Simulation analysis of cooling methods of an on-board organic Rankine cycle exhaust heat recovery system

Zhao, Meng; Xu, Fei; Wei, Mingshan; Tian, Guohong; Zhang, Hong

doi:10.1002/er.3809

Cited by 7 publications

(5 citation statements)

References 45 publications

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“…To improve the economy of vehicles and to protect the environment, the waste gas energy should be reused. Turbo compounding [1,2], direct heat recovery [3] and turbocharging [4,5] are the common ways to do so. The turbocharger is essentially a kind of air pumps, which is widely used in vehicle internal combustion engines to increase the intake pressure.…”

Section: Introductionmentioning

confidence: 99%

Multi Field Coupling Stress Calculation and Analysis of CentrifugalCompressor Impeller Under Different Atmospheric Conditions

Hong¹,

Zhang²,

Ma³

et al. 2019

dteees

Self Cite

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To improve the power density, air pressurization systems are widely used in vehicle internal combustion engines, hybrid engines and fuel cell engines. Centrifugal compressor is the core component of air pressurization system. It's aerodynamic and reliability performance is the key to the whole system design. The atmospheric environment has great influence on the performance and reliability of the centrifugal compressor. When the atmospheric environment changes, unexpected failures may happen to the compressor impeller, affecting the reliability of vehicle engine.Aiming at a centrifugal compressor impeller of turbocharger for diesel engine, the multi field coupling stress under different atmospheric conditions is studied, and the key influencing factors of impeller stress are analyzed. Based on experimental tests, the working conditions of the centrifugal compressor for turbocharged diesel engine operating as external characteristics are obtained. By establishing a numerical calculation model of multi field coupling stress, and applying BKIN model to the material, the variation law of impeller stress with atmospheric environment is analyzed in the range of elastic-plastic mechanics. The results show that the centrifugal stress is always the major component of the coupling stress and the high coupling stress region of the investigated impeller appears in the shaft hole near the rear face. The results could provide reliability design strategies for solving the problem of impeller strength under different atmospheric conditions and for structural optimization.

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Section: Introductionmentioning

confidence: 99%

Multi Field Coupling Stress Calculation and Analysis of CentrifugalCompressor Impeller Under Different Atmospheric Conditions

Hong¹,

Zhang²,

Ma³

et al. 2019

dteees

Self Cite

View full text Add to dashboard Cite

show abstract

“…As for waste heat recovery techniques, organic Rankine cycle (ORC) is considered as a promising technology due to its small size, low emissions, and great power adaptability . Zhao et al found that for engines combined with ORC system, water cooling method was conducive to waste heat recovery, leading to a higher power output and thermal efficiency. They also concluded that ambient temperature influenced system performance directly.…”

Section: Introductionmentioning

confidence: 99%

Composition shift in zeotropic mixture-based organic Rankine cycle system for harvesting engine waste heat

Tian

Shu

et al. 2018

Int J Energy Res

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Summary Zeotropic mixture–based organic Rankine cycle (ORC) is a promising technology for harvesting engine waste heat as the property called temperature glide can efficiently improve the temperature mismatch between working fluid and varying temperature heat source. However, a phenomenon called composition shift appearing as different fractions between circulating composition and charge composition accompanies in zeotropic mixtures–based ORC system, which affects system performance directly. To investigate the influence of composition shift on system performance, this paper establishes the thermodynamic model and composition shift model of ORC system. On the basis of simulation results for selected alkanes/R123 zeotropic mixture, the circulating fraction of R123 is higher than its charge fraction, which results in a lower performance of ORC system. For cyclohexane/R123 mixture, the actual mass fraction of R123 increases from 0.5 to 0.52, leading to a maximum decrease of net power by 3%. The factors affecting composition shift such as charge fraction, evaporation pressure, and charge quality are discussed. By increasing the charge fraction of R123, the composition shift can be alleviated within the limitation of safety boundary in this paper. Higher evaporation pressure and larger charge quality can also mitigate the composition shift. Besides, the results indicate that composition shift and temperature glide have similar changing trends, thus temperature glide could be used as predicting the degree of composition shift.

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“…With the development of the use of renewable energy and waste heat, supercritical ORCs are attracting more and more attention as a promising energy‐to‐power transition technology . In recent years, the focus of ORC research has gradually shifted from thermodynamic studies for working fluids and system optimization to experimental and components studies, which has raised more pressing requirements for fluid‐to‐fluid scaling methods. So many kinds of working fluids are used for various heat sources in ORC systems that it is impossible to conduct experiments with every fluid.…”

Section: Introductionmentioning

confidence: 99%

Fluid-to-fluid scaling of heat transfer to mixed convection flow of supercritical pressure fluids

et al. 2018

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Summary Fluid‐to‐fluid scaling for supercritical heat transfer can effectively reduce the difficulty and cost of heat transfer experiments in supercritical boilers and supercritical water reactors and can reduce the number of experiments by converting experimental data of the model fluid to the prototype fluid in organic Rankine cycles. Currently, most existing scaling methods are only suitable for forced convection, while few are developed for mixed convection where buoyancy significantly affects the heat transfer. This paper attempts to extend the applicability of scaling method to mixed convection with the aid of computational fluid dynamic simulations. The scaling parameters were analyzed first and then the shear‐stress transport k‐ω model was used to analyze the supercritical heat transfer characteristics of water and R134a to provide further information for developing a dimensionless number. The results show that significant variations of properties and flow parameters occur in the layer of y+ = 5 to 100 and the axial velocity gradient in this layer changes in quite a similar manner to the wall temperature. Based on numerical results, the axial velocity gradient was used with a thermal resistance analogy to derive a new dimensionless number, Re−0.9πA, to scale the mass flux. Then, a set of fluid‐to‐fluid scaling laws were developed to predict the heat transfer to supercritical fluids. To validate the newly proposed scaling laws, well‐developed correlations were used for forced convection flow and a direct validation method was developed for buoyancy‐influenced flow. Results show that this new scaling method exhibits reasonable accuracy for both forced and mixed convection heat transfer with supercritical fluids.

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Simulation analysis of cooling methods of an on-board organic Rankine cycle exhaust heat recovery system

Cited by 7 publications

References 45 publications

Multi Field Coupling Stress Calculation and Analysis of CentrifugalCompressor Impeller Under Different Atmospheric Conditions

Multi Field Coupling Stress Calculation and Analysis of CentrifugalCompressor Impeller Under Different Atmospheric Conditions

Composition shift in zeotropic mixture-based organic Rankine cycle system for harvesting engine waste heat

Fluid-to-fluid scaling of heat transfer to mixed convection flow of supercritical pressure fluids

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