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Organic Rankine Cycle for Energy Recovery System

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A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "J: Thermal Management".

Deadline for manuscript submissions: closed (29 February 2020) | Viewed by 30075

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Special Issue Editor

Dr. Andrea De Pascale

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Guest Editor

Department of Industrial Engineering, University of Bologna, 40126 Bologna, Italy
Interests: thermodynamics of advanced energy systems; advanced gas turbines; CHP and micro-CHP systems; renewable-based and waste heat-recovery technologies; micro-generators; ORC technology
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Special Issue Information

Dear Colleagues,

Organic Rankine Cycle (ORC) is an emerging energy system for power production and waste-heat recovery. In the future, this technology can play an increasing role within the energy generation sectors, and it can aid the achievement of the carbon footprint reduction targets of many industrial processes. In particular, there is still a huge amount of un-used hot streams in various stationary power generators, and in several highly intensive industries, that could be recovered. Additional applications can come from the transportation sector, where engine-wasted heat in heavy vehicles can be used to achieve fuel savings. Moreover, low and high enthalpy flows from renewable sources (solar, geothermal, etc.) can be exploited in thermodynamic cycles based on Rankine architecture.

The ORC is already a well-proven option for large plants, but not all technological aspects are currently solved/optimized; the state-of-the-art still requires cost-effective improvements, in order to enlarge market opportunities. Meanwhile, the ORC is still developing in small-scale and/or micro-generation applications, in which efficient and low-cost components are not fully ready for the market yet and problems must be solved.

This Special Issue will focus on the current state-of-the-art and on cutting-edge research activities ongoing in ORC technology. Topics of interest for publication include, but are not limited to, the following:

Waste-Heat Recovery applications
Advanced thermodynamic cycles
Combined heat and power generation
Expanders for waste-heat recovery
Renewable heat and low-enthalpy applications
Experiments on micro ORC generators
New organic fluids for power generation
New integrations of ORC with other energy systems

Prof. Dr. Andrea De Pascale
Guest Editor

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Keywords

Organic Rankine Cycle (ORC)
Waste Heat Recovery (WHR)
Combined Heat and Power (CHP)
renewable
thermodynamic cycle
expanders
micro generators
organic fluids

Published Papers (10 papers)

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Editorial

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3 pages, 174 KiB

Open AccessEditorial

Organic Rankine Cycle for Energy Recovery System

by Andrea De Pascale

Energies 2021, 14(17), 5253; https://doi.org/10.3390/en14175253 - 25 Aug 2021

Cited by 1 | Viewed by 1237

Abstract

This book contains the successful invited submissions [...] Full article

(This article belongs to the Special Issue Organic Rankine Cycle for Energy Recovery System)

Research

Jump to: Editorial

24 pages, 5050 KiB

Open AccessArticle

Thermodynamic, Exergy and Environmental Impact Assessment of S-CO₂ Brayton Cycle Coupled with ORC as Bottoming Cycle

by Edwin Espinel Blanco, Guillermo Valencia Ochoa and Jorge Duarte Forero

Energies 2020, 13(9), 2259; https://doi.org/10.3390/en13092259 - 04 May 2020

Cited by 18 | Viewed by 2662

Abstract

In this article, a thermodynamic, exergy, and environmental impact assessment was carried out on a Brayton S-CO₂ cycle coupled with an organic Rankine cycle (ORC) as a bottoming cycle to evaluate performance parameters and potential environmental impacts of the combined system. The performance variables studied were the net power, thermal and exergetic efficiency, and the brake-specific fuel consumption (BSFC) as a function of the variation in turbine inlet temperature (TIT) and high pressure (P_HIGH), which are relevant operation parameters from the Brayton S-CO₂ cycle. The results showed that the main turbine (T1) and secondary turbine (T2) of the Brayton S-CO₂ cycle presented higher exergetic efficiencies (97%), and a better thermal and exergetic behavior compared to the other components of the System. Concerning exergy destruction, it was found that the heat exchangers of the system presented the highest exergy destruction as a consequence of the large mean temperature difference between the carbon dioxide, thermal oil, and organic fluid, and thus this equipment presents the greatest heat transfer irreversibilities of the system. Also, through the Life Cycle Analysis, the potential environmental impact of the system was evaluated to propose a thermal design according to the sustainable development goals. Therefore, it was obtained that T1 was the component with a more significant environmental impact, with a maximum value of 4416 Pts when copper is selected as the equipment material. Full article

(This article belongs to the Special Issue Organic Rankine Cycle for Energy Recovery System)

