Flow interaction of thermal carriers with heat exchange surface is characteristic for simultaneous proceeding processes of heat and impulse transfer at viscous interaction with the surface and eddy formation. These processes are physically connected between each other as they have a common power carrier towards the normal to the surface. Simultaneousness and different directionality of these processes on heat exchange surface create a competitive situation between thermal voltage of unit Q, W, power consumption for pumping heat carries N, W: the first one increases approximately proportionally to the heat carrier rate, the second one increases proportionally to the rate cubed. If one neglects technical limitations the efficiency increase of heat exchange units operation requires intensification of the processes with respect to Q and intensity decrease concerning N. These reasonings should be also mapped for determination of operation efficiency of heat exchange units under alternating operation duty. It is of great importance for heat exchange units of regenerating type.

The shape and dimensions of boiler units and other thermal units protection barriers should be optimized according to industrial and economic criteria. However it is essential to take into consideration the requirements of mechanical, thermal and physical-chemical tolerance of protection materials at operating temperatures of the process. The authors represent the thermal-physical problem of temperature change of a protection barrier wall and thermal flows in it under unsteady-state conditions as an asymmetric process of thermal conduction.