excel_for_eng_02.pdf

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Excel for Engineers-part2 1 Excel for Engineers-part2 2

Excel for Engineers Part 2

1-Macros in Excel

2-User defined functions

3-Controls from form Toolbar

4-User form and controls

5-VBA (Visual Basic for Applications)

Excel for Engineers-part2 3

1-Macros in Excel


How to record a macro

1-Go to tools→macro→ record a new macro

2-Go to cell B6 and type x, and type y in cell C6

3-Write the numbers 1 to 10 in cells B7 to B16

4-Go to cell B18 and type =sum(B7:B16)

5-Go to Cell C7 and write =B7^2

6-Copy from cell C7 to C16

7-stop recording the macro by pressing the stop button

Now go to visual basic editor (i.e. press Alt+F11)

And then click on module

You will see the macro that you have created

Macros in Excel

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Macros in ExcelRecord a macro


Record a macro Macros in Excel





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Record another macro Macros in Excel


How to create a command button on the excel sheet and link it to a macro

1-After creating a button

2-Go to view→toolsbar→forms

3-A small window will pop up showing some of the controls that you can place on the excel sheet

4-Choose the Command button and place it some where in the excel sheet

5-Once you release the mouse another window will pop up asking you to attach or link the command button you have created to the macro available

Macros in ExcelAssign a macro to a command button


Assign a macro to a command button Macros in Excel



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Macros in ExcelAssign a macro to a command button


Form controls

You can create scroll bar, list_box, combo_box and others on Excel sheet using the form controls


Form controls

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Form controls


Command button

Group box

Combo Box

List Box

Scroll Bar

Check Box

Option button

Form controls


Form controls


Form controls

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Form controls


msgBox and inputBox


InputBox Function

Value=inputBox(Prompt, title, default)

Prompt is a text ( i.e. it must be written between two quotes)

Title is also a string

Value1=inputBox(“Enter A value”, “Heat Transfer”,111)

InputBox(prompt[, title] [, default] [, xpos] [, ypos] [, helpfile, context])

Syntax


InputBox Function

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Input Box


MsgBox(prompt[, buttons] [, title] [, helpfile, context])

Massage Box

Syntax


User Defined Functions

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User defined functions

To access the visual basic editor

tools→macros →visual basic editor

Or just type Alt-F11

You will see the visual basic

Go to insert and insert a module

You can view the project ad see that a module is added to the project. In the module now you can add functions and subroutines

Creating user defined functions




Suppose we want to add a function that do the followings

2210 xaxaay ++=

Function myfun(x)

a0=5

a1=0.5

a2=0.75

myfun=a0+a1*x+a2*x^2

End function

Now you can go to the excel sheet and type =myfun(1) the answer will be 6.25




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Select a cell and type

=myfun(1)





To see all user defined functions and subroutines

go to tools→macro→visual basic editor

And press on module


Notes on creating user defined functions

1-Try to document every function you write. So that when you come back to it after a while you can remember what was the purpose of the function and the source of it

2-if you start the first line with single quote or the word rem, then that statement is a remark statement

3-use the command debug.print to send values of the variable to immediate window

4-Keep all related functions and subroutines in separate module.

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Another Example of creating A user defined functions

The effectiveness for counter current flow heat exchanger


Example on creating functions


Function eff_counter(NTU, Cr)' This function finds the heat effectivness for' counter current heat exchanger' The input parameters' 1-NTU is the no of transfer unit' 2-Cr is the capacity ratio=Cmin/cmax'' C=m_dot*Cp' NTU=Cmin/UA' the output is the heat exchanger effectivenessIf Cr = 1 ThenCr = 0.999End Ifx1 = 1 - Exp(-NTU * (1 - Cr))y1 = 1 - Cr * Exp(-NTU * (1 - Cr))eff_counter = x1 / y1End Function

List of the function eff_counter

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Modules can be saved and insert in new worksheet

Steps to export a module

Go to visual basic editor

Choose the module to export

With mouse right click select Export file

Choose the prefer name and location to save the module file [The extension of the file will be *.bas]. It can be several functions and modules


Steps to insert a module into a worksheet

1-In a new or current workbook go to Visual Basic editior (Alt-F11)

