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clear ;
clc;
printf("\t Example 7.1\n");
D=0.001; //diameter of tube,m
T1=293; // temperature of cold water, K
T2=347; // temperature of hot water, K
T3=320; //operating temperature of hot water, K
Q=6000; //heat flux,W/m^2
v=0.2 ; //speed of water,m/s
k=0.6367; //thermal conductivity,W/(m*K)
v1=1.541*10^-7; // molecular diffusivity, m^2/s
v2=0.556*10^-6; //molecular diffusivity, m^2/s
Re=D*v/v2; //reynolds no.
L=D*(54-11/48*Q*D/k)*v*k/(4*Q*v1); //length that is down the tube for water reach to 74 C at its hottest point,m
printf("length that is down the tube for water reach to 74 C at its hottest point is : %.3f m ,while we did not evaluate the thermal entry length here, it may be shown to be much, much less than 1785 diametres.\n",L);
//end
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