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Organic Rankine Cycle Systems for Waste-Heat Recovery

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A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Energy Science and Technology".

Deadline for manuscript submissions: closed (20 April 2019) | Viewed by 31698

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Special Issue Editor

Dr. Dimitris S. Manolakos

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Guest Editor

Department of Natural Resources Management & Agricultural Engineering, Agricultural University of Athens, Iera Odos 75, 11855 Athens, Greece
Interests: low-temperature heat-to-power conversion with ORC; solar sub-critical ORC prototypes (power generation and desalination) design, manufacturing and testing; volumetric expanders and heat exchangers design, manufacturing and testing; super-critical, TransCritical prototypes design manufacturing and testing; trilateral flash cycle
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Special Issue Information

Dear Colleagues,

Large amounts of excess heat are currently wasted in various processes, with the waste heat recovery market experiencing a high growth rate globally. This market concerns the further utilisation of waste heat, with the most mainstream techniques being the re-use of this heat or its conversion to power. Heat-to-power conversion is a challenging technical and market field, and has drawn attention because it yields a high-value end-product: electricity. For medium to low temperature ranges, the Organic Rankine Cycle (ORC) is currently the prevailing heat-to-power conversion technology, citing numerous references and many companies with commercial products. The ORC market has been growing rapidly, especially in heat recovery projects, revealing the potential of the sector.

Further evolution of ORC is a challenging technological field gathering the strong interest of the both scientific and industrial society, emphasising aspects relevant to the increment of thermal efficiency, increase of reliability, working fluids of low/negligible environmental impact, novel system architectures, design optimisation, advancements in key components, etc.

Assist. Prof. Dimitris Manolakos
Guest Editor

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Keywords

system modelling: simulation/optimisation and design tools
new/novel working fluids (including mixtures): properties, characterization, applications
expander technologies: turbines, volumetric expanders
waste heat recovery application: light-duty and heavy-duty, stationary and marine vessels
ORC variants: trilateral flash cycle (TFC), supercritical ORC (SCORC), transcritical ORC (TCORC)
innovative system architectures
heat exchanger: evaporators, condensers, recuperators
interaction with other heat generation/handling sources: solar collectors, heat pumps, CPV/T, hybrid systems
The testing of prototypes: results, assessment, experience gain
novel control techniques
polygeneration systems

Published Papers (7 papers)

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Research

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19 pages, 4555 KiB

Open AccessArticle

Operational Optimisation of a Non-Recuperative 1-kWe Organic Rankine Cycle Engine Prototype

by Chinedu K. Unamba, Paul Sapin, Xiaoya Li, Jian Song, Kai Wang, Gequn Shu, Hua Tian and Christos N. Markides

Appl. Sci. 2019, 9(15), 3024; https://doi.org/10.3390/app9153024 - 26 Jul 2019

Cited by 17 | Viewed by 3112

Abstract

Several heat-to-power conversion technologies are being proposed as suitable for waste-heat recovery (WHR) applications, including thermoelectric generators, hot-air (e.g., Ericsson or Stirling) engines and vapour-cycle engines such as steam or organic Rankine cycle (ORC) power systems. The latter technology has demonstrated the highest efficiencies at small and intermediate scales and low to medium heat-source temperatures and is considered a suitable option for WHR in relevant applications. However, ORC systems experience variations in performance at part-load or off-design conditions, which need to be predicted accurately by empirical or physics-based models if one is to assess accurately the techno-economic potential of such ORC-WHR solutions. This paper presents results from an experimental investigation of the part-load performance of a 1-kWe ORC engine, operated with R245fa as a working fluid, with the aim of producing high-fidelity steady-state and transient data relating to the operational performance of this system. The experimental apparatus is composed of a rotary-vane pump, brazed-plate evaporator and condenser units and a scroll expander magnetically coupled to a generator with an adjustable resistive load. An electric heater is used to provide a hot oil-stream to the evaporator, supplied at three different temperatures in the current study: 100, 120 and 140

