Augmentation of Laminar Forced Convective Heat Transfer of an Oil Flow in an Enhanced Tube by EHD Effect

摘要

An experimental study investigated the effect of a DC applied electric field on the enhanced heat transfer of the laminar forced convection for oil through a horizontal smooth tube and an enhanced tube. The experimental results are summarized as follows: 1. For the smooth tube, the enhanced heat transfer ratio is dependent on both the applied electric field strength and the heat flux. In the low heat flux range, the enhanced heat transfer ratio increases quickly with increasing the electric field strength. While, the increase ratio of the friction factor is effectively restrained. In the high heat flux range, the enhanced heat transfer is not significant. 2. For the enhanced tube, the enhanced heat transfer ratio is mainly dependent on the applied electric field strength. The enhanced heat transfer ratio increases quickly with increasing the applied electric field strength and is basically independent of the heat flux in the whole experimental range. The friction factor is nearly not change with the increase in the heat transfer coefficient. Therefore, a favorably comprehensive effect can be achieved. 3. Both the flow velocity and the oil-temperature have only a little influence on the enhanced heat transfer caused by the EHD effect.