The sustainable development of modern society requires the efficient use of energy in industry and in the communal sector. This is possible by increasing heat recuperation and using intensified heat exchangers. Recuperative heat exchangers enable the use of heat from streams exiting high-temperature processes to heat the cold supply streams. They have a lot of applications, such as ammonia and methanol synthesis, high-temperature nuclear reactors, the Brayton power cycle, pasteurisation of food products, etc. A new method for selecting the best channel geometry for specific applications of recuperative heat exchangers is proposed, based on the use of mini- and micro-channels of various types and sizes. It involves the numerical solution of a novel equation developed to evaluate the thermal-hydraulic performance of mini- and micro-channels in certain process conditions. This allows the comparison of performance for channels using different methods of heat transfer enhancement. The new simplified formulas for micro-channel performance evaluation in the laminar flow regime are also proposed. The influence of operating heat load on optimal channel geometry is discussed, and the way to modernise channel parameters specifically for use in micro-process systems. The methodology is illustrated by the example of an industrial application. Compared to macro-channels, the heat transfer area of HE with mini-channels can be reduced by 1.2 to 3 times for intensified mini-channels with a hydraulic diameter of 1 mm, with possible reduction by 3 to 5 times in micro-channels of the hydraulic diameter 0.1 mm. The use of the proposed equation and the correct adjustment of the channel length results in up to 12% smaller heat transfer area with channels of the same geometry. It can be improved by about 37% by selection of a proper channel type.