2-Insert a new module

3-Click on the module with mouse right click select import file

4-A pop up window will appear to select the module you want to insert

5-Choose the location and the name of the file (module) you want to insert


Inserting a module into excel sheet


Some Useful Applications

1-Table interpolation

2-Friction factor in pipes

3-Moist air properties

4-Thermodynamic properties of water

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1- Table interpolation

Program name:

table interpolation.xls







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Cp_air(T)

Prandtl_air(T)

Density_air(T)

Conductivity_air(T)

Air properties

Water propertiesCp_water(T)

Prandtl_water(T)

Spvolliq_water(T)

Conductivity_water(T)



2- Friction factor for flow inside pipes

Program name f_factor.xls


⎥⎦

⎤⎢⎣

⎡+−= 5.05.0 Re

51.27.3

/log0.21f

Def

Re64

=fLaminar flow


Re<2300

Turbulent flow Re>=2300



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Dry bulb temp

Wet bulb temperature

Total pressure

Humidity ratio

Enthalpy

Relative humidity

Dew point temperature


Given tdry, twet, air pressure pa

Find h, RH, dew point temp. humidity ratio etc


Given two thermodynamic properties of air along with total pressure, one then can find the rest of the properties

For example


hW

dry temp.

hu

mid

ity r

atio

Ws

W

tt d

h

sat. t *

1

Ws*

f


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)t 4.186 - t 1.8 + (2501t- (t - )t 2.3 - 2501 (W

= W s*

***

6) 26

W+0.622P W = )t(P dvs

P-PP0.622 = W

v

v

) t* 1.8 + (2501 W+ t = ) t* C+ (2501 W +t C = h pvpa 6*

(T) C + T C + T C + T C + T C + C + /TC = )P( 74

63

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4321vs lnln

vs

v

PP = φ

Some of the moist air properties relation




4-Water thermodynamic properties

File name: Xsteam_excel_v2.6.xls

Site: http://www.x-eng.com

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Steam and water thermodynamic and thermo-physical properties

Sub-cooled region

Saturation region

Superheated region



P

P

T

CP

1

2 > P1

Saturated liquid line

Saturated vapor line

Saturated region Super heated region

Sub-cooled region

s






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Given the pressure P ( in bar)

Saturated temperature (Tsat) : Tsat_p(P)

Saturated liquid enthalpy hf: hl_p(P)

Saturated vapor enthalpy hg: hv_p(P)

Saturated liquid specific volume vf: vl_p(P)

Saturated vapor specific volume vg: vv_p(P)

1 bar=100 kPa



Given the temperature T ( in deg. C)

Saturated pressure (Psat) : Psat_p(T)

Saturated liquid enthalpy hf: hl_t(T)

Saturated vapor enthalpy hg: hv_t(T)

Saturated liquid specific volume vf: vl_t(T)

Saturated vapor specific volume vg: vv_t(T)



Superheated steam properties given P & T

1-Enthalpy h: h_pt(P,T)

2-Entropy s: s_pt(P,T)

3-Density rho: rho_pt(P,T)


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User form and creating a user interface

1-Go to Visual Basic editor

2-Insert a userform

3-On the userform insert tools

4-Change the properties of each tools as required

5-Program other tools such as command button, listBox, ComboBox, etc


Userform

Forms, user form1

Toolbox for Controls

Insertion of a form

Properties window


Userform

Tools

Properties window

Command button

ComboBox

frame

Text Box

Label

Insert controls on the userform

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Example: Simple Program

Construct a program with user interface to add two numbers and show the result



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Summary

1-Cell Referencing (Relative & absolute)

2-Introducing some of the built in functions & Extend your use of Excel

3-Use of Goal & Seek and Solver

4-Macros in Excel

5-Forms toolbox

6-User defined functions

7-Usful Engineering Applications

8-Userform and VBA


Conclusions & Recommendations

1-Excel is handy, available and powerful

2-Lots of help and examples from the net

3-It is highly recommended to extend you capability of using Excel for your courses

4-Learn how to use new functions, build your own functions and form modules

5-For full excel usefulness learn VBA

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References for Excel uses and VBA programming

1-Excel for Engineers

2-Internet (lots of sites, examples and forums

Documents

excel_for_eng_02.pdf