SinapsPlus® Fin Prebuilt Model
Contents
1. Model Description 3 0 Fin Model Description 3 1 User Defined Registers Although other inputs may be changed throughout the model like most prebuilts the fin model is designed to use Registers as a control panel for making global changes to key model parameters Registers are accessed from the left menu of the model control tab in the model control window These registers are used through out the model in network definitions logic blocks and in the calculation of other registers The values can eas ily be modified by the user to tailor the analysis to a specific design or application The registers also provide a convenient mechanism to perform parametric analyses without excessive need for user logic The register val ues can be modified within the program and then update the parameters which used the registers in their defi nition Table 1 summarizes the registers along with their default values A more complete discussion of these vari ables can be found in Appendix A on page 10 Table 1 Register Summary Fin Model Register Initial Name Value Units Description Change Notes LENGTH 0 1m m or ft Fin length from base to tip must be positive WIDTH 0 1m m or ft Width of the fin Used in the calculation of the cross sectional area Set to 0 for circular fins THICK 0 00im mor ft Thickness of the fin Used in the calculation of the cross sectional2. Stepping Through a Save File Once one or more groups of objects have been colored the user may step through the save file This is accom plished with the next time current time previous time and animate options under the Color Thickness Control menu If multiple groups of objects have been colored e g nodes and conductors stepping through the save file will update all of them This option also updates any thicken by value operations that have been requested as will be described below in Section 9 3 There are two options for updating the display that are controlled by editing the color bars If autoscaling is on then stepping through a save file will update the scaling numbers of the color bar If autoscaling is turned off the colors will change on the nodes lump and conductors paths etc As guidance note that the color bar default of autoscaling is usually undesirable when stepping through or animating results Otherwise the scale changes while the color of the selected icons remains roughly invariant On the other hand when using fixed scaling the user must apply foresight in selecting the scale limits to avoid ranges that are too limited The animate option will bring up a data form that allows the user to specify how many steps to take through the save file and whether SinapsPlus should wait for a mouse click between steps or step continuously The user also has control over whether the steps are forward or backward through the file a
3. area DIAMETER 0 0m m or ft Diameter of a circular fin For non circular fins set to 0 CONDUCT 10 W m K Thermal conductivity of the fin Avoid choosing extremely large val W m K Btu hr material ues gt 500 or extremely low values ft R lt 0 01 SPHEAT 1 0 J kg K Specific heat of the fin material Not used in this release of the pre J kg K Btu built fin For transient simulations Ibm F DENSITY 1 0 kg m Density of the fin material Not used in this release of the pre kg m lb ft built fin For transient simulations EMISS 0 25 Emissivity of the fin surface Must be between 0 0 and 1 0 To turn off radiation set to near zero TBASE 300 K KorR Base temperature of the fin Must be positive TAMB 270K KorR Convection temperature sink Must be positive TRAD 200 K KorR Radiation temperature sink Must be positive HCOEFF 1 0 Wim K Convective heat transfer Must be positive Set to zero to turn W m2 K Btu hr coefficient of convective heat transfer ft R SB sbconsi W m K Stefan Boltzmann constant Set to either sbconsi SI or sbcon Btu hr English These are built in ft R SinapsPlus register values ITERATE 10000 Maximum number of iterations Avoid values too small SinapsPlus Fin Prebuilt Model User Documentation September 22 2003 Rev 4 6 Page 4 Fin Model Description Table 1 Register Summary Fin Model Register Initial Nam
4. at run time are not affected by this operation Initialize Submodel should not be used by unlicensed users SinapsPlus Fin Prebuilt Model Page 21 User Documentation September 22 2003 Rev 4 6
5. few differences is that bar plots have a slightly different axis limits form since there is only one axis the y or independent variable axis that may be scaled Bar plots also provide a unique and very useful node lump balance option that is similar to the SINDA FLU INT NODMAP and LMPMAP routines This type of plot may only be performed on a single node or lump A bar plot can be produced that shows the energy into and out of the node on a per conductor path basis For lumps the user has a choice of mass flowrate energy flowrate tie conductance or tie heat rate as the plotting criteria The legend in such plots contains further details about the node or lump in question Lump balance plotting can only be performed if the save file record was created using the ALL option in the SAVE or RESAVE argument Otherwise SinapsPlus will report an error reading the save file since all required information could not be found in that file Also all relevant network elements nodes conductors etc should be depicted within SinapsPlus and should not be contained within INCLUDE files Otherwise misleading plots may be produced Since SAVE files produced by SINDA FLUINT Version 2 6 and earlier contain no information regarding which subset of submodels are currently active i e named on the current BUILD statement SinapsPlus con siders all submodels to be active at all times under such circumstances For node and lump balance plots where the
