DESIGN, CONTROL PROCEDURE AND START -UP OF THE SCO2 …

W. Flaig, R. Mertz, J. Starflinger

,

Institute of Nuclear Technologyand Energy Systems

DESIGN, CONTROL PROCEDURE AND START-UP OF THE SCO2 TEST FACILITY SCARLETT

2nd European supercritical CO2 Conference, August 30-31, 2018, Essen, Germany

• Motivation

• Objectives

• Test Facility

• Start-up and control strategy

• Calculation model

• Results

• Summary

03.09.2018The 2nd European Supercritical CO2 Conference, August 30-31, 2018, Essen, Germany 2

Outline


Motivation

• High achievable heat transfer coefficients due to variable thermodynamic properties near the (pseudo-)critical point

• Heat transfer applications for conventional and nuclear power plants

• High cycle efficiency envisaged for high temperature applications

m = 0.07 kg/sdi = 10.1 mm

𝑵𝑵𝑵𝑵 =𝜶𝜶 ⋅ 𝒅𝒅𝒉𝒉𝒌𝒌𝒍𝒍𝒍𝒍𝒍𝒍𝒍𝒍𝒍𝒍

= 𝟎𝟎.𝟎𝟎𝟎𝟎𝟎𝟎 ⋅ 𝑹𝑹𝒍𝒍𝟎𝟎.𝟖𝟖 ⋅ 𝑷𝑷𝒍𝒍𝟎𝟎.𝟒𝟒

• Basic investigations and fundamental research on sCO2 as working fluid, e.g.• Heat transfer using supercritical CO2 as working fluid.• Passive safety system for nuclear power plants.• Validation of DNS and Large-Eddy-Simulations.

• Design and construction of a test facility for experiments with supercritical CO2 for variable test sections.

• CO2 technology development and testing.

• Data measurement and analysis regarding heat transfer and pressure drop in compact heat exchanger.

Optimization of suitable compact heat exchanger.


Objectives


Operating Range of the Test Facility

1

8 2 3

46

7

5

1

8 2

3

4

6

7


Piping and Instrumentation Diagram

03/09/2018The 2nd European Supercritical CO2 Conference, August 30-31, 2018, Essen, Germany 7

CAD-Sketch of the Test Facility

Conditioning

EvaporatorSuperheater

Condenser

Conditioning for Cryostats

Storage Vessel

Storage Vessel

Compressor

Cryostat

Oil Separator

Pump


Recent Pictures

• Construction, insulation and first improvements finished.

• Start-Up successful.

• Digital controlling implemented.

• Measurement campaigns are running.


Operating Range

Parameter Symbol Value Unit

Mass flow m 0.013 – 0.111 kg/sTemperature T 5.0 – 150.0 °C

Pressure p 7.5 – 12.0 MPaInner Pipe Diameter di 10.1 mm

Cooling Power Pcool 20 - 50 kWElectrical Power Pel 130 kW

Volume Pressure Vessel VPV 0.072 m³


Measurement Equipment

Parameter Device Range Accuracy

Mass flow Coriolis flow meter 0.013 – 0.130 kg/s 0.5 %

Temperature Pt-100 resistance thermometer -20 – 200 °C 0.15 K + 0.002 • [T/°C]

Pressure Piezoresistive pressure transmitter

0 – 30 MPa 0.15 %

Liquid level Differential pressure transmitter 200 – 1000 mm 0.075 %


Characteristic line of compressor „Bitzer 4PTC-7K“

��𝐦 = ��𝐕𝐃𝐃𝐃𝐃𝐃𝐃𝐃𝐃𝐃𝐃𝐃𝐃𝐃𝐃𝐃𝐃𝐦𝐦𝐃𝐃𝐃𝐃𝐃𝐃 ⋅ 𝛌𝛌(𝐃𝐃𝐃𝐃,𝐃𝐃𝟎𝟎, 𝐓𝐓𝟎𝟎) ⋅ 𝛒𝛒𝟎𝟎(𝐓𝐓𝟎𝟎,𝐃𝐃𝟎𝟎)

𝜆𝜆𝑅𝑅 = 1 − 𝑐𝑐 ⋅𝑝𝑝𝐻𝐻𝐻𝐻𝑝𝑝0

1𝑛𝑛− 1 𝜆𝜆𝐻𝐻 = 1 −

1 + 𝑐𝑐 ⋅ Δ𝑝𝑝0𝜆𝜆0 ⋅ 𝑝𝑝0

𝜆𝜆𝑇𝑇 =𝑇𝑇0𝑇𝑇𝑐𝑐

𝜆𝜆𝐷𝐷 = 0,95 … 1,00

• Mass flow depends on

condition at compressor inlet

and the pressure ratio pHP/p0.

• Small changes in load lead to

shift of the point of operation.


Test-facility in non-controlled operation

• Factors influencing high pressure and mass flow: Expansion valve, frequency

converter (FC) of compressor, superheating of suction gas, gas cooler power,

conditioning, heating power of test section...