^{°}

C. The optimal operating conditions, that is, pump speed and expander load, are determined at various heat-source conditions, thus resulting in a total of 124 steady-state data points used to analyse the part-load performance of the engine. A maximum thermal efficiency of 4.2 ± 0.1% is reported for a heat-source temperature of 120

^{°}

C, while a maximum net power output of 508 ± 2 W is obtained for a heat-source temperature at 140

^{°}

C. For a 100-

^{°}

C heat source, a maximum exergy efficiency of 18.7 ± 0.3% is achieved. A detailed exergy analysis allows us to quantify the contribution of each component to the overall exergy destruction. The share of the evaporator, condenser and expander components are all significant for the three heat-source conditions, while the exergy destroyed in the pump is negligible by comparison (below 4%). The data can be used for the development and validation of advanced models capable of steady-state part-load and off-design performance predictions, as well as predictions of the transient/dynamic operation of ORC systems. Full article

(This article belongs to the Special Issue Organic Rankine Cycle Systems for Waste-Heat Recovery)

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21 pages, 2957 KiB

Open AccessFeature PaperArticle

Experimental Study and Optimization of the Organic Rankine Cycle with Pure Novec^TM649 and Zeotropic Mixture Novec^TM649/HFE7000 as Working Fluid

by Quentin Blondel, Nicolas Tauveron, Nadia Caney and Nicolas Voeltzel

Appl. Sci. 2019, 9(9), 1865; https://doi.org/10.3390/app9091865 - 07 May 2019

Cited by 18 | Viewed by 4008

Abstract

The Organic Rankine Cycle (ORC) is widely used in industry to recover low-grade heat. Recently, some research on the ORC has focused on micro power production with new low global warming potential (GWP) replacement working fluids. However, few experimental tests have investigated the real performance level of this system in comparison with the ORC using classical fluids. This study concerns the experimental analysis and comparison of a compact (0.25 m³) Organic Rankine Cycle installation using as working fluids the Novec^TM649 pure fluid and a zeotropic mixture composed of 80% Novec^TM649 and 20% HFE7000 (mass composition) for low-grade waste heat conversion to produce low power. The purpose of this experimental test bench is to study replacement fluids and characterize them as possible replacement fluid candidates for an existing ORC system. The ORC performance with the pure fluid, which is the media specifically designed for this conversion system, shows good results as a replacement fluid in comparison with the ORC literature. The use of the mixture leads to a 10% increase in the global performance of the installation. Concerning the expansion component, an axial micro-turbine, its performance is only slightly affected by the use of the mixture. These results show that zeotropic mixtures can be used as an adjustment parameter for a given ORC installation and thus allow for the best use of the heat source available to produce electricity. Full article

(This article belongs to the Special Issue Organic Rankine Cycle Systems for Waste-Heat Recovery)

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18 pages, 5787 KiB

Open AccessArticle

Operation Characteristics and Transient Simulation of an ICE-ORC Combined System

by Tong Liu, Enhua Wang, Fanxiao Meng, Fujun Zhang, Changlu Zhao, Hongguang Zhang and Rui Zhao

Appl. Sci. 2019, 9(8), 1639; https://doi.org/10.3390/app9081639 - 19 Apr 2019

Cited by 6 | Viewed by 2256

Abstract

Currently, internal combustion engines (ICEs) are still the main power for transportation. Energy conservation and emission reduction for ICEs have become the driving force of the industrial R&D in recent years. Organic Rankine cycle (ORC) is a feasible technology to recover the waste heat of an ICE so that the energy efficiency can be enhanced apparently. However, there are still many obstacles needed to be overcome for the application of an ORC together with an ICE. When a vehicle is driving, the operation conditions of the ICE vary in a large range. The operation of the ORC needs to be regulated accordingly to achieve maximum efficiency. In this study, the operation characteristics of an ICE-ORC combined system is investigated and the transient performance is analyzed. First, an integrated simulation model of the ICE and the ORC was built in GT-POWER software. A 5 kW single-screw expander was employed for the ORC system. The working characteristics of the ORC system were evaluated under various working conditions of the ICE. The matching principles of the ORC with the ICE were discussed and the optimal operation conditions of the ORC over the entire engine’s working range were obtained. Subsequently, a feedforward control strategy for the ORC system was designed in MATLAB/SIMULINK. Finally, the entire model was simulated under a transient driving cycle of a vehicle. The results indicate that the pump speed and the expander speed are two important parameters and must be adjusted according to the engine’s working condition. The speed of the single-screw expander maintains in the low-speed region and the pump speed is tuned to achieve a high evaporation pressure and a proper superheat degree of the working fluid at the inlet of the expander. Thus, the net power output can be maximized. The designed feedforward control strategy can adjust the working condition of the ORC automatically to match with the working condition of the ICE. The ORC operates intermittently and an impulse power is output under the urban driving conditions. However, the working time of the ORC is increased significantly and the power output is relatively higher under the highway conditions. Full article

