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![A problem that doesn’t require iterative solution
𝑄 = ℎ𝐴 𝑇𝑠 − 𝑇𝑎
Let’s say:
𝑄 = 2000𝑊
𝐴 = 1𝑚2
𝑇𝑎 = 25°𝐶
ℎ = 10𝑃
Where,
𝑃 = 𝑃𝑟 𝑇𝑎 for ‘Air’
Find 𝑇𝑠?
Q = h*A*(Ts-Ta)
Q = 2000 [W]
A = 1 [m^2]
Ta = 25 [C]
h = 10*P
P = prandtl(Air,T=Ta)
EES Codes (Code-1.EES)
5](https://image.slidesharecdn.com/eesiterations-180604041932/75/Performing-Iterations-in-EES-5-2048.jpg)
![A problem that require iterative solution
𝑄 = ℎ𝐴 𝑇𝑠 − 𝑇𝑎
Let’s say:
𝑄 = 2000𝑊
𝐴 = 1𝑚2
𝑇𝑎 = 25°𝐶
ℎ = 10𝑃
Where,
𝑃 = 𝑃𝑟 𝑇𝑠 for ‘Air’
Find 𝑇𝑠?
Q = h*A*(Ts-Ta)
Q = 2000 [W]
A = 1 [m^2]
Ta = 25 [C]
h = 10*P
P = prandtl(Air,T=Ts)
EES Codes (Code-2.EES) Wrong approach!
8
MANUAL](https://image.slidesharecdn.com/eesiterations-180604041932/75/Performing-Iterations-in-EES-8-2048.jpg)
![A problem that require iterative solution
𝑄 = ℎ𝐴 𝑇𝑠 − 𝑇𝑎
Let’s say:
𝑄 = 2000𝑊
𝐴 = 1𝑚2
𝑇𝑎 = 25°𝐶
ℎ = 10𝑃
Where,
𝑃 = 𝑃𝑟 𝑇𝑠 for ‘Air’
Find 𝑇𝑠?
Q = h*A*(Ts-Ta)
Q = 2000 [W]
A = 1 [m^2]
Ta = 25 [C]
h = 10*P
Ts_guess = 100 [C]
check = Ts_guess - Ts
P = prandtl(Air,T=Ts_guess)
EES Codes (Code-3.EES) Right approach!
Assume some ‘guess’ value of
the unknown variable. Your
guess will correct only when
the difference between the
solution and your guess will
be ‘0’ i.e. check = 0
Evaluate
material
property at
guess value.
9
MANUAL](https://image.slidesharecdn.com/eesiterations-180604041932/75/Performing-Iterations-in-EES-9-2048.jpg)
![Check is not ‘0’ so
an iteration is
required.
Set the guess
variable value to the
current solution.
A problem that require iterative solution
𝑄 = ℎ𝐴 𝑇𝑠 − 𝑇𝑎
Let’s say:
𝑄 = 2000𝑊
𝐴 = 1𝑚2
𝑇𝑎 = 25°𝐶
ℎ = 10𝑃
Where,
𝑃 = 𝑃𝑟 𝑇𝑠 for ‘Air’
Find 𝑇𝑠?
Q = h*A*(Ts-Ta)
Q = 2000 [W]
A = 1 [m^2]
Ta = 25 [C]
h = 10*P
Ts_guess = 305.9 [C]
check = Ts_guess - Ts
P = prandtl(Air,T=Ts_guess)
EES Codes (Code-3.EES) Right approach!
10
MANUAL](https://image.slidesharecdn.com/eesiterations-180604041932/75/Performing-Iterations-in-EES-10-2048.jpg)
![A problem that require iterative solution
𝑄 = ℎ𝐴 𝑇𝑠 − 𝑇𝑎
Let’s say:
𝑄 = 2000𝑊
𝐴 = 1𝑚2
𝑇𝑎 = 25°𝐶
ℎ = 10𝑃
Where,
𝑃 = 𝑃𝑟 𝑇𝑠 for ‘Air’
Find 𝑇𝑠?
