Page 130 - DJJ20063- Thermodynamics 1

DJJ20063- Thermodynamics 1

Example 3.7

A boiler operates at a constant pressure of 15 bar, and evaporates fluid at the rate of

1000 kg/h. At entry to the boiler, the fluid has an enthalpy of 165 kJ/kg and on leaving

the boiler the enthalpy of the fluid is 2200 kJ/kg. Determine the heat energy supplied

to the boiler.

Solution to Example 3.7

The steady flow energy equation gives

  C 2 −C 2  
+
Q −W = m   (h − h )  2 1   ( + gZ − gZ )


 2 1  2  2 1 



Q = heat energy per hour entering system
W = work energy per hour leaving system = 0

m = fluid flow rate = 1000 kg/h
h2 = 2200 kJ/kg

h1 = 165 kJ/kg

C1& C2 = neglected

Z1& Z2 = neglected

Thus, the steady flow energy equation becomes

kJ kg ) kJ
Q = 1000 (2200 − 165
h h kg

kJ
Q = . 2 035 x10 6
h
121 | P a g e