Organic rankine cycle Research Papers (original) (raw)

The objective of this paper is to model and optimise solar organic rankine cycle (ORC) engines for reverse osmosis (RO) desalination using currently available solar thermal collectors. The proposed systems are intended to be potentially... more

- by
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- Mechanical Engineering, Case Study, Process Simulation, Solar Collector

In this paper, the exergy analysis of “(56MW) the rmal power plant Raipur (India); a case study” are presented. The main objectives of this paper are to analyze the plant’s component separately and to id entify the parts having largest exergy losses. This paper will also justify the major sources of losses and exergy dest ruction in the power plant. According to the study, percentage rat io of the exergy destruction to the total exergy de struction was found to be maximum in the boiler system (57 %) followed by the turbine (33.3%), and then the condense r (5.34%). the exergy efficiency of the power plant was 31.12% . Which are low compared to modern power plants. According to analysis found that boiler is the major source o f irreversibility in the power plant, but exergy de struction rate in boiler can be reduced by reheating the system. It i s a suitable technique for decrease boiler’s irreve rsibility. How reheating is the best tool for improvement of overa ll performance and com...

- by Sahil Suryvanshee
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- Exergy, Exergy Analysis, Thermal Power Plant, Organic rankine cycle

In the last ten years, the increasing attention to pollutants and greenhouse gases emission from the power generation sector and the concerns about fossil fuel supply and price have led to a massive growth of those technologies that can produce electric energy from renewable sources or from waste heat recovery. In this context, the exploitation of heat from a wide variety of sources, like hot geothermal brines, sun and exhaust gases from engines and industrial processes using an Organic Rankine Cycle (ORC) is certainly one of the most promising solution. The basic idea is to exploit low and medium enthalpy energy sources by a Rankine cycle using an organic fluids instead of water as working fluid. This choice is confirmed by several feasibility studies and industrial applications which clearly show that, in a range from 500kW to 5MW, ORC power plants can reach higher efficiencies than common Rankine steam cycles. Moreover, ORC power plants guarantee a compact design of turbines, pri...

- by Ennio Macchi
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- Materials Science, Organic rankine cycle
- by Rinaldo Rinaldi
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- Mechanical Engineering, Applied Mathematics, Thermodynamics, Modeling

In this paper we evaluate the environmental sustainability of a small combined heat and power (CHP) plant operating through an Organic Rankine Cycle (ORC). The heat sources of the system are from geothermal energy at low temperature (90-95°C) and solar energy. The designed system uses a solar field composed only of evacuated, non-concentrating solar collectors, and work is produced by a single turbine of 50 kW. The project addresses an area of Tuscany, but it could be reproduced in areas where geothermal energy is extensively developed. Therefore, the aim is to exploit existing wells that are either unfit for high-enthalpy technology, abandoned or never fully developed. Furthermore, this project aims to aid in downsizing the geothermal technology in order to reduce the environmental impact and better tailor the production system to the local demand of combined electric and thermal energy. The environmental impact assessment was performed through a Life Cycle Analysis and an Exergy Life Cycle Analysis. According to our findings the reservoir is suitable for a long-term exploitation of the designed system, however, the sustainability and the energy return of this latter is edged by the surface of the heat exchanger and the limited running hours due to the solar plant. Therefore, in order to be comparable to other renewable resources or geothermal systems, the system needs to develop existing wells, previously abandoned.

- by Franco Ruzzenenti
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- Geography, Soil, Soft Matter, Agriculture

In this work, low temperature Organic Rankine Cycles are studied as bottoming cycle in medium and large scale combined cycle power plants. The analysis aims to show the interest of using these alternative cycles with high efficiency heavy duty gas turbines, for example recuperative gas turbines with lower gas turbine exhaust temperatures than in conventional combined cycle gas turbines. The following organic fluids have been considered: R113, R245, isobutene, toluene, cyclohexane and isopentane. Competitive results have been obtained for toluene and cyclohexane ORC combined cycles, with reasonably high global efficiencies.The paper is structured in four main parts. A review of combined cycle and ORC cycle technologies is presented, followed by a thermodynamic analysis of combined cycles with commercial gas turbines and ORC low temperature bottoming cycles. Then, a parametric optimization of an ORC combined cycle plant is performed in order to achieve a better integration between these two technologies. Finally, some economic considerations related to the use of ORC in combined cycles are discussed.

- by Jorge Muñoz
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- Engineering, Thermodynamics, Economics, GAS TURBINE

A cost-effective optimum design criterion for Organic Rankine power cycles utilizing low-temperature geothermal heat sources is presented. The ratio of the total heat exchanger area to net power output is used as the objective function and was optimized using the steepest descent method. Evaporation and condensation temperatures, geothermal and cooling water velocities are varied in the optimization method. The optimum cycle performance is evaluated and compared for working fluids that include ammonia, HCFC123, n-Pentane and PF5050. The optimization method converges to a unique solution for specific values of evaporation and condensation temperatures and geothermal and cooling water velocities. The choice of working fluid can be greatly affect the objective function which is a measure of power plant cost and in some instances the difference could be more than twice. Ammonia has minimum objective function and maximum geothermal water utilization, but not necessarily maximum cycle efficiency. Exergy analysis shows that efficiency of the ammonia cycle has been largely compromised in the optimization process than that of other working fluids. The fluids, HCFC 123 and n-Pentane, have better performance than PF 5050, although the latter has most preferable physical and chemical characteristics compared to other fluids considered.

