EJEMPLO DE DIFERENCIAS DIVIDIDAS FINITAS En una planta se bombea esencia de trementina, 60 ◦C, desde la base de una colu
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EJEMPLO DE DIFERENCIAS DIVIDIDAS FINITAS En una planta se bombea esencia de trementina, 60 ◦C, desde la base de una columna de fraccionamiento hasta un gran tanque de almacenamiento descubierto. La columna opera a 1,29 atmósferas. En la siguiente tabla se representan los datos relativos los litros por hora que puede bombear la bomba en función de la potencia en watios a la que es necesario que trabaje: Punto 0 Q(l/h) 500 N(w) 365
1 700 361.6
2 900 370.6 4
3 1100 379.6 8
4 1300 384.4 6
5 1500 395.5
6 1700 395.9 5
7 1900 397
PRIMERAS DIFERENCIAS
-
f(X0,
X1) =
-
f(X1,
X2) =
-
f(X2,
X3) =
-
f(X3,
X4) =
-
f(X4,
X5) =
-
f(X5,
X6) =
-
f(X6,
X7) =
f ( x 1) −f ( x 0) x 1−x 0
=
361.6−36 5 700−500
x 2−x 1
=
370.64−361.6 900−700
f ( x 3 )−f ( x 2) x 3−x 2
=
379.68−370.64 1100−900
= 0.045200000
x 4 −x 3
=
384.46−379.68 1300−1100
= 0.023980000
f ( x 5 )−f ( x 4 ) x 5−x 4
=
395.5−384.46 1500−1300
x 6 −x5
=
395.95−395.5 1700−1500 = 0.002250000
f ( x 7 )−f ( x 6) x 7−x 6
=
397−395.95 1900−1700
f ( x 2) −f ( x 1)
f ( x 4 ) −f ( x 3 )
f ( x 6 )−f ( x 5)
SEGUNDAS DIFERENCIAS
= -0.017000000
= 0.045200000
= 0.055200000
= 0.005250000
-
f(X0,
X1, X2) =
f ( x 1 , x 2 )−f (x 0 , x 1)
=
0.0452−(−0.017) 900−500
=
0.0452−0.0452 1100−700
x 4−x 2
=
0.02398−0.0452 1300−900
=
f ( x 4 , x 5 ) −f ( x 3 , x 4) x 5−x 3
=
0.0552−0.02398 1500−1100
=
x 6 −x 4
=
0.00225−0.0552 1700−1300
=
f ( x 6 , x 7 )−f (x 5 , x 6 ) x7 −x 5
=
0.00525−0.00225 1900−1500
x 2−x 0
=
0.000155500 -
f(X1,
X2, X3) =
f ( x 2 , x 3 )−f (x 1 , x 2) x 3−x 1
=
0.0000000000 -
f(X2,
X3, X4) =
f ( x 3 , x 4 ) −f (x 2 , x3 )
-0.000053050 -
f(X3,
X4, X5) =
0.000132535 -
f(X4,
X5, X6) =
f ( x 5 , x 6 )−f ( x 4 , x 5)
-0.000132375 -
f(X5,
X6, X7) =
=
0.000007500 TERCERAS DIFERENCIAS -
f(X0,
X1, X2, X3) =
f ( x 1 , x 2 , x 3 )−f ( x 0 , x 1 , x 2) x 3−x 0
=
0−0.0001555 1100−500
f ( x 2 , x 3 , x 4 ) −f ( x1 , x2 , x3 ) x 4−x 1
=
−0.00005305−0 1300−700
-0.000000259 -
f(X1,
X2, X3, X4) =
= -0.000000088 -
f(X2,
X3, X4, X5) =
f ( x 3 , x 4 , x5 ) −f ( x2 , x3 , x 4 )
0.00007805−(−0.00005305) 1500−900
x 5−x 2
=
=0.000000219
=
-
f(X3,
X4, X5, X6) =
f ( x 4 , x 5 , x6 ) −f ( x 3 , x 4 , x 5 ) x 6−x 3
−0.000132375−0.00007805 1700−1100
-
f(X4,
X5, X6, X7) =
=
=
-0.000000351
f ( x 5 , x 6 , x 7 )−f ( x 4 , x 5 , x 6 ) x 7−x 4
0.0000075−(−0.000132375) 1900−1300
=
= 0.000000233
CUARTAS DIFERENCIAS
-
f(X0,
f ( x 1 , x 2 , x 3 , x 4 ) −f ( x0 , x 1 , x 2 , x 3) x 4−x 0
X1, X2, X3, X4) =
−0.000000088+0.000000259 1300−500
-
f(X1,
X2, X3, X4, X5) =
=0
f ( x 2 , x 3 , x 4 , x5 ) −f ( x1 , x 2 , x 3 , x 4 ) x 5−x 1
0.000000219+ 0.000000088 1500−700
-
f(X2,
X3, X4, X5, X6) =
f(X3,
X4, X5, X6, X7) =
0.0 00000233+ 0.000000351 1900−1100
QUINTA DIFERENCIAS
=
=0
f ( x 3 , x 4 , x5 , x 6 )−f ( x 2 , x 3 , x 4 , x5 ) x 6−x 2
−0. 000000351−0.000000219 1700−900
-
=
=
= -0.0000001
f ( x 4 , x 5 , x6 , x 7 )−f ( x 3 , x 4 , x5 , x 6) x 7−x 3
= 0.000000001
=
f(X0,
-
X1, X2, X3, X4, X5) = 0−0
= 1500−500 f(X1,
-
=
= i
x 5−x 0
=0
X2, X3, X4, X5, X6) =
f ( x 2 , x 3 , x 4 , x5 , x 6 )−f ( x 1 , x 2 , x 3 , x 4 , x 5) x 6−x 1
−0.0000 001−0 =0 1700−700
f(X2,
-
f ( x 1 , x 2 , x 3 , x 4 , x5 ) −f ( x 0 , x 1 , x 2 , x 3 , x 4 )
X3, X4, X5, X6, X7) =
0.000000001+0.00000001 1900−1900
xi
f(xi)
0 500
365
Primeras
f ( x 3 , x 4 , x5 , x 6 , x 7 )−f ( x 2 , x 3 , x 4 , x 5 , x 6) x 7 −x2
=0
Segundas
Tercera s
Cuartas
Quintas
0.0170000 00 1 700
361.6
0.00015550 0 0.0452000 00
2 900
370.6 4
0.00000 0259 0
0.0452000 00 3 110 0
379.6 8
0.00000 0088 0.00005305 0
0.0239800 00 4 130 0
384.4 6
395.9 50
0 0.0000000 01
0.00000 0351 0.00013237 5
0.0022500 00 6 170 0
0
0.00013253 5
395.5
0
0.00000 0219
0.0552000 00 5 150 0
0
0
0.00000 0233 0.0000075
0
0.0525000 00 7 190 0
937