Q = h*A*(Ts-Ta)
Q = 2000 [W]
A = 1 [m^2]
Ta = 25 [C]
h = 10*P
Ts_guess = 313.3 [C]
check = Ts_guess - Ts
P = prandtl(Air,T=Ts_guess)
EES Codes (Code-3.EES) Right approach!
11
Check is still not ‘0’
so another iteration
is required.
Set the guess
variable value to the
current solution.
MANUAL](https://image.slidesharecdn.com/eesiterations-180604041932/75/Performing-Iterations-in-EES-11-2048.jpg)
![A problem that require iterative solution
𝑄 = ℎ𝐴 𝑇𝑠 − 𝑇𝑎
Let’s say:
𝑄 = 2000𝑊
𝐴 = 1𝑚2
𝑇𝑎 = 25°𝐶
ℎ = 10𝑃
Where,
𝑃 = 𝑃𝑟 𝑇𝑠 for ‘Air’
Find 𝑇𝑠?
Q = h*A*(Ts-Ta)
Q = 2000 [W]
A = 1 [m^2]
Ta = 25 [C]
h = 10*P
Ts_guess = 313.3 [C]
check = Ts_guess - Ts
P = prandtl(Air,T=Ts_guess)
EES Codes (Code-3.EES) Right approach!
Check is approx. ‘0’
so no further
iteration is required.
The current solution
(or guess) is the final
answer.
12
MANUAL](https://image.slidesharecdn.com/eesiterations-180604041932/75/Performing-Iterations-in-EES-12-2048.jpg)
![A problem that require iterative solution
15
Subprogram solver(Ts_guess : Ts)
Q = h*A*(Ts-Ta)
Q = 2000 [W]
A = 1 [m^2]
Ta = 25 [C]
h = 10*P
P = prandtl(Air,T=Ts_guess)
End
EES Codes (Code-4.EES) Step #1
Create a ‘solver ‘ subprogram as
shown containing the original
codes of your main problem.
Make sure that you are
evaluating the material
properties at the guess value.
AUTOMATED](https://image.slidesharecdn.com/eesiterations-180604041932/75/Performing-Iterations-in-EES-15-2048.jpg)
![Ts_guess = 100 [C]
Call control(Ts_guess : Ts)
A problem that require iterative solution
17
EES Codes (Code-4.EES) Step #3
Write these codes outside any
procedure or subprogram.
Yes, this is the initial guess.
AUTOMATED](https://image.slidesharecdn.com/eesiterations-180604041932/75/Performing-Iterations-in-EES-17-2048.jpg)
![Subprogram solver(Ts_guess : Ts, P, h)
Q = h*A*(Ts-Ta)
Q = 2000 [W]
A = 1 [m^2]
Ta = 25 [C]
h = 10*P
P = prandtl(Air,T=Ts_guess)
End
A problem that require iterative solution
20
EES Codes (Code-5.EES) Step #1
More variables at output
AUTOMATED
Multiple outputs](https://image.slidesharecdn.com/eesiterations-180604041932/75/Performing-Iterations-in-EES-20-2048.jpg)
![Ts_guess = 100 [C]
Call control(Ts_guess : Ts, P, h)
A problem that require iterative solution
22
EES Codes (Code-5.EES) Step #3
More variables at output
AUTOMATED
Multiple outputs](https://image.slidesharecdn.com/eesiterations-180604041932/75/Performing-Iterations-in-EES-22-2048.jpg)
![A problem that require iterative solution
24
EES Codes (Code-6.EES)
Subprogram solver(Ts_guess, Q, A, Ta : Ts, P, h)
Q = h*A*(Ts-Ta)
h = 10*P
P = prandtl(Air,T=Ts_guess)
End
Procedure control(Ts_guess, Q, A, Ta : Ts, P, h)
nmax = 100
dTmin = 0.001
n:=0
Ts := Ts_guess
Repeat
T = Ts
Call solver(T, Q, A, Ta : Ts, P, h)
n := n +1
dT = abs(T-Ts)
Until ( (n=nmax) or (dT < dTmin))
End
Q = 2000 [W]
A = 1 [m^2]
Ta = 25 [C]
Ts_guess = 100 [C]
Call control(Ts_guess, Q, A, Ta : Ts, P, h)
Step #1 Step #2 Step #3
AUTOMATED
Multiple inputs and outputs](https://image.slidesharecdn.com/eesiterations-180604041932/75/Performing-Iterations-in-EES-24-2048.jpg)
Uploaded byNaveed Rehman
Performing Iterations in EES
The document discusses manual and automated iterations in the Engineering Equation Solver (EES) for problems related to heat transfer. It contrasts problems that require iterative solutions with those that do not, providing specific examples and coding steps for EES. The author outlines methods for both manual and automated iteration processes to find unknown variables like temperature and material properties.
