INFLUENCE OF THE SWITCHING PERIODS FREQUENCY ON THE THERMAL EMISSIVITY OF A REGENERATIVE AIR PREHEATER

A laboratory stand with a regenerative air preheater, an automated control system and measurement of airflow parameters and a nozzle designed to study the heat transfer of a packet of parallel plates under non-stationary conditions for different periods is described. The technique of measuring the unsteady temperature of cold and hot coolant flows adjusted for inertia of the thermocouples and the method of measuring the heat transfer co efficient of plates. The time variations of the Nusselt number and the heat load transmitted by the nozzle for individual periods are shown. Obtained in experiments with the packages of plates of different materials and thickness values of the average Nusselt number for the period criterial generalized equation for convenient engineering calculations RAPH with leaf nozzles of various types.