Fundamentals of designing inductive-conductive heaters

The article presents the design features of inductive-conductive heaters, determines the relationship between electromagnetic loads, material properties and dimensions of the heat exchanger, presents the results of compiling a universal dependence of the main parameters of inductive-conductive heaters as a function of heat output, frequency and voltage value. Values determined by the properties and cost of materials, conditions of heat resistance and electrical safety, technological capabilities of production and operating conditions are taken as design constants. These values are selected at the beginning of the design and remain constant until the results of the calculation of the acceptable basic dimensions of the device are obtained. Nomograms of the dependence of the wall thickness of the heating chamber on the value of the current density and heat flux were obtained. The choice of the optimal design result is carried out by means of an economic assessment of the investigated options from the point of view of minimizing the cost of production and losses of electricity during the operation of the electric heater. An algorithm for designing the main dimensions of single-phase and three-phase inductive-conductive heaters with a capacity of 1 to 250 kW per unit of a product for a voltage of 0.4 kV and a frequency of 50 Hz is given and the results of calculating the main mass-cost indicators are presented. The analysis of the calculated data indicates the preference of electric heaters with a higher heat output in terms of specific cost and specific weight. At the same time, the relative capital costs of funds per unit mass of the product remain practically constant.