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12. H$%# &!SS

The main use of this module is to estimate total heat loss or draw the temperature profile

of a wall or reactor. However, it can also be used to compare different materials and

different setups, for example the use of insulation when a material has a critical

maximum temperature or when the outside air cannot exceed a certain temperature. The

conduction, convection and radiation databases also provide a resource as simple

reference tables for material properties. Figure 1 shows an example of a heat loss wall

calculation for a smelting reactor with the temperature profile shown in rows 9 and 10.

'i(ure 1)Heat Loss calculation example of a smelting reactor wall.

The basic concept of the module is that the user specifies the system setup by selecting

the geometry of the obect, inserting columns, specifying a material for each column,

specifying thic!nesses "if any# and entering either one temperature point and a total heat

loss or two arbitary temperature points within the same sheet. From these inputs the

program can calculate either the temperature profile or the total heat loss. The

temperature profile "profiles# can then be plotted graphically.

The main wor!boo! is very similar to $xcel%type wor!sheets in terms of the properties

that can be found in the menu and also most of the $xcel wor!sheet functions are

available.

The new Heat &oss module may be used, for example, to estimate heat loss values needed

in the 'alance module. The user must first specify the column types, which can be &*yer,

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&*yer +nt*+t, Sur*+eand $n+lsure. The thic!ness must be specified for &*yerand

$n+lsure columns, while &*yer +nt*+t and Sur*+e columns have (ero thic!ness.

Two basic types of calculations may be carried out)

1. #emer*ture rilewith fixed heat loss and one temperature point.

2. He*t &sswith two fixed temperature points. This will return the heat loss but also

the temperature profile.

The calculation routine handles conduction, convection and radiation properties as

functions of temperature but fixed values may also be used by selecting the value and

pressing the 'i/ *luebutton. These fixed values are shown in red on the calculation

sheet.

Temperature profile as well as some other user specified values may also be presented in

graphical form. Target dialog may be used to find, for example, minimum layer

thic!ness. The calculation specifications may be saved to files for later use.

12.1 B*si+ C*l+ul*tin Pr+edure

1. Sele+t (emetry.

To select the choice of geometry, clic! on the desired option button in the frame

Sh*e *nd imensins. The available options are wall, cube, cylinder and sphere.

It is highly recommended to start the calculations with a simple wall caseand then

to continue with more complicated shapes later.

2. Sele+t dimensin.

*hen selecting the geometry, appropriate dimension textboxes automatically pop

up. The dimensions are always inner dimensions.

. nsert ne3 +lumn.

The user may specify the layout of the heat transfer obect by selecting nsertfrom

the menu bar and then the desired column type. There are four types of columns)

Sur*+e,$n+lsure,&*yerand &*yer +nt*+t. Sur*+ecolumns must be inserted

to the left and+or to the right of the other columns. $n+lsurecolumns must be

inserted between two &*yer columns. Finally &*yer +nt*+t, $n+lsure and

&*yercolumns must all be inserted between Sur*+ecolumns.

4. Se+iy he*t tr*nser tye.

ou can select the type of heat transfer to study in two ways) either manuallyor

using the database.

Manually)

1. *rite the name of the material+gas+li-uid on the second row of the table in the

current column.

1. elect the desired heat transfer factor)

&ayer column ) $nter the mean conductivity for the material "!# on row /.

urface column ) $nter the convection and+or the radiation coefficient"hc and+or hr# on row and+or row . 2t is also possible to specify the

emissivities and+or absorptivities on rows 30%34, in this case please ma!e

sure that the radiation coefficient is unfixed.

&ayer contact column ) $nter the thermal resistance on row 11.

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$nclosure column ) $nter the convection coefficient on row and+or the

radiation coefficient on row . 2t is also possible to specify the emissivities

on the adjacent layer columns, in this case please ma!e sure that the

radiation coefficient is unfixed.

3. For each value entered press the 'i/ *luebutton, unless the value is alreadyfixed. 'y doing this the program will use these given values, indicated by a red

font, when calculating instead of the database values.

Using the database)

1. 5ress the corresponding button in the frame et *t* r Clumn)

&ayer column )Conductionbutton.

urface column )ConvectionorRadiationbutton.

$nclosure column ) Convection or Radiation button "radiation for adacentlayer columns#.

To specify the desired material+gas+li-uid, place the cursor on top of it and

press Sele+t. 6ow the data for the material will be transferred automaticallyto the column on the main sheet where the cursor is located. 6ote that

sometimes several database sheets are available, for example the convection

table or function sheet. ou will !now that the data has been transferred

from the database sheet to the calculation sheet, once the selected material

name appears on the material name rows 3 or 4.

5. Se+iy thi+knesses.

Type theThicness xon row 7 for every &*yerand $n+lsurecolumn. Sur*+e

and &*yer +nt*+tcolumns have (ero thic!ness.

6. "ee*t stes , 4 *nd 5 until the desired l*yut is *+hie7ed.

. C*l+ul*te results.

To calculate results for a cylinder or cube, first select whether to calculate all

sheets or ust the active sheet, by pressing the appropriate option button in the

C*l+ul*teframe. 'y, for example, calculating only the wall sheet of a cylinder,

pipe calculations can be obtained. The two basic calculation types are)

Temperature Profile"press the #emer*ture rilebutton#:

pecify the total heat loss by selecting the appropriate unit "*, !* or 8*# andby typing the heat loss in the textbox.

pecify one fixed temperature point by the cursor. For cube or cylinder geometry, specify calculation range by selecting either

C*l+ul*te *ll sheets"calculates all walls# or C*l+ul*te *+ti7e sheet"calculates

active wall# from the option buttons.

6ote that when calculating all sheets, the temperature profiles will be iterated sothat the temperatures in the first columns "inside temperatures#, as well as the

outside temperatures, are the same for all sheets.

Heat Flow "press theHe*t l3button#)

pecify temperature points using the cursor.

0 or 1 point selected "by cursor position#) The whole rangewill be calculated.

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ube or cylinder geometry) pecify calculation range by selecting either

C*l+ul*te *ll sheets "calculates all walls# or C*l+ul*te *+ti7e sheet

"calculates active wall#.

!ll sheets will have the same inside and outside temperatures as on the

current sheet, once the calculation is completed.

3 points selected "by selection#) The range between these points will becalculated.

ube or cylinder geometry) The other sheets will notbe calculated.

The end temperature pointsin the selection will remain constant.

8. Press theDraw Diagram 9uttn r * (r*hi+*l lt the temer*ture rile.

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12.2 He*t &ss $/*mles

12.2.1 $/*mles r7ided 9y HSC

ee the examples provided by the H pac!age by selecting 'ile:!enfrom the menuand selecting the appropriate file "examples exist in :H;:Heatloss %folder#.

1. Simle C*se 3ith i/ed +ndu+tin *nd +n7e+tin 7*lues ;SimleC*se.H#"ell K..) 6'+6E team Tables) Thermodynamic and Transport

5roperties and omputer 5rograms for Oapor and &i-uid tates of *ater in 2 nits. Hemisphere

5ublishing orporation, 197. 2'6 0%911/%4;4%0.

9. \o!ilaa!so @.) Oirtauste!nii!an, l^mm_nsiirron a aineensiirron perusteet. Technical niversity ofHelsin!i, Cta!ustantamo, 19. 2'6 9;1%/3%01;%4.

10. $dwards, A.>. Kas radiation properties. Heat $xhanger Aesign Handboo!, 6o. ; 5hysical

5roperties. OA2%Oerlag KmbH, Hemisphere 5ublishing orp. 194 "about 3;0 p.#