6. may also be selected and moved like any other icon using either the menu bar or the lt shift gt select keys The latter provides a convenient means of bringing the color bar over to a particular colored icon in order to compare colors Up to three color bars may be displayed simultaneously one for nodes lumps one for conductors paths and a third one in FLUINT models for ties 9 2 3 Selecting Objects to Color and Values by Which to Color Object selection for post processing is performed by the same methods used elsewhere in SinapsPlus Further more operations not applicable to certain selected items will be ignored by those items e g coloration of nodes will not affect any inadvertently selected conductors etc The user will then be shown a select menu to obtain the parameter to be read T C TL etc and the network will be colored As with other post processing options many values are derived e g delta temperature or pressures and have no standard representation in SINDA FLUINT SinapsPlus Fin Prebuilt Model Page 16 User Documentation September 22 2003 Rev 4 6 Appendix B Selected Post Processing Sections from the SinapsPlus Manual After selecting the items and the operations for the first time a box will appear under the cursor for placement This box describes the current time being postprocessed Next a color bar will appear for placement and the selected network items will be colored as requested 9 2 4
7. BUILD or BUILDF configuration changes this may cause spurious heat and mass flows to appear to ele ments in other models that are not currently active Heat flows for active paths and conductors will be correct but the net term may be in error This difficulty does not exist when using SINDA FLUINT Version 3 0 and later 9 6 Text Output In addition to plots and colorization and thickening the user may request ASCII text output for requested post processing operations This option allows the user to request data for the current time or for all times When SinapsPlus Fin Prebuilt Model Page 20 User Documentation September 22 2003 Rev 4 6 Appendix B Selected Post Processing Sections from the SinapsPlus Manual invoked a pop up text edit window will appear containing the requested data This option is supplemented by the Text option feature found under bar and X Y plots 9 7 Submodel Initialization Initialize Submodel operates analogously to the model level option However in this option the save file already selected for postprocessing will be used for the initialization which will be confined to the current submodel only The user must use the set starting time record option to determine which data is to be read Warning Using this option will destroy any expressions including calculator register references entered into data fields SIV options and other similar time and temperature varying options that are calculated
8. English or W m2 K metric This value must be nonnegative To turn off convection to the environment set hcoeff to zero sb This is the Stefan Boltzmann constant and it is used for radiative heat transfer In the English system its value is 1 712E 9 Btu hr ft2 R4 and in the metric system it is 5 67E 8 w m2 K4 These values are stored as built in SinapsPlus registers sbcon and sbconsi respectively Set sb to sbcon when using English units and to sbconsi when using metric units If the emissivity has been zeroed the value of this constant is irrelevant iterate This is the maximum number of iterations that the code will perform before giving up on a steady state solu tion This term sets NLOOPS in the SINDA FLUINT Model numnodes This is the number of segments into which the fin is subdivided SinapsPlus Fin Prebuilt Model Page 13 User Documentation September 22 2003 Rev 4 6 Appendix A Detailed Description of the Variables THIS VALUE SHOULD NOT BE CHANGED BY THE UNLICENSED USER It is supplied for the conve nience of licensed users Changing facilitates the task of changing the fin resolution but the user must still add delete nodes and conductors in the diagram window tipact This factor controls whether or not the fin tip is exposed to the radiation and or convection environment It is set to 1 0 initially meaning the tip is active To turn off heat transfer at the tip adiabatic pe
9. User Documentation September 22 2003 Rev 4 6 Appendix A Detailed Description of the Variables diameter If a circular fin is used this is the diameter of the fin when the fin has a circular cross section For non circular fin this must be set to zero In the SI system the diameter is in meters while in the English system the diameter is in feet Conduct The variable conduct is used to describe the thermal conductivity of the fin In the English system the term should have units of Btu hr ft F In the SI system this term should have units of W m K This value must be positive Some suggested values of conductivity are listed below Copper pure 393 W m K 227 BTU shr ft F Aluminum pure 221 W m K 128 BTU hr ft F Steel typical 36 W m K 20 8 BTU hr ft F spheat This term represents the specific heat of the fin material Its units should be Btu lb F in the English system while it in the SI system its units should be J kg K This term is used in the calculation of transient phenome non This value must be positive Suggested values of specific heat Copper pure 383 J kg K 0 165 BTU Ib F Aluminum pure 896 J kg K 0 385 BTU lb F Steel typical 486 J kg K 0 209 BTU Ib F This value is not currently used It is reserved for future options density The variable density represents the density of the fin material This term is used with the specific heat in the calculation of transient phenomenon Units for densi
10. and extra line positions are window dependent If you resize the window it is likely that these items will no longer be in the appropriate position Note that the usual mode of select then operate is not available for editing plots The user must first select the operation from the pull down menu bar or from the pop up operate menu and a select cursor will appear to prompt the user to choose the desired element e g annotation extra line etc 9 4 1 3 Appearance Grids and Coloring Lines If desired a grid can be toggled on or off This grid follows the resolution of the axes which can be customized separately Section 9 4 1 4 If more than one value is plotted and it becomes difficult to distinguish between lines the user may choose to color the data lines When this option is chosen the program assigns a distinct color to each line An internal SinapsPlus Fin Prebuilt Model Page 18 User Documentation September 22 2003 Rev 4 6 Appendix B Selected Post Processing Sections from the SinapsPlus Manual list of approximately 8 distinct colors is used and plotting more than that number of data values in one plot will result in at least two lines sharing the same color 9 4 1 4 Axis Limits and Expressions The axis limits may be changed so that all or part of a set of curves is visible If axis limits is chosen a data form will appear to obtain the new minimum maximum and step size for each axis Only data points falling with