- by Don Hettiarachchi
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- Mechanical Engineering, Energy, Performance, Heat Exchanger

Laboratory experiments were performed to determine the maximum operating temperature for cyclopentane as an organic Rankine cycle working fluid. The thermochemical decomposition of cyclopentane was measured in a recirculation loop at 240, 300, and 350°C at 43 bar in a glass-lined heated tube. It was determined that, in the absence of air at the two lower temperatures, decomposition was minor after more than 12 days of continuous operation. At 240°C, the total cyclopentane decomposition products were approximately 65 ppm, and at 300°C, the total decomposition products were on the order of 270 ppm at the end of the experiment. At 350°C, the decomposition products were significantly higher and reached 1500 ppm. When the feed was saturated with air under prevailing atmospheric conditions, the decomposition rate increased dramatically. Residues found in the reactor after the decomposition experiments were examined by a number of different techniques. The mass of the residues increased with experimental temperature but was lower at the same temperature when the feed was saturated with air. Analysis of the residues suggested that the residues were primarily heavy saturated hydrocarbons.

- by Donna Guillen
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- Engineering, Laboratory experiment, Temperature Dependence, CHEMICAL SCIENCES

In this paper we thermodynamically assess the performance of an ammonia-water Rankine cycle that uses no boiler, but rather the saturated liquid is flashed by a positive displacement expander (e.g., reciprocating, centrifugal, rotating vane, screw or scroll type expander) for power generation. This cycle has no pinch point and thus the exergy of the heat source can be better used by matching the temperature profiles of the hot and the working fluids in the benefit of performance improvement. The second feature comes from the use of the ammonia-water mixture that offers further opportunity to better match the temperature profiles at the sink level. The influence of the expander efficiency, ammonia concentration and the coolant flow rate is investigated and reported for a case study. The optimized cycle is then compared to four organic Rankine cycles and a Kalina-type cycle and shows the best performance. It is also shown that, in order to determine the best cycle configuration and parameters, energy efficiency must be used only in conjunction with the amount of the heat recovered from the source. The efficiency of the cycle running with ammonia-water is 0.30 in contrast to steam-only case showing 0.23 exergy efficiency, which means an increment of 7.0% is obtained for the same operating conditions. If cogeneration is used the cycle effectiveness may even be over 70%. The cycle can be applied for low power/low temperature heat recovery from geothermal sources, ocean thermal energy conversion, solar energy or process waste heat, etc.

- by Calin Zamfirescu
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- Thermodynamics, Analytical Chemistry, Water, Performance
- by Bruce Hedman
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- Engineering, Power Systems, Climate Change, Biomass

Research in concentrated thermal solar power plants of all types and, in particular, those based on central receiver, namely solar tower plants, has experienced great impetus in the last decade, reaching full commercial operation with the PS10 plant in Spain. In spite of previous demonstration plants testing different receivers and power cycle layouts, this first commercial power plant adopted a cavity receiver generating saturated steam and therefore penalising cycle efficiency in order to gain plant reliability. According to the experience gained, if a competitive Levelised Cost of Electricity is to be reached, capital and maintenance costs must be reduced and efficiencies must be increased. To achieve these goals, modifying the power cycle is deemed essential, whether using superheated steam or alternative fluids.

- by Ricardo Chacartegui
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- Mechanical Engineering, Carbon Dioxide, GAS TURBINE, Power Plant

This work presents an experimental investigation of a small scale (1 kW range) organic Rankine cycle system
for net electrical power output ability, using low-grade waste heat from steam. The system was
designed for waste steam in the range of 1–3 bar. After the organic Rankine cycle system was designed
and thermodynamic simulation was performed, equipment selection and construction of test rig was
carried out. R245fa was used as working fluid, a scroll type expansion directly coupled with electrical
generator produced a maximum electrical power output of 1.016 kW with 0.838 kW of net electrical
power output. The thermal efficiency of the system was 5.64%, net efficiency was 4.66% and expander
isentropic efficiency was 58.3% at maximum power output operation point. Maximum thermal efficiency
was 5.75% and maximum expander isentropic efficiency obtained was 77.74% during the experiment.
Effect of superheating of working fluid at expander inlet was also investigated which show that an
increase in the degree of superheating by 1 C reduces thermal efficiency of system by 0.021% for current
system. The results indicated that the measured electric power output and enthalpy determined power
output (after accounting for isentropic efficiency) differed by 40%. Similarly, the screw pump converted
42.25% of electric power to the enthalpy determined pumping power delivered to the working fluid. Both
expander and screw pump were losing power in electric and mechanical losses (generator/motor) presenting
a need of further development of these components for better efficiency. Heat loss in piping is
also a factor for improving efficiency along with the ability of heat exchangers and control system to
maintain the least possible degree of superheat of working fluid at expander inlet.

- by Byung-sik Park and +2
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- Renewable Energy, Geothermal Energy, Plate Heat Exchanger, Organic rankine cycle
- by Husain Almuslim
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- Mechanical Engineering, Chemical Engineering, Thermodynamics, Energy

Though the concept of Power Plants based on the Organic Rankine Cycle (ORC) is the new technology in Bangladesh, it can play a significant role to produce power from various heat sources when other alternatives were either technically not practical or not eco- nomical. These power plants in sizes from 300 kW to 130 MW have demonstrated the maturity of this technology. (6) The cycle is well adapted to low moderate temperature heat sources such as waste heat from industrial plants. This paper represents the feasibility of ORC based power plant in Bangladesh which has been suffering from energy crisis and unable to meet the present demand. The ORC technol- ogy is applicable to heat recovery of steel mills, rerolling mills, cement plants, and offers significant advantages over conventional steam bottoming cycles. One such system, the 2.630 MW Power Plant is now under analysis forecasts at Rahim Steel Mill in Bangladesh. (2) The environmentally friendly power plant is the first to be ins...