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Similar to Performing Iterations in EES
Performing Iterations in EES
- 1. Performing Manual and AutomatedIterations in Engineering Equation Solver (EES) Examples from Heat Transfer Naveed ur Rehman http://www.naveedurrehman.com/ 4th June, 2018
- 2. All the EEScodes shown in the examples are available at: https://goo.gl/KExGFi 2
- 3. A problem thatdoesn’t require iterative solution 3
- 4. A problem thatdoesn’t require iterative solution 𝑄 = ℎ𝐴 𝑇𝑠 − 𝑇𝑎 Let’s say: 𝑄 = 2000𝑊 𝐴 = 1𝑚2 𝑇𝑎 = 25°𝐶 ℎ = 10𝑃 Where, 𝑃 = 𝑃𝑟 𝑇𝑎 for ‘Air’ Find 𝑇𝑠? Note: The Prandtl number, which is a material property, is required at a known temperature (Ta=25⁰C). No iteration is needed! 4
- 5. A problem thatdoesn’t require iterative solution 𝑄 = ℎ𝐴 𝑇𝑠 − 𝑇𝑎 Let’s say: 𝑄 = 2000𝑊 𝐴 = 1𝑚2 𝑇𝑎 = 25°𝐶 ℎ = 10𝑃 Where, 𝑃 = 𝑃𝑟 𝑇𝑎 for ‘Air’ Find 𝑇𝑠? Q = h*A*(Ts-Ta) Q = 2000 [W] A = 1 [m^2] Ta = 25 [C] h = 10*P P = prandtl(Air,T=Ta) EES Codes (Code-1.EES) 5
- 6. A problem thatrequire iterative solution 6 Performing manual iteration in EES
- 7. A problem thatrequire iterative solution 𝑄 = ℎ𝐴 𝑇𝑠 − 𝑇𝑎 Let’s say: 𝑄 = 2000𝑊 𝐴 = 1𝑚2 𝑇𝑎 = 25°𝐶 ℎ = 10𝑃 Where, 𝑃 = 𝑃𝑟 𝑇𝑠 for ‘Air’ Find 𝑇𝑠? Note: The Prandtl number, which is a material property, is required at an unknown temperature! This problem can not be solved without performing iteration. 7 MANUAL
- 8. A problem thatrequire iterative solution 𝑄 = ℎ𝐴 𝑇𝑠 − 𝑇𝑎 Let’s say: 𝑄 = 2000𝑊 𝐴 = 1𝑚2 𝑇𝑎 = 25°𝐶 ℎ = 10𝑃 Where, 𝑃 = 𝑃𝑟 𝑇𝑠 for ‘Air’ Find 𝑇𝑠? Q = h*A*(Ts-Ta) Q = 2000 [W] A = 1 [m^2] Ta = 25 [C] h = 10*P P = prandtl(Air,T=Ts) EES Codes (Code-2.EES) Wrong approach! 8 MANUAL
- 9. A problem thatrequire iterative solution 𝑄 = ℎ𝐴 𝑇𝑠 − 𝑇𝑎 Let’s say: 𝑄 = 2000𝑊 𝐴 = 1𝑚2 𝑇𝑎 = 25°𝐶 ℎ = 10𝑃 Where, 𝑃 = 𝑃𝑟 𝑇𝑠 for ‘Air’ Find 𝑇𝑠? Q = h*A*(Ts-Ta) Q = 2000 [W] A = 1 [m^2] Ta = 25 [C] h = 10*P Ts_guess = 100 [C] check = Ts_guess - Ts P = prandtl(Air,T=Ts_guess) EES Codes (Code-3.EES) Right approach! Assume some ‘guess’ value of the unknown variable. Your guess will correct only when the difference between the solution and your guess will be ‘0’ i.e. check = 0 Evaluate material property at guess value. 9 MANUAL
