The Experts below are selected from a list of 24252 Experts worldwide ranked by ideXlab platform
Elias Stefanakos - One of the best experts on this subject based on the ideXlab platform.
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energetic and exergetic analysis of co2 and r32 based transcritical Rankine cycles for low grade heat conversion
Applied Energy, 2011Co-Authors: Huijuan Chen, Yogi D Goswami, Muhammad M Rahman, Elias StefanakosAbstract:Transcritical Rankine cycles using refrigerant R32 (CH2F2) and carbon dioxide (CO2) as the working fluids are studied for the conversion of low-grade heat into mechanical power. Compared to CO2, R32 has higher thermal conductivity and condenses easily. The energy and exergy analyses of the cycle with these two fluids shows that the R32-based transcritical Rankine cycle can achieve 12.6–18.7% higher thermal efficiency and works at much lower pressures. An analysis of the exergy destruction and losses as well as the exergy efficiency optimization of the transcritical Rankine cycle is conducted. Based on the analysis, an “ideal” working fluid for the transcritical Rankine cycle is conceived, and ideas are proposed to design working fluids that can approach the properties of an “ideal” working fluid.
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a supercritical Rankine cycle using zeotropic mixture working fluids for the conversion of low grade heat into power
Energy, 2011Co-Authors: Huijuan Chen, Yogi D Goswami, Muhammad M Rahman, Elias StefanakosAbstract:A supercritical Rankine cycle using zeotropic mixture working fluids for the conversion of low-grade heat into power is proposed and analyzed in this paper. Unlike a conventional organic Rankine cycle, a supercritical Rankine cycle does not go through the two-phase region during the heating process. By adopting zeotropic mixtures as the working fluids, the condensation process also happens non-isothermally. Both of these features create a potential for reducing the irreversibilities and improving the system efficiency. A comparative study between an organic Rankine cycle and the proposed supercritical Rankine cycle shows that the proposed cycle can achieve thermal efficiencies of 10.8–13.4% with the cycle high temperature of 393 K–473 K as compared to 9.7–10.1% for the organic Rankine cycle, which is an improvement of 10–30% over the organic Rankine cycle. When including the heating and condensation processes in the system, the system exergy efficiency is 38.6% for the proposed supercritical Rankine cycle as compared to 24.1% for the organic Rankine cycle.
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a supercritical Rankine cycle using zeotropic mixture working fluids for the conversion of low grade heat into power
Energy, 2011Co-Authors: Huijuan Chen, Yogi D Goswami, Muhammad M Rahman, Elias StefanakosAbstract:A supercritical Rankine cycle using zeotropic mixture working fluids for the conversion of low-grade heat into power is proposed and analyzed in this paper. Unlike a conventional organic Rankine cycle, a supercritical Rankine cycle does not go through the two-phase region during the heating process. By adopting zeotropic mixtures as the working fluids, the condensation process also happens non- isothermally. Both of these features create a potential for reducing the irreversibilities and improving the system efficiency. A comparative study between an organic Rankine cycle and the proposed supercritical Rankine cycle shows that the proposed cycle can achieve thermal efficiencies of 10.8e13.4% with the cycle high temperature of 393 Ke473 K as compared to 9.7e10.1% for the organic Rankine cycle, which is an improvement of 10e30% over the organic Rankine cycle. When including the heating and conden- sation processes in the system, the system exergy efficiency is 38.6% for the proposed supercritical Rankine cycle as compared to 24.1% for the organic Rankine cycle.
Vincent Grelet - One of the best experts on this subject based on the ideXlab platform.
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transient performance evaluation of waste heat recovery Rankine cycle based system for heavy duty trucks
Applied Energy, 2016Co-Authors: Vincent Lemort, Vincent Grelet, Thomas Reiche, Madiha Nadri, Pascal DufourAbstract:The study presented in this paper aims to evaluate the transient performance of a waste heat recovery Rankine cycle based system for a heavy duty truck and compare it to steady state evaluation. Assuming some conditions to hold, simple thermodynamic simulations are carried out for the comparison of several fluids. Then a detailed first principle based model is also presented. Last part is focused on the Rankine cycle arrangement choice by means of model based evaluation of fuel economy for each concept where the fuels savings are computed using two methodologies. Fluid choice and concept optimization are conducted taking into account integration constraints (heat rejection, packaging, …). This paper shows the importance of the modeling phase when designing Rankine cycle based heat recovery systems and yields a better understanding when it comes to a vehicle integration of a Rankine cycle in a truck.
