Flow Pulsation and Modified Duct Surface for Process Heat Transfer Intensification

Abstract

An experimental investigation of the combined influence of flow pulsation and modified duct surface on cross-flow transport and convective heat transfer intensification in laminar flow was carried out. The experiments were performed with a fluid with a kinematic viscosity of 1.8x10-6 m2/s and Prandtl number of Pr = 15. The active length L of the channel is 900 mm and lateral extension is W = 90 mm. Pulsation amplitude (A range of 0.28 mm – 0.53 mm) was used together with pulsation frequency (range of 16 Hz ? f ? 54 Hz). A steady flow Reynolds number range of 100 < Re < 600 was studied. All the geometric parameters of the device such as the relative fin spacing and relative fin thickness were constant. The results of the flow visualization showed recirculation eddies formation when flow pulsation and fins are combined. This enhances the mixing of the fluid within the channel. The intensification of the heat transfer coefficient due to pulsation and use of fins becomes more significant with increasing pulsation amplitude. The combined influence of flow pulsation and modified surface geometry on the heat transfer coefficient was found to be significant at moderately low but non-zero net flow rates or Peclet number Pe. Maximum heat transfer intensification of 2.4 was obtained. In general, no significant heat transfer was obtained at very low and very high flow rates.