PEM electrolyzer model for Apros

Jari Pennanen / VTTLotta Kannari / VTT

Contents

• PEM electrolysis– Alkaline electrolyzer PEM electrolyzer

• Case study: Siemens SILYZER 200– Reverse engineering study by Jari Pennanen

• Apros model for SILYZER 200– Model and results by Lotta Kannari

Polymer electrolyte membrane (PEM) electrolysis

• Liquid water only at anode side

• Only H2 at cathode side• Temperature 50-80°C

Input parameters for PEM modelling• The Apros model is based on the SILYZER 200

• Reverse engineering required for all parameters– IV-curve ? from lab. size cell (300 cm2) valid for large cell ?– Number of cells ? estimate from figures = 250– Cell area ? guess + reverse engineering = 35 cm x 35 cm– Dimensions of the stack ? guess + estimate 40 x 50 x 65 cm– Thermal mass ? guess + estimate = 2600 kg steel , 50 l H2O– Operational window ? Web search: 0 2.1 MW– Cooling ? Water circulation assumed, will be removed ? – Flow rates ? fixed temperature assumed flow rate– Temperature related data ? fixed temperature assumed

Input parameters for PEM modelling• We don’t have IV-

curve for SILYZER 200

• This figure from SILYZER 100 presentation.

• But the IV-curve is from laboratory size device where the cell area was 300 cm2

The key assumptions for reverse engineering

• The IV curve is valid also for SILYZER 200• Iave,max 3/cm2 is valid also for large cells• Max Stack Power = 2.1 MW (confirmed)• The total number of cells is 250

SILYZER 200

Max. Stack Power = 2.1 MW

50 cells / stack

Assumption based on figures and data sheet Max 5 m

3.6 m

0.6 m

Reverse engineering results

Reverse engineering results

Reverse engineering results

Reverse engineering results

Operational window

For large cells (Heat production in cell/ the width of the cell) ratio is bigger: cooling is not so effective Pmax / Pnominal is smaller for large cells (?).

For SILYZER Pmax / Pnominal = 2.1/1.25 = 1.68 operational window is smallerCycles 0 % .. 160 % without relevant aging (information from Siemens)

Cell area 300 cm2 ?

The Apros model

Lotta Kannari

Input parameters for Apros model

The following figures are calculated using older reverse engineer-ing results. But that isnot important since we can always change the input parameters.

The results of the Apros model are verified by independent MATLAB based model.For 2.1 MW

Iave=1.89 A/cm2For 1.25 MWIave=1.22 A/cm2

Reverse engineering for SILIZER 200Assuming 500 cells. Cell size 33 cm x 33 cm

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APROS PEM-MODEL

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Apros Model

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Thermal mass

Apros Model

Heat losses to the ambient

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Input water and water+O2 circulation

Apros Model

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H2 and O2 output

Apros Model

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Current

0

500

1000

1500

2000

2500

0 100 200 300 400 500

[A]

I[A]

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 200 400 600

[A/c

m2]

I_ave [A/cm2]

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Power and cell voltage

0

0.5

1

1.5

2

2.5

0 100 200 300 400 500

[MW

]

P [MW]

1.4

1.5

1.6

1.7

1.8

1.9

2

2.1

0 100 200 300 400 500

[V]

U_cell[V]

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H2 and O2 produktion

0

1

2

3

4

5

6

0 50 100 150 200 250 300 350 400 450

[mol

/s]

O2_simulated_[mol/s]

H2_simulated_[mol/s]

Conclusions• Siemens SILYZER 200

– We don’t know a lot. The reverse engineering step is based assumptions which may not be valid for large cells.

– Assume at least 15% margin of error in the production of H2

• Apros model for SILYZER 200– Based on previous alkaline electrolyzer model. Remove one

electrolyte + change IV curve + change cooling system + … – Model works OK, but the final fine tuning round using the

latest reverse engineering results is still needed