By applying the first and second laws to systems consisting of two subsystems separated by a wall, it is possible to determine the equilibrium conditions relevant for that wall's properties, e.g. a fixed diatermal wall, a mobile diathermal wall, a fixed permeable wall. The second law imposes a condition on the entropy production rate which implies relations between heat and temperature difference, matter transfer rate and chemical potential difference, volume rate of change and pressure difference. Thus, transport equations are introducted, akin to Fourier law, Fick law and Poiseuille law. These processes are examples of dissipative processes. A worked solution shows that when two subsystems are subjected to a mechanical action, non-symmetric heat flow may occur.