THE FIRST LAW OF THERMODYNAMICS

According to eq. (30) the ''first law of thermodynamics'' has to be us ed (understand) to describe closed systems only. In that case, the int ernal energy u of the system can be changed by using heat and work onl y. The work is defined by integral F(x) dx. The heat is defined by the ''first law of thermodynamics''. Because of the difference between ac cumulation of energy, transport of energy and conversion of energy it is necessary to take into account more energies than u= e(th) + e(cp) + e(w) such as kinetical energy and potential energy in the field of t hermodynamics. In agreement to Baehr [1] the ''first law of thermodyna mics'' is a general energy flow balance for the internal energy the ki netical energy and the potential energy. Work, heat and enthalpy are t he variables of the transfer processes.