

Working Fluid ◽

Working Fluids ◽

Mean Temperature ◽

Working Medium ◽

Working Fluid Selection ◽

Selection Of

The working fluid selection is one of the most important issues faced when designing Organic Rankine Cycle (ORC) systems. The choice of working fluid is dictated by different criteria. The most important of them are safety of use, impact on the environment, and physical and chemical parameters. The type of ORC system in which the working fluid is to be used and the type of expander applied in this system is also affecting the working fluid selection. Nowadays, volumetric expanders are increasingly used in ORC systems. In the case of volumetric expanders, in addition to the aforementioned working fluid selection criteria, additional parameters are considered during the selecting of the working fluid, such as the range of operating pressures and geometric dimensions (determining the volume of working chambers) affecting the achieved power and efficiency of the expander. This article presents a method of selecting a working medium for ORC systems using volumetric expanders. This method is based on the dimensionless rating parameters applied for the comparative analysis of different working fluids. Dimensionless parameters were defined for selected thermal properties of the working fluids, namely thermal capacity, mean temperature of evaporation, mean temperature of condensation, pressure and volumetric expansion ratio, volumetric expandability, as well as the heat of preheating, vaporization, superheating, cooling, and liquefaction. Moreover, isentropic expansion work was considered as the rating parameter. In this article, in addition to the working fluid selection method, computational examples related to the selection of the working fluid for the ORC system fed by a heat source featuring specified temperatures are presented. The results of calculations of rating parameters and their comparison gave an outlook on the selection of appropriate working fluids.

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Model, simulation and experiments for a Buoyancy Organic Rankine Cycle

The European Physical Journal Applied Physics ◽

10.1051/epjap/2020200113 ◽

2020 ◽

Vol 92 (1) ◽

pp. 10906

Author(s):

Jeroen Schoenmaker ◽

Pâmella Gonçalves Martins ◽

Guilherme Corsi Miranda da Silva ◽

Julio Carlos Teixeira

Keyword(s):

Model Simulation ◽

Organic Rankine Cycle ◽

Thermodynamic Cycle ◽

Rankine Cycle ◽

Test Body ◽

Working Fluid ◽

Proof Of Concept ◽

Energy Scenario ◽

New Type ◽

Fluid Reservoir

Organic Rankine Cycle (ORC) systems are increasingly gaining relevance in the renewable and sustainable energy scenario. Recently our research group published a manuscript identifying a new type of thermodynamic cycle entitled Buoyancy Organic Rankine Cycle (BORC) [J. Schoenmaker, J.F.Q. Rey, K.R. Pirota, Renew. Energy 36, 999 (2011)]. In this work we present two main contributions. First, we propose a refined thermodynamic model for BORC systems accounting for the specific heat of the working fluid. Considering the refined model, the efficiencies for Pentane and Dichloromethane at temperatures up to 100 °C were estimated to be 17.2%. Second, we show a proof of concept BORC system using a 3 m tall, 0.062 m diameter polycarbonate tube as a column-fluid reservoir. We used water as a column fluid. The thermal stability and uniformity throughout the tube has been carefully simulated and verified experimentally. After the thermal parameters of the water column have been fully characterized, we developed a test body to allow an adequate assessment of the BORC-system's efficiency. We obtained 0.84% efficiency for 43.8 °C working temperature. This corresponds to 35% of the Carnot efficiency calculated for the same temperature difference. Limitations of the model and the apparatus are put into perspective, pointing directions for further developments of BORC systems.

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