11. ases all that is required is to only slightly change these value as little as 2 3 The model should be run using realistic values for the thermophysical properties the convective heat transfer coefficient and the emissivity If realistic conditions are not used the model may not converge For example the conductivity should be no greater than 400 W m k Copper the convective heat trans fer coefficient should be greater than 0 5 W m2 K Minimum Natural Heat Transfer Coefficient and the emissivity should be greater than 0 03 A Highly Polished Metal 4 When the convective heat transfer coefficient is set to zero the emissivity should be set a moderately large value 0 30 or greater This ensures that the model will converge for most situations SinapsPlus Fin Prebuilt Model Page 10 User Documentation September 22 2003 Rev 4 6 For More Information 7 0 For More Information For questions about this or other prebuilt models or about the use or availability of SINDA FLUINT and SinapsPlus contact Cullimore and Ring Technologies Inc Voice 303 971 0292 Fax 303 971 0035 If you have access to the internet you may contact us via e mail at info crtech com Also our web site is available at www crtech com This site contains demonstration versions training materials newsletters manu als and other announcements 8 0 Appendix A Detailed Description of the Variables Below is a listing of all the calculator reg
12. asily evaluate specific system and design requirements for any constant area fin The user can quickly perform various parametric siz ing analyses through the use of pre defined registers Future updates to this fin model will include transient analyses and variable areas 1 3 Introduction to Fin Heat Transfer Fins or extended surfaces are used to increase heat transfer in a variety of applications This increase in heat transfer occurs because there is a substantial increase in heat transfer area Some common applications of fin heat transfer are automobile radiators compact heat exchangers evaporators condensers and electronic heat sinks While many fin heat transfer applications are associated with the heat rejection process fins may also be used to improve the heat acquisition process The heat transfer associated with an extended surface is shown schematically for a single fin in Figure 1 Here heat flows from the root or base of the fin to its tip Along the length of the fin heat is transferred with the environment by both convection and radiation thereby producing a temperature gradient along its length Heat transfer with the environment may also occur through the tip area of the fin The important parameters affect ing this heat transfer process are the thermal conductivity of the fin the cross sectional area of the fin the sur face emissivity the convective heat transfer coefficient the length of the fin the base temperatur
13. be set before or after it is displayed The user has control over whether or not the bar is autoscaling and if not what the min imum and maximum values should be There are toggles for a vertical or horizontal bar and toggles for color or grey scale The user may also control the number of colors that are used by the bar For certain directional val ues such as heat rates flow rates delta pressures and delta temperatures the user can signal that only the abso lute value of requested data is to be displayed via the abs value button Note The displayed scale numbers represent the edges and not the centers of each data range When autoscal ing is off values out of range are colored or shaded according to the ends of each bar roughly purple and pink which were chosen to catch the user s attention The data for new option is used to set the characteristics of the next color bar to be created The edit old option allows the use to select a color bar and then edit the characteristics of that bar although simply double clicking the color bar is a faster means of modifying an existing color bar The network will then be recolored to reflect the changes in the color bar Color bars may also be resized with the resize option whereby the user indicated the desired dimensions and location via an areal drag The reset option is used to remove all color bars from the graph and the remove option can be used to delete them individually Color bars
14. convection See section 3 2 for definition Function Btu hr R conductor GR2 Defined W K Program defined radiation con See section 3 2 for definition Function Btu hr R ductor for tip heat transfer GH2 Defined W K Program defined convection See section 3 2 for definition Function Btu hr R conductor for tip heat transfer CN Defined J K Program defined capacitance See section 3 2 for definition Function Btu R A more complete discussion of these variables can be found in Appendix A Internal logic in the SINDA FLU INT model is employed to ensure than the user does not input unrealistic values SinapsPlus Fin Prebuilt Model User Documentation September 22 2003 Rev 4 6 Page 5 Running SINDA FLUINT 3 2 The Fin Model The thermal submodel EXTENDED represents the fin material and the radiative and convective heat transfer to their respected environmental sinks A summary of the node descriptions is provided in Table 2 Table 3 Table 2 EXTENDED Node Summary NODE ID TYPE Description Definition 10000 HEATER Sets Base Temperature 9999 BOUNDARY Convection Sink Temperature 9998 BOUNDARY Radiative Sink Temperature 1 25 DIFFUSION Fin Density Specific Heat Volume summarizes the definitions and descriptions for the various conductors in the EXTENDED submodel While the user has the ability to modify the parameters in these equations it is not recommended that the user modify thes
