blob: 587ded94a09350e0f896980cd4c325b83930fe30 (
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
35
|
clear;
clc;
printf('FUNDAMENTALS OF HEAT AND MASS TRANSFER \n Incropera / Dewitt / Bergman / Lavine \n EXAMPLE 9.3 Page 577 \n'); //Example 9.3
// Heat Loss from duct per meter of length
//Operating Conditions
Ts = 45+273; //[K] Surface Temperature
Tsurr = 15+273 ;//[K] Surrounding Temperature
H = .3 ;//[m] Height
w = .75 ;//[m] Width
//Table A.4 Air Properties T = 303 K
k = 26.5*10^-3 ;//[W/m.K]
uv = 16.2*10^-6 ;//[m^2/s] Kinematic Viscosity
al = 22.9*10^-6 ;//[m^2/s] alpha
be = 3.3*10^-3 ;//[K^-1] Tf^-1
Pr = .71 ;// Prandtl number
g = 9.81 ;//[m^2/s] gravitational constt
Ra = g*be*(Ts-Tsurr)/al*H^3/uv; //Length = Height
//From equatiom 9.27
Nu = [.68 + .67*Ra^.25/[1+(.492/Pr)^(9/16)]^(4/9)];
//for Sides
hs = Nu*k/H;
Ra2 = g*be*(Ts-Tsurr)/al*(w/2)^3/uv; //Length = w/2
//For top eq 9.31
ht = [k/(w/2)]*.15*Ra2^.3334;
//For bottom Eq 9.32
hb = [k/(w/2)]*.27*Ra2^.25;
q = (2*hs*H+ht*w+hb*w)*(Ts-Tsurr);
printf("\n Rate of heat loss per unit length of duct is %i W/m",q);
//END
|