Li Zhao - One of the best experts on this subject based on the ideXlab platform.
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a review of working fluid and expander selections for organic Rankine cycle
Renewable & Sustainable Energy Reviews, 2013Co-Authors: Li ZhaoAbstract:How to effectively utilize low and medium temperature energy is one of the solutions to alleviate the energy shortage and environmental pollution problems. In the past twenty years, because of its feasibility and reliability, organic Rankine cycle has received widespread attentions and researches. In this paper, it reviews the selections of working fluids and expanders for organic Rankine cycle, including an analysis of the influence of working fluids' category and their thermodynamic and physical properties on the organic Rankine cycle's performance, a summary of pure and mixed working fluids' screening researches for organic Rankine cycle, a comparison of pure and mixture working fluids' applications and a discussion of all types of expansion machines' operating characteristics, which would be beneficial to select the optimal working fluid and suitable expansion machine for an effective organic Rankine cycle system.
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analysis of zeotropic mixtures used in low temperature solar Rankine cycles for power generation
Solar Energy, 2009Co-Authors: X D Wang, Li ZhaoAbstract:Abstract This paper presents the analysis of low-temperature solar Rankine cycles for power generation using zeotropic mixtures. Three typical mass fractions 0.9/0.1 (Ma) 0.65/0.35 (Mb), 0.45/0.55 (Mc) of R245fa/R152a are chosen. In the proposed temperature range from 25 °C to 85 °C, the three zeotropic mixtures are investigated as the working fluids of the low-temperature solar Rankine cycle. Because there is an obvious temperature glide during phase change for zeotropic mixtures, an internal heat exchanger (IHE) is introduced to the Rankine cycle. Investigation shows that different from the pure fluids, among the proposed zeotropic mixtures, the isentropic working fluid Mb possesses the lowest Rankine cycle efficiency. For zeotropic mixtures a significant increase of thermal efficiencies can be gained when superheating is combined with IHE. It is also indicated that utilizing zeotropic mixtures can extend the range of choosing working fluids for low-temperature solar Rankine cycles.
Huijuan Chen - One of the best experts on this subject based on the ideXlab platform.
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energetic and exergetic analysis of co2 and r32 based transcritical Rankine cycles for low grade heat conversion
Applied Energy, 2011Co-Authors: Huijuan Chen, Yogi D Goswami, Muhammad M Rahman, Elias StefanakosAbstract:Transcritical Rankine cycles using refrigerant R32 (CH2F2) and carbon dioxide (CO2) as the working fluids are studied for the conversion of low-grade heat into mechanical power. Compared to CO2, R32 has higher thermal conductivity and condenses easily. The energy and exergy analyses of the cycle with these two fluids shows that the R32-based transcritical Rankine cycle can achieve 12.6–18.7% higher thermal efficiency and works at much lower pressures. An analysis of the exergy destruction and losses as well as the exergy efficiency optimization of the transcritical Rankine cycle is conducted. Based on the analysis, an “ideal” working fluid for the transcritical Rankine cycle is conceived, and ideas are proposed to design working fluids that can approach the properties of an “ideal” working fluid.
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a supercritical Rankine cycle using zeotropic mixture working fluids for the conversion of low grade heat into power
Energy, 2011Co-Authors: Huijuan Chen, Yogi D Goswami, Muhammad M Rahman, Elias StefanakosAbstract:A supercritical Rankine cycle using zeotropic mixture working fluids for the conversion of low-grade heat into power is proposed and analyzed in this paper. Unlike a conventional organic Rankine cycle, a supercritical Rankine cycle does not go through the two-phase region during the heating process. By adopting zeotropic mixtures as the working fluids, the condensation process also happens non-isothermally. Both of these features create a potential for reducing the irreversibilities and improving the system efficiency. A comparative study between an organic Rankine cycle and the proposed supercritical Rankine cycle shows that the proposed cycle can achieve thermal efficiencies of 10.8–13.4% with the cycle high temperature of 393 K–473 K as compared to 9.7–10.1% for the organic Rankine cycle, which is an improvement of 10–30% over the organic Rankine cycle. When including the heating and condensation processes in the system, the system exergy efficiency is 38.6% for the proposed supercritical Rankine cycle as compared to 24.1% for the organic Rankine cycle.