15. e and the temperature of the surroundings 2 0 Purpose Capabilities and Limitations 2 1 Purpose The primary purpose of this prebuilt is to allow a user to perform a parametric analysis of a simple constant area fin over a range of user specified parameters Output maybe in the form of plots of temperature gradients in the fin or plots of fin efficiencies or temperatures at various locations along the length of fin versus various user specified input parameters or coloring of the node network diagram by temperature or heat rate For example the user will be able to see how the performance of a fin changes as a function of environmental tem perature system dimensions or material properties Keller J R and Vogel M R Validation of the SINDA FLUINT Thermal Analyzer Code Using Several Analytical Solution SAE Paper number 961452 1996 SinapsPlus Fin Prebuilt Model Page 2 User Documentation September 22 2003 Rev 4 6 Purpose Capabilities and Limitations Qeonvection h A Cross Sectional Area Qradiation s A FIGURE 1 Schematic of a Constant Area Fin Another purpose of this prebuilt is to demonstrate simple modeling in SINDA FLUINT using SinapsPlus It can also be used by licensed users as a starting point for generating more complex models of fins 2 2 Modeling Assumptions and Limitations The assumptions for the fin model are 1 2 The model can use either metric m W K o
16. e may be used to invoke a file selector window If SINDA FLUINT has been rerun without changing the save file name then the user must so indicate to SinapsPlus via the reopen button Otherwise the save file from the previous postprocessing session will still be used SinapsPlus Fin Prebuilt Model Page 15 User Documentation September 22 2003 Rev 4 6 Appendix B Selected Post Processing Sections from the SinapsPlus Manual 9 2 Color The color options provide a means to color nodes lumps conductors paths and ties by data values that are found on a SINDA save file or that can be calculated using those values The user has control over the color scaling and is able to step through or animate the save file and monitor changes propagating through the net work 9 2 1 Setting a Time Before any color displays maybe created the user must first specify the desired time or record in the save file that contains the data This is accomplished by selecting the Set Starting Time Record option in the Post Pro cessing pull down When this option is selected a scrolling list of records will be displayed Pressing and releasing the select mouse button over a highlighted time record will select that time When colorization is later performed a boxed comment will appear that lists the current time being postprocessed 9 2 2 The Color Bar When a set of objects are colored a color bar will appear The characteristics of this color bar may
17. e Value Units Description Change Notes NUMNODE 25 Number of nodes representing This value can only be changed by the fin a licensed user TIPACT 1 0 Sets heat transfer from tip Set to one for tip heat transfer Set to zero for no tip heat transfer THKACT 1 0 Sets heat transfer from edges Set to one for edge heat transfer Set to zero for no edge heat trans fer PSTUDY 2 Puts model in the parametric See Section 4 2 for list of parame study phase ters PMAX 100 0 Maximum value for the para Must be positive metric study PMIN 10 0 Minimum value for the paramet Must be less than PMAX and must ric study be positive PNUM 9 Number of divisions for para Must be greater than one metric study FINEFF 1 0 Storage location for fin effi The user may postprocess this reg ciency the value is calculated ister to plot fin efficiency for the vari internally ous parametrics QFIN Defined W Total heat rejected by the fin Function Btu hr Calculated internally PERIM User m or ft Perimeter around the fin Maybe be overridden with a value Defined or different expression CSAREA User Cross sectional area of the fin Maybe be overridden with a value Defined m or ft or different expression GC Defined W K Program defined conduction See section 3 2 for definition Function Btu hr R conductor GR Defined W K Program defined radiation con See section 3 2 for definition Function Btu hr R ductor GH Defined W K Program defined
18. e expected temperature decrease along the length of the fin 15 x a EXTENDED Network Create Edit Select Layout Print Export PostProcessing Sinda Input Check Help Convective Boundary Temperature Base Temperature Convective Heat Loss From Fin Tip AA Bea S C ibe eee P Pp pW pp p ppp ROR RR RR ROR Radiative Heat Loss From Fin Tip Current time is 10 0 Radiative Boundary Condition 200 0 200 0 210 0 220 0 230 0 240 0 260 0 260 0 270 0 280 0 290 0 gt 300 0 v 4 gt FIGURE 2 Predicted Nodal Temperatures In addition to coloring the nodes to evaluate the results the results may also be plotted on X Y plots or Bar Plots Figure 3 shows the nodal temperatures along the length of the fin for various values of thermal conduc tivity This figure was generated by setting PSTUDY to 2 parametric study of fin conductivity PMAX to 10 and PMIN to 5 while the rest of the variable were held to the initial register values These results show that as the conductivity of the fin s material increases the temperature along the length approaches the root tempera SinapsPlus Fin Prebuilt Model Page 8 User Documentation September 22 2003 Rev 4 6 Postprocessing fj Line Plot Joy x Exit Grid Axis Labels Color Legend Annotate ExtraLines Axis Limits File Ops Help 295 0 300 0 290 0 Leb eb chick th ga ob Mile
19. e standard text book definitions Table 3 EXTENDED Conductor Summary Conductor ID Type Definition Description 100 125 L GH HCOEFF PERIM LENGTH NUMNODE Convective heat transfer to the ambient temperature sink 200 225 R GR EMISS SB PERIM LENGTH NUMNODE ee conductors to the radia 300 325 I L GC CONDUCT LENGTH NUMNODE ie aa along the length of 9998 R GR2 EMISS SB CSAREA TIPACT Radiation heat transfer from the 9999 L GH2 HCOEFF CSAREA TIPACT Convecion heat transfer from the ip 4 0 Running SINDA FLUINT The executable for the prebuilt fin model allows the user to perform steady state analyses for either a single condition or for a parametric study 4 1 Generating New Results To run this executable change the desired calculator registers or network inputs and then select Run SINDA FLUINT from the model control tab in the model control window then Preprocess and Run gt Rerun Existing Executable Unlicensed users do not use the Clean up option nor any other options within this submenu structure SinapsPlus Fin Prebuilt Model Page 6 User Documentation September 22 2003 Rev 4 6 Running SINDA FLUINT Upon completion of a run the user should find that the model has generated four files The file EXTENDED OUT file is the standard SINDA FLUINT output file The user should check file to ensure that there were no errors during the execution of the prog
