Transient Thermal Analysis Winter Semester

2 Goals  In this workshop, we will analyze the electrically heated base typical of consumer steam irons like the one shown below.

3 Assumptions Assumptions:  The heating element contacts and transfers heat to the base using the pattern shown here  Upon initial startup a heat flow of 1000 W is applied until a steady state is reached  Heating follows a 30 second step cycle of 0 to 1000 W after steady state is reached  The analysis will begin with the steady state solution and proceed through the cyclic loading described above

4 Start Page  From the launcher start Simulation.  Choose “Geometry > From File... “ and browse to the file “Iron.x_t”.

5 Preprocessing  Change the part material to “ Stainless Steel ”: –Highlight “Part1” –In the Detail window “Material” field “Import...” –Choose the “Stainless Steel” material Set the working units to (mm, kg, N, C, s, mV, mA)

6 Preprocessing  Start new thermal analysis by selecting “Transient Thermal” under the “New Analysis” menu.  The initial conditions include thermal load, which is constant temp, will be applied for 1sec. –Highlight the initial condition branch. –Set the ‘Initial temp’, in the ‘Details window’, to ‘Uniform Temperature’. –Highlight the ‘Analysis settings’ branch and make sure that the ‘Step end time’ is 1 sec.

7 Transient Thermal Select surface representing the heating element on the face of the iron “RMB > Insert > Heat Flow”. Set “Magnitude” field to 1000 W.

8 Environment Select the bottom surface (opposite the heat flux side) and 6 side surfaces of the iron (7 faces) “RMB > Insert > Convection” Change to “Temperature Dependent” by choosing “Tabular (temperature)” in the details window.

9 Environment Choose “Import” in the correlation field Select “Stagnant Air – Vertical Planes1” Set ambient temperature to 20 deg. C

10 Environment Select the 2 surfaces surrounding the heated surface. “RMB > Insert > Convection” Change to “Temperature Dependent” Choose “Import” in the correlation field Select “Stagnant Air – Vertical Planes” Set ambient temperature to 40 deg. C Please see previews slides for the stages above

11 Solution  Add temperature and total heat flux results. Highlight the Solution branch. “RMB > Insert > Thermal > Temperature”, repeat for total heat flux Solve

12 Results  A review of the results shows that after 1 sec of heating, the maximum temperature is approximately 36.8° C

13 Transient Solution We will apply a periodic load during 180 sec. Highlight the “Analysis setting” branch, begin the transient setup by specifying an end time of 180 seconds

14 Transient Setup Highlight “Heat Flow” in the Thermal Transient branch In the heat flow details windows, select the Magnitude and choose “Add to Engineering Data”

15 Transient Setup  Change to Engineering Data tab  The Engineering Data application will open and a new “Heat Flux vs. Time” chart/graph will be created  Enter the time and load data as shown on the next page

16 Transient Setup Enter time and load information as described in the problem statement: 30 second increments W Heat Flow

17 Transient Setup Highlight the “Analysis Settings” branch In the Details window omit all parameters except the Heat Flow and temperature. Toggling off all but the heat flow allows easier inspection of the timeline chart in this case

18 Transient Results Solve  When the solution is complete, results can be reviewed just as with steady state solutions Note: due to the long exposure time to heat flow, the max temp achieved was °C (comparing to 36.8°C during 1 sec)

19 Transient Results – Postprocessing 34.To review results from specific time points, LMB in the timeline chart to locate the time of interest 35.RMB > Retrieve This Results

20 Transient Results  Notice: when a new time point is selected in the time line, the result details window is displayed in red until the results matching the time selection are retrieved  Plotting the “Global Maximum” temperature from the ‘Solution Information’ branch shows the model has not reached a cyclic equilibrium

21 Transient Results  Using the Probe Tool allows individual parts of the model to be evaluated over time  Add probe tool for heat flow the center area: Highlight the Solution branch: RMB  Insert  Probe  Heat flux  Add probe tool for temperature for the same area

22 Transient Results  In the details window, select the results to display the total result  RMB on the solution branch  Evaluate all results

23 Results for the heat flux probe Results for the Temperature probe