THE FIRST LAW OF THERMODYNAMICS

According to eq. (30) the ''first law of thermodynamics'' has to be used (understand) to describe closed systems only. In that case, the internal energy u of the system can be changed by using heat and work only. The work is defined by integral F(x) dx. The heat is defined by the ''first law of thermodynamics''. Because of the difference between accumulation 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 thermodynamics. In agreement to Baehr [1] the ''first law of thermodynamics'' is a general energy flow balance for the internal energy the kinetical energy and the potential energy. Work, heat and enthalpy are the variables of the transfer processes.