20. ehhboud Hid Ot g alah cheb Ld sig o g E iD N iva N LD i N 2 Dgs FIGURE 3 Predicted Nodal Temperature for Various Conductivities ture This occurs because the thermal resistance decreases which in turn allows more heat to be conducted down the length of the fin The fin efficiency is calculated in logic and stored as register FINEFF The user may plot the fin efficiency for a parametric by selecting Registers from the model Control Panel From the pull down menu select Post Processing gt Save File Info A window will pop up prompting you to locate the save file Unlicensed users cannot change the name of the save file so simply select Exit gt Save and Exit The select Post Processing gt XY Plot for the menu A window will pop up listing all defined registers Find FINEFF and highlight it Then select Exit gt Save and Exit A window will then appear waiting for you to place it with the curser After you place the window a plot will appear in the window This plot depicts the fin efficiency as a function of save file record In the pull down menu of the plot window select Axis Control gt X axis Points gt Register and a window will appear listing all the register names Select Conduct representing the thermal conductivity of the fin Select OK to exit the register list The plot
21. fferent submodels and from different save files in addition to manipulating plot items and plotting from multiple submodels It is important to note that a plot must first be created before the plot control features can be invoked 9 4 1 6 File Ops Saving Printing and Exporting Data Plots may be saved independently of models and images via the File Ops gt Save Plot option The resulting machine independent binary file may be used for archival purposes or can be read into any model desktop Although the plot can then be changed and edited the underlying data upon which the plot is based will remain unchanged as later post processing operations are performed including save file changes To access new data a new plot must be created The purpose of this option is to enable users to exchange plots to prepare and save report graphics independently of other model changes A print option also exists under File Ops which operates analogously to the network diagram print option As part of the print option the user will be prompted for a plot title In addition the user will have a choice of por trait or landscape modes as well as control over the plot scaling An important option under File Ops is Save Points which allows the user to export files containing ASCII tables of the data underlying the plot These tables can then be imported into third party plotting software or spreadsheets SinapsPlus Fin Prebuilt Model Page 19 User Documenta
22. he length of the fin For a rectangular fin this area is its thickness multiplied by its width the initial expression For a circular fin the cross sectional area is PI multiplied by the radius squared pi is a built in SinapsPlus register This value must be positive SinapsPlus Fin Prebuilt Model Page 14 User Documentation September 22 2003 Rev 4 6 Appendix B Selected Post Processing Sections from the SinapsPlus Manual If using the English system this value should be in feet whereas if using the SI system this value should be in meters The user must also change sb named calculator register to the appropriate units system if a radia tion environment is active perim Perim is the perimeter of the fin This term is currently set to calculate the perimeter for either a circular or rectangular fin It is recommended the user not alter the formula This parameter is important in determining the convective and radiative heat transfer from the surface of the fin For a rectangular fin the perimeter is twice the thickness plus twice the width the initial expression If only one side of the fin is active set perim equal to the width For a circular fin the perimeter is diameter mul tiplied by PI pi is a built in SinapsPlus register This value must be positive If using the English system this value should be in feet whereas if using the SI system this value should be in meters The user must also cha
23. ic study portion of this prebuilt model since these terms are interrelated and a relationship describing each is needed This would require that the internal SINDA logic be modified each time a new relationship was used which the unlicensed user can not do The SINDA routine PSWEEP is used for the parametric analysis PSWEEP performs a series of steady state solutions varying the PSTUDY variable between the values of PMIN and PMAX across PNUM increments SinapsPlus Fin Prebuilt Model Page 7 User Documentation September 22 2003 Rev 4 6 Postprocessing 5 0 Postprocessing Once a run has been made and completed successfully SinapsPlus can be used to postprocess data in a variety of graphical methods The user can postprocess the network based on temperature capacitance conductance etc To begin postprocessing the user should go to the submodel Extended network diagram and choose the desired SAVE file Save File Info under PostProcessing as explained in Appendix B and the tutorial avail able at www crtech com Appendix B contains the portion of the SinapsP us manual which describes post processing Some examples of postprocessing are presented in this section Figure 2 depicts postprocessing of the EXTENDED submodel nodes for the initial conditions listed in Table 1 This is a single steady state run A color scale is added to the network and the nodes are displayed in color based on temperature These color results clearly show th
24. ide useful analysis tools to the heat transfer and fluid flow engineering community Pre built models are built using SINDA FLUINT general purpose thermal fluid modeling software and SinapsPlus its graphical user interface Prebuilts may be used without a license to run either SINDA FLUINT or SinapsPlus nor do they need the For tran compiler normally required to execute SINDA FLUINT The user of the prebuilt model will be able to change input parameters dimensions thermophysical properties boundary conditions and generate new Page 1 Purpose Capabilities and Limitations results Using the parametric study option the user will be able to evaluate fin performance over a range of user specified parameters As explained in separately available documentation on prebuilt models unlicensed users cannot make changes to the thermal fluid network itself nor to the user logic 1 2 About This Prebuilt This model performs a steady state analysis of a generic constant area fin Unlike most textbook solutions for extended surfaces which only include convective heat transfer this prebuilt model includes simultaneous con vective and radiative heat transfer to the environment This prebuilt model was validated with several steady state analytical solutions This model was generated in SinapsPlus SINDA Application Programming System a graphical SINDA FLUINT pre and postprocessing system This prebuilt can be used as a design tool to e
