The thermomass theory was proposed by Guo Zengyuan.
Recently the thermomass theory has been compared with the extended irreversible thermodynamics and phonon hydrodynamics theory. As a statistic foundation, it has been found that the convective term in the generalized heat conduction equation based on thermomass theory actually comes from the nonlinear part of the phonon distribution function, thus the derivation can be regarded as a nonlinear solution of the phonon Boltzmann equation, which extends the content of the GK model. For nonequilibrium thermodynamics the thermomass theory presents a modification of the entropy and entropy production, avoiding the paradox of negative entropy production in heat wave propagation. Furthermore, the entropy production originates from the establishment of Onsager reciprocal relations.So the validation of the reciprocal relation is also made from a thermomass perspective. The concept of generalized forces and fluxes are clarified to remove the controversy of the proof of reciprocal relations, i.e. whether or not the generalized flux can be expressed as the time derivative of certain state variables.