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Heat Pipe Science and Technology, An International Journal

Publication de 4  numéros par an

ISSN Imprimer: 2151-7975

ISSN En ligne: 2151-7991

INFRARED THERMOGRAPHY OF PULSATING TAYLOR BUBBLE-TRