Numerical study of the thermohydraulic performance of printed - - PowerPoint PPT Presentation

2nd International Conference on Sustainable Energy and Resource Use in Food Chains

RCUK Centre for Sustainable Energy Use in Food Chains

Numerical study of the thermohydraulic performance of printed circuit heat exchangers for supercritical CO2 Brayton cycle applications

Lei Chai*, Savvas A Tassou

Institute of Energy Futures, Brunel University London

Paphos, Cyprus 17-19 October 2018

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Lei Chai

Outline

• Introduction

– Why sCO2? Why printed circuit heat exchanger?

• Computational method

– Element, model, boundary condition.

• Data acquisition

– Local, average and overall parameters.

• Results and discussion

– Thermohydraulic performance, comparison with correlations.

• Future work

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Why sCO2?

• working fluid with a

high power density

• smaller equipment sizes
• smaller plant footprint
• lower capital cost
• use of standard materials
• improved electrical-power-

conversion efficiency

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2nd International Conference on Sustainable Energy and Resource Use in Food Chains

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Why printed circuit heat exchanger?

Recuperator

• increase the average

temperature of the heat source

• results in higher efficiencies

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2nd International Conference on Sustainable Energy and Resource Use in Food Chains

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Why printed circuit heat exchanger?

• highly compact construction
• high heat transfer coefficient
• high pressure capability
• wide range of operating

temperatures

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Computational element and model

• standard k-ε model
• NIST real gas

thermophysical properties

• buoyant effect

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2nd International Conference on Sustainable Energy and Resource Use in Food Chains

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Boundary and operating conditions

• Periodic for upper and lower surfaces
• Symmetry for left and right surfaces
• Mass-flow-rate for two inlet
• Pressure-outlet for two outlet
• Mass flux balances: 254.6 to 1273.2 kg/(m2·s)
• Cold side :100 °C of inlet temperature and 150 bar of outlet pressure
• Hot side: 400 °C of inlet temperature and 75 bar of outlet pressure

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2nd International Conference on Sustainable Energy and Resource Use in Food Chains

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Data acquisition

Local thermohydraulic parameters Average thermohydraulic parameters Overall thermohydraulic parameters

z z

GD Re  

z z w,z f,z

q h T T  

z z f,z

h D Nu  

2 z z f

2 D dp G f dz  

z L Re dz

Re L  

z L h dz

h L  

z L Nu dz

Nu L  

z L f dz

f L  

m

U Q A T  

hi co ho ci m hi co ho ci

( ) ( ) ln( ) T T T T T T T T T       

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2nd International Conference on Sustainable Energy and Resource Use in Food Chains

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Validation of CFD model

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Local heat transfer coefficient

G = 763.9 kg/(m2·s) z = 136 mm

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2nd International Conference on Sustainable Energy and Resource Use in Food Chains

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Local pressure drop

G = 763.9 kg/(m2·s) z = 136 mm

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Average thermohydraulic performance

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Overall thermohydraulic performance

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Lei Chai Comparison with prediction from empirical correlation

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Lei Chai Comparison with prediction from empirical correlation

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Lei Chai Future work – modeling for heater, recuperator, cooler

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Lei Chai Future work - numerical study for different flow passages

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Lei Chai Future work – sCO2 heat exchanger test facility

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Acknowledgements

• Engineering and Physical Sciences Research Council (EPSRC) of the UK

under research grants EP/P004636/1 and EP/K011820/1

• European Union’s Horizon 2020 research and innovation programme

under grant agreement No. 680599.

• The authors would like to acknowledge the financial support received by

the project funders and the industry partners.

RCUK Centre for Sustainable Energy Use in Food Chains

2nd International Conference on Sustainable Energy and Resource Use in Food Chains

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Thank you !

Lei Chai Savvas A Tassou lei.chai@brunel.ac.uk savvas.tassou@brunel.ac.uk