25. in the chosen range will be shown potentially truncating some lines In addition to scaling specifications an expression may be applied as a filter for the data being plotted along each axis In other words mathematical operations can be specified that operate on the data being plotted in order to change units for display purposes etc This expression may be consist of any equation that is recog nized by the SinapsPlus calculator but should include the name of the axis X or Y For example to change the X axis from hours to seconds enter x 3600 0 or to change the Y axis from degrees F to degrees C enter y 32 0 1 8 These expressions do not apply to the range limits in the upper part of the form since those values are based on the raw data The original data i e that contained on the save file was produced in units of hours but the plot shows units of seconds along the x axis Thus the axis limits in the top part of the form are defined in terms of hours but the expression in the bottom field converts the display units to seconds The X Axis Points option in the Axis Control pull down menu allows the user to select which parameter is to be plotted on the X axis 9 4 1 5 Plot Control Under the Plot Control pull down are several options which can greatly enhance the presentation of the SINDA FLUINT predictions and the control the appearance and usefulness of plots These features allow the plotting of results from di
26. ister values length This term is the length of the fin from its base to its tip This term is important in determining the conduction along the length of the fin and the convective and radiative exchange with the ambient environment This value must be positive If using the English system this value should be in feet whereas if using the SI system this value should be in meters The user must also change sb named calculator register if a radiation environment is active width This is the width or depth of the fin when the fin has a rectangular cross section This term should be set to zero for circular fins In the SI system the width is in meters while in the English system the width is in feet The user must also change sb named calculator register if a radiation environment is active This value must be positive If the csarea and perim expressions have been overridden this value may become irrelevant thick This is the thickness of a rectangular fin when the fin has a rectangular cross section For circular fins this term has no meaning and is irrelevant In the SI system the width is in meters while in the English system the width is in feet The user must also change sb named calculator register if a radiation environment is active This value must be positive If the csarea and perim expressions have been overridden this value may become irrelevant SinapsPlus Fin Prebuilt Model Page 11
27. nd if save file records should be skipped between the steps The user may step by time or by record number 9 3 Thickness Conductors paths and ties may be thickened by value This operation is analogous to the previously described color operations except that the objects are thickened instead of and perhaps in addition to being colored The user is encouraged to explore this option since thickening often results in presentations that are more intu itively understood than colorization Objects may be both colored and thickened independently For example conductors may be simultaneously colored by conductance and thickened by heat rate while nodes are colored by temperature This usage visu ally provides the same information as does QMAP When a group of objects are thickened a thickness scale will appear that will follow the cursor until dropped in its final location The numbers on the thickness scales represent edges rather than centers of each range Cau tion should be used when interpreting data if negative values are present since the thickness scale is one dimensional An abs value option is available if helpful in such circumstances The thickness scale are editable in a manner analogous to that of color bars and they contain analogous subop tions whose descriptions will not be repeated here Analogous to the number of colors in a color scale the user may select the number of lines in a thickness scale The user should note
28. nge sb named calculator register to the appropriate units system if a radia tion environment is active 9 0 Appendix B Selected Post Processing Sections from the SinapsPlus Manual After SINDA FLUINT has been executed the results that it produces can be visualized using the SinapsPlus post processing features Perusing SAVE files and manipulating display options is the domain of the post pro cessing option of the main menu Once post processing is chosen the user is led into a menu tree where vari ous options maybe utilized This section is generic for all SinapsPlus usage not just for this pre built 9 1 Save Files This section describes the selection and usage of save files that are produced by SINDA FLUINT Selecting the Save File Before any postprocessing can be performed a save file must be specified When the user picks save file info from the post processing menu a data form will appear At the top of the form the user chooses the source machine from the available machine types SUN HP PC Use the select button to select the type of machine which produced the save file e g if SINDA FLUINT was run on a SUN and that was where the save file was created select SUN In the middle of the form is a field in which the user enters the name of the save file including possible subdi rectory information If the user is unsure of the name or location of the save file the button near the bottom of the form Find Save Fil
