Assessment of organic Rankine cycle performance with binary working fluid mixtures

Waste heat dissipated in the exhaust system in a combustion engine represents a major source of energy to be recovered and converted into useful work. A waste heat recovery system (WHRS) based on an Organic Rankine Cycle (ORC) is a promising approach, and has gained interest in the last few years in an automotive industry interested in reducing fuel consumption and exhaust emissions. Understanding the thermodynamic response of the boiler employed in an ORC plays an important role in steam cycle performance prediction and control system design. The aim of this study is therefore to present a methodology to study these devices by means of pattern recognition with infrared thermography. In addition, the experimental test bench and its operating conditions are described. The methodology proposed identifies the wall coordinates, traces paths, and tracks wall temperature along them in a way that can be exported for subsequent post-processing and analysis. As for the results, through the wall temperature paths on both sides (exhaust gas and working fluid) it was possible to quantitatively estimate the temperature evolution along the boiler and, in particular, the beginning and end of evaporation.

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Thermo-Economic and Heat Transfer Optimization of Working-Fluid Mixtures in a Low-Temperature Organic Rankine Cycle System

Energies ◽

10.3390/en9060448 ◽

2016 ◽

Vol 9 (6) ◽

pp. 448 ◽

Cited By ~ 58

Author(s):

Oyeniyi Oyewunmi ◽

Christos Markides

Keyword(s):

Heat Transfer ◽

Low Temperature ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Working Fluid ◽

Fluid Mixtures ◽

Cycle System ◽

Heat Transfer Optimization

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Development of a Pattern Recognition Methodology with Thermography and Implementation in an Experimental Study of a Boiler for a WHRS-ORC

Sensors ◽

10.3390/s19071680 ◽

2019 ◽

Vol 19 (7) ◽

pp. 1680

Author(s):

Concepción Paz ◽

Eduardo Suárez ◽

Miguel Concheiro ◽

Antonio Diaz

Keyword(s):

Pattern Recognition ◽

Wall Temperature ◽

Waste Heat ◽

Combustion Engine ◽

Organic Rankine Cycle ◽

Exhaust System ◽

Rankine Cycle ◽

Operating Conditions ◽

Cycle Performance ◽

Working Fluid

Waste heat dissipated in the exhaust system in a combustion engine represents a major source of energy to be recovered and converted into useful work. A waste heat recovery system (WHRS) based on an Organic Rankine Cycle (ORC) is a promising approach, and it gained interest in the last few years in an automotive industry interested in reducing fuel consumption and exhaust emissions. Understanding the thermodynamic response of the boiler employed in an ORC plays an important role in steam cycle performance prediction and control system design. The aim of this study is, therefore, to present a methodology to study these devices by means of pattern recognition with infrared thermography. In addition, the experimental test bench and its operating conditions are described. The methodology proposed identifies the wall coordinates, traces the paths, and tracks the wall temperature along them in a way that can be exported for subsequent post-processing and analysis. As for the results, through the wall temperature paths on both sides (exhaust gas and working fluid), it was possible to quantitatively estimate the temperature evolution along the boiler and, in particular, the beginning and end of evaporation.

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Working Fluid and Parametric Optimization of a Two-Stage ORC Utilizing LNG Cold Energy and Low Grade Heat of Different Temperatures

Volume 3: Coal, Biomass and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration Applications; Organic Rankine Cycle Power Systems ◽

10.1115/gt2017-63164 ◽

2017 ◽

Author(s):

Zhixin Sun ◽

Shujia Wang ◽

Fuquan Xu ◽

Tielong Wang

Keyword(s):

Heat Source ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Cycle Performance ◽

Maximum Efficiency ◽

Working Fluid ◽

Low Grade ◽

Two Stage ◽

Cold Energy ◽

Low Grade Heat

Natural gas is considered as a green fuel due to its low environmental impact. LNG contains a large amount of cold exergy and must be regasified before further utilization. ORC (Organic Rankine Cycle) has been proven to be a promising solution for both low grade heat utilization and LNG cold exergy recovery. Due to the great temperature difference between the heat source and LNG, the efficiency of one-stage ORC is relatively small. Hence, some researchers move forward to a two-stage Rankine cycle. Working fluid plays a quite important role in the cycle performance. Working fluid selection of a two-stage ORC is much more challenging than that of a single-stage ORC. In this paper, a two-stage ORC is studied. Heat source temperatures of 100,150 and 200°C are investigated. 20 substances are selected as potential candidates for both the high and low Rankine cycles. The evaporating, condensing and turbine inlet temperatures of both Rankine cycles are optimized by PSO (Particle Swarm Optimization). The results show that the best combination for heat source temperature of 100°C is R161/R218 with the maximum exergy efficiency of 35.27%. The best combination for 150°C is R161/RC318 with the maximum efficiency of 37.84% and ammonia/ammonia with the maximum efficiency of 39.15% for 200°C. Fluids with intermediate critical temperature, lower triple point temperature and lower normal boiling temperature are good candidates.

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Design and Optimization of a Low Temperature Organic Rankine Cycle and Turbine

Volume 6A: Energy ◽

10.1115/imece2013-66727 ◽

2013 ◽

Cited By ~ 1

Author(s):

Murat Erbas ◽

Mehmet Alper Sofuoglu ◽

Atilla Biyikoglu ◽

Ibrahim Uslan

Keyword(s):

Low Temperature ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Cycle Performance ◽

Working Fluid ◽

Design Criteria ◽

Design And Optimization ◽

Turbine Efficiency ◽

Design Requirements ◽

R 134A

In this study, low temperature Organic Rankine Cycle (ORC) systems with single and two-stage turbine are proposed for the production of electricity. The refrigerant R-134a is selected as working fluid based on peak temperature of the cycle for solar and geothermal applications. The design criteria of ORC system is introduced and explained in detail. The radial inflow turbine is selected to satisfy the design requirements. The cycle performance is taken as a key point in the design criteria. The system performance map is constructed based on both velocity triangles and approximate efficiency of turbine. The procedures for turbine and cycle design are introduced in detail. The components of cycle and turbine are modeled using baseline correlations via real gas tables and macros created on Excel for the refrigerant, R134a. Finally, the turbine geometry is optimized to attain maximum turbine efficiency via MATLAB optimization toolbox.

