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| author | priyanka | 2015-06-24 15:03:17 +0530 |
|---|---|---|
| committer | priyanka | 2015-06-24 15:03:17 +0530 |
| commit | b1f5c3f8d6671b4331cef1dcebdf63b7a43a3a2b (patch) | |
| tree | ab291cffc65280e58ac82470ba63fbcca7805165 /530/CH6/EX6.3 | |
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initial commit / add all books
Diffstat (limited to '530/CH6/EX6.3')
| -rwxr-xr-x | 530/CH6/EX6.3/example_6_3.sce | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/530/CH6/EX6.3/example_6_3.sce b/530/CH6/EX6.3/example_6_3.sce new file mode 100755 index 000000000..fb624c2dd --- /dev/null +++ b/530/CH6/EX6.3/example_6_3.sce @@ -0,0 +1,51 @@ +clear;
+clc;
+
+// A Textbook on HEAT TRANSFER by S P SUKHATME
+// Chapter 6
+// Heat Transfer by Natural Convection
+
+
+// Example 6.3
+// Page 260
+printf("Example 6.3, Page 260 \n \n");
+
+s = 0.2 ; // [m]
+d = 0.005 ; // [m]
+rho = 7900 ; // [kg/m^3]
+Cp = 460 ; // [J/kg K]
+
+T_air = 20 ; // [C]
+// For 430 C to 330 C
+T_avg = 380 ; // [C]
+Tm = (T_avg + T_air)/2 ; // [C]
+
+
+v = 34.85*10^-6 ; // [m^2/s]
+Pr = 0.680 ;
+k = 0.0393 ; // [W/m K]
+
+Re = 9.81*1/(273+Tm)*(T_avg-T_air)*(s^3)/(v^2)*Pr;
+
+// From eqn 6.2.31
+Nu = 0.68 + 0.670*(Re^(1/4))/[1+(0.492/Pr)^(4/9)]^(4/9);
+
+h = Nu*k/s; // [W/m^2 K]
+t1 = rho*s*s*d*Cp/((s^2)*2*h)*log((430-T_air)/(330-T_air)); // [s]
+printf("Time required for the plate to cool from 430 C to 330 C is %f s\n",t1);
+
+// for 330 to 230
+h2 = 7.348 ; // [W/m^2 K]
+t2 = rho*s*s*d*Cp/((s^2)*2*h2)*log((330-T_air)/(230-T_air)); // [s]
+printf("Time required for the plate to cool from 330 C to 230 C is %f s\n",t2);
+
+// for 230 to 130
+h3 = 6.780; // [W/m^2 K]
+t3 = rho*s*s*d*Cp/((s^2)*2*h3)*log((230-T_air)/(130-T_air)); // [s]
+printf("Time required for the plate to cool from 230 C to 130 C is %f s\n",t3);
+
+// Total time
+
+time = t1+t2+t3;
+minute = time/60;
+printf("Hence, time required for the plate to cool from 430 C to 130 C \n = %f s\n = %f min",time,minute);
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