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clear;
clc;
disp('Example .10');
// aim : To determine
// (a) the mass of steam entering the heater
// (b) the mass of water entering the heater
// Given values
x = .95;// Dryness fraction
P = .7;// pressure,[MN/m^2]
d = 25;// internal diameter of heater,[mm]
C = 12; // steam velocity in the pipe,[m/s]
// solution
// from steam table at .7 MN/m^2 pressure
hf = 697.1;// [kJ/kg]
hfg = 2064.9;// [kJ/kg]
hg = 2762.0; // [kJ/kg]
vg = .273; // [m^3/kg]
// (a)
v = x*vg; // [m^3/kg]
ms_dot = %pi*(d*10^-3)^2*C*3600/(4*v);// mass of steam entering, [kg/h]
mprintf('\n (a) The mass of steam entering the heater is = %f kg/h \n',ms_dot);
// (b)
h = hf+x*hfg;// specific enthalpy of steam entering heater,[kJ/kg]
// again from steam tables
hf1 = 376.8;// [kJ/kg] at 90 C
hf2 = 79.8;// [kJ/kg] at 19 C
// using energy balance,mw_dot*(hf1-hf2)=ms_dot*(h-hf1)
mw_dot = ms_dot*(h-hf1)/(hf1-hf2);// mass of water entering to heater,[kg/h]
mprintf('\n (b) The mass of water entering the heater is = %f kg/h \n',mw_dot);
// End
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