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17 pages, 1833 KiB

Open AccessArticle

Life Cycle Assessment of a Commercially Available Organic Rankine Cycle Unit Coupled with a Biomass Boiler

by Anna Stoppato and Alberto Benato

Energies 2020, 13(7), 1835; https://doi.org/10.3390/en13071835 - 10 Apr 2020

Cited by 18 | Viewed by 3496

Abstract

Organic Rankine Cycle (ORC) turbogenerators are a well-established technology to recover from medium to ultra-low grade heat and generate electricity, or heat and work as cogenerative units. High firmness, good reliability and acceptable efficiency guarantee to ORCs a large range of applications: from waste heat recovery of industrial processes to the enhancement of heat generated by renewable resources like biomass, solar or geothermal. ORC unit coupled with biomass boiler is one of the most adopted arrangements. However, despite biomass renewability, it is mandatory to evaluate the environmental impact of systems composed by boilers and ORCs taking into account the entire life cycle. To this purpose, the authors perform a life cycle assessment of a commercially available 150 kW cogenerative ORC unit coupled with a biomass boiler to assess the global environmental performance. The system is modelled in SimaPro using different approaches. Results show that the most impacting processes in terms of CO₂ equivalent emissions are the ones related to biomass production and organic fluid leakages with 71% and 19% of the total. Therefore, being fluid release in the environment high impacting, a comparison among three fluids is also performed. Analysis shows that adopting a hydrofluoroolefin fluid with a low global warming potential instead of the hydrocarbon fluid as already used in the cycle guarantees a significant improvement of the environmental performance. Full article

(This article belongs to the Special Issue Organic Rankine Cycle for Energy Recovery System)

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20 pages, 4734 KiB

Open AccessArticle

Regression Models for the Evaluation of the Techno-Economic Potential of Organic Rankine Cycle-Based Waste Heat Recovery Systems on Board Ships Using Low Sulfur Fuels

by Enrico Baldasso, Maria E. Mondejar, Ulrik Larsen and Fredrik Haglind

Energies 2020, 13(6), 1378; https://doi.org/10.3390/en13061378 - 16 Mar 2020

Cited by 8 | Viewed by 2785

Abstract

When considering waste heat recovery systems for marine applications, which are estimated to be suitable to reduce the carbon dioxide emissions up to 20%, the use of organic Rankine cycle power systems has been proven to lead to higher savings compared to the traditional steam Rankine cycle. However, current methods to estimate the techno-economic feasibility of such a system are complex, computationally expensive and require significant specialized knowledge. This is the first article that presents a simplified method to carry out feasibility analyses for the implementation of organic Rankine cycle waste heat recovery units on board vessels using low-sulfur fuels. The method consists of a set of regression curves derived from a synthetic dataset obtained by evaluating the performance of organic Rankine cycle systems over a wide range of design and operating conditions. The accuracy of the proposed method is validated by comparing its estimations with the ones attained using thermodynamic models. The results of the validation procedure indicate that the proposed approach is capable of predicting the organic Rankine cycle annual energy production and levelized cost of electricity with an average accuracy within 4.5% and 2.5%, respectively. In addition, the results suggest that units optimized to minimize the levelized cost of electricity are designed for lower engine loads, compared to units optimized to maximize the overall energy production. The reliability and low computational time that characterize the proposed method, make it suitable to be used in the context of complex optimizations of the whole ship’s machinery system. Full article

(This article belongs to the Special Issue Organic Rankine Cycle for Energy Recovery System)

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22 pages, 5697 KiB

Open AccessArticle

Optimum Organic Rankine Cycle Design for the Application in a CHP Unit Feeding a District Heating Network