29. now depicts fin efficiency as a function of thermal conductiv ity This plot can then be enhanced as shown in Figure 4 by the user by adding axes tables colorization or other parameters See the SinapsPlus user manual for future details on plotting SinapsPlus Fin Prebuilt Model Page 9 User Documentation September 22 2003 Rev 4 6 Usage Cautions ini x Exit Appearance Axis Control Legend Annotate ExtraLines Plot Control Help Results of Conductivity Parametric i ta I gt 6 a E W E TE 46 0 64 0 Thermal Conductivity FIGURE 4 Parametric Plotting 6 0 Usage Cautions The user should be aware of the following before running this prebuilt model 1 When the fin conductivity is high and its length short more iterations are required to resolve the small variations in temperature along the length of the fin Reducing the fin thickness or conductivity or increasing the emissivity or the heat transfer coefficient may overcome this problem 2 There may be instances when the numeric solution is not converged When this occurs the user will find the message Solution Not Converged in the output file The user can try several of the following tech niques to obtain a converged solution increase the number of iterations ITERATE increase the heat transfer coefficient HCOEFF increase the emissivity EMISS decrease the thickness THICK and or decrease the conductivity CONDUCT In some c
30. r English ft BTU hr R units The fin has constant thermophysical properties along its length conductivity specific heat emissivity density The cross sectional area is constant along its length 4 The convective heat transfer coefficient is constant along its length 8 While real fin applications have sets of fins only one fin will be considered This approach neglects fin to fin heat transfer There are separate sinks for both radiation heat transfer and convective heat transfer There are many sit uations where separate sink occurs such a fin at night radiating to the cold sky and being warmed by the night air The fin tip may be active open to the environment or inactive insulated or representing an adiabat by symmetry if a half fin is being modeled Only steady state conditions are considered specific heat and density inputs are currently ignored The following parameters can be changed by the user Nm WN The dimension of the fin length width diameter and thickness The material properties conductivity specific heat emissivity density The convective heat transfer coefficient The temperature boundary conditions The fin tip may be active or inactive Heat transfer from the edges may be turned on open to the environment or off infinite fin or adiabatic due to insulation SinapsPlus Fin Prebuilt Model Page 3 User Documentation September 22 2003 Rev 4 6 Fin
31. ram The file EXTENDED ECH is an input check of the registers The file EXTENDED DAT contains the heat rejection by the fin and its fin efficiency If the paramet ric study option has been selected these results will be printed at each variable change Finally the model writes out the save file EXTENDED SAV which is used for processing 4 2 Running Parametric Studies A parametric study is invoked when the user sets the variable PSTUDY to a value from 1 to 12 The parame ters that PSTUDY affects are listed below This variable invokes the parametric study feature of the prebuilt model When PSTUDY is set to zero the model will use the standard inputs When the variable is set to one or higher the parametric option is invoked and one variable can be altered A list of the variables changed for different values of PSTUDY are listed below 1 length of the fin LENGTH 2 thermal conductivity of the fin CONDUCT 3 specific heat SPHEAT reserved for future options 4 density DENSITY reserved for future options 5 emissivity EMISS 6 the base root temperature TBASE 7 the ambient environment temperature TAMB 8 the radiation environment temperature TRAD 9 the convective heat transfer coefficient HCOEFF 10 the width of the fin WIDTH 11 the thickness of the fin THICK 12 the diameter of the fin for round fins DIAMETER The cross sectional area and perimeter are not included in this parametr
32. re CsR TECHNOLOGIES Sinaps Plus Fin Prebuilt Model User Documentation September 22 2003 Rev 4 6 C amp R Technologies Inc Voice 303 971 0292 Fax 303 971 0035 info crtech com http www crtech com 1 0 Introduction This document explains the use of the prebuilt SinapsPlus model of a constant area fin The software and other supporting documentation are freely distributed and are available separately To run this model you must 1 Install SinapsPlus Version 4 6 or later for your machine PC Sun or HP 2 Install the fin prebuilt package in the location where SinapsPlus was installed per the instructions in the generic prebuilt document available separately A basic understanding of SINDA FLUINT and SinapsPlus is necessary to utilize this model Tutorials training notes and on line users manuals for SINDA FLUINT and SinapsPlus are available separately as are generic descriptions of prebuilt models and their usage These documents along with SinapsPlus and the prebuilt package may be accessed via C amp R s web page http www crtech com Please contact Cindy Beer at 303 567 4514 cindy crtech com for more information or for copies of these documents and software for those lacking Internet access 1 1 Prebuilt Models using SINDA FLUINT and SinapsPlus This paper documents one of a series of prebuilt models prebuilts offered by Cullimore and Ring Technol ogies C amp R that prov
33. rhaps by symmetry set this value to zero thkact This factor controls whether or not the fin edge is exposed to the radiation and or convection environment It is set to 1 0 initially meaning the edge is active To turn off heat transfer at the edge adiabatic perhaps by sym metry set this value to zero pstudy This integer variable invokes the parametric study feature of the prebuilt model When pstudy is set to set to zero the model will use the standard inputs When the variable is set to one through twelve the parametric option is invoked and one variable can be altered pmax This is the maximum value to be used in the parametric study pmin This is the minimum value to be used in the parametric study pnum This is the number of steps to be used in the parametric study Must be an integer fineff Storage location for fin efficiency the value is calculated internally and should not be changed by the user The user may postprocess this register to plot fin efficiency for the various parametrics qfin Total heat rejected by the fin This term is calculated internally and should not be changed by the user Units Watt or BTU HR csarea The variable csarea is the constant cross sectional area of the fin This term is currently set to calculate the cross sectional area for either a circular or rectangular fin It is recommended the user not alter the formula This value is important in determining the conduction along t
