FIRST LAW OF THERMODYNAMICS
A thermodynamic balance across the reactor core gives an indication of the amount of
heat removed by the coolant that is given off by the fuel rods.
Example 4: Thermodynamic Balance across Heat Source
In a particular facility, the temperature leaving the reactor core is 612°F, while that
entering the core is 542°F. The coolant flow through the heat source is 1.32 x 108
lbm/hr. The cp of the fluid averages 1.47 Btu/lbm°F. How much heat is being removed
from the heat source? The pe and ke energies are small compared to other terms and
may be neglected.
where cp = specific heat capacity.
1.32 x 108 lbm/hr (1.47 Btu/lbm -oF) (612 - 542oF)
1.36 x 1010 Btu/hr
For this example
has been used to calculate the heat transfer rate since no
phase change has occurred. However,
(hout-hin) could also have been used had
the problem data included inlet and outlet enthalpies.
The individual principal components of a reactor system have been thermodynamically
analyzed. If all components were combined into an overall system, the system could be
analyzed as a "closed" system problem. Such an analysis is illustrated in the following