heat transfer and fluid dynamics at supercritical pressure...

The 3rd International Meeting of Specialistson

Heat Transfer and Fluid Dynamics at Supercritical Pressure

(HFSCP2016)

The University of Sheffield, The DiamondSheffield, UK

25th & 26th August 2016

The 3rd International Meeting of Specialists on Heat Transfer and

Fluid Dynamics at Supercritical Pressure (HFSCP2016)

25 & 26 August 2016

The Diamond, University of Sheffield, Sheffield, UK

Program

Morning 25 August 2016

Title of presentation Presenter

08:00-

08:50 Registration

LT6, The Diamond

08:50-

09:00 Welcome

Session 1: Experimental investigations

Chair: Derek Jackson

09:00-

09:40

Convection heat transfer of fluids at super-critical pressure and its applications in renewable energy (Keynote)

Jiang, Peixue

09:40-

10:05 Onset of heat transfer deterioration to CO2 in heated vertical tubes at supercritical pressures

Kline, Nathan

10:05-

10:30

Investigation and modeling of the heat transfer of CO2 at supercritical pressure in vertical tubes of various scales during heating

Zhao, Chen-Ru

10:30-

10:45 Refreshment break

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Morning 25 August 2016 (continued)

Session 2: Cycles

Chair: Don McEligot

10:45-

11:25 University of Wisconsin research on fluid dynamics of supercritical fluids (Keynote)

Anderson, Mark

11:25-

11:50 Supercritical organic Rankine cycle for geothermal power conversion

Schulenberg, Thomas

11:50-

12:15 Supercritical cycles for power generation: component design and analysis

Hooman, Kamel

12:15-

12:40

Supercritical organic Rankine cycle systems for waste-heat recovery applications using SAFT-VR Mie

Markides, Christos

12:40-

12:50 Group photo All

Lunch 12:50 – 13:40

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Afternoon 25 August 2016


Session 3: Fundamentals

Chair: Thomas Schulenberg

13:40-14:05

Modelling of heat transfer with influences of buoyancy and acceleration of fluids at supercritical pressure

Jackson, J.D.

14:05-14:30

A dominant thermal resistance approximation for heat transfer to supercritical-pressure fluids

McEligot, Donald

14:30-14:55

The evaluation of various turbulence models under supercritical conditions

Zang, Jinguang

14:55-15:20

Numerical simulation of highly-buoyant fluids with the variable effective viscous sub-layer and property-dependent turbulent Prandtl number

Bae, Yoon Y.

15:20-15:35

Refreshment break

Session 4: Carbon capture and storage (CCS)

Chair: Christos Markides

15:35-16:00

Effect of CO2 supercritical state on its performance in porous rock

Fan, Xianfeng

16:00-16:25

Fluid flow and heat transfer of supercritical pressure CO2 related to CO2 transportation, geological storage and utilization

Xu, Ruina

16:25-16:50

Synthesis and stability of different nanoparticles under supercritical CO2 conditions

Raza, Ghulam

16:50-17:15

Effects of wall thickness on the heat transfer and flow instability of supercritical pressure water in a tube (CFD)

Zhang, Zhen

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Morning 26 August 2016


Session 5: CFD 1

Chair: Peixue Jiang

09:00-09:40

The update progress of thermal hydraulics of supercritical fluids in NPIC (Keynote)

Huang, Yanping

09:40-10:05

Considerations on CFD studies about heat transfer to supercritical fluids

Pucciarelli, Andrea

10:05-10:30

Explanations of mechanism of heat transfer enhancement and deterioration for supercritical fluid using prediction of experimental results by CFD

Dubey, S.K.

10:30-10:55

Assessment of low-Reynolds number turbulence models against highly buoyant flow

Bae, Yoon Y.

10:55-11:10

Refreshment break

Session 6: Direct numerical simulations (DNS)

Chair: Laurence Leung

11:10-11:35

Direct numerical simulations of heat transfer to a turbulent annular upward flow at supercritical pressure

Peeters, J.W. R.

11:35-12:00

A numerical study of heat transfer in pipe flow with supercritical CO2

Chu, Xu

12:00-12:25

Turbulence channel flow at transcritical wall heated conditions

Hickey , Jean-Pierre

12:25-12:50

Mechanisms of flow laminarisation due to buoyancy

He, Shuisheng

Lunch 12:50 – 13:50

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Afternoon 26 August 2016


Session 7: CFD 2

Chair: Yoon Y. Bae

13:50-14:30

Development of super-critical water-cooled reactor concepts for local deployment (Keynote) – [special topic]

Leung, Laurence

14:30-14:55

Investigation into the performance of near-wall treatment strategies in simulating transient flow and mixed convection

Yan, Guojun

14:55-15:15

Session 8: Closure discussion

Chair: Shuisheng He All

End of HFSCP2016

Notes:

1. All sessions will be held in Lecture Theatre 6, The Diamond, The

University of Sheffield.

2. A computer and a projector will be available for presentations.

Alternatively, one can plug in their laptop to the projector if they

wish.

3. Each Standard presentation is scheduled for 25 minutes; please

prepare to speak for 18 to 20 minutes and leave at least 5 minutes

for questions and changeover. Each Keynote talk is scheduled for 40

minutes, with approximately 32 minutes presentation and 8 minutes

for questions.

4. The joint HFSCP2016–IAEA Technical Meeting Conference Dinner will

take place on Wednesday 24 August to start at 7pm at Piccolino, an

Italian restaurant in the heart of Sheffield city centre. The cost is £25

per person to be paid on the day. Please register online.

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Contents

Session 1: Experimental investigation 1Convection heat transfer of fluids at super-critical pressure and its

applications in renewable energy(Peixue Jiang) . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Onset of heat transfer deterioration to CO2 in heated vertical tubesat supercritical pressures(N. Kline and S. Tavoularis) . . . . . . . . . . . . . . . . . . . 3

Investigation and modeling of the heat transfer of CO2 at supercrit-ical pressure in vertical tubes of various scales during heating(Chenru Zhao, Zhen Zhang, Peixue Jiang and Hanliang Bo) . . 4

Session 2: Cycles 6University of Wisconsin research on fluid dynamics of supercritical

fluids(Mark Anderson and Kate Lyons) . . . . . . . . . . . . . . . . . 6

Supercritical organic Rankine cycle for geothermal power conversion(T. Schulenberg, D. Kuhn and H.J. Wiemer) . . . . . . . . . . 7

Supercritical cycles for power generation: component design andanalysis(Kamel Hooman) . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Supercritical organic Rankine cycle systems for waste-heat recoveryapplications using SAFT-VR Mie(Oyeniyi A. Oyewunmi, Simo Ferre-Serres and Christos N.Markides) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Session 3: Fundamentals 12Modelling of heat transfer with influences of buoyancy and acceler-

ation to fluids at supercritical pressure(J.D. Jackson) . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

A dominant thermal resistance approximation for heat transfer tosupercritical-pressure fluids(Donald M. McEligot, Eckart Laurien, Wei Wang and ShuishengHe) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

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The evaluation of various turbulence models under supercritical con-ditions(Jinguang Zang, Xiao Yan, Xiaokang Zeng, Yongliang Li andYanping Huang) . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Numerical simulation of highly-buoyant fluids with the variable effec-tive viscous sub-layer and property-dependent turbulent Prandtlnumbers(Yoon-Yeong Bae, Eung-Seon Kim and Minhwan Kim) . . . . . 15

Session 4: Carbon capture and storage (CCS) 16Effect of CO2 supercritical state on its performance in porous rock

(Xingxun Li, Al Zaidi Ebraheam and Xianfeng Fan) . . . . . . 16Fluid flow and heat transfer of supercritical pressure CO2 related to

CO2 transportation, geological storage and utilization(Ruina Xu and Peixue Jiang) . . . . . . . . . . . . . . . . . . . 17

Synthesis and stability of different nanoparticles under supercriticalCO2 conditions(Ghulam Raza, Shahid Pervaiz, Ehsan Nourafkan, MuhammadAmjad and Dongsheng Wen) . . . . . . . . . . . . . . . . . . . 19

Effects of wall thickness on the heat transfer and flow instability ofsupercritical pressure water in a tube(Zhen Zhang, Xingtuan Yang and Peixue Jiang) . . . . . . . . 20

Session 5: CFD 1 21The update progress of thermal hydraulics of supercritical fluids in

NPIC(Yanping Huang, Jinguang Zang, Junfeng Wang, Guangxu Liuand Shenghui Liu) . . . . . . . . . . . . . . . . . . . . . . . . . 21

Considerations on CFD studies about heat transfer to supercriticalfluids(Andrea Pucciarelli, Walter Ambrosini and Medhat Sharabi) . . 22

Explanations of mechanism of heat transfer enhancement and dete-rioration for supercritical fluid using prediction of experimentalresults by CFD(S.K. Dubey, K.N. Iyer, R.P. Vedula and A.J. Gaikwad) . . . . 23

Assessment of low-Reynolds number turbulence models against highlybuoyant flow(Yoon-Yeong Bae, Eung-Seon Kim and Minhwan Kim) . . . . . 24

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Session 6: Direct numerical simulations (DNS) 25Direct numerical simulations of heat transfer to a turbulent annular

upward flow at supercritical pressure(J.W.R. Peeters, R. Pecnik, M. Rohde and B.J. Boersma) . . . 25

A numerical study of heat transfer in pipe flow with supercriticalCO2(Xu Chu, Sandeep Pandey and Eckart Laurien) . . . . . . . . . 26

Turbulent channel flow at transcritical wall heated conditions(Kukjin Kim, Carlo Scalo and Jean-Pierre Hickey) . . . . . . . 27

Mechanisms of flow laminarisation due to buoyancy(Shuisheng He, Kui He, Mehdi Seddighi) . . . . . . . . . . . . . 28

Session 7: CFD 2 29Development of super-critical water-cooled reactor concepts for local

deployment(Laurence Leung) . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Investigation into the performance of near-wall treatment strategiesin simulating transient flow and mixed convection(Guojun Yan, Xinyi Miao and Shuisheng He) . . . . . . . . . . 30

Author Index 31

Committees 33

Participants List 34

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Session 1: Experimental investi-gation

Convection heat transfer of fluids at super-criticalpressure and its applications in renewable energy

Peixue JiangBeijing Key Laboratory for CO2 Utilization and Reduction Technology; Key Laboratory

for Thermal Science and Power Engineering of Ministry of Education; Department ofThermal Engineering, Tsinghua University, Beijing, China

This keynote speech will introduce convection heat transfer of fluids atsuper-critical pressures in straight small/mini/micro tubes and serpentinetube and fractures. The influence of multiple factors including the buoyancy,flow acceleration, centrifugal force, rotation, lubricating oil and instability onconvection heat transfer was studied. It was found that for vertical mini tubethe buoyancy is the dominant factor affecting convection heat transfer ratherthan the flow acceleration even in cases with relatively high inlet Reynoldsnumber when the heat flux was high, and the local wall temperatures varyin a complex and nonlinear form with deterioration and recovery of the heattransfer observed in upward flows but not in downward flows. However, forthe vertical micro tube the buoyancy effect on the heat transfer could beneglected, while the flow acceleration was the main factor that leads to theabnormal local wall temperature distribution at high heat fluxes. The effectsof the flow acceleration due to heating and pressure drop on the heat trans-fer, described by non-dimensional parameters, KvT and Kvp respectively, arein similar magnitude in micron scale channels. The influence of centrifugaland buoyancy forces on heat transfer in mini serpentine tube were studied.The heat transfer for upward flow generally performed better than downwardflows at high heat fluxes due to the effect of buoyancy on centrifugal force.The bend direction of the serpentine tube changes periodically, enhanced theflow instability and then weakened the stabilizing effect of buoyancy; the cen-trifugal force in the serpentine tube also enhanced the heat transfer. Theaverage heat transfer coefficient increases with rotation rate, and 3 times ofstatic condition at 1500 rpm. The convection heat transfer of CO2 mixedwith lubricating oil is worse than the convection heat transfer of pure CO2.

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HFSCP 2016August 25&26, 2016, Sheffield, UK

Flow and heat transfer instability of N-decane at supercritical pressures werestudied experimentally.

The advanced CO2 Solar Power Cycles, CO2-Enhanced Geothermal Sys-tems and CO2-Solar-Enhanced Geothermal Hybrid System, and convectionheat transfer of CO2 at super-critical pressures in horizontal and vertical frac-tures will be introduced.

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Onset of heat transfer deterioration to CO2 in heatedvertical tubes at supercritical pressures

N. Kline and S. TavoularisDepartment of Mechanical Engineering, University of Ottawa, Ottawa, ON, Canada

Extensive convective heat transfer measurements have been collected inthe Supercritical University of Ottawa Loop (SCUOL) with carbon dioxideat supercritical pressures flowing vertically upwards in tubular test sectionshaving inner diameters equal to 22.0, 8.0, and 4.6 mm. Outer wall tempera-ture was measured by a large number of thermocouples, from which the innerwall temperature and the local heat transfer coefficient were estimated. Themeasurements extend over wide ranges of conditions, which cover both thenormal and deteriorated heat transfer modes. Of particular interest was todetermine the conditions at the onset of heat transfer deterioration (HTD).These conditions were determined by gradually increasing the wall heat fluxq, while keeping the pressure P , mass flux G and inlet temperature Tin con-stant, until a temperature spike was observed in the wall temperature profile.Reported measurements were taken for P ≈ 1.13Pcritical, 0 ◦C ≤ Tin ≤ 35 ◦Cand 200 kg/m2s ≤ G ≤ 1000 kg/m2s.

It was found that, at the onset of HTD, the wall heat flux could be repre-sented as a power law of the mass flux with the same exponent but differentproportionality coefficients for each of the three test sections. It was alsofound that, for the onset wall heat flux, HTD only occurred when the inlettemperature was within a range particular to each tube, whereas, for Tin val-ues both above and below this range, heat transfer was normal. In an effortto account for the inlet temperature effect, we developed a two-step empiri-cal process for predicting HTD onset. The large sets of data from the threetest sections were also used to test normal heat transfer correlations and toexplore the influence of buoyancy in mixed convective flows in an effort todevise an improved theoretically-based model for predicting heat transfer insupercritical CO2.

3


Investigation and modeling of the heat transfer of CO2at supercritical pressure in vertical tubes of various

scales during heatingChenru Zhao1, Zhen Zhang1, Peixue Jiang2 and Hanliang Bo1

1Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing, China2Beijing Key Laboratory of CO2 Utilization and Reduction Technology; Key Laboratory

for Thermal Science and Power Engineering of Ministry of Education; Department ofThermal Engineering, Tsinghua University, Beijing, China

The special characteristics and complicate mechanism of the heat transferof fluids at supercritical pressures in vertical tubes are mainly resulted fromthe sharp variation of the thermophysical properties, the buoyancy effect andthe thermal acceleration effect during heating. It is interesting to notice thatthe buoyancy effect and the thermal acceleration effect on the heat transfer offluids at supercritical pressures differ when the flow channel size varies evenwhen the local Reynolds number variation is the same (which means that theflow is similar) and the local fluid temperature and pressure variation is thesame (which means the local fluid thermophysical properties are the same,especially the Prandtl number).

In the present paper, experimental data for heat transfer of CO2 at super-critical pressure in vertical tubes with inner diameter of 2 mm and 0.27 mmare compared and analyzed to investigate the buoyancy effect and the flowacceleration effect on the heat transfer in various tube scales. Cases are care-fully selected with the operating pressure, the inlet Reynolds number, andthe ratio of the heat flux to the mass flow rate (qw/G, qw is in kW/m2, andG in kg/m2s) are kept as close as much to ensure the flow is similar and thelocal fluid thermophysical properties are close. Local variations of the walltemperature, local Nusselt number, as well as the local buoyancy parameter,Bo∗, and the local thermal acceleration parameter, Kv, are compared anddiscussed for heat transfer of CO2 at supercritical pressure in vertical tubeswith inner diameter of 2 mm and 0.27 mm.

Numerical simulations under corresponding conditions are performed us-ing various low Reynolds number turbulence models including LS, AKN andYS models. The predicted local wall temperatures are compared with theexperimental results and the performance of various LRN turbulence mod-els in simulating the strongly buoyancy or thermal acceleration affected heattransfer for fluids at supercritical pressures in vertical tubes are assessed. Themechanism of the buoyancy effect and the thermal acceleration effect are ex-

4


plained based on the detailed information of the flow field obtained from thenumerical results.

Results show that although the flow is similar and the local fluid thermo-physical properties are close for heat transfer in 0.27 mm and 2 mm tubes, thethermal acceleration effect significantly dominates in 0.27 mm tube, resultingin local heat transfer deterioration, whereas for 2 mm tube, although the localKv value is close with that for 0.27 mm tube, the thermal acceleration effect isinsignificant. The local Bo∗ is one or two orders of magnitude for 2 mm tubethan that for 0.27 mm tube, and the heat transfer is significantly enhanceddue to the strong buoyancy for heat transfer of CO2 at supercritical pressuresin 2 mm tube. Numerical results show that the large radial temperature andvelocity gradient in 0.27 mm tube greatly affect the turbulence productionand the heat transfer.

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Session 2: Cycles

University of Wisconsin research on fluid dynamics ofsupercritical fluids

Mark Anderson and Kate LyonsThe University of Wisconsin - Madison College of Engineering, 1500 Engineering Dr,

Madison WI 53705, United States

The University of Wisconsin has been conducting fundamental researchon the use of supercritical fluids for advanced reactor systems and advancedpower cycles for new high temperature reactors for the past ten years. Sev-eral areas of research will be discussed related to the fluid dynamics andheat transfers of supercritical water (SCW) and supercritical carbon dioxide(sCO2). Among the research that will be discussed are a new series of rodbundle tests with an axial cosine power profile that is being constructed toprovide unique data for SCW heat transfer. In addition to running with SCWthe facility will also be run with sCO2 as the working fluid with scaled tem-peratures, heat flux and flow rates. This data will be used in a benchmarkexercise to test CFD models and scaling analysis approaches. The test fa-cility is similar in design to tests conducted by SJTU with uniformly heatedrods and will allow a detailed look at the effects of the different power pro-files. Details of the facility and description of the planed tests will be given.The second area that will be discussed is current work with regard to thesCO2 power cycle. This power cycle is being considered for several reactorsystems due to the higher efficiency and higher power density as comparedto the Rankine cycle for temperatures above 500 ◦C. In particular flow ofsupercritical carbon dioxide through compact printed circuit heat exchangers(PCHE’s) and regenerators will be discussed both from an experimental andcomputational perspective.

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Supercritical organic Rankine cycle for geothermalpower conversion

T. Schulenberg, D. Kuhn and H.J. WiemerKarlsruhe Institute of Technology (KIT), Institute for Nuclear and Energy Technologies,

Hermann-von Helmholtz Platz 1, D-76344 Eggenstein-Leopoldshafen

Geothermal energy is exploitable in several countries as hot water withtemperatures around 100 ◦C to 200 ◦C. Such low temperature reservoirs canhardly be converted to electric power with a conventional steam cycle, butrequire rather organic working media. A supercritical Rankine cycle withpropane has been designed by Vetter (2014) for maximum electric power froma given mass flow of hot water at 150 ◦C, which is pseudo-evaporating andsuperheating supercritical propane up to 117 ◦C at 5.5 MPa. As an advantageof supercritical media, the heat-up curve of propane follows closely the cool-down curve of water, resulting in best utilization of the hot water with a lowreturn temperature of 51.6 ◦C. The cycle reaches a specific net power of morethan 42 kJ/kg at a condenser temperature of 30 ◦C.

A small prototypical power plant for such application is just being built atKIT. It shall convert a thermal power of 1 MW at 150 ◦C to an electric powerof around 100 kW, and consists of a piston compressor, an screw expander andan air-cooled condenser. For pure water, the evaporator has been designed asa plate heat exchanger with a heat exchanger surface of 38 m2. As geothermalbrine may cause significant scale, however, different heat exchanger designsmay be preferred in other cases. With its modular design, the facility canbe operated for test at different geothermal locations, but shall be commis-sioned first with a conventional heater. An extensive test instrumentationshall provide detailed information of the performance of each component.

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Supercritical cycles for power generation: componentdesign and analysis

Kamel HoomanRenewable Energy Conversion Centre of Excellence, School of Mechanical and Mining

Engineering, The University of Queensland, Australia

The Renewable Energy Conversion Centre of Excellence at The Universityof Queensland has been working on developing sub-MW supercritical powercycles for remote and off-grid regions in Australia. In particular, the work isfocused on developing supercritical turbines and heat exchangers/condensersfor which no off-the-shelf product is available. Design and testing of suchcomponents are being carried out based on fundamentals of thermohydraulicsof supercritical fluid flows. Denser working fluid in the turbine, in case ofsupercritical power cycles, leads to miniaturized design which brings in ex-tra challenge of having the thermofluid mechanics linked to solid mechanics,rotor dynamics and vibration on top of bearing and sealing issues. Theseare addressed using a combination of theoretical, numerical and experimentaltechniques. This paper will present more details and shed some light on theway froward and future application of such equipment in different sections ofthe industry.

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Supercritical organic Rankine cycle systems forwaste-heat recovery applications using SAFT-VR Mie

Oyeniyi A. Oyewunmi, Simo Ferre-Serres and Christos N. MarkidesClean Energy Processes (CEP) Laboratory, Department of Chemical Engineering,

Imperial College London, SW7 2AZ, U.K.

Organic Rankine cycle (ORC) systems are increasingly being deployed forwaste-heat recovery and conversion in industrial settings. A key componentin the economic appraisal of such systems is the modelling and simulation ofthe physical system; the accurate prediction of working-fluid thermo-physicalproperties is essential to this assessment. Furthermore, working-fluid mixturesand supercritical ORC configurations have been suggested to improve theperformance of ORC systems. The costs and economic implications of suchsystems are however yet to be fully investigated. Here, we present the SAFT-VR Mie equation of state (EoS) for the accurate prediction of thermodynamicproperties of working fluids employed in subcritical and supercritical ORCsystems, and an economic assessment of the optimized ORC systems. Using acase study of an exhaust flue-gas stream at a temperature of 380 ◦C as the heatsource, an ORC system power output in excess of 10 MW is predicted. Theworking fluids considered are the normal alkanes-butane, pentane, hexane,and CO2.

By comparison with available experimental data, the thermodynamic prop-erties of working fluids are shown to be reliably predicted by the SAFT-VRMie EoS. In particular, properties such as enthalpies, entropies and heat ca-pacities which were not used in the SAFT model development, were accuratelypredicted. Various cycle configurations and the use of working-fluid mixturesare also investigated. ORC systems operating on supercritical cycles andthose incorporating an internal heat exchanger are seen to be beneficial froma thermodynamic perspective, they are, however, more expensive than thesimple ORC system considered (subcritical cycle with no internal heat ex-changer). Furthermore, ORC systems using pure working fluids are associatedwith slightly lower costs than those with fluid mixtures. It is concluded thata basic ORC system utilizing pure working fluids shows the lowest specificinvestment cost in the case study considered.

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Figure 1: Selected thermodynamic properties (ρ, Cp and s) of n-pentane,at subcritical and supercritical pressures predicted using SAFT-VR Mie EoS(curves). Validation data from the NIST database are indicated by the sym-bols.

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Figure 2: Performance indices of optimised supercritical CO2 and ORC plantswithout regeneration (− IHE) and with internal regeneration (+ IHE), withpure working fluids (butane, pentane, hexane and CO2 respectively) andworking-fluid mixtures. Left: Exergy efficiency. Middle: Net power output.Right: Specific costs.

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Session 3: Fundamentals

Modelling of heat transfer with influences of buoyancyand acceleration to fluids at supercritical pressure

J.D. JacksonThe University of Manchester, U.K.

During the 1970’s the author and his colleagues developed simple ap-proaches for screening experimental data on turbulent forced convection heattransfer in tubes to fluids at supercritical pressure to check whether influ-ences of buoyancy and bulk flow acceleration were negligibly small. Theywent on to develop semi-empirical models aimed at describing heat transferbehaviour under buoyancy and acceleration influenced-conditions. Althoughthese models were found to work quite well for fluids at normal pressure,it was found that the ideas on which they were based were too simplisticfor use with fluids at pressures above the critical value. With present-daycomputers, it is now feasible to use more sophisticated models designed to ac-count the strong dependence of fluid properties under supercritical pressureconditions. Physically-based semi-empirical models of buoyancy-influencedand acceleration-influenced heat transfer at supercritical pressure will be pre-sented. These take improved account of fluid property non-uniformity. Themodels lead to improved criteria for screening and categorising experimentaldata on buoyancy and acceleration influenced heat transfer to such fluids. Anoutcome of this extended modelling study is that the very extensive databasesnow available on heat transfer to fluids at supercritical pressure in tubes canbe used in conjunction with improved criteria for onset of significant effectsof buoyancy and acceleration to re-evaluate correlation equations for forcedconvection heat transfer to such fluids. A further outcome is that it might nowbe possible to correlate the buoyancy-influenced and acceleration-influenceddata using these models. Extended physically-based, semi-empirical modelsof buoyancy-influenced and acceleration convective heat transfer to fluids atsupercritical pressure flowing will be presented at the meeting. These takecareful account of the strong temperature dependence of physical propertiesexhibited by such fluids. Finally, work on the application of the models forthe purpose of screening, categorising and correlating experimental data onheat transfer to fluids at supercritical will be discussed.

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A dominant thermal resistance approximation for heattransfer to supercritical-pressure fluids

Donald M. McEligot1,2, Eckart Laurien3, Wei Wang4 and Shuisheng He4

1Nuclear Engineering Program, University of Idaho, Japan2Department of Aerospace and Mechanical Engineering, University of Arizona

3Institut fur Kernergetik und Energiesysteme (IKE), University of Stuttgart4Department of Mechanical Engineering, University of Sheffield

Heat transfer to supercritical-pressure fluids flowing turbulently in ductsis a lovely, complicated situation. Considerable research has been devotedto it for decades – and is continuing. We now have computational thermalfluid dynamics (CTFD) predictions, direct numerical simulation (DNS) re-sults and scads of correlations to address the problem. The present studytakes a different tack. Quasi-developed turbulent flow in a duct is simpli-fied in order to develop semi-analytic treatments of dominant phenomena inthe pseudo-critical region. Via approximations and basic assumptions, themodels are developed to provide closed-form relations accounting for extremeproperty variations with wall and/or core temperatures in the pseudo-criticalregion. Typical predictions are compared to the DNS results of Wang andHe to evaluate levels of confidence that might be warranted. Consequences ofreference property selection are considered. One is able to see sensitivities tosome key assumptions which also are the foundations of popular CTFD ap-proaches. The analyses can provide approximate predictions and foundationsof more generalized treatments, such as wall functions for turbulence modelsand (hopefully) improved empirical correlations.

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The evaluation of various turbulence models undersupercritical conditions

Jinguang Zang, Xiao Yan, Xiaokang Zeng, Yongliang Li and Yanping HuangCNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology, Nuclear

Power Institute of China

The heat transfer behavior of supercritical water has large difference withthat of subcritical water due to its unusual fluid property variation in thepseudocritical region. Computational Fluid Dynamics techniques are play-ing more and more important roles in investigating the hidden mechanismsof that, however, whether the extension of subcritical turbulence models tosupercritical conditions has not yet been fully resolved. In this paper, variousturbulence models were compared with the experimental data in a wide rangeof parameters. It is found that the performance of each turbulence modeldepends on the thermal hydraulic parameter of the experimental data whichis compared to. In this case, this turbulence model is good; and in othercase, another turbulence model behaves better. This kind dependency on ex-perimental data displays the complexity of giving justice of each turbulencemodel. The boundary layer is the main region responsible for the heat andmomentum transport between the wall and the bulk fluid part, so it is veryimportant for the turbulence models to describe the boundary layer charac-teristics. A new method of analyzing the boundary layer characteristic wasproposed and was hoped to give some new thoughts.

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Numerical simulation of highly-buoyant fluids with thevariable effective viscous sub-layer and

property-dependent turbulent Prandtl numbersYoon-Yeong Bae, Eung-Seon Kim and Minhwan Kim

Korea Atomic Energy Research Institute, Daedeokdaero 989-111, Yuseong, Daejeon,Republic of Korea

Earlier numerical simulations of thermal-hydraulic behaviour have resultedin, without exception, unrealistic predictions, when fluids experience a strong-enough property variation. The wrong predictions might have been derivedfrom an inappropriateness of conventional turbulence models as well as theconstant turbulent Prandtl number.

In most of numerical simulations of fluid flow with constant properties ornegligible variations, the value of turbulent Prandtl number has been consid-ered to be unity or close to it. However, the numerical works with a constantturbulent Prandtl number have failed or been only partially successful in es-timating the wall temperature in highly-buoyant supercritical fluids throughvertical tubes. Several experimental data and numerical studies indicatedthat the turbulent Prandtl number can be very smaller or larger than unityin a region of severe property variation. Recent research, both numerical andexperimental, indicated that the turbulent Prandtl number was very likely afunction of fluid-thermal variables, when the gradients of physical propertiesof fluid are significant. In this regards, a new concept of a property-dependentturbulent Prandtl number according to property variation was developed.

Another point to be considered in the numerical simulation of fluids withstrong buoyancy, the turbulent boundary layer deforms so severely that thewidely-used damping function is no longer applicable. When a velocity over-shoot (or peak) appears in turbulent boundary layer, a new turbulent bound-ary layer may develop between the point of the velocity peak and the wall.Accordingly, the damping function in the new TBL must be different fromthe one without a velocity peak. The effective viscous sublayer, A+, was ex-pressed as a function of buoyancy to account for the deformation of turbulentboundary layer.

The results of numerical simulations of fluids at supercritical pressuresflowing upward through vertical tubes with the application of the property-dependent turbulent Prandtl number and A+ as a function of buoyancy agreedextremely well with the experimental data.

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Session 4: Carbon capture andstorage (CCS)

Effect of CO2 supercritical state on its performance inporous rock

Xingxun Li, Al Zaidi Ebraheam and Xianfeng FanSchool of Engineering, The University of Edinburgh, King’s Buildings, Edinburgh, U.K.

CO2 has been used for enhanced oil/gas recovery, the production of geother-mal power, and the production of water from CO2 storage in saline forma-tions. The processes are a displacement in porous rocks. The dynamics ofthe displacement is controlled by CO2 phase (gas/liquid/supercritical), thewetting behaviour of CO2-fluid in porous rocks, and pore structure. This pa-per will report our recent findings on the effect of CO2 phase, particularly itssupercritical state, on it pore wetting behaviour and its displacement in sandstone core samples. CO2 wetting behaviour in a pore is very different fromits behaviour on a flat surface in an open space, in which CO2 pore contactangle is much higher than that measured from a flat surface. The CO2 phasesignificantly affects the CO2-fluid contact angle in an oil-wet pore. Supercrit-ical CO2-fluid contact angles are larger than gas CO2-fluid contact angles,but are smaller than liquid CO2-fluid contact angles. Salinity has a signif-icant effect on the CO2-brine-glass pore contact angle in a water-wet pore,θbrine > θwater.

Our investigation on gas CO2-water, liquid CO2-water and supercriti-cal CO2-water displacements in sand stone core samples indicates that CO2phase significantly affect the capillary pressure-saturation curve, water pro-duction behaviour and relative permeability. For the gas CO2-water system,the cumulative volume of water production is significantly smaller than thecumulative volume of CO2 injection. Liquid CO2-water drainage gives a lin-ear relationship between water production volume and time. The cumulativevolume of water production almost equals the cumulative volume of CO2 injec-tion. For the supercritical CO2-water system, an irregular water productioncurve is obtained.

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Fluid flow and heat transfer of supercritical pressureCO2 related to CO2 transportation, geological storage

and utilization

Ruina Xu and Peixue JiangDepartment of Thermal Engineering, Tsinghua University, Beijing, China

Carbon Capture, Utilization and Storage (CCUS) is a new technology thatcan mitigate greenhouse gas emissions on a large scale and decrease the cost ofCarbon Capture and Storage (CCS). The flow and thermal behavior of CO2in pipeline, injection wells and the target reservoirs are important to all CO2geological storage (CCS) and utilization technologies. What makes it morechallenging is that while stored 800 m–3000 m below the surface, CO2 takes asupercritical state, as such, its thermodynamic and transport properties varyhugely with temperature, especially as the temperature crosses its pseudo-critical value. In this paper, we will introduce the research work about theheat transfer in CO2 injection well and production well, supercritical CO2migration and heat transfer in reservoir, and the thermodynamic analysisof energy conversion system for the CO2 geological storage and EnhancedGeothermal System.

1. CO2 injector modelling: A full-field model of a coupled injection welland reservoir to simulate the CO2 behaviour during CO2 injection throughthe wellbore and reservoir, taking into account thermal exchanges withrocks and natural convection of water in the annulus. The model wasused to analyze the temperature drop in the wellbore in China OrdosCO2 storage project, and wellbore dynamics of a CO2 injector duringtransient well close-in and start-up operations.

2. The heat transfer of supercritical CO2 in CO2-EGS by core scale experi-ments and field scale local thermal non-equilibrium model: The internalheat transfer between supercritical CO2 and hot rock was investigatedby core scale experiments. The single blow method was used to studythe transient heat transfer between the high temperature rock and thesupercritical CO2 in the fracture. The local thermal non-equilibriummodel, which accounts for the temperature difference between solid andfluid components in porous media and uses two energy equations todescribe heat transfer in the solid matrix and in the fluid, respectively.

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3. Two-phase flow properties of a sandstone rock for the CO2/water sys-tem by core-flooding experiments: The two-phase flow characterization(CO2/water) of a Triassic sandstone core from the Paris Basin, Francewill be reported in this talk. Absolute properties (porosity and waterpermeability), capillary pressure, relative permeability with hysteresisbetween drainage and imbibition, and residual trapping capacities havebeen assessed at 9 MPa pore pressure and 28 ◦C (CO2 in liquid state) us-ing a single core-flooding apparatus associated with magnetic resonanceimaging.

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Synthesis and stability of different nanoparticles undersupercritical CO2 conditions

Ghulam Raza, Shahid Pervaiz, Ehsan Nourafkan, Muhammad Amjad andDongsheng Wen

School of Chemical and Process Engineering, University of Leeds, U.K.

Nanoparticles for different applications require a synthesis approach whichcan meet extreme process conditions like high temperature, high pressure andhigh salinity. Fabrication of different nanoparticles (NP) at high temperatureand high pressure (HTHP) was carried out using SEPAREX supercriticalCO2 rig with Supercritical Anti-Solvent (SAS) technique. The major aim ofthis work is to study the prospects of in-situ synthesis nanomaterials underextreme conditions. The main focus was to control the size and shape of NPsat high temperature, high pressure and to evaluate the synthesis character-istics at high salinity for the applications related to different industry. TheSAS technique is validated to meet the oil reservoir like conditions and Ag,Au, Cu, TiO2 and ZnO NPs are synthesized at varying temperatures, pres-sures and salinity conditions. In a fully controlled process, CO2 was filledinto the rig to achieve any desired level of pressure and temperature. Whensupercritical CO2 temperature and pressure was achieved, the precursor so-lutions were pumped slowly with HPLC pump. Salinity levels of 0.05 –2 %NaCl were developed to study the effect of salinity on synthesis process. Theresults indicated that NPs can be synthesized as varying temperatures andpressures. Salinity levels increased the overall particle sizes and promote ag-gregation. Generally the temperature and pressure showed insignificant effecton the NPs diameter. The shape of NPs was changed at high pressure andhigh temperature while high salinity gave rise to the relatively bigger chunksof NPs aggregates of more than 5 micron in size in some cases but the pri-mary particle size was varied from 20 –180 nm. Crystalline TiO2 and ZnONPs were obtained at temperatures above 150 ◦C. Generally concentration ofprecursors is directly proportional to the size of NPs.

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Effects of wall thickness on the heat transfer and flowinstability of supercritical pressure water in a tube

Zhen Zhang1, Xingtuan Yang1 and Peixue Jiang2

1Institute of Nuclear and New Energy Technology, Collaborative Innovation Center ofAdvanced Nuclear Energy Technology, Key Laboratory of Advanced Nuclear ReactorEngineering and Safety of Ministry of Education, Tsinghua University, Beijing, China

2Key Laboratory of Thermal Science and Power Engineering of Ministry of Educations,Department of Thermal Engineering, Tsinghua University, Beijing, China

The subcritical steam generators in the current high temperature gas-cooled reactor pebble-bed module (HTR-PM) in China can be replaced bysupercritical steam generators to work with the reactors and the supercriticalsteam turbine unit considering the high thermal efficiency and no fluid phasechange at the supercritical pressures, so the heat transfer and flow instabilityof supercritical pressure water in a vertical tube with zero- and finite-thicknesswalls are studied numerically in this paper. The effect of the wall thickness onheat transfer of supercritical pressure water at steady state is negligible. Inthe transient-state calculations, the fluid flow rate oscillates intensely beyonda certain heat flux with zero-thickness wall, while the flows in the tube withfinite-thickness walls act totally different. The wall properties including thedensity, specific heat and thermal conductivity are varied to analyze whythe oscillations are suppressed when finite-thickness wall is considered in thecalculation. The flow and heat transfer characteristics, and the heat stored inthe wall compared with the total power during the heating process at variousmoments are also presented.

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Session 5: CFD 1

The update progress of thermal hydraulics ofsupercritical fluids in NPIC

Yanping Huang, Jinguang Zang, Junfeng Wang, Guangxu Liu and ShenghuiLiu

CNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology, NuclearPower Institute of China

The SCWR thermal hydraulics research in Nuclear Power Institute ofChina includes four major aspects: heat transfer tests of SCW in tubes, annu-lar channel and 2 × 2 rod bundles; and flow behaviour tests in tubes, annularchannel and 2 × 2 rod bundles; safety performance related tests includingnatural circulation, flow stability in parallel channels; assessment and appli-cability of prediction codes. Besides the research on supercritical water, latelyNPIC has devoted to investigate the supercritical carbon dioxide (S-CO2). Bynow, the heat transfer tests of S-CO2 in forced circulation have been done.The natural circulation behaviour of S-CO2 has also been investigated. Thenatural circulation instability was also observed in the tests. In this paper, abrief introduction of latest progress in NPIC will be presented.

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Considerations on CFD studies about heat transfer tosupercritical fluids

Andrea Pucciarelli, Walter Ambrosini and Medhat SharabiDepartment of Civil and Industrial Engineering, Universita di Pisa, Pisa, PI, Italy

The paper reports on the activities performed in the last years at theUniversity of Pisa. Heat transfer to supercritical fluids has been a relevanttopic since 2005 when it was selected as the main subject of research in theframe of a Ph.D. programme.

RANS calculations were performed both adopting commercial and in-house codes. The capabilities of different turbulence models were evaluatedhighlighting both interesting features and weaknesses. In particular, heattransfer deterioration proved to be the most difficult phenomenon to be pre-dicted as it seems showing a threshold behaviour. In fact, even little changesin the boundary conditions may trigger it and, in addition, further difficultiesare due to the fact that, depending on the selected turbulence model, thephenomenon may be predicted or not.

In the frame of the latest studies, advanced models for the calculation ofthe turbulent heat fluxes, such as AHFM were considered. At the beginning,AHFM was adopted only for calculating the production terms of turbulencedue to buoyancy, obtaining interesting results; nevertheless, problems still ap-pears for cases in correspondence of crossing the pseudo-critical temperature.

In later analyses, AHFM was also adopted in the energy equation. Afull use of the relation was allowed only with the in-house code while whenadopting commercial codes the simple gradient approach had to be main-tained. Consequently, in the latter case AHFM was used as an advanced toolfor calculating the turbulent Prandtl number. Improvements were obtained inparticular for near critical conditions suggesting that the considered approachcould be the best one for dealing with supercritical fluids.

After this long time of studies, it is time to make a summary of the per-formed work and to learn the lessons drawn in order to pave the way forfurther improvements and understandings to be reached in the next years.This is the main purpose of this paper.

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Explanations of mechanism of heat transferenhancement and deterioration for supercritical fluid

using prediction of experimental results by CFDS.K. Dubey1, K.N. Iyer2, R.P. Vedula2 and A.J. Gaikwad1

1NSAD, Atomic Energy Regulatory Board, Anushaktinagar, Mumbai, India2Department of Mechanical Engineering, IIT Bombay, Powai, Mumbai, India

The use of water at supercritical conditions in power plants is very at-tractive since high thermal efficiencies can be achieved at these conditions.It has been well documented for tubular flow geometries that Heat TransferEnhancement (HTE) and Heat Transfer Deterioration (HTD) are observed atlow and high wall heat flux respectively. However, wall heat transfer coeffi-cient measurements are not sufficient to understand the mechanism of HTEand HTD and local fluid dynamic measurements or computations must beutilized to explain the phenomenon. The effects of heat flux and inlet tem-perature on HTE and HTD have been investigated in this study using theCFD approach and it is shown that inlet temperature can significantly affectthe HTD behaviour whereas the HTE is not affected. The k–ω SST tur-bulence model is used for computations and the results are compared withexperimental data from a Supercritical Freon Test Facility (SFTF) with R22as the working fluid. Measurements were made for vertically upward flow in atube and the local wall temperatures were measured using a thermal camera.The available k–ω SST turbulence model in the CFD code ‘FLUENT R©’ hasbeen shown to be able to predict both HTE and HTD provided the turbulentPrandtl number is adjusted. The value was modified to match the experimen-tal data for one heat flux value and this value was used for all other cases. Avalue of 0.85 is able predict reduction in HTE with increase in heat flux sat-isfactorily. However, HTD was well predicted when the value was changed to1.1 for low heat flux values, but for the case with very high heat flux coupledwith low mass flux, a value of 1.7 was needed for better predictability. Eventhough this model is unable to predict the data without modifications basedon experimental data, the mechanism of HTE and HTD are explained usingthe results where better predictions were obtained. The fundamental reasonfor HTD appears to be the reduction of shear stress in the near wall regiondue to reduced turbulent intensity induced by increased buoyancy near thewall. The transformation of the normal velocity profile into an M shaped onewas clearly captured in the computations leading to this conclusion.

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Assessment of low-Reynolds number turbulence modelsagainst highly buoyant flow

Yoon-Yeong Bae, Eung-Seon Kim and Minhwan KimKorea Atomic Energy Research Institute, 111 Daedeok-daero 989, Yuseong, Daejeon,

Republic of Korea

The low-Reynolds number turbulence models have been successfully usedby numerous researchers in various applications. It has been found that theMyong-Kasagi model (MK) among them has shown a relatively better per-formance in the simulations of thermal-fluid field at supercritical pressuresand near the corresponding pseudo-critical temperature. However, the reasonfor its relatively better performance has never been critically examined andhas been used as it is. In this paper several well-known low-Reynolds numberturbulence models including the MK were critically reviewed to find reasons,if any, for the relative superiority to other models.

The most outstanding factor was identified to be the fact that MK in-troduced the Taylor microscale as the near-wall length scale and combinedit with the integral length to result in a combined turbulence length scale,which is valid over the entire range of turbulent boundary layer. The formulafor eddy viscosity with an incorporation of the combined turbulence lengthscale naturally expected to better represent the flow with a strong buoyancydue to wall heating, where a buoyancy effect mainly occurs near the wall. Asa result MK simulated highly buoyant flows with excellent agreement withthe experimental data, when applied with the property-dependent turbulentPrandtl number and shear-stress-dependent viscous sublayer thickness. Com-parison with the DNS data of the turbulence data obtained from the RANScalculation with MK also showed a good agreement between them.

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Session 6: Direct numerical sim-ulations (DNS)

Direct numerical simulations of heat transfer to aturbulent annular upward flow at supercritical pressure

J.W.R. Peeters, R. Pecnik, M. Rohde and B.J. BoersmaDelft, University of Technology, the Netherlands

Heated or cooled fluids at supercritical pressure show large variations inthermophysical properties, such as the density, dynamic viscosity and molec-ular Prandtl number, which strongly influence turbulence characteristics. Toinvestigate this, direct numerical simulations were performed of a turbulentflow at supercritical pressure (CO2 at 8 MPa) in an annulus with a hot innerwall and a cold outer wall. The pseudo-critical temperature lies close to theinner wall, which results in strong thermophysical property variations in thatregion. We aim to obtain a better theoretical understanding of how the vari-able thermophysical properties attenuate both the flow field, as well as theheat transfer.

Turbulence in the near wall cycle can be thought of as a cycle of eventsor coherent structures; near wall streaks (coherent low speed fluid regions)become unstable, which results in the formation of quasi streamwise vorticesthat in turn may create streaks. The disruption of a component of this cyclemay lead to laminarization of the flow. First, we will present how the gener-ation of streaks is affected by variable density effects (such as local thermalexpansion and buoyancy) as well as variable viscosity effects. We will alsopresent a similar analysis for the generation of streamwise vorticity.

Secondly, we will focus on the effect of the (highly) variable molecularPrandtl number. The turbulent heat flux can be interpreted as the result ofdifferent turbulent events. The effectiveness of these turbulent events withrespect to heat transfer is modulated due variations in the density, as well asthe Prandtl number.

We believe that the presented insights may be of use in developing betterheat transfer prediction models for heated fluids at supercritical pressure.

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A numerical study of heat transfer in pipe flow withsupercritical CO2

Xu Chu, Sandeep Pandey and Eckart LaurienInstitute of Nuclear Technology and Energy Systems Pfaffenwaldring 31, 70569 Stuttgart,

Germany

In this research article, some recent works about heat transfer mechanismof supercritical CO2 will be introduced. The heated pipe flow at Re0 = 5400is investigated using direct numerical simulation (DNS). The inflow temper-ature is defined slightly lower than the pseudo-critical point at P = 8 MPa.The results of both horizontal cases and vertical cases are shown here. In thehorizontal cases, flow stratification is observed as a result of density differencesnear the pseudo-critical point. The temperature near the upper wall is signif-icantly higher than that near the lower wall. A secondary flow is built up inthe downstream direction. In the vertical pipe flow, the heat transfer deterio-ration is observed in the buoyancy-induced flow. Thermo-physical propertiesare considered separately in different cases. Furthermore, an incompressiblecode and a compressible code are implemented and compared with the sameboundary conditions. An analysis of the results is given.

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Turbulent channel flow at transcritical wall heatedconditions

Kukjin Kim1, Carlo Scalo1 and Jean-Pierre Hickey2

1School of Mechanical Engineering, Purdue University, 585 Purdue Mall, West Lafayette,IN, USA

2Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200University Avenue W., Waterloo, Ontario, Canada

We have performed direct numerical simulations (DNS) of transcriticalturbulent channel flow with R-134a as an working fluid at transcritical pres-sures by solving the fully compressible 3D Navier-Stokes equations closed withthe Peng-Robinson (PR) equation of state. A pseudo-boiling line (PBL) existsat pressure conditions greater than the critical pressure, pc, of fluid and eachone of the conditions has the corresponding pseudo-critical temperature, Tpc.We chose 1.1pc as the pressure condition, pb, where the critical pressure forR-134a equals to 40.59 bar and 5 K, 10 K, and 20 K as ∆T which representsthe difference between the top and bottom wall temperature and includes thecorresponding pseudo-critical temperature in the center. In this study, theeffects of pseudo-phase change on wall-bounded turbulence are investigated.Rapid change of thermodynamic properties occurs near the top and bottomwalls and such a trend becomes stronger as ∆T decreases with the constantpressure condition (pb = 1.1pc). The profiles of Reynolds normal stressesin the core flow move towards the top wall region and the sharpness of theroot-mean-square (RMS) profiles of thermodynamic properties become morestronger as ∆T increases. The degree of fluctuation of thermodynamic prop-erties is higher in the liquid phase compared to the gas phase. The differencebetween the top and bottom wall temperature condition affects significantlythe trend of turbulent enthalpy flux profiles. It is observed visually in thetemporal development of the isosurfaces of Q-criterion and density that theliquid-like flow near the bottom wall is ejected and it changes the structuresand dynamics of turbulent core flow. From the grid resolution study, it isinvestigated that the mean temperature profiles affect the RMS quantities ofthermodynamic properties near the top wall region significantly so that thisstudy for transcritical characteristics in the turbulent channel flow needs thestrict DNS grid resolution.

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Mechanisms of flow laminarisation due to buoyancyShuisheng He1, Kui He1, Mehdi Seddighi2

1Department of Mechanical Engineering, University of Sheffield, Sheffield, U.K.2Department of Maritime and Mechanical Engineering, Liverpool John Moores University,

Liverpool, U.K.

Direct numerical simulation of a turbulent flow subjected to various dis-tributions of buoyant forces has been carried out to gain new insights intothe mechanisms of flow laminarisation. It is well established that when aturbulent flow is subjected to a non-uniform body force, the turbulence maybe significantly suppressed when compared with that of the flow of the sameflow rate and hence the flow is said to be laminarised. This is the situationin buoyancy-aided mixed convection when severe heat transfer deteriorationmay occur. It is shown in this paper however that it causes little changesto the key characteristics of the turbulence when a buoyant force is addedto a turbulent flow while keeping the initial pressure force unchanged. Inparticular, the mixing characteristics of the turbulence represented by theturbulent viscosity, and the wall-normal and the spanwise turbulent stresses,remain largely unaffected. In terms of the near-wall turbulence structure, thenumbers of ejections and sweeps are little influenced by the imposition of thebody force, whereas the strength of each event may/may not be stronger de-pendent on the distribution of the body force. The former is true when thecoverage of the buoyant force extends significantly away from the wall, andunder such a condition, the body-force induced flow perturbation results ina greater turbulent shear stress. The streamwise turbulent stress may alsobe increased, which is associated with the observation of more and strongerelongated streaks. In light with these new insights, the so-called flow laminar-isation due to a buoyant force is in effect a reduction in the flow’s apparentReynolds number, based on an apparent friction velocity associated with onlythe pressure force of the flow (i.e., excluding the component due to the bodyforce). Within this new framework, the level of the flow ‘laminarisation’ andwhen the full laminarisation occurs are readily predictable.

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Session 7: CFD 2

Development of super-critical water-cooled reactorconcepts for local deployment

Laurence LeungCanadian Nuclear Laboratories, Chalk River, Ontario, Canada

A Super-Critical Water-cooled Reactor (SCWR) concept has been devel-oped in Canada for large base-load power generation. It is developed forgenerating 1200 MWe, which is suitable for large metropolitans and areasconnecting to the grid. The reactor core consists of 336 fuel channels, eachhousing a fuel assembly with 5-m-long active length. Each fuel assembly has64 fuel pins containing pellets with a mixture of thorium and plutonium.Batch refuelling is implemented in three cycles. Layouts of the safety system,start-up system and refuelling system have been configured for the reactorbuilding. Safety analyses demonstrated the maximum cladding temperaturesbelow the melting point of the Alloy 800H cladding material for a postulatedlarge-break loss-of-coolant accident with loss of emergency core cooling.

A small SCWR core concept generating 300 MWe power has also beenproposed for small communities. It is a scaled down version of the referenceSCWR core and consists of 120 fuel channels. Components, such as fuelchannel and fuel assembly, are the same as those in the reference SCWR core.

Both the reference and small SCWR concepts are excessive for small re-mote communities, mining operations and oil-sands production. A surveyof the Canadian northern communities illustrates the needs of 5 MW for asmall remote community, 25 MW for a small mining communities and about125 MW for oil-sand production. With its modular configuration, a furtherscaled down SCWR concept is possible to generate 25 MWe (or less) powerfor these applications. Components will be optimized for deployment within20 years.

In this presentation, the reference SCWR concept and the small SCWRcore concept will be described. The future development of a very small SCWRconcept will be introduced.