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a supercritical Rankine cycle using zeotropic mixture working fluids for the conversion of low grade heat into power
Energy, 2011Co-Authors: Huijuan Chen, Yogi D Goswami, Muhammad M Rahman, Elias StefanakosAbstract:A supercritical Rankine cycle using zeotropic mixture working fluids for the conversion of low-grade heat into power is proposed and analyzed in this paper. Unlike a conventional organic Rankine cycle, a supercritical Rankine cycle does not go through the two-phase region during the heating process. By adopting zeotropic mixtures as the working fluids, the condensation process also happens non- isothermally. Both of these features create a potential for reducing the irreversibilities and improving the system efficiency. A comparative study between an organic Rankine cycle and the proposed supercritical Rankine cycle shows that the proposed cycle can achieve thermal efficiencies of 10.8e13.4% with the cycle high temperature of 393 Ke473 K as compared to 9.7e10.1% for the organic Rankine cycle, which is an improvement of 10e30% over the organic Rankine cycle. When including the heating and conden- sation processes in the system, the system exergy efficiency is 38.6% for the proposed supercritical Rankine cycle as compared to 24.1% for the organic Rankine cycle.
Nishith B Desai - One of the best experts on this subject based on the ideXlab platform.
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thermo economic analysis and selection of working fluid for solar organic Rankine cycle
Applied Thermal Engineering, 2016Co-Authors: Nishith B DesaiAbstract:Abstract Organic Rankine cycle (ORC), powered by line-focusing concentrating solar collectors (parabolic trough collector and linear Fresnel reflector), is a promising option for modular scale. ORC based power block, with dry working fluids, offers higher design and part-load efficiencies compared to steam Rankine cycle (SRC) in small-medium scale, with temperature sources up to 400 °C. However, the cost of ORC power block is higher compared to the SRC power block. Similarly, parabolic trough collector (PTC) system has higher optical efficiency and higher cost compared to linear Fresnel reflector (LFR) system. The thermodynamic efficiencies and power block costs also vary with working fluids of the Rankine cycle. In this paper, thermo-economic comparisons of organic Rankine and steam Rankine cycles powered by line-focusing concentrating solar collectors are reported. A simple selection methodology, based on thermo-economic analysis, and a comparison diagram for working fluids of power generating cycles are also proposed. Concentrating solar power plants with any collector technology and any power generating cycle can be compared using the proposed methodology.
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optimization of concentrating solar thermal power plant based on parabolic trough collector
Journal of Cleaner Production, 2015Co-Authors: Nishith B Desai, Santanu BandyopadhyayAbstract:Abstract Concentrating solar power (CSP) plant with parabolic trough collector (PTC) using synthetic or organic oil based heat transfer fluid is the most established and commercially attractive technology. In this paper, extensive energy and economic analysis of PTC based CSP plants, without storage, are reported. Effects of turbine inlet pressure, turbine inlet temperature, design radiation, plant size, and various modifications of Rankine cycle on overall efficiency as well as levelized cost of energy are studied. Furthermore, the variation in optimal turbine inlet pressure with turbine inlet temperature, design radiation, plant size, and various modifications of Rankine cycle are also analyzed. Energy and cost optimal turbine inlet pressures for 1 MWe plant (with basic Rankine cycle) are about 4.5–7.5 MPa and 3.5–7.5 MPa, respectively. The optimum pressure is observed to be a weak function of design solar radiation. The overall efficiency increases and levelized cost of energy decreases with increase in turbine inlet temperature, plant size and various modifications of the Rankine cycle.