- by Subrato Biswas
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- Engineering, Organic rankine cycle, Steam Turbine, Waste Heat Recovery

Power plant system consists of generation, transmission, and distribution. One of power plants is steam generator. The main components in steam generator are boiler, steam turbine, condenser and synchronous generator. Rankine cycle is used for steam generator teoritically. Steam generator usually is used for handling basic load, because starting time is too long round about 6 -8 hours.

A thermal-economic analysis of a transcritical Rankine power cycle with reheat enhancement using a low-grade industrial waste heat is presented. Under the identical operating conditions, the reheat cycle is compared to the non-reheat baseline cycle with respect to the specific net power output, the thermal efficiency, the heat exchanger area, and the total capital costs of the systems. Detailed parametric effects are investigated in order to maximize the cycle performance and minimize the system unit cost per net work output. The main results show that the value of the optimum reheat pressure maximizing the specific net work output is approximately equal to the one that causes the same expansion ratio across each stage turbine. Relative performance improvement by reheat process over the baseline is augmented with an increase of the high pressure but a decrease of the turbine inlet temperature. Enhancement for the specific net work output is more significant than that for the thermal efficiency under each condition, because total heat input is increased in the reheat cycle for the reheat process. The economic analysis reveals that the respective optimal high pressures minimizing the unit heat exchanger area and system cost are much lower than that maximizing the energy performance. The comparative analysis identifies the range of operating conditions when the proposed reheat cycle is more cost effective than the baseline. Copyright © 2012 John Wiley & Sons, Ltd.

- by Hanfei Tuo
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- Carbon Dioxide, Energy Conversion, Organic rankine cycle, Waste Heat Recovery

More than seventy district heating (DH) plants based on biomass are operating in South Tyrol (Italy) and most of them supply heat to residential districts. Almost 20% of them are cogenerative systems, thus enabling primary energy savings with respect to the separate production of heat and power. However, the actual performance of these systems in real operation can considerably differ from the nominal one. The main objectives of this work are the assessment of the energy performance of a biomass boiler coupled with an Organic Rankine Cycle (i.e., ORC) generator under real operating conditions and the identification of its potential improvements. The fluxes of energy and mass of the plant have been measured onsite. This experimental evaluation has been supplemented with a thermodynamic model of the ORC generator, calibrated with the experimental data, which is capable to predict the system performance under different management strategies of the system. The results have highlighted that a decrease of the DH network temperature of 10 °C can improve the electric efficiency of the ORC generator of one percentage point. Moreover, a DH temperature reduction could decrease the main losses of the boiler, namely the exhaust latent thermal loss and the exhaust sensible thermal loss, which account for 9% and 16% of the boiler input power, respectively. The analysis of the plant has pointed out that the ORC pump, the flue gases extractor, the thermal oil pump and the condensation section fan are the main responsible of the electric self-consumption. Finally, the negative effect of the subsidisation on the performance of the plant has been discussed.

- by dario prando
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- Organic rankine cycle, CHP, Biomass Boilers

Escalating fuel prices and future carbon dioxide emission limits are creating a renewed interest in methods to increase the thermal efficiency of engines beyond the limit of in-cylinder techniques. One promising mechanism that accomplishes both objectives is the conversion of engine waste heat to a more useful form of energy, either mechanical or electrical. This paper reviews the history of internal combustion engine exhaust waste heat recovery focusing on Organic Rankine Cycles since this thermodynamic cycle works well with the medium-grade energy of the exhaust. Selection of the cycle expander and working fluid are the primary focus of the review, since they are regarded as having the largest impact on system performance. Results demonstrate a potential fuel economy improvement around 10% with modern refrigerants and advancements in expander technology.

- by Charles Sprouse
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- Organic rankine cycle, Waste Heat Recovery

This review deals with organic Rankine cycle powered by geothermal resource which is one favorable substitute for conventional fossil energy. Organic Rankine cycle power plants are suitable for utilization of low-temperature energy sources (low grade energy) such as geothermal resource having low temperature (below 150 ᵒC). The applications of organic Rankine cycle for electricity production from geothermal energy resource was reviewed first, where the choice of geothermal energy resources and organic fluids was discussed for different ORC configurations and operating conditions. Hybrid optimization approaches for the purpose of maintaining long term performance of enhanced geothermal system reservoirs were also summarized. Furthermore, an in-depth review of energy and exergy efficiencies of ORCs was conducted. Key factors that influence the energy and energy efficiencies of organic Rankine cycle were discussed in detail. Then, the economic indexes such as electricity production cost and levelized cost of electricity for different organic Rankine cycle configurations were compared with other conventional power generation systems to examine the commercialization of the Organic Rankine cycle. Finally, life cycle assessment that evaluates the whole life performance of geothermal organic Rankine cycle energy systems was reviewed. The Environmental impacts of geothermal ORC were also considered. Compared with other review papers on geothermal organic Rankine cycle s, the present review provides the latest materials for more systematically surveying the geothermal organic Rankine cycle, which will be a valuable source of guidance and directions for engineers and researchers in this field.