(This article belongs to the Special Issue Organic Rankine Cycle Systems for Waste-Heat Recovery)

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23 pages, 3476 KiB

Open AccessArticle

Thermodynamic Performance Analyses and Optimization of Dual-Loop Organic Rankine Cycles for Internal Combustion Engine Waste Heat Recovery

by Zhong Ge, Jian Li, Yuanyuan Duan, Zhen Yang and Zhiyong Xie

Appl. Sci. 2019, 9(4), 680; https://doi.org/10.3390/app9040680 - 16 Feb 2019

Cited by 22 | Viewed by 4091

Abstract

Waste heats of an internal combustion engine (ICE) are recovered by a dual-loop organic Rankine cycle (DORC). Thermodynamic performance analyses and optimizations are conducted with 523.15–623.15 K exhaust gas temperature (T_g1). Cyclopentane, cyclohexane, benzene, and toluene are selected as working fluids for high-temperature loop (HTL), whereas R1234ze(E), R600a, R245fa, and R601a are selected as working fluids for low-temperature loop (LTL). The HTL evaporation temperature, condensation temperature, and superheat degree are optimized through a genetic algorithm, and net power output is selected as the objective function. Influences of T_g1 on system net power output, thermal efficiency, exergy efficiency, HTL evaporation temperature, HTL condensation temperature, HTL superheat degree, exhaust gas temperature at the exit of the HTL evaporator, heat utilization ratio, and exergy destruction rate of the components are analyzed. Results are presented as follows: the net power output is mainly influenced by HTL working fluid. The optimal LTL working fluid is R1234ze(E). The optimal HTL evaporator temperature increases with T_g1 until it reaches the upper limit. The optimal HTL condensation temperature increases initially and later remains unchanged for a cyclopentane system, thus keeping constant for other systems. Saturated cycle is suitable for cyclohexane, benzene, and toluene systems. Superheat cycle improves the net power output for a cyclopentane system when T_g1 is 568.15–623.15 K. Full article

(This article belongs to the Special Issue Organic Rankine Cycle Systems for Waste-Heat Recovery)

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26 pages, 5389 KiB

Open AccessArticle

Economic Analysis of Organic Rankine Cycle Using R123 and R245fa as Working Fluids and a Demonstration Project Report

by Xinxin Zhang, Min Cao, Xiaoyu Yang, Hang Guo and Jingfu Wang

Appl. Sci. 2019, 9(2), 288; https://doi.org/10.3390/app9020288 - 15 Jan 2019

Cited by 30 | Viewed by 5286

Abstract

The organic Rankine cycle (ORC) is a popular technology used in waste heat recovery and low-grade heat utilization, which are two important measures to solve the problems brought by the energy crisis. The economic performance of ORC system is an important factor affecting its application and development. Therefore, the economic analysis of ORC is of great significance. In this study, R123 and R245fa, two frequently-used working fluids during the transition period, were selected for calculating and analyzing the economic performance of an ORC used for recovery of waste heat with a low flow rate and medium-low temperature. Five traditional economic indicators, namely total cost, net earnings, payback period, return on investment, levelized energy cost, and present value of total profit in system service life, which is a relatively new indicator, were used to establish the economic analysis model of ORC. The variation effects of evaporation temperature, condensation temperature of working fluid, flue gas inlet temperature, and mass flow rate of flue gas on the above six economic indicators were analyzed. The results show that the optimal evaporation temperature of R123 is 125 °C, the optimal condensation temperature is 33 °C, and the optimal heat source temperature is 217 °C. For R245fa, the optimal evaporation temperature is 122 °C, the optimal condensation temperature is 27 °C, and the optimal heat source temperature is 177 °C. The economic performance of an ORC demonstration project was reported and used for comparison with the estimation and analysis. It was found that the single screw expander has an excellent economy performance, which greatly reduces the proportion of expander cost in the ORC system. Full article

