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+
+
+// Display mode
+mode(0);
+
+// Display warning for floating point exception
+ieee(1);
+
+clc;
+disp("Principles of Heat Transfer, 7th Ed. Frank Kreith et. al Chapter - 7 Example # 7.5 ")
+
+//Initial temperature in degree F
+Ti = 58;
+//Final temperature in degree F
+Tf = 86;
+//Film temperature of air in degree F
+Tair = (Ti+Tf)/2;
+//Temperature of condensing steam in degree F
+Tsteam = 212;
+//Heat transfer coeffcient in Btuh/ft2F
+ho = 1000;
+//Length of tube in ft
+L = 2;
+//Diameter of tube in in
+d = 0.5;
+//Wall thickness in inches
+t = 0.049;
+//Pitch in inches
+p = 3/4;
+//Width in ft and height in inches of rectangular shell
+H = 15;
+W = 2;
+//Mass flow rate of air in lb/h
+m = 32000;
+
+//Appendix 2, Table 28 then gives for the properties of air at this mean
+//bulk temperature
+
+//Density in lb/ft3
+rho = 0.072;
+//Thermal conductivity in Btu/h F ft
+k = 0.0146;
+//Dynamic viscosity in lb/fth
+mu = 0.0444;
+//Prandtl number for air and steam
+Pr = 0.71;
+
+//Calcaulating minimum free area in ft2
+A = ((H/p)*W)*((p-d)/12);
+//Maximum gas velocity in lb/h.ft2
+Gmax = m/A;
+//Hence the reynolds number is
+Re = (Gmax*d)/(12*mu);
+
+//Assuming that more than 10 rows will be required, the heat transfer coefficient is calculated from Eq. (7.29)
+
+//h value in Btu/h ft2 F
+h = ((((k*12)/d)*(Pr^0.36))*0.27)*(Re^0.63);
+
+//The resistance at the steam side per tube in h F/Btu
+R1 = 12/(((ho*%pi)*(d-2*t))*L);
+
+//The resistance of the pipe wall in h F/Btu
+R2 = 0.049/(((60*%pi)*L)*(d-t));
+
+//The resistance at the outside of the tube in h F/Btu
+R3 = 1/((((h*%pi)*d)*L)/12);
+
+//Total resistance in h F/Btu
+R = R1+R2+R3;
+
+//Mean temperature difference between air and steam in degree F is
+deltaT = Tsteam-Tair;
+
+//Specific heat of air in Btu/lb F
+c = 0.241;
+
+//Equating the rate of heat flow from the steam to the air to the rate of enthalpy rise of the air
+
+//Solving for N gives
+disp("Total number of transverse tubes needed are")
+//Total number of transverse tubes
+N = (((m*c)*(Tf-Ti))*R)/(20*deltaT)
+disp("Rounding off = 5 tubes")
+
+if N<10 then
+  //Correction for h value, again in Btu/h ft2 F
+  h = 0.92*h;
+end;
+
+//The pressure drop is obtained from Eq. (7.37) and Fig. 7.25.
+
+//Velocity in ft/s
+Umax = Gmax/(3600*rho);
+//Acceleration due to gravity in ft/s2
+g = 32.2;
+disp("Corresponding pressure drop in lb/ft2")
+//Corresponding pressure drop in lb/ft2
+P = ((((6*0.75)*rho)*Umax)*Umax)/(2*g)