29


Investigation into the performance of near-walltreatment strategies in simulating transient flow and

mixed convectionGuojun Yan, Xinyi Miao and Shuisheng He

Department of Mechanical Engineering, University of Sheffield, U.K.

The performance of four typical near-wall treatments inbuilt in ANSYSFLUENT R© 16.0 in simulating transient flow and mixed flow is evaluatedagainst DNS or experimental data. Such near-wall treatments are claimedto capture turbulent characteristics in near-wall region, but when simulatingflows with non-equilibrium features, such as transient flow in a pipe or channel,or mixed convection, the performance of those near-wall treatments is stillinconclusive.

Near-wall treatment and low-Reynolds number turbulence model are thetwo primary schemes to simulate turbulence near the wall under the RANSframework. Earlier CFD studies have shown that some low-Reynolds num-ber turbulence models, like Lauder-Sharma k–ε (L-S) model, can predict thegeneral trend of the transient ramp flow and mixed convection at sub-criticalpressure conditions. However, supercritical pressure heat transfer in a ver-tical tube, especially in strong-buoyancy-influenced cases, is evidently morechallenging for any turbulence models to predict reliably.

The purpose of this paper is to investigate Standard Wall Functions (SWF),Non-equilibrium Wall Functions (NeF), Enhanced Wall Treatment (EWT)and Menter-Lechner Wall Treatment (M-L) systematically by simulating theflows mentioned above, and comparing the results with those of L-S modeland TSST model and also with DNS or experimental data. Considering allthe results of the simulations, the performance of these four near-wall treat-ments is worse than that of the L-S Model and TSST model. The differ-ence between the near-wall treatments and low-Reynolds turbulence modelsin mixed convection is smaller than in transient flow. Within these four near-wall treatments, the M-L model performed much better than the other threeones.

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Author Index

Ambrosini, Walter, 22Amjad, Muhammad, 19Anderson, Mark, 6

Bae, Yoon-Yeong, 15, 24Bo, Hanliang, 4Boersma, B.J., 25

Chu, Xu, 26

Dubey, S.K., 23

Ebraheam, Al Zaidi, 16

Fan, Xianfeng, 16Ferre-Serres, Simo, 9

Gaikwad, A.J., 23

He, Kui, 28He, Shuisheng, 13, 28, 30Hickey, Jean-Pierre, 27Hooman, Kamel, 8Huang, Yanping, 14, 21

Iyer, K.N., 23

Jackson, J.D., 12Jiang, Peixue, 1, 4, 17, 20

Kim, Eung-Seon, 15, 24Kim, Kukjin, 27Kim, Minhwan, 15, 24Kline, N., 3Kuhn, D., 7

Laurien, Eckart, 13, 26Leung, Laurence, 29Li, Xingxun, 16Li, Yongliang, 14Liu, Guangxu, 21Liu, Shenghui, 21Lyons, Kate, 6

Markides, Christos N., 9McEligot, Donald M., 13Miao, Xinyi, 30

Nourafkan, Ehsan, 19

Oyewunmi, Oyeniyi A., 9

Pandey, Sandeep, 26Pecnik, R., 25Peeters, J.W.R., 25Pervaiz, Shahid, 19Pucciarelli, Andrea, 22

Raza, Ghulam, 19Rohde, M., 25

Scalo, Carlo, 27Schulenberg, T., 7Seddighi, Mehdi, 28Sharabi, Medhat, 22

Tavoularis, S., 3

Vedula, R.P., 23

Wang, Junfeng, 21

31


Wang, Wei, 13Wen, Dongsheng, 19Wiemer, H.J., 7

Xu, Ruina, 17

Yan, Guojun, 30

Yan, Xiao, 14Yang, Xingtuan, 20

Zang, Jinguang, 14, 21Zeng, Xiaokang, 14Zhang, Zhen, 4, 20Zhao, Chenru, 4

32

Committees

Organising CommitteeShuisheng He (Chairman), University of Sheffield, U.K.Derek Jackson, University of Manchester, U.K.Walter Ambrosini, University of Pisa, ItalyPeixue Jiang, Tsinghua University, China

International Advisory CommitteeAustria: Katsumi YamadaAustralia: Kamel HoomanCanada: Laurence Leung (Chair), Stavros TavoularisChina: Baowen YangGermany: Thomas Schulenberg, Joerg Starflinger,

Eckart LaurienIndia: P.K. VijayanKorea: Yoon Y. BaeThe Netherlands: Martin Rohde, Rene PecnikPoland: Dariusz MikielewiczRussia: Aleksei SedovSweden: Henryk AnglartSwitzerland: Medhat SharabiU.K.: Christos Markides, Dongsheng Wen, Juan UribeU.S.A: Donald M. McEligot, Michael Podowski

Local Organisation and Support TeamShuisheng He, Muhsin Mohd Amin, Xinyi Miao, Cosimo Trinca,Xiao Zhang

Websitehttp://hfscp2016.group.shef.ac.uk

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http://hfscp2016.group.shef.ac.uk/

Participants List

Anderson, Mark: [email protected] of Wisconsin - Madison

Bae, Yoon-Yeong: [email protected] Atomic Energy Research Institute (KAERI)

Chu, Xu: [email protected], University of Stuttgart

Duan, Yu: [email protected] University of Manchester

Dubey, Santosh Kumar: [email protected] Energy Regulatory Board

Fan, Xianfeng: [email protected] University of Edinburgh

Hare, Vincent: [email protected] of Oxford

He, Shuisheng: [email protected] of Mechanical Engineering, The University of Sheffield

Hickey, Jean-Pierre: [email protected] of Waterloo

Hooman, Kamel: [email protected] University of Queensland

Huang, Yanping: [email protected] Power Institute of China

Jackson, J.D.: [email protected] University of Manchester

Jiang, Peixue: [email protected] University

34


Keshmiri, Amir: [email protected] University of Manchester

Kline, Nathan: [email protected] of Ottawa

Leung, Laurence: [email protected] Nuclear Laboratories

Liu, Xiaojing: [email protected] Jiaotong University

Lyons, Kathleen: [email protected] of Wisconsin - Madison

Markides, Christos: [email protected] College London

McEligot, Donald M.: [email protected]/Center for Advanced Energy Studies

Miao, Xinyi: [email protected] of Mechanical Engineering, The University of Sheffield

Mohd Amin, Muhsin: [email protected] of Mechanical Engineering, The University of Sheffield

Oluwadare, Benjamin Segun: [email protected] of Mechanical Engineering, The University of Sheffield

Peeters, Jurriaan W. R.: [email protected], University of Technology

Pucciarelli, Andrea: [email protected] of Civil and Industrial Engineering, University of Pisa

Raza, Ghulam: [email protected] of Leeds

Schulenberg, Thomas: [email protected] Institute of Technology (KIT)

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Seddighi, Mehdi: [email protected] John Moores University

Trinca, Cosimo: [email protected] of Mechanical Engineering, The University of Sheffield

Wang, Wei: [email protected] Daresbury Laboratory

Xu, Ruina: [email protected] University

Yan, Guojun: [email protected] of Mechanical Engineering, The University of Sheffield

Zang, Jinguang: [email protected] Power Institute of China

Zhang, Xiao: [email protected] of Mechanical Engineering, The University of Sheffield

Zhang, Zhen: [email protected] of Nuclear and New Energy Technology, Tsinghua University

Zhao, Chenru: [email protected] of Nuclear and New Energy Technology, Tsinghua University

Zhu, Jie: [email protected] of Nottingham

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heat transfer and fluid dynamics at supercritical pressure...

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