34. that turning off autoscaling for thick ness scales can sometimes result in exceptionally thick lines and that for this reason an upper limit approxi mately one inch is placed on the maximum possible thickness for any tie path or conductor 9 4 Plotting SinapsPlus provides a number of different plotting options including X Y plots bar plots and polar plots Any information found on the SINDA save file may be displayed with these options SinapsPlus Fin Prebuilt Model Page 17 User Documentation September 22 2003 Rev 4 6 Appendix B Selected Post Processing Sections from the SinapsPlus Manual 9 4 1 X Y Plots Several types of X Y plots may be created plots of variables versus time or save file points or snapshots in the case of sets of parametric steady state plots of variables versus icon position plots of variable verses loop count and plots of variable verses registers In the first case the user need not first specify the starting time since the entire save file will be plotted by default As with colorization options once a group of objects is selected a query form will appear to determine which information to plot This selection form will be appropriate to the type of object selected e g nodes will query for T Q and C conductors for G SinapsPlus will then produce an independent X Y plot window which the user may place and size like any other SinapsPlus window Resizing the window automatically resizes
35. the plot Once the plot is created a number of options exist within the plot window The various plot options that will be described below allow the user to toggle a grid color the lines add or edit labels for the X and Y axes save the plot to be accessed later from the edit old plot option and print 9 4 1 1 Legends Legends may be turned on or off moved and edited When the legend is turned on or moved it will follow the cursor until the select button is pressed like placing a node The on move refresh option brings up a new legend and allows its placement The old legend will remain until the new one is placed at which time the old legend will be erased Legends may also be turned off the default state If edit is chosen a text editing window will appear that contains the legend text Once saved the new legend will appear for placement 9 4 1 2 Annotations and Extra Lines Annotations comments are added in a manner analogous to that used to create comments in a network dia gram If annotate is chosen a window will appear to obtain the annotation text Once this text is accepted the text will appear on the plot and will follow the cursor until the select button is pressed The extra lines choice will cause a select cursor to appear Place the cursor over the start point of the line and press the select button A line will then appear that will follow the cursor until the select button is pressed again Legend annotation
36. tion September 22 2003 Rev 4 6 Appendix B Selected Post Processing Sections from the SinapsPlus Manual 9 4 1 7 Plotting vs Location In addition to X Y plotting by time SinapsPlus provides for plotting vs icon location To plot by location select group of nodes or lumps are chosen and then choose a data value temperature etc to plot A plot of temperature versus the location of the nodes and lumps in the diagram will be produced Since there is no actual geometry in SinapsPlus the location displayed is the relative screen location of the object in units of pixels However if the user has evenly spaced the icons then the SinapsPlus depiction may be used to represent a spatial relationship The axis scaling expressions Section 9 4 1 4 can then be used to convert to real dimensions The legend lists the screen locations to aid in the development of the rescale expression For example if 10 nodes were known to represent 33 4 feet of a rod and the legend in the plot showed the x axis limit to be 1032 pixels then the following expression can be used to convert the display diagram from pix els to feet x 33 4 1032 The reader should note that certain gradient information is also accessible by coloring and or thickening paths ties and conductors by delta temperature or delta pressure 9 5 Bar Plots These plotting options work in the same manner as X Y plots refer to the prior subsection for a description One of the
37. ty are either lb ft3 English or Kg m3 metric This value must be positive Suggested values of density Copper pure 8900 kg m3 556 1b ft3 Aluminum pure 2740 kg m3 171 1b ft3 Steel typical 7830 kg m3 489 1b ft3 This value is not currently used It is reserved for future options emiss This is the emissivity of the fin This is a unitless term Emissivity should be between 0 0 and 1 0 By setting the emissivity to zero radiative heat transfer is turned off SinapsPlus Fin Prebuilt Model Page 12 User Documentation September 22 2003 Rev 4 6 Appendix A Detailed Description of the Variables Suggested values of emissivity are listed below Copper 0 10 polished Aluminum 0 05 polished Steel 0 20 polished Tbase This term represents the base or root temperature of the fin This temperature can be either in Rankin English or Kelvin Metric This value must be positive Tamb This is the temperature of the ambient environment for convective heat transfer This temperature can be either is Rankin English or Kelvin Metric This value must be positive Trad This is the temperature of the ambient environment for convective heat transfer This temperature can be either is Rankin English or Kelvin Metric This value must be positive hcoeff This variable describes the convective heat transfer coefficient for the fin It is assumed constant the entire length of the fin It units are Btu hr ft2 R
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