- 10. Check is not‘0’ so an iteration is required. Set the guess variable value to the current solution. A problem that require iterative solution 𝑄 = ℎ𝐴 𝑇𝑠 − 𝑇𝑎 Let’s say: 𝑄 = 2000𝑊 𝐴 = 1𝑚2 𝑇𝑎 = 25°𝐶 ℎ = 10𝑃 Where, 𝑃 = 𝑃𝑟 𝑇𝑠 for ‘Air’ Find 𝑇𝑠? Q = h*A*(Ts-Ta) Q = 2000 [W] A = 1 [m^2] Ta = 25 [C] h = 10*P Ts_guess = 305.9 [C] check = Ts_guess - Ts P = prandtl(Air,T=Ts_guess) EES Codes (Code-3.EES) Right approach! 10 MANUAL
- 11. A problem thatrequire iterative solution 𝑄 = ℎ𝐴 𝑇𝑠 − 𝑇𝑎 Let’s say: 𝑄 = 2000𝑊 𝐴 = 1𝑚2 𝑇𝑎 = 25°𝐶 ℎ = 10𝑃 Where, 𝑃 = 𝑃𝑟 𝑇𝑠 for ‘Air’ Find 𝑇𝑠? Q = h*A*(Ts-Ta) Q = 2000 [W] A = 1 [m^2] Ta = 25 [C] h = 10*P Ts_guess = 313.3 [C] check = Ts_guess - Ts P = prandtl(Air,T=Ts_guess) EES Codes (Code-3.EES) Right approach! 11 Check is still not ‘0’ so another iteration is required. Set the guess variable value to the current solution. MANUAL
- 12. A problem thatrequire iterative solution 𝑄 = ℎ𝐴 𝑇𝑠 − 𝑇𝑎 Let’s say: 𝑄 = 2000𝑊 𝐴 = 1𝑚2 𝑇𝑎 = 25°𝐶 ℎ = 10𝑃 Where, 𝑃 = 𝑃𝑟 𝑇𝑠 for ‘Air’ Find 𝑇𝑠? Q = h*A*(Ts-Ta) Q = 2000 [W] A = 1 [m^2] Ta = 25 [C] h = 10*P Ts_guess = 313.3 [C] check = Ts_guess - Ts P = prandtl(Air,T=Ts_guess) EES Codes (Code-3.EES) Right approach! Check is approx. ‘0’ so no further iteration is required. The current solution (or guess) is the final answer. 12 MANUAL
- 13. A problem thatrequire iterative solution 13 Performing automated iteration in EES
- 14. A problem thatrequire iterative solution 𝑄 = ℎ𝐴 𝑇𝑠 − 𝑇𝑎 Let’s say: 𝑄 = 2000𝑊 𝐴 = 1𝑚2 𝑇𝑎 = 25°𝐶 ℎ = 10𝑃 Where, 𝑃 = 𝑃𝑟 𝑇𝑠 for ‘Air’ Find 𝑇𝑠? 14 Same problem AUTOMATED
- 15. A problem thatrequire iterative solution 15 Subprogram solver(Ts_guess : Ts) Q = h*A*(Ts-Ta) Q = 2000 [W] A = 1 [m^2] Ta = 25 [C] h = 10*P P = prandtl(Air,T=Ts_guess) End EES Codes (Code-4.EES) Step #1 Create a ‘solver ‘ subprogram as shown containing the original codes of your main problem. Make sure that you are evaluating the material properties at the guess value. AUTOMATED
- 16. Procedure control(Ts_guess :Ts) nmax = 100 dTmin = 0.001 n:=0 Ts := Ts_guess Repeat T = Ts Call solver(T : Ts) n := n +1 dT = abs(T-Ts) Until ( (n=nmax) or (dT < dTmin)) End A problem that require iterative solution 16 EES Codes (Code-4.EES) Step #2 Create a ‘control‘ procedure to control the flow of iterations. There is no need to change anything else in this procedure. ‘nmax’ is the maximum number of iterations (100 is more than enough!) dTmin is the stopping condition, similar to ‘check’. If you want to be super precise, use dTmin=0 AUTOMATED