- by Danial Hamedi Jamali
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- Renewable Energy, Geothermal Energy, Organic rankine cycle

The popularity of Organic Rankine Cycle technology in waste heat recovery applications has experienced a fast growth in the last decade. One of the main fields of application is the Iron&Steel industry, and in particular waste heat recovery from Electric Arc Furnace. The very characteristics of the exhaust heat (non-continuous availability, thermal power fluctuations and amount of power) makes ORC the most suitable technology to produce electric power from the EAF sources. The experience of a Turboden ORC plant installed at Feralpi-Riesa steel plant in Germany-first EAF waste recovery system based on ORC-will be presented. To conclude the paper, achievement of Riesa plant and new investments on waste heat recovery plants from EAF around the world will be exposed.

- by Filippo Vescovo
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- Energy efficiency, Steel Making, Electric arc furnace, Organic rankine cycle

This paper presents the development of small-scale solar Organic Rankine Cycles for rural electrification in remote areas of Lesotho. It is subdivided in two parts. The first part deals with the success conditions of decentralized rural electrification projects. Through a literature survey, relevant guiding principles and recommendations are formulated. The second part of the paper describes the proposed system, which is designed in agreement with the formulated recommendations. A framework for benchmarking the performance and cost of various micro-utility platforms and rural electrification distribution models is proposed.

- by Sanusi Ohiare
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- Rural Electrification, Green energy technology, Organic rankine cycle, Offgrid

The combined cycle gas turbine integrates the Brayton cycle as topping cycle and the steam turbine Rankine cycle as bottoming cycle in order to achieve higher thermal efficiency and proper utilization of energy by minimizing the energy loss to a minimum. In this work, the effect of various operating parameters such as maximum temperature and pressure of Rankine cycle, turbine inlet temperature and pressure ratio of Brayton cycle on the net output work and thermal efficiency of the combine cycle are investigated. The outcome of this work can be utilized in order to facilitate the design of a combined cycle with higher efficiency and output work. A MATLAB simulation has been carried out to study the effects and influences of the above mentioned parameters on the efficiency and work output.

The system performance analysis and optimization of an organic Rankine cycle (ORC) system using HFC-245fa (1,1,1,3,3-pentafluoropropane) as working fluid driven by exhaust heat is presented. The thermodynamic performances of an ORC system under disturbances have been analyzed. The results show: maximizing the usage of exhaust heat as much as possible is a good way to improve system output net power and efficiency; the degree of sub-cooling at the condenser outlet should be small (0.5-0.6 K); when the ambient temperature is too high, the system output net power and efficiency will deteriorate with the departure from nominal state possibly exceeding 30%. According to the running environment, choosing a proper nominal state is a good idea for improving the system output net power and efficiency.

- by Ababacar Thiam
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- Thermodynamics, Performance, Optimization, System Analysis

Energy efficiency is more and more a crucial matter in the agenda of energy intensive industries: it constitutes a source of competitive advantage, indicator to social responsibility and environmental awareness. Among the various solutions available, the Organic Rankine Cycle (ORC) turbo-generators address to this topic by turning the waste heat sources into electrical power.
Thanks to the peculiarities of the ORC technology, these turbo-generators present key advantages such as long-life, very few maintenance and operation activities required, high availability, automatic and high-efficient operation at partial loads; for all these reasons ORC turbo-generators are more and more the preferred solution to waste-heat recovery projects in energy-intensive processes such as iron & steel, glass, waste incinerator, refineries and cement industries.

- by Filippo Vescovo and +1
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- Energy efficiency, Wast heat recovery, Organic rankine cycle

- by el bah menny
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- Thermodynamics, Performance, Optimization, System Analysis

Power production from low grade heat and waste heat does not only mitigate environmental impact but also improve energy efficiency and reduce energy cost. The type and design of expander for a low grade heat engine are critical and affect the performance, efficiency and cost of low grade heat and waste heat recovery system. The choice of expansion machine is strongly correlated with operating conditions, working fluid and size of the system. Low grade heat and waste heat recovery systems for electricity production are usually smaller in size. Turbines cannot be used due to their high rotational speed and high cost for waste heat and low grade heat recovery systems less than 50kWe. Therefore, volumetric expanders are more suitable in low grade heat and waste heat engines for a smaller size. The current article provides a comprehensive review of volumetric expanders including vane expander, screw expander, scroll expander, and piston expander applications for low grade heat and waste heat recovery using organic Rankine cycle. The operational performance, design optimizations, leakage and frictional losses, modeling techniques for each type of expander has been investigated in detail. Technical constraints and operational performance of expanders have been analyzed followed by the comparative assessment based on their performance, current market status, and economics. The comparative assessment shows that screw expander and scroll expander are most suitable having a relative score of 73.6 and 70.4 respectively on a scale of 100. The vane expanders have the lowest score of 47.2 due to low power range, leakage and frictional losses, and technical complexities.

- by Muhammad Imran
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- Organic rankine cycle, Waste Heat Recovery, Expanders, Low Grade Heat Sources

The content of this internship report is devoted to the latest research on the ORC machine. The first part is dedicated to the presentation of the ORC machine and its presence in the world. While the second part is consecrated to the latest theoretical and experimental researches including pures or zeotropics fluids. The last part is dedicated to the presentation of the Dymola software and the ThermoCycle library which are essential for the simulation and modeling of ORC machines.