(This article belongs to the Special Issue Organic Rankine Cycle Systems for Waste-Heat Recovery)

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17 pages, 5422 KiB

Open AccessArticle

An Improved Analysis Method for Organic Rankine Cycles Based on Radial-Inflow Turbine Efficiency Prediction

by Peng Li, Zhonghe Han, Xiaoqiang Jia, Zhongkai Mei, Xu Han and Zhi Wang

Appl. Sci. 2019, 9(1), 49; https://doi.org/10.3390/app9010049 - 24 Dec 2018

Cited by 6 | Viewed by 5967

Abstract

The organic Rankine cycle (ORC) has been demonstrated to be an effective method for converting low-grade heat energy into electricity. This paper proposes an improved analysis method for the ORC system. A coupling model of the ORC system with a radial-inflow turbine efficiency prediction model is presented. Multi-objective optimization was conducted for a constant turbine efficiency ORC system (ORC_CTE) and a predicted turbine efficiency ORC system (ORC_DTE), and the optimization results were compared. Additionally, a sensitivity analysis was conducted with respect to the heat source temperature and the ambient temperature. It can be found that the predicted turbine efficiency decreases with the increasing evaporation temperature, and increases with the increasing condensation temperature. The turbine efficiency is not constant and it varies with operating conditions. The distribution of the Pareto frontier for ORC_CTE system and ORC_CTE system is different. Compared with the ORC_CTE system, the ORC_DTE system has a lower optimal evaporation temperature, but a higher optimal condensation temperature. The deviation between the predicted turbine efficiency and the constant turbine efficiency increases with the increasing heat source temperature but decreases with the increasing ambient temperature. Thus, the difference in the theoretical analysis results between ORC_CTE system and ORC_DTE system increases with the increasing heat source temperature but decreases with the increasing ambient temperature. Full article

(This article belongs to the Special Issue Organic Rankine Cycle Systems for Waste-Heat Recovery)

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Review

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26 pages, 1670 KiB

Open AccessFeature PaperReview

Review of Experimental Research on Supercritical and Transcritical Thermodynamic Cycles Designed for Heat Recovery Application

by Steven Lecompte, Erika Ntavou, Bertrand Tchanche, George Kosmadakis, Aditya Pillai, Dimitris Manolakos and Michel De Paepe

Appl. Sci. 2019, 9(12), 2571; https://doi.org/10.3390/app9122571 - 25 Jun 2019

Cited by 39 | Viewed by 5982

Abstract

Supercritical operation is considered a main technique to achieve higher cycle efficiency in various thermodynamic systems. The present paper is a review of experimental investigations on supercritical operation considering both heat-to-upgraded heat and heat-to-power systems. Experimental works are reported and subsequently analyzed. Main findings can be summarized as: steam Rankine cycles does not show much studies in the literature, transcritical organic Rankine cycles are intensely investigated and few plants are already online, carbon dioxide is considered as a promising fluid for closed Brayton and Rankine cycles but its unique properties call for a new thinking in designing cycle components. Transcritical heat pumps are extensively used in domestic and industrial applications, but supercritical heat pumps with a working fluid other than CO₂ are scarce. To increase the adoption rate of supercritical thermodynamic systems further research is needed on the heat transfer behavior and the optimal design of compressors and expanders with special attention to the mechanical integrity. Full article

(This article belongs to the Special Issue Organic Rankine Cycle Systems for Waste-Heat Recovery)

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