- 17. Ts_guess = 100[C] Call control(Ts_guess : Ts) A problem that require iterative solution 17 EES Codes (Code-4.EES) Step #3 Write these codes outside any procedure or subprogram. Yes, this is the initial guess. AUTOMATED
- 18. A problem thatrequire iterative solution 18 Performing automated iteration in EES and getting more than single output
- 19. A problem thatrequire iterative solution 𝑄 = ℎ𝐴 𝑇𝑠 − 𝑇𝑎 Let’s say: 𝑄 = 2000𝑊 𝐴 = 1𝑚2 𝑇𝑎 = 25°𝐶 ℎ = 10𝑃 Where, 𝑃 = 𝑃𝑟 𝑇𝑠 for ‘Air’ Find 𝑇𝑠, P and ℎ? 19 Same problem but required variables are more than single. AUTOMATED Multiple outputs
- 20. Subprogram solver(Ts_guess :Ts, P, h) Q = h*A*(Ts-Ta) Q = 2000 [W] A = 1 [m^2] Ta = 25 [C] h = 10*P P = prandtl(Air,T=Ts_guess) End A problem that require iterative solution 20 EES Codes (Code-5.EES) Step #1 More variables at output AUTOMATED Multiple outputs
- 21. Procedure control(Ts_guess :Ts, P, h) nmax = 100 dTmin = 0.001 n:=0 Ts := Ts_guess Repeat T = Ts Call solver(T : Ts, P, h) n := n +1 dT = abs(T-Ts) Until ( (n=nmax) or (dT < dTmin)) End A problem that require iterative solution 21 EES Codes (Code-5.EES) Step #2 More variables at output AUTOMATED Multiple outputs
- 22. Ts_guess = 100[C] Call control(Ts_guess : Ts, P, h) A problem that require iterative solution 22 EES Codes (Code-5.EES) Step #3 More variables at output AUTOMATED Multiple outputs
- 23. A problem thatrequire iterative solution 23 Performing automated iteration in EES and working with inputs from outside subprogram
- 24. A problem thatrequire iterative solution 24 EES Codes (Code-6.EES) Subprogram solver(Ts_guess, Q, A, Ta : Ts, P, h) Q = h*A*(Ts-Ta) h = 10*P P = prandtl(Air,T=Ts_guess) End Procedure control(Ts_guess, Q, A, Ta : Ts, P, h) nmax = 100 dTmin = 0.001 n:=0 Ts := Ts_guess Repeat T = Ts Call solver(T, Q, A, Ta : Ts, P, h) n := n +1 dT = abs(T-Ts) Until ( (n=nmax) or (dT < dTmin)) End Q = 2000 [W] A = 1 [m^2] Ta = 25 [C] Ts_guess = 100 [C] Call control(Ts_guess, Q, A, Ta : Ts, P, h) Step #1 Step #2 Step #3 AUTOMATED Multiple inputs and outputs
- 25. Performing Manual and AutomatedIterations in Engineering Equation Solver (EES) Examples from Heat Transfer Thank you! Naveed ur Rehman http://www.naveedurrehman.com/