Convective Heat Transfer Intensification in Laminar Duct Flow

An experimental investigation was carried out to study the influence of pulsation and special surface geometry on the convective heat transfer in laminar flow. The experiments were performed using a glycerol-water mixture of 23 wt% glycerol. Ethanol was used as a coolant. The amplitude of pulsation was between 0.37 and 0.91 mm and the frequency range was 26.7 to 42.7 Hz. The mean flow Reynolds number range was between 50 and 1143. All the geometrical parameters of the channel such as the relative fin spacing and relative fin thickness were constant. The enhancement factor E, i.e. the ratio of heat transfer coefficient due to pulsation compared to steady flow diminishes at low Pe. A maximum E was observed in medium ranges of Pe and small Pe. The amount of heat transferred from the working fluid also depends on κ value. So far, a maximum heat transfer enhancement of E = 2.5 at κ = 3 and Pe = 2750 was obtained. The enhancement factor also increases with increasing pulsation amplitude.