- by Yassine Taleb
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- Organic rankine cycle, Organic Rankine Cycle (ORC), Dymola

Özet : Çeşitli atık ısı kaynaklarından elektrik enerjisi elde edebilmek için, sistem çevriminde geleneksel akışkan olarak su yerine hidrokarbon bileşenli organik akışkanların kullanıldığı Rankine çevrimi, aynı zamanda " Organik Rankine Çevrimi " olarak adlandırılmaktadır. Bu çalışmada, düşük ısı kaynaklı çalışan Organik Rankine çevrimi modellenmiş olup bu sistem termodinamik açıdan incelenmiştir. Modellenen sistemde, organik akışkanlardan R717, R 134a, R 22, R600a, R404a, R236fa, R1234yf, R245fa, R142b,R290, n pentane seçilmiştir. Seçilen bu 12 organik akışkan için, sistemin güç çevrimi ve toplam çevrim verimleri ayrı ayrı hesaplanmış olup, sistem performansını etkileyen parametreler teorik olarak araştırılmıştır. Sistem termodinamik açıdan incelendiğinde modellenen sistem için en uygun akışkanın R717 olduğu görülmektedir. Anahtar Kelimeler : Organik Rankine, ORC , Organik Akışkanlar 1.GİRİŞ Enerji, sanayileşmenin alt yapısı ve günlük hayatın vazgeçilmez bir unsurudur. Bu nedenle, enerji ihtiyacı ulusal ve uluslararası gündemde oldukça önemli bir yer tutar. Enerji kaynaklarının tükenebilir oluşu, dışa bağımlılığın varlığı ve çevresel etkiler sebebiyle; günümüzde ülkeler için güvenli, yeterli miktarda, ucuz ve temiz enerji üretmek, ekonomik ve sosyal hayatın temel problemleri arasında yerini almaktadır. Sanayisi, ekonomisi ve nüfusu ile hızla büyümekte olan ülkemizde paralel olarak enerji ihtiyacı sürekli artmaktadır. Bu nedenle, üretilen enerjinin yüksek verimle kullanılması, mevcut enerji kaynaklarının yanı sıra alternatif ve yenilenebilir enerji kaynaklarına ait potansiyelin değerlendirilmesi büyük önem taşımaktadır[1]. Günümüzde tüketimi durmadan artan ve gelecekte de durmadan artmaya devam edecek olan en önemli ihtiyaçlarımızdan biri hiç şüphesiz enerjidir. Dünyadaki enerji üretimi daha çok fosil yakıtlı termik santraller, hidroelektrik ve nükleer enerji santrallerinden karşılanmaktadır. Atmosfere verilen kirleticilerin ve sera gazlarının büyük bir bölümü enerji sektöründe yani enerji üretimi ve tüketimi, ya da çevriminden kaynaklanmaktadır.

- by Başak ALTUNBAŞAK and +1
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- Organic rankine cycle, Organic Fluids

Steam are a major energy consumer. Optimising process operating conditions can considerably improve turbine water rate, which in turn will significantly reduce energy requirement. Various operating parameters affect condensing and back pressure turbine steam consumption and efficiency. The industrial sector is the largest energy consumer, accounting for about 30 % of total energy used. Fuel and energy prices are continuously rising. With the present trend of energy prices and scarcity of hydrocarbon resources lowering energy requirement is a top priority. Energy conservation benefits depend on the adopting minor or major modifications and using the latest technology. Turbines are designed for a particular operating conditions like steam inlet pressure, steam inlet temperature and turbine exhaust pressure/ exhaust vacuum, which affects the performance of the turbines in a significant way. Variations in these parameters affects the steam consumption in the turbines and also the turbine efficiency. The present study was done to improve the power output of the turbine, thermal efficiency and specific steam consumption in conventional steam power plants. Three cycles i.e regenerative cycle, superheater cycle and cogeneration cycle are considered to formulate the data and obtain a better result in steam turbine power plants.

- by IOSR Journals
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- Renewable Energy, Organic rankine cycle
- by Kiyarash Rahbar and +2
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- GAS TURBINE, Computational Fluid Dynamics (CFD) modelling and simulation, Power Generation, Turbomachinery
- by Kiyarash Rahbar and +2
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- Optimization techniques, Mathematical Modelling, GAS TURBINE, Organic rankine cycle

The organic Rankine cycle (ORC) is commonly accepted as a viable technology to convert low temperature heat into electricity. Furthermore, ORCs are designed for unmanned operation with little maintenance. Because of these excellent characteristics, several ORC waste heat recovery plants are already in operation. Although the basic ORC is gradually adopted into industry, the need of increased cost-effectiveness persists. Therefore, a next logical step is the development of new ORC architectures.

- by Steven Lecompte and +1
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- Engineering, Architectures, Organic rankine cycle, Waste Heat Recovery

Turbo-expander is the most crucial and expensive component in Organic Rankine Cycle (ORC) power generation systems. The turbine engineering, design and research development process for ORC system is costly, time-consuming, and difficult for new-entrants in the ORC field. This paper investigates the re-design and retrofit of an off-the-shelf turbocharger for use in a 1 kW ORC system. The expander requirements were determined for the 1 kW Capstone Gas Turbine bottoming cycles from the ORC system design. A radial turbine was selected and an off-the-shelf turbocharger from a small petrol-driven vehicle was acquired. The turbocharger was simulated to study the off-design performance in an ORC system. The turbocharger was evaluated by expansion of compressed air at room temperature to assess the leakage of working fluid and the lubrication requirements. A preliminary design was developed to deal with leakage and lubrication issues. The conceptual design of an ORC turbine was presented including the casing design and selection of auxiliary components such as bearings, seals and lubrication systems.

