A supercritical Rankine cycle using zeotropic mixture working fluids for the conversion of low-grade heat into power

Chen, Huijuan; Goswami, D. Yogi; Rahman, Muhammad M.; Stefanakos, Elias K.

doi:10.1016/j.energy.2010.10.006

Cited by 255 publications

(82 citation statements)

References 31 publications

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“…This is primarily due to the higher net power output and lower exergy losses. Chen et al (2011) showed that a supercritical ORC with a zeotropic mixture as the working fluid could improve the thermal efficiency by 10%-30% more than the subcritical ORC.…”

Section: Introductionmentioning

confidence: 99%

Dynamic model of supercritical Organic Rankine Cycle waste heat recovery system for internal combustion engine

Chowdhury

Nguyen

Thornhill

2017

Int.J Automot. Technol.

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ABSTRACTThe supercritical Organic Rankine Cycle (ORC) for the Waste Heat Recovery (WHR) from Internal Combustion (IC) engines has been a growing research area in recent years, driven by the aim to enhance the thermal efficiency of the ORC and engine. Simulation of a supercritical ORC-WHR system before a real-time application is important as high pressure in the system may lead to concerns about safety and availability of components. In the ORC-WHR system, the evaporator is the main contributor to thermal inertia of the system and is considered to be the critical component since the heat transfer of this device influences the efficiency of the system. Since the thermophysical properties of the fluid at supercritical pressures are dependent on temperature, it is necessary to consider the variations in properties of the working fluid. The well-known Finite Volume (FV) discretization method is generally used to take those property changes into account. However, a FV model of the evaporator in steady state condition cannot be used to predict the thermal inertia of the cycle when it is subjected to transient heat sources. In this paper, a dynamic FV model of the evaporator has been developed and integrated with other components in the ORC-WHR system. The stability and transient responses along with the performance of the ORC-WHR system for the transient heat source are investigated and are also included in this paper.

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Section: Introductionmentioning

confidence: 99%

Dynamic model of supercritical Organic Rankine Cycle waste heat recovery system for internal combustion engine

Chowdhury

Nguyen

Thornhill

2017

Int.J Automot. Technol.

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“…Lecompt et al [7] showed that the second law efficiency of a supercritical cycle for low temperature waste heat recovery is 10.8% more than a subcritical cycle. Chen et al [8] showed that a supercritical ORC with a zeotropic mixture as the working fluid can improve the thermal efficiency by 10%-30% more than the subcritical ORC.…”

Section: Introductionmentioning

confidence: 99%

“…For this reason, the Jackson correlation for supercritical fluids [28,29] is used to calculate the Nusselt number Nu for the refrigerant in Equation (8). This neutralizes the variation effects around the pseudo-critical point.…”

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confidence: 99%

Modelling of Evaporator in Waste Heat Recovery System using Finite Volume Method and Fuzzy Technique

2015

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Abstract:The evaporator is an important component in the Organic Rankine Cycle (ORC)-based Waste Heat Recovery (WHR) system since the effective heat transfer of this device reflects on the efficiency of the system. When the WHR system operates under supercritical conditions, the heat transfer mechanism in the evaporator is unpredictable due to the change of thermo-physical properties of the fluid with temperature. Although the conventional finite volume model can successfully capture those changes in the evaporator of the WHR process, the computation time for this method is high. To reduce the computation time, this paper develops a new fuzzy based evaporator model and compares its performance with the finite volume method. The results show that the fuzzy technique can be applied to predict the output of the supercritical evaporator in the waste heat recovery system and can significantly reduce the required computation time. The proposed model, therefore, has the potential to be used in real time control applications.

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“…The zeotropic mixture has a character of "temperature slip", which can benefit the heat transfer between cold and hot fluids, thus reducing the irreversible loss caused by the heat transfer temperature difference [23]. ORC systems that use mixed working fluids may have better running performances than pure working fluids [24][25]. Mixed working fluids have drawn the attention of several scholars [26][27].…”

Section: Introductionmentioning

confidence: 99%

Study on Mixed Working Fluids with Different Compositions in Organic Rankine Cycle (ORC) Systems for Vehicle Diesel Engines

Yang

Zhang

Wang

et al. 2014

Entropy

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Abstract:One way to increase the thermal efficiency of vehicle diesel engines is to recover waste heat by using an organic Rankine cycle (ORC) system. Tests were conducted to study the running performances of diesel engines in the whole operating range. The law of variation of the exhaust energy rate under various engine operating conditions was also analyzed. A diesel engine-ORC combined system was designed, and relevant evaluation indexes proposed. The variation of the running performances of the combined system under various engine operating conditions was investigated. R245fa and R152a were selected as the components of the mixed working fluid. Thereafter, six kinds of mixed working fluids with different compositions were presented. The effects of mixed working fluids with different compositions on the running performances of the combined system were revealed. Results show that the running performances of the combined system can be improved effectively when mass fraction R152a in the mixed working fluid is high and the engine operates with high power. For the mixed working fluid M1 (R245fa/R152a, 0.1/0.9, by mass fraction), the net power output of the combined system reaches the maximum of 34.61 kW. Output energy density of working fluid (OEDWF), waste heat recovery OPEN ACCESSEntropy 2014, 16 4770 efficiency (WHRE), and engine thermal efficiency increasing ratio (ETEIR) all reach their maximum values at 42.7 kJ/kg, 10.90%, and 11.29%, respectively.

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A supercritical Rankine cycle using zeotropic mixture working fluids for the conversion of low-grade heat into power

Cited by 255 publications

References 31 publications

Dynamic model of supercritical Organic Rankine Cycle waste heat recovery system for internal combustion engine

Dynamic model of supercritical Organic Rankine Cycle waste heat recovery system for internal combustion engine

Modelling of Evaporator in Waste Heat Recovery System using Finite Volume Method and Fuzzy Technique

Study on Mixed Working Fluids with Different Compositions in Organic Rankine Cycle (ORC) Systems for Vehicle Diesel Engines

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