by Lisa Branchini, Andrea De Pascale, Francesco Melino and Noemi Torricelli

Energies 2020, 13(6), 1314; https://doi.org/10.3390/en13061314 - 12 Mar 2020

Cited by 6 | Viewed by 2392

Abstract

Improvement of energy conversion efficiency in prime movers has become of fundamental importance in order to respect EU 2020 targets. In this context, hybrid power plants comprising combined heat and power (CHP) prime movers integrated with the organic Rankine cycle (ORC) create interesting opportunities to additionally increase the first law efficiency and flexibility of the system. The possibility of adding supplementary electric energy production to a CHP system, by converting the prime movers’ exhaust heat with an ORC, was investigated. The inclusion of the ORC allowed operating the prime movers at full-load (thus at their maximum efficiency), regardless of the heat demand, without dissipating not required high enthalpy-heat. Indeed, discharged heat was recovered by the ORC to produce additional electric power at high efficiency. The CHP plant in its original arrangement (comprising three internal combustion engines of 8.5 MW size each) was compared to a new one, involving an ORC, assuming three different layout configurations and thus different ORC off-design working conditions at user thermal part-load operation. Results showed that the performance of the ORC, on the year basis, strongly depended on its part-load behavior and on its regulation limits. Indeed, the layout that allowed to produce the maximum amount of ORC electric energy per year (about 10 GWh/year) was the one that could operate for the greatest number of hours during the year, which was different from the one that exhibited the highest ORC design power. However, energetic analysis demonstrated that all the proposed solutions granted to reduce the global primary energy consumption of about 18%, and they all proved to be a good investment since they allowed to return on the investment in barely 5 years, by selling the electric energy at a minimum price equal to 70 EUR/MWh. Full article

(This article belongs to the Special Issue Organic Rankine Cycle for Energy Recovery System)

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15 pages, 678 KiB

Open AccessArticle

Off-Design Performances of an Organic Rankine Cycle for Waste Heat Recovery from Gas Turbines

by Carlo Carcasci, Lapo Cheli, Pietro Lubello and Lorenzo Winchler

Energies 2020, 13(5), 1105; https://doi.org/10.3390/en13051105 - 02 Mar 2020

Cited by 8 | Viewed by 2308

Abstract

This paper presents an off-design analysis of a gas turbine Organic Rankine Cycle (ORC) combined cycle. Combustion turbine performances are significantly affected by fluctuations in ambient conditions, leading to relevant variations in the exhaust gases’ mass flow rate and temperature. The effects of the variation of ambient air temperature have been considered in the simulation of the topper cycle and of the condenser in the bottomer one. Analyses have been performed for different working fluids (toluene, benzene and cyclopentane) and control systems have been introduced on critical parameters, such as oil temperature and air mass flow rate at the condenser fan. Results have highlighted similar power outputs for cycles based on benzene and toluene, while differences as high as 34% have been found for cyclopentane. The power output trend with ambient temperature has been found to be influenced by slope discontinuities in gas turbine exhaust mass flow rate and temperature and by the upper limit imposed on the air mass flow rate at the condenser as well, suggesting the importance of a correct sizing of the component in the design phase. Overall, benzene-based cycle power output has been found to vary between 4518 kW and 3346 kW in the ambient air temperature range considered. Full article

(This article belongs to the Special Issue Organic Rankine Cycle for Energy Recovery System)

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13 pages, 2235 KiB

Open AccessArticle

Structured Mesh Generation and Numerical Analysis of a Scroll Expander in an Open-Source Environment

by Ettore Fadiga, Nicola Casari, Alessio Suman and Michele Pinelli

Energies 2020, 13(3), 666; https://doi.org/10.3390/en13030666 - 04 Feb 2020

Cited by 12 | Viewed by 3184

Abstract

The spread of the organic rankine cycle applications has driven researchers and companies to focus on the improvement of their performance. In small to medium-sized plants, the expander is the component that has typically attracted the most attention. One of the most used types of machine in this scenario is the scroll. Among the other methods, numerical analyses have been increasingly exploited for the investigation of the machine’s behaviour. Nonetheless, there are major challenges for the successful application of computational fluid dynamics (CFD) to scrolls. Specifically, the dynamic mesh treatment required to capture the movement of working chambers and the nature of the expanding fluids require special care. In this work, a mesh generator for scroll machines is presented. Given few inputs, the software described provides the mesh and the nodal positions required for the evolution of the motion in a predefined mesh motion approach. The mesh generator is developed ad hoc for the coupling with the open-source CFD suite OpenFOAM. A full analysis is then carried out on a reverse-engineered commercial machine, including the refrigerant properties calculations via CoolProp. It is demonstrated that the proposed methodology allows for a fast simulation and achieves a good agreement with respect to former analyses. Full article

(This article belongs to the Special Issue Organic Rankine Cycle for Energy Recovery System)

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22 pages, 4047 KiB

Open AccessArticle

Energy and Exergy Analysis of Different Exhaust Waste Heat Recovery Systems for Natural Gas Engine Based on ORC

by Guillermo Valencia, Armando Fontalvo, Yulineth Cárdenas, Jorge Duarte and Cesar Isaza

