blob: f0fb0366dfaf2044c034845f91f4622dc87fdf39 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
|
clear;
clc;
printf('FUNDAMENTALS OF HEAT AND MASS TRANSFER \n Incropera / Dewitt / Bergman / Lavine \n EXAMPLE 5.5 Page 280 \n'); //Example 5.5
// Two step cooling process of Sphere
//Operating Conditions
ha = 10; //[W/m^2.K] Heat Convection coefficientat air
hw = 6000; //[W/m^2.K] Heat Convection coefficientat water
k = 20; //[W/m.K] Thermal Conductivity
rho = 3000; //[kg/m^3] Density
c = 1000; //[J/kg.K] Specific Heat
alpha = 6.66*10^-6; //[m^2/s]
Tiw = 335+273; //[K] Initial Temp
Tia = 400+273; //[K] Initial Temp
Tsurr = 20+273; //[K] Temp of surrounding
T = 50+273; //[K] Temp of center
ro = .005; //[m] radius of sphere
//Using eqn 5.10 and
Lc = ro/3;
Bi = ha*Lc/k;
ta = rho*ro*c*2.30*(log10((Tia-Tsurr)/(Tiw-Tsurr)))/(3*ha);
//From Table 5.1 at this Bi
C1 = 1.367;
eta = 1.8;
Fo = -1*2.30*log10((T-Tsurr)/((Tiw-Tsurr)*C1))/eta^2;
tw = Fo*ro^2/alpha;
printf("\n (a) Time required to accomplish desired cooling in air ta = %.1f s\n\n (b) Time required to accomplish desired cooling in water bath tw = %.2f s",ta,tw);
//END
|
