The influence of the period switching frequency on the heat exchange of a regenerative air heater

A laboratory stand with a regenerative air heater, an automated system for control and measurement of air flow parameters and a nozzle designed to study the heat transfer of a package of parallel plates under non-stationary conditions for different periods are described. The technique of measuring the transient temperature of cold and hot coolant flows taking into account the inertia of thermocouples and the method of measuring the heat transfer coefficient of plates are presented. The time variations of the Nusselt number and the heat power transmitted by the nozzle for individual periods are shown. Values of the average Nusselt number for the period obtained in experiments with the packages of plates of different materials and thicknesses are generalized by a criterial equation convenient for engineering calculations of regenerative air heaters with sheet packing of various types.