Effect of the heat-transfer agent flow nonstationarity in the matrix channel of a rotating heat exchanger on its thermal parameters with the laminar flow

Abstract

The paper studies influence of the non-stationarity process of the laminar gas flow in the band flat matrix channel of the rotating heat exchanger on its thermal characteristics. Conjugate heat transfer was mathematically simulated with the airflow along the steel walls forming the channel under study. In view of peculiarities of the rotating heat exchanger operation and to obtain parameters of the conjugate heat transfer in the nominal mode, mathematical simulation was performed many times using the results previously obtained as the initial conditions for the following calculations. It was established that gas flow in the investigated matrix channel of the heat exchanger became cyclically repetitive after the sixty cycles. Distribution curves of Nusselt criterion local values along the channel length at all time steps of the gas flow process, as well as the Nusselt criterion values averaged over the channel length were obtained. It was shown that the length-averaged Nusselt criterion value was smoothly increasing with time. The time-averaged Nusselt criterion value was determined, and it was somewhat exceeding the values obtained in the stationary setting.