FIRST LAW OF THERMODYNAMICS Thermodynamics Example 5:   Overall Thermodynamic Balance A  nuclear  facility  (primary  side)  is  to  be  studied  as  a  complete  system.    The  heat produced  by  the  heat  source  is  1.36  x  10¹⁰  Btu/hr.    The  heat  removed  by  the  heat exchanger (steam generator) is 1.361 x 10¹⁰ Btu/hr.  What is the required pump power to maintain a stable temperature? Solution: = pump work, = heat produced by the heat source, heat transferred W_p Q_c Q into steam generator m(h pe ke) W_p Q_c Q_sg m(h pe ke) 1) For a closed system, the mass entering and leaving the system is zero, therefore, is constant.   The energy entering and leaving the system is zero, and you can m assume that the ke and pe are constant so that: _c+ _p= sg Q W Q 2) = W_p Q_sg Q_c = 1.361 x 10¹⁰ Btu/hr - 1.36 x 10¹⁰ Btu/hr = 1.0 x 10⁷ Btu/hr = 4007 hp W_p Of the examples just completed, emphasis should be placed on the heat exchanger analysis.  Both the primary side  and the  secondary side  have their own  energy balances  as the  heat energy  is transferred  from  one  fluid  to  the  other.    In  calculating  heat  exchanger  heat  transfer  rates,  we found that we could use the equations . Q mc_pDh Perhaps a short analysis of the secondary side of the heat exchanger will aid in understanding the heat exchanger’s importance in the energy conversion process. HT-01 Page 66 Rev. 0