Book excerpt: Heat-transfer equipment, typically represented by, for example, heat exchangers, process furnaces, and steam boilers, is among the essential equipment used for production processes in a number of industries (e.g., chemical and petrochemical, food, pharmaceutical, power, aviation and space) as well as for processes and applications in the communal sphere (e.g., waste incineration plants, heating plants, laundries, hospitals, server rooms, agriculture applications). Increasing demands for economical and efficient heat energy management can only be met when not only the layout of the whole system but also the individual heat-transfer equipment and its details are designed according to state-of-the-art knowledge. The purpose of this Special Issue is to present the latest advances in designing, modeling, testing, and operating heat-transfer equipment, including unconventional and innovative designs of heat-transfer equipment and their applications.