Alexander GRECHKO, Dr. Sc. (Technology), leading researcher of the State Institute of Non-Ferrous Metallurgy (GINTSVETMET) Heat exchange is one of the most complex physical phenomena which is hardly amenable to formalization and, therefore, is studied mostly by experimental methods. First, we collect experimental data on various instances of heat exchange, then we generalize these data by the similarity theory and deduce criteria-related dependences in the form of functions and mathematical equations. A large contribution to this field has been made by Academicians Mikhail Mikheyev and Samson Kutateladze. Heat exchange through contact (contact heat exchange, or transfer) is one of the hardest cases for pyrometallurgy. This phenomenon relates to thermal processes taking place between the contacting surfaces of two machine parts. Such assemblies are quite common in power engineering (generators, engines), machine manufacturing (detachable and permanent joints, clad, or composite metals), in transportation (slide faces and surfaces, fuel and lubricant layers on the surface) and the like. A theory has now been developed for obtaining quite reliable criteria of technical decision making in various industries. The contact heat-exchange theory involves research findings on the heat conduction (heat resistance) of contact places (joints) of two surfaces having a definite degree of roughness. The heat-transfer (resistance) value comprises the conductivity indicator at points of the actual contact of surfaces (prominent microroughnesses) and the same indicator for the medium (liquid or gas) filling the contact gap. A correlation of these two characteristics is the subject of the theory of the heat-exchange of contacting surfaces. Here such things are considered as the quality of surface working (of particular interest are cases when the precision factor is in the 1 to 10 u, range of roughness height), page 69 compressive force (in values of thousands and tens of thousa ... Читать далее