Transient behaviour of the SCARLETT facility

• Heat transfer from or

into the test facility

leads to a transient in

pressure.

• Change of mass flow,

due to compressor

characteristic

New stationary

operation point.

• Governing equations:


Calculation of stationary operation points

��𝑄𝐻𝐻𝑇𝑇 = 𝛼𝛼 ⋅ 𝐴𝐴 ⋅ 𝜃𝜃𝑙𝑙𝑙𝑙𝑙𝑙

��𝑚𝑠𝑠𝑠𝑠𝑠𝑠2 = 𝑛𝑛 ⋅ 𝑉𝑉𝑝𝑝𝑝𝑝 ⋅ 𝜌𝜌0 𝑇𝑇𝑠𝑠, 𝑝𝑝0 ⋅ 𝜆𝜆(Π) 𝑛𝑛 =𝑓𝑓𝑐𝑐𝑚𝑚

Δ𝑝𝑝𝐸𝐸𝐸𝐸 = 𝑝𝑝1 − 𝑝𝑝0 =1𝜌𝜌𝑚𝑚

⋅��𝑚𝑠𝑠𝑠𝑠𝑠𝑠2𝐾𝐾𝐸𝐸

2

𝑑𝑑𝑚𝑚𝐻𝐻𝐻𝐻𝑑𝑑𝑑𝑑 = −

𝑑𝑑𝑚𝑚𝐿𝐿𝐻𝐻𝑑𝑑𝑑𝑑 ⇒

𝑑𝑑𝜌𝜌𝐻𝐻𝐻𝐻 𝑇𝑇, 𝑝𝑝 ⋅ 𝑉𝑉𝐻𝐻𝐻𝐻𝑑𝑑𝑑𝑑 = −

𝑑𝑑𝜌𝜌𝐿𝐿𝐻𝐻 𝑇𝑇, 𝑝𝑝 ⋅ 𝑉𝑉𝐿𝐿𝐻𝐻𝑑𝑑𝑑𝑑

Δ𝑝𝑝𝐻𝐻𝑃𝑃𝑝𝑝𝑃𝑃 =12⋅ ��𝑚𝑠𝑠𝑠𝑠𝑠𝑠2

2 ⋅ 𝑓𝑓 ⋅𝐿𝐿

𝐴𝐴𝐻𝐻𝑃𝑃𝑝𝑝𝑃𝑃2 ⋅ 𝑑𝑑𝑃𝑃 ⋅ 𝜌𝜌

• 0-D-Model implemented in Matlab

• Prediction of stationary operation points in dependence of influence factors:

• compressor-frequency, degree of opening of expansion valve and condenser

temperature.

Implementing of a PID multi-input-multi-output (MIMO) controlling.


Test-facility in controlled operation

Separate controllers for high pressure, mass-flow (digital), temperature and superheating of suction gas (analogue).

• Setting by expansion-valve, compressor FC, cryostats and evaporator-thyristor.

• Stable measurement operation possible. Disturbances supressed. Minor oscillations.


Test-facility in controlled operation


Simulation Results

• Sufficient congruence between

calculation and the experimental data.

• Quantitative accordance is given in

general.

• Discrepancy less than 10 g/s

• sCO2-test facility is designed as closed loop.

• sCO2-test facility has been built and is in operation.

• Transient behavior in non-controlled mode.

• Decentral PID controlling is implemented to enable stable values of test temperature, pressure and mass flow.

• A zero dimensional model of the test facility was used to design the facility and the targeted stationary operating points.

• The data calculated with the help of this model show sufficient congruence with experimental ones.


Summary

• This work was supported by a grant from the Ministry of Science, Research and the Arts of Baden-Württemberg (Az: 32-7533.-8-112/81) to Wolfgang Flaig.


Acknowledgment

The project leading to this application has received funding from the Euratom research and training programme 2014-2018 under grant agreement No 662116.

Thank you!

e-mailphone +49 (0) 711 685-fax +49 (0) 711 685-

University of Stuttgart

Pfaffenwaldring 3170569 Stuttgart

Wolfgang Flaig

6245462010

Institute of Nuclear Technology and Energy Systems

[email protected]

Institute of Nuclear Technology and Energy Systems

202nd European supercritical CO2 Conference, August 30-31, 2018, Essen, Germany

21

Literature OverviewCO2 in power plants:V. Dostal, M.J. Driscoll, P. Heijzlar: A supercritical Carbon Dioxide Cycle for Next generation

Nuclear Reactors, MIT-ANP-TR-100 (2004).S.A. Wright, P. S. Pickard, Bob Fuller.:”S-CO2 Heated Un-Recuperated Brayton Cycle

Development and Test Results” Sandia National Laboratories and Barber Nichols April 29,30 2009, RPI, New York

Heat Transfer with CO2 as working fluid:M. D. Carlson, A., Kruizenga, M. Anderson, M. Corradini.: Measurements of Heat Transfer and

Pressure Drop Characteristics of Supercritical Carbon Dioxide Flowing in Zig-Zag Diffusion-Welded Heat Exchanger Channels, Supercritical CO2 Power Cycle Symposium, Boulder, Colorado, 24.-25. May 2011.

