From b1f5c3f8d6671b4331cef1dcebdf63b7a43a3a2b Mon Sep 17 00:00:00 2001
From: priyanka
Date: Wed, 24 Jun 2015 15:03:17 +0530
Subject: initial commit / add all books

---
 405/CH7/EX7.13/7_13.sce | 39 +++++++++++++++++++++++++++++++++++++++
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+clear;
+clc;
+printf("\t\t\tExample Number 7.13\n\n\n");
+// combined free and forced convection with air
+// Example 7.12 (page no.-353-355) 
+// solution
+
+p = 101325;// [Pa] pressure of air
+Ta = 27;// [degree celsius] temperature of air
+d = 0.025;// [m] diameter of tube
+u = 0.3;// [m/s] velocity of air
+Tw = 140;// [degree celcius] temperature of tube wall
+L = 0.4;// [m] length of tube
+R = 287;// [] universal gas constant
+// the properties of air are evaluated at the film temperature:
+Tf = (Tw+Ta)/2;// [degree celcius]
+// the properties of interest are thus
+kf = 0.0305;// [W/m degree celcius]
+Pr = 0.695;// prandtl number
+Beta = 1/(Tf+273);// [K^(-1)]
+g = 9.8;// [square meter/s] acceleration due to gravity
+mu_f = 2.102*10^(-5);// [Kg/m s]
+mu_w = 2.337*10^(-5);// [Kg/m s]
+rho_f = p/(R*(Tf+273));// [Kg/cubic meter]
+// let us take the bulk temperature as 27 degree celsius for evaluating mu_b;then
+mu_b = 1.8462*10^(-5);// [Kg/m s]
+// the significant parameters are calculated as 
+Re_f = rho_f*u*d/mu_f;
+Gr = rho_f^(2)*g*Beta*(Tw-Ta)*d^(3)/mu_f^(2);
+Z = Gr*Pr*d/L;// constant
+// according to figure(7-14)(page no.-354), the mixed convection flow regime is encountered. thus we must use equation(7-77).
+// The graetz number is calculated as 
+Gz = Re_f*Pr*d/L;
+// and the numerical calculation for equation(7-77) becomes
+Nu = 1.75*(mu_b/mu_w)^(0.14)*[Gz+0.012*(Gz*Gr^(1/3))^(4/3)]^(1/3);
+// the average heat transfer coefficient is calculated as 
+h_bar = Nu*kf/d;// [W/square meter degree celsius]
+printf("heat transfer coefficient is %f W/square meter degree celsius",h_bar);
+
-- 
cgit