Energies 2019, 12(12), 2378; https://doi.org/10.3390/en12122378 - 20 Jun 2019

Cited by 65 | Viewed by 4907

Abstract

Waste heat recovery (WHR) from exhaust gases in natural gas engines improves the overall conversion efficiency. The organic Rankine cycle (ORC) has emerged as a promising technology to convert medium and low-grade waste heat into mechanical power and electricity. This paper presents the energy and exergy analyses of three ORC–WHR configurations that use a coupling thermal oil circuit. A simple ORC (SORC), an ORC with a recuperator (RORC), and an ORC with double-pressure (DORC) configuration are considered; cyclohexane, toluene, and acetone are simulated as ORC working fluids. Energy and exergy thermodynamic balances are employed to evaluate each configuration performance, while the available exhaust thermal energy variation under different engine loads is determined through an experimentally validated mathematical model. In addition, the effect of evaporating pressure on the net power output, thermal efficiency increase, specific fuel consumption, overall energy conversion efficiency, and exergy destruction is also investigated. The comparative analysis of natural gas engine performance indicators integrated with ORC configurations present evidence that RORC with toluene improves the operational performance by achieving a net power output of 146.25 kW, an overall conversion efficiency of 11.58%, an ORC thermal efficiency of 28.4%, and a specific fuel consumption reduction of 7.67% at a 1482 rpm engine speed, a 120.2 L/min natural gas flow, 1.784 lambda, and 1758.77 kW of mechanical engine power. Full article

(This article belongs to the Special Issue Organic Rankine Cycle for Energy Recovery System)

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18 pages, 13147 KiB

Open AccessArticle

Pressure Pulsation and Cavitation Phenomena in a Micro-ORC System

by Nicola Casari, Ettore Fadiga, Michele Pinelli, Saverio Randi and Alessio Suman

Energies 2019, 12(11), 2186; https://doi.org/10.3390/en12112186 - 08 Jun 2019

Cited by 18 | Viewed by 3354

Abstract

Micro-ORC systems are usually equipped with positive displacement machines such as expanders and pumps. The pumping system has to guarantee the mass flow rate and allows a pressure rise from the condensation to the evaporation pressure values. In addition, the pumping system supplies the organic fluid, characterized by pressure and temperature very close to the saturation. In this work, a CFD approach is developed to analyze from a novel point of view the behavior of the pumping system of a regenerative lab-scale micro-ORC system. In fact, starting from the liquid receiver, the entire flow path, up to the inlet section of the evaporator, has been numerically simulated (including the Coriolis flow meter installed between the receiver and the gear pump). A fluid dynamic analysis has been carried out by means of a transient simulation with a mesh morphing strategy in order to analyze the transient phenomena and the effects of pump operation. The analysis has shown how the accuracy of the mass flow rate measurement could be affected by the pump operation being installed in the same circuit branch. In addition, the results have shown how the cavitation phenomenon affects the pump and the ORC system operation compared to control system actions. Full article

(This article belongs to the Special Issue Organic Rankine Cycle for Energy Recovery System)

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25 pages, 932 KiB

Open AccessArticle

Assessment of Methods for Performance Comparison of Pure and Zeotropic Working Fluids for Organic Rankine Cycle Power Systems

by Jesper Graa Andreasen, Martin Ryhl Kærn and Fredrik Haglind

Energies 2019, 12(9), 1783; https://doi.org/10.3390/en12091783 - 10 May 2019

Cited by 8 | Viewed by 2315

Abstract

In this paper, we present an assessment of methods for estimating and comparing the thermodynamic performance of working fluids for organic Rankine cycle power systems. The analysis focused on how the estimated net power outputs of zeotropic mixtures compared to pure fluids are affected by the method used for specifying the performance of the heat exchangers. Four different methods were included in the assessment, which assumed that the organic Rankine cycle systems were characterized by the same values of: (1) the minimum pinch point temperature difference of the heat exchangers; (2) the mean temperature difference of the heat exchangers; (3) the heat exchanger thermal capacity (

\bar{U} A

); or (4) the heat exchanger surface area for all the considered working fluids. The second and third methods took into account the temperature difference throughout the heat transfer process, and provided the insight that the advantages of mixtures are more pronounced when large heat exchangers are economically feasible to use. The first method was incapable of this, and deemed to result in optimistic estimations of the benefits of using zeotropic mixtures, while the second and third method were deemed to result in conservative estimations. The fourth method provided the additional benefit of accounting for the degradation of heat transfer performance of zeotropic mixtures. In a net power output based performance ranking of 30 working fluids, the first method estimates that the increase in the net power output of zeotropic mixtures compared to their best pure fluid components is up to 13.6%. On the other hand, the third method estimates that the increase in net power output is only up to 2.56% for zeotropic mixtures compared to their best pure fluid components. Full article

(This article belongs to the Special Issue Organic Rankine Cycle for Energy Recovery System)

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