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Thermodynamic, Economic and Sustainability Analysis of Solar Organic Rankine Cycle System with Zeotropic Working Fluid Mixtures for Micro-Cogeneration in Buildings

Applied Sciences ◽

10.3390/app10217925 ◽

2020 ◽

Vol 10 (21) ◽

pp. 7925

Author(s):

Wahiba Yaïci ◽

Evgueniy Entchev ◽

Pouyan Talebizadehsardari ◽

Michela Longo

Keyword(s):

Low Temperature ◽

Heat Source ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Optimum Operating ◽

Working Fluid ◽

Condensation Temperature ◽

Fluid Mixtures ◽

Thermodynamic Performance ◽

Cycle Efficiency

Globally there are several viable sources of renewable, low-temperature heat (below 130 °C), particularly solar energy, geothermal energy, and energy generated from industrial wastes. Increased exploitation of these low-temperature options has the definite potential of reducing fossil fuel consumption with its attendant very harmful greenhouse gas emissions. Researchers have universally identified the organic Rankine cycle (ORC) as a practicable and suitable system to generate electrical power from renewable sources based on its beneficial usage of volatile organic fluids as working fluids (WFs). In recent times, researchers have also shown a preference towards deployment of zeotropic mixtures as ORC WFs because of their capacity to improve thermodynamic performance of ORC systems, a feat enabled through the greater matching of the temperature profiles of the WF and the heat source/sink. This paper demonstrates the thermodynamic, economic and sustainability feasibility, and the notable advantages of using zeotropic mixtures as WFs through a simulation study of an ORC system. The study examines first the thermodynamic performance of ORC systems using zeotropic mixtures to generate electricity powered by a low-temperature solar heat source for building applications. A thermodynamic model is developed with a solar-driven ORC system both with and excluding a regenerator. Twelve zeotropic mixtures with varying compositions are evaluated and compared to identify the best combinations of mixtures that can yield high performance and high efficiency in their system cycles. The study also examines the effects of the volume flow ratio, and evaporation and condensation temperature glides on the ORC’s thermodynamic performance. Following a detailed analysis of each mixture, R245fa/propane and butane/propane are selected for parametric study to investigate the influence of operating parameters on the system’s efficiency and sustainability index. For zeotropic mixtures, results disclosed that there is an optimal composition range within which binary mixtures are inclined to perform more efficiently than the component pure fluids. In addition, a substantial enhancement in cycle efficiency can be obtained by a regenerative ORC, with cycle efficiency ranging between 3.1–9.8% and 8.6–17.4% for ORC both without and with regeneration, respectively. Results also revealed that exploiting zeotropic mixtures could enlarge the limitation experienced in selecting WFs for low-temperature solar ORCs. Moreover, a detailed economic with a sensitivity analysis of the solar ORC system was performed to evaluate the cost of the electricity and other economic criteria. The outcome of this investigation should be useful in the thermo-economic feasibility assessments of solar-driven ORC systems using working fluid mixtures to find the optimum operating range for maximum performance and minimum cost.

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Hydrate-based gas separation for working fluid mixtures: application to composition-adjustable organic Rankine cycle

Chemical Engineering Journal ◽

10.1016/j.cej.2022.134626 ◽

2022 ◽

pp. 134626

Author(s):

Yue Zhang ◽

Ruikai Zhao ◽

Xianhua Nie ◽

Shuai Deng ◽

Weicong Xu ◽

...

Keyword(s):

Gas Separation ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Working Fluid ◽

Fluid Mixtures

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A Comparative Study of Scroll Expander Performance Using CO2 and Zeotropic Mixtures As Working Fluids

Volume 1: Compressors, Fans, and Pumps; Turbines; Heat Transfer; Structures and Dynamics ◽

10.1115/gtindia2019-2711 ◽

2019 ◽

Author(s):

Arun Kumar Narasimhan ◽

Diego Guillen Perez ◽

D. Yogi Goswami

Keyword(s):

Comparative Study ◽

Organic Rankine Cycle ◽

Volume Ratio ◽

Rankine Cycle ◽

Operating Conditions ◽

Cycle Performance ◽

Working Fluid ◽

Brayton Cycle ◽

Working Fluids ◽

Scroll Expander

Abstract Scroll expanders are generally used for low temperature power generation applications due to their inherently small built-in volume ratio. The working fluid and operating conditions play an important role in the expander performance as well as its physical size and volume ratio. Hence, a comparative study of scroll expander performance was carried out between two different working fluids, R433C and supercritical (s-CO2). The s-CO2 Brayton cycle achieved a maximum cycle efficiency of 13.6% at an expander supply pressure of 11 MPa. Two separate scroll geometries were modeled for supercritical Organic Rankine Cycle (SORC) using R433C and s-CO2 Brayton cycle for the operating conditions that provided the maximum cycle performance. The s-CO2 scroll geometry achieved a maximum expander efficiency of 80% with a volume ratio of 2.5 and a diameter of 19 cm. The high inlet temperatures required a much higher volume ratio of 6.2 and scroll diameter of 30 cm for the R433C based SORC leading to greater leakages and lower expander efficiency of 62%. The comparative study shows that s-CO2 is better suited for scroll expander than R433C at such high expander supply temperatures.

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