vk.com/club152685050Simulating a Single Battery| vkCell.com/id446425943Using the MSMD Battery Model

Click No in the Question dialog box when asked if you would like to append the new data to the existing file, and then click Yes in the Warning dialog box to overwrite the existing file.

4. Once the calculation is complete, enable the ROM.

Setup → Models → MSMD Battery Model Edit...

a.In the MSMD Battery Model dialog box, select Reduced Order Method.

b.Set Number of Sub-Steps/Time Step to 10.

5.Continue running your simulation from the direct method solution.

The solution of the simulation using the ROM is significantly faster than when using the direct method without any changes in results.

25.4.8. External and Internal Short-Circuit Treatment

You will again use the ntgk.cas.gz case file that you saved earlier to illustrate how to treat external and internal short-circuits in a battery simulation. It is assumed that the battery is experiencing external and internal short-circuit simultaneously. This extreme case will be used to demonstrate the problem setup and postprocessing in a short simulation. This section assumes that you are already familiar with the ANSYS Fluent battery model, only the steps related to short simulation are emphasized here.

25.4.8.1. Setting up and Solving a Short-Circuit Problem

1.Read the NTGK model case file ntgk.cas.gz.

2.Set up the external electric short-circuit.

a.In the MSMD Battery Model dialog box, under the Model Options tab, in the Solution Options group box, enable Specified Resistance.

b.For External Resistance, enter 0.5 Ohm and click OK.

3.Set up the internal electric short-circuit in the center of the battery cell.

a.Mark the short-circuit zone shown in Figure 25.15: Internal Short Circuit Region Marked for Patching (p. 853) using the region adaption feature.

Solution → Cell Registers New → Region...

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Setup and Solution

Figure 25.15: Internal Short Circuit Region Marked for Patching

i.In the Region Register dialog box, enter the following values for Input Coordinates.

X Min	X Max	Y Min	Y Max	Z Min	Z Max
-0.01	0.01	-0.01	0.02	-1	1

ii.Click Save.

Fluent reports in the console that 12 cells were marked for refinement.

4.Initialize the field variables using the standard initialization method.

5.Patch the internal short circuit zone with the short resistance value.

Solution → Initialization → Patch...

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a.In the Solution Initialization task page, click Patch.

b.In the Patch dialog box, select Short Circuit Resistance under Variable.

c.Select region_0 under Registers to Patch.

d.For Value, enter 5.0e-7.

e.Click Patch and close the Patch dialog box.

6.Save the case file as ntgk_short_circuit.cas.gz.

7.Run the simulation for 5 seconds.

Solution → Run Calculation

a.Set Time Step Size to 1 second and No. of Time Steps to 5.

b.Click Calculate.

8.Save the case and data files (ntgk_short_circuit.cas.gz and ntgk_short_circuit.dat.gz).

25.4.8.2. Postprocessing

1.Compute the battery tab voltage .

Results → Reports → Surface Integrals...

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Setup and Solution

a.In the Surface Integrals dialog box, from the Report Type drop-down list, select Area-Weighted Average.

b.From the Field Variable drop-down lists, select User Defined Scalar... and Potential Phi+.

c.In the Surfaces filter, type t to display surface names that begin with "t" and select tab_p from the selection list.

d.Click Compute.

The battery tab voltage of approximately 4.077 V is printed in the Area-Weighted Average field and in the Fluent console.

2.Compute the battery tab current .

Results → Reports → Volume Integrals...

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a.In the Report Type group box, select Volume Integrals.

b.From the Field Variable drop-down lists, select User Defined Memory... and Volumetric Current Source.

c.From the Cell Zones selection list, select e_zone.

d.Click Compute.

Fluent reports in the Total Volume Integral field and in the console that the total volume integral for the volumetric current source is approximately 8.155 A.

The computed values of the battery tab current and voltage satisfy the tab boundary condition .

3.Display the vector plot of current at the positive and negative current collectors.

Results → Graphics → Vectors → Edit...

a.In the Vectors dialog box, select current-density-jp from the Vectors of drop-down list.

b.Select User Defined Memory... and Magnitude of Current Density from the Color by drop-down lists.

c.From the Surfaces selection list, select Wall.

The surfaces of the "wall" type are automatically selected in the Surfaces list.

d.Click Display.

e.The plot shows the vector plot of electric current flow in the positive current collector of the battery cell.

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vk.com/club152685050 | vk.com/id446425943	Setup and Solution
Figure 25.16: The Vector Plots of Current at the Positive Current Collectors

f.In a similar manner, display the current for the negative current collector by selecting current-density- jn from the Vectors of drop-down list.

The plot shows the vector plots of electric current flow in the negative current collector of the battery cell. These plots clearly show that besides providing tab current, short current flows from positive electrode to the negative electrode through the short area.

Figure 25.17: The Vector Plots of Current at the Negative Current Collectors

g.Close the Vectors dialog box.

4.Display the contour plot of the temperature as you did previously.

Results → Graphics → Contours → Edit...

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a.In the Contours dialog box, under Options, enable Filled.

b.From the Contours of drop-down list, select Temperature... and Static Temperature.

c.From the Surface Types selection list, select wall.

d.Click Display and close the Contours dialog box.

Figure 25.18: Contour Plot of Temperature

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