- by Choon Seng Wong and +1
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- Turbomachinery, Turbocharger, Organic rankine cycle

In this study, the heat transfer characteristics of an ORC evaporator and condenser applied
on diesel engine were analyzed using measured data such as flue gas mass flow rate and flue gas
temperature. A mathematical model was developed with regard to the preheater , boiler and the
superheater zones of a counter flow evaporator but desuperheater and condenser zones of a
counter flow condenser. The performance of the ORC system was evaluated under variable heat
input. Three steps applied in this paper starting with determine optimum pressure for working
fluid followed by design the ORC system and finally investigate the variable heat input on the ORC
system. Can be seen from result that there are optimum evaporation pressure to obtain maximum
net power depending on working fluid type. The maximum net power output for R141b (3.361 kW)
followed by R123 (3.198 kW) followed by R245fa (2.454 kW) and finally R600a (2.112 kW). The
design area of evaporator and condenser proportional to net power output that’s mean we need
big area for maximum net power output. As well as can be seen from our analysis the total area of
evaporator is very close from the total area of condenser for all cases and this is easy for
manufacturer. The refrigerant mass flow rate is a very important control parameter on the
maximize the net power output as well as to be sure that the vapor at inlet turbine is superheated
to avoided dangerous of the droplets in expander. Most cases larger part of heat add go to
preheater zone and the remaining part subdivided on boiler and superheater zones .The preheater
heat input for R123 it is the largest between working fluids but for R245fa it is smallest that’s
mean we need more heat to convert R123 from liquid state to saturation liquid but need less heat
for R245fa. In the same way we need more heat to convert R141b from saturation liquid to
saturation vapor but need less heat for R600a. Finally we need more heat to convert R600a from
saturation vapor to be superheated but need less heat for R245fa.

- by mahdi hatf
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- Organic rankine cycle

The rise of fuel prices due to the depletion of fossil fuel energy and unlimited carbon dioxide let-off are creating a renewed interest in techniques to increase the thermal efficiency of marine diesel engines. One promising mechanism to achieve improvement in system thermal efficiency is the conversion of engine waste heat to a more useful form of energy, either mechanical energy or electrical energy. Thus, this study investigates the potential of exhaust waste heat recovery from marine diesel engines using bioethanol production from selected microalgae as the working fluid via organic Rankine cycle (ORC). It also examines the system thermal efficiency and determines the pinch temperature of the plant. The microalgae Dunaliella tertiolecta, Chlamydomonas fasciata Ettl 437 and Synechococcus PCC 7002 are chosen as bioethanol producers based on the high yield of production. The maximum net power output and high system thermal efficiency are chosen as the evaluation criteria to select the microalgae with the best performance. The results demonstrate that among the three selected microalgae, Synechococcus PCC 7002 shows the highest efficiency of approximately 2.28% for the mass flowrate of exhaust gas of 4189 kgh1, while the net power output was approximately 5.10kW

- by Su Shiung Lam
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- Organic rankine cycle

Organic Rankine Cycle (ORC) is one of the best methods to utilize renewable energy source which has low temperature. Radial turbine as one of the most influencimg component in the efficiency of ORC has not been researched, so the effort to research radial turbine is important to be done.
In this study, geometry determination of radial turbine with R134a as working fluid is researched. The range inlet condition are mass flow rate about 1-2 kg/s, inlet pressure 1.5 to 5 bar, and inlet temperature 80 to 130 ⁰C with power output target is 20 to 25 kW. The geometry determination scope are the preliminary and detail design of rotor, nozzle geometry, and volute geometry. After the geometry of radial turbine achieved, simulation with Computational Fluid Dynamics (CFD) using ANSYS CFX performed. The simulation used Redlich-Kwong real gas to model gas physical condition and Shear Stress Transport to model the turbulence. Performance prediction of the radial turbine then derived from the simulation result.
Writer used load coefficient (ψ) at 0.905, flow coefficient (φ) at 0.26, ratio of r2/r3 at 1.2, 13 rotor blades, and rotational speed at 20,000 RPM achieved best performance results. Best performance result showed specific output power at 16.77 kW/kg with output power 24.98 kW and total to total efficiency at 89.44%.

- by Prasetyo Prihadi
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- Mechanical Engineering, Renewable Energy, Organic rankine cycle, Radial Turbine

Power generation from low enthalpy geothermal resources using Organic Rankine Cycle systems is markedly influenced by the temperature level of the heat source and heat sink. During plant operation the actual temperature of the geofluid may be different from the value assumed in the design phase. In addition, the seasonal and daily variations of the ambient temperature greatly affect the power output especially when a dry condensation system is used. This paper presents a detailed off-design model of an Organic Rankine Cycle that includes the performance curves of the main plant components. Two capacitive components in the model have the key function of damping the temporary disequilibrium of mass and energy inside the system. Isobutane and R134a are considered as working fluids, mainly operating in subcritical and supercritical cycles, respectively. The off-design model is used to find the optimal operating parameters that maximize the electricity production in response to changes of the ambient temperatures between 0 and 30°C and geofluid temperatures between 130 and 180°C.

