Boiler Pump
The system in the below diagram pumps 60,000 kg of water per hour into a boiler. The pump discharges compressed liquid at 50°C and 20 MPa. The boiler discharges superheated vapor at 550°C and 20 MPa. In the boiler, what is the heat transfer rate to the working fluid?
Expand Hint
$$$\dot{Q}=\dot{m}(h_2-h_1)$$$
where
$$\dot{Q}$$
is the heat transfer rate on the working fluid,
$$\dot m$$
is the mass flowrate, and
$$h$$
is the specific enthalpy.
Hint 2
Mass flowrate is measured in kg/sec.
An energy balance on the boiler:
$$$\dot{Q}=\dot{m}(h_2-h_1)$$$
where
$$\dot{Q}$$
is the heat transfer rate on the working fluid,
$$\dot m$$
is the mass flowrate, and
$$h$$
is the specific enthalpy.
Because mass flowrate is measured in kg/sec:
$$$\frac{60,000kg}{1hr}\cdot \frac{1hr}{60min}\cdot \frac{1min}{60sec}=\frac{60,000kg}{3,600sec}$$$
Thus,
$$$\dot Q=\frac{60,000kg}{3,600sec}\cdot [(4,000-200)\frac{kJ}{kg}]=(16.67)(3,800)\frac{kJ}{s}$$$
$$$\dot Q=63,333\:kW\approx 63\:MW$$$
63 MW
Time Analysis
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