P. C. Simões, J. Fernandes, J.P. Mota.: Dynamic model of a supercritical carbon dioxide heat exchanger, J. of Supercritical Fluids 35, S.167-173 (2005).

J.H. Song, H.Y. Kim, H. Kim, Y.Y. Bae.: Heat transfer characteristics of a supercritical fluid flow in a vertical pipe, J. of Supercritical Fluids 44, S.164–171 (2008).

Heat removal system:J. Venker, D. von Lavante, M. Buck, D. Gitzel, J. Starflinger: Concept of a Passive Cooling

System to Retrofit Existing Boiling Water Reactors, Proceedings of the 2013 International Congress on Advances in Nuclear Power Plants, ICAPP 2013, Jeju Island, Korea (2013).

03.09.2018The 2nd European Supercritical CO2 Conference, August 30-31, 2018, Essen, Germany

22

Motivation: Heat Removal at BWR

• System shall be retrofitted in current nuclear reactors, example shows BWR application. sCO2 as working fluid.

• Compact heat exchanger necessary due to restriction of space inside containment.

TPrimary Loop ~ 286 °C

TAmbient ~ 35 °C

11.7 MPa

7.8

MPa

46 °C

280 °C

DWHE

Compressor

Turbine

Pressure-vessel

Gas cooler


23

Diffusion-Welded Heat Exchanger (DWHE)

„cold“ flow-channel „hot“

flow-channel b = 2 mm

h =

2 m

m

• Relation: Surface to volume ratio β =AHEVHE

is very high. Compact heat

exchanger are necessary due to restriction of space inside containment.

• Low weight, low space requirements and less mass of structure material. Applicable for temperatures from -200 to 900 °C and pressure up to 60 MPa. Suitable for gas, liquids and 2-phase-mixtures.

• Higher heat transfer coefficients obtainable.

tf = 2 mm


24

Diffusion-Welded Heat Exchanger

Diffusion bonding area, IKE

Milling/etching of channels

(Diffusion-)bonding

of single plates

Combining to plate-packages

Welding of flanges

In house welding sample of a diffusion-bonded micro heat exchanger


25

Test-section: DWHE

Flow-channel

DWHEPt-100

Thermography camera

Insulation

Heating Cartridge

Copper-Plate

• Simulation of flow and heat transfer.

e.g. Comsol (FEM), Matlab

• Experiments on behaviour of sCO2 in a Diffusion Welded Heat Exchanger (DWHE).

Heat transfer power, heat transfer coefficients and pressure loss.

Advantageous and disadvantageous range of operation.

��𝐪 =𝛌𝛌𝐃𝐃 𝚫𝚫𝐓𝐓

Thin-layer-Pt-100

��𝐐

Pt-100


26

Test-Section

Integrated Test-Section Test-Section-DWHE before welding

Flow-Channels:

Number: 50

width = 2 mm

height = 2 mm

length = 198 mm

Distributor:

width = 10 mm

length = 184 mm

Material:

Alloy800

G = 200...600 kg/m²s

q = 0...100 kW/m²

Heating plate:

height = 40 mm

diameter heating cartridge = 10 mm


27

First experimental results - pressure drop

pin = 8.5 MPa

pin = 9.5 MPa

pin = 7.5 MPa

pin = 7.0 MPa

Tin = 30 °C


28

First experimental results – surface temperature

Q = 1,3 kW

pin = 80 bar

Tin = 30 °C

m = 40 g/s

ΔQQ ≈ 5 %

x

y

CO2

• Thermography shows maldistribution of surface temperature.

• 3D effects in heat transfer detected.


29

Application: Heat Removal at BWR

Parameter Value Unit

Predicted Heat Flux 60 MW

Heat flux density 100 kW/m²

Mass flow 165 kg/s

Mass flow density 515 kg/m²s

Hydraulic diameter 1.1 mm

Channels per plate 200 -

Basic area 650 x 650 mm

Surface area 600 m²

Volume 1.2 m³

Surface Density 500 m²/m³

Inlet temperature 67 °C

Inlet pressure 17.5 MPa


30

First Test-Section: DWHE

CAD-sketch of the first Test-Section: DWHE

Test section before welding

200 mm

Welding sample


31

Welding of the Heat Exchanger

1.4301

V2A-Stainless-Steel

• High quality weldseams achievable.

• Small deformation of channels.

Welding sample


32

Cover Plate

Heating Plate (Copper)

Flow channels

Plenum

Fluid Inlets


33

Flow-channel

DWHEPt-100

Thermography camera

Insulation

Heating Cartridge

Copper-Plate

Pt-100


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