The development of engine waste heat recovery (WHR) technologies attracts ever increasing interests due to the rising strict policy requirements and environmental concerns. Organic Rankine Cycle (ORC) can convert low medium grade heat into electrical or mechanical power and has been widely recognized as the most promising heat-driven technologies. A typical internal combustion engine (ICE) converts around 30% of the overall fuel energy into effective mechanical power and the rest of fuel energy is dumped through the engine exhaust system and cooling system. Integrating a well-designed ORC system to ICE can effectively improve the overall energy efficiency and reduce emissions with around 2-5 years payback period through fuel saving. This book chapter is meant to provide an overview of the technical development and application of ORC technology to recover wasted thermal energy from the ICE with a particular focus on vehicle applications.

- by Dr Yiji Lu and +1
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- Organic rankine cycle, Waste Heat Recovery

Finally, explaining the procedure of analysis of thermal power plant systems by exegetical approach.

This article compares the part-load operation of air cooled and cooling tower based low-medium temperature geothermal Organic Rankine Cycle (ORC) systems installed at different geographical locations. Working fluid R245fa was compared with a newer competitor R1233zde for thermo-economic performance , environment-friendly and efficient system integration. Monthly averaged, weather data is used to simulate ambient conditions of Ulsan, London, Vegas and Kuala Lumpur. Mathematical models for condenser part load operation were formulated for both air cooled and mechanical draft wet cooling tower based systems. Numerical study and experimental validation was performed for the condenser when wet cooling tower based system was investigated. The ORC system design was optimized for maximum power output to grid and operational control optimization was performed on the heat sink to achieve maximum power output at different ambient or off-design conditions. Economic analysis was performed by comparing the capital investment/kW and levelized cost of electricity (LCOE) over the lifetime of the system. Based on the economic analysis, the results reveal that R1233zde has potential to replace R245fa working fluid when the source temperature is higher (around 145 C). Cooling tower based system are preferable for hot dry regions while air-cooled systems can be implemented with R1233zde for Ulsan and London.

- by Muhammad Imran
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- Economics, Optimization, Organic rankine cycle, Air Cooled Condensers

A domestic-scale combined solar heat and power (CSHP) system is simulated in the UK climate. The CSHP system comprises a solar collector array, an ORC engine and a hot-water cylinder. An exergy analysis, parametric study and annual performance assessment are performed. An average electrical power of 89 W plus an 86% hot water coverage are demonstrated. A total system cost as low as £2700 and a levelised cost electricity of 44 p/kW h are reported. a b s t r a c t Performance calculations are presented for a small-scale combined solar heat and power (CSHP) system based on an Organic Rankine Cycle (ORC), in order to investigate the potential of this technology for the combined provision of heating and power for domestic use in the UK. The system consists of a solar collector array of total area equivalent to that available on the roof of a typical UK home, an ORC engine featuring a generalised positive-displacement expander and a water-cooled condenser, and a hot water storage cylinder. Preheated water from the condenser is sent to the domestic hot water cylinder, which can also receive an indirect heating contribution from the solar collector. Annual simulations of the system are performed. The electrical power output from concentrating parabolic-trough (PTC) and non-concentrating evacuated-tube (ETC) collectors of the same total array area are compared. A parametric analysis and a life-cycle cost analysis are also performed, and the annual performance of the system is evaluated according to the total electrical power output and cost per unit generating capacity. A best-case average electrical power output of 89 W (total of 776 kW h/year) plus a hot water provision capacity equivalent to $80% of the total demand are demonstrated, for a whole system capital cost of £2700-£3900. Tracking PTCs are found to be very similar in performance to non-tracking ETCs with an average power output of 89 W (776 kW h/year) vs. 80 W (701 kW h/year).

- by Christos N Markides
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- Engineering, Economics, Organic rankine cycle, Applied Energy

Present study deals with the flow boiling of R245fa, a commercial working fluid used in organic Rankine cycle, in brazed plate heat exchanger with chevron angle of 45 degree and 60 degree. The effects of the heat flux, mass flux rate of refrigerant, saturation temperature on convective heat transfer coefficients are investigated. The operating conditions of the experiment are as mass flux: 30–40 kg m À2 s À1 quality at evaporator inlet: 0.1–0.8, heat flux: 2–15 kW m À2. The heat transfer result suggests a nucleate boiling dominant process in the evaporator. The convective heat transfer coefficient showed a strong dependence on the heat flux and vapor quality at evaporator inlet. Moreover convective heat transfer coefficient show a linear relationship with mass flux of the refrigerant. It is worth mentioning that heat transfer coefficient is higher at higher saturation temperature and chevron angle. Based on the experimental data, empirical correlations were developed for the prediction of heat transfer coefficients and frictional pressure drop of refrigerant R245fa in brazed plate heat exchanger.

- by Muhammad Imran and +1
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- Plate Heat Exchanger, Friction Correction Factor, Organic rankine cycle, Boiling Heat Transfer Coefficient

Keywords: Recuperated Organic Rankine Cycle Regenerative Organic Rankine Cycle Thermo-economic optimization a b s t r a c t Present study deals with the comparative assessment of three different configurations of ORC (Organic Rankine Cycle) system including basic ORC, recuperated ORC, and regenerative ORC system for low temperature geothermal heat source. The comparison of the performance of each cycle is carried out at their optimum operating condition using Non-dominated Sorting Genetic Algorithm-II for minimum specific investment cost and maximum exergy efficiency under logical bounds of evaporation temperature , pinch point temperature difference and superheat. Objective functions are conflicting, therefore, optimization results are presented in the form of a Pareto Front Solution. Thermal efficiency and the exergy efficiency for recuperated and regenerative are higher than basic ORC but with an additional average specific investment cost of 3% for basic and 7% for regenerative cycle. Working fluids with critical temperature in the same range of heat source results in better thermal performance. R245fa has highest Exergy efficiency of 51.3% corresponding to minimum specific cost of 2423$/kW for basic cycle, 53.74% corresponding to 2475$/kW for recuperated, and 55.93% corresponding to 2567$/kW for regenerative cycle.

- by Muhammad Imran and +1
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- Optimization techniques, Geothermal Energy, Thermoeconomics, Technoeconomic studies

An ORC based power plant for waste heat recovery in stationary applications has been developed and experimentally characterized. The aim of the study was to investigate the performance of a sliding vane rotary expander as the device to convert the enthalpy of the working fluid, namely R236fa, into mechanical and electric energy. A theoretical model of the expander supported the design and allowed to assess the thermodynamic transformations that take place in it. Furthermore, a deep experimental campaign explored the behavior of the expander and the one of the recovery system also at off design conditions. The experimental activity on the expander included the reconstruction of the indicated diagram using a set of high frequency piezoelectric pressure transducers that provided an accurate prediction of the pressure evolution inside the cell. The overall cycle efficiency achieved was close to 8% and further improvements concerned to the expander design have been addressed. The temperature of the upper thermal source at around 120 • C and the mechanical output power close to 2 kW make the expander and the whole system suitable for plenty of potential recovery applications.

- by Giuseppe Bianchi and +2
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- Internal Combustion Engines, Energy Recovery Systems, Organic rankine cycle

The study of the dense gas flows which occur in many technological applications demands for fluid dynamic simulation tools incorporating complex thermodynamic models that are not usually available in commercial software. Moreover, the... more

- by Stefano Rebay
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- Engineering, Thermodynamics, Equations of State, Fluid Dynamics

Improving energy efficiency in every sector (e.g., building, industrial, transport) is a priority to reduce the effects
of the human impact on the environment. Among the techniques which can be applied, waste heat recovery has received
growing interest in the last few decades. Normally, waste heat can be utilized for power production or process heating. In
the first case, recovery plants based on Organic Rankine Cycles (ORCs) are a common solution. Even though ORC systems
are considered a consolidated technology, their application is not always economically convenient, especially for smalland
medium-scale plants. This is due to the low temperature of the heat source made available to the ORC system, which
inevitably implies a low thermodynamic cycle efficiency. Therefore, given a reference thermal source available for the
ORC plant, particular attention has to be paid to the layout arrangement, in particular to the selection of some key
components among which there is the expander. The paper deals with the comparative analysis of three small-scale plant
layouts designed for the same reference waste heat source. In particular, three different expanders have been taken into
consideration for electrical power production <100 kWe, i.e., 1) one-stage radial turbine, 2) twin-screw expander, and 3)
two-stage radial turbine. Each expander imposes several constraints on the cycle and, consequently, the overall ORC plant
performance is affected by the preliminary choice of such a machine. The three cases have been preliminarly designed and
comparatively analyzed. Namely, they were compared from the view point of economic performance, to highlight potential
trade-offs between improved thermodynamic efficiency and resulting costs. Moreover, a life cycle analysis completed the
comparison by evaluating the overall environmental impact of the three cases in order to establish their benefits and
drawbacks in terms of sustainable electricity production.

- by Pietro Bartocci
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- Organic rankine cycle, Life Cycle Assessment ( LCA )

This paper presents the analysis of organic Rankine cycle (ORC) based waste heat recovery system. Both the positive and negative effects of ORC system installation on a light duty vehicle were evaluated. Engine exhaust data for a light duty vehicle was used to design an ORC based system. Optimum cycle design suggests that ORC system installation is feasible. Results presented that for the vehicle operation at 100 km/h, engine power can be enhanced by 10.88% which is 5.92 kW of additional power and at the lower speed of 23.5 km/h, the engine power enhancement was 2.34%. ORC component weight data from manufacturers were used to estimate the weight of the designed system. The performance decline due to added weight is calculated. Effects of added back pressure and performance decline due to the part-load operation of ORC unit were also calculated and an overall effect of waste heat recovery system was evaluated. The results then suggested that maximum power enhancement is 5.82% at the vehicle speed of 100 km/h instead of previously mentioned 10.88% can be achieved if negative effects are also considered. Furthermore, it was concluded that at speeds lower than 48 km/h the waste heat recovery system was not beneficial at all and low-speed operation was in fact not preferable as it results in additional power demand from the engine by 6.39% at 23.5 km/h. The vehicles for city driving cycles are not recommended for ORC installation. Another finding revealed that if exhaust heat recovery heat exchanger is designed for maximum heat recovery, at part load operation, the heat exchanger is not suitable to maintain working fluid temperature below the critical temperature of working fluid and minimum exhaust gas temperature at heat exchanger exit.

- by Muhammad Imran and +1
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- Internal Combustion Engines, Organic rankine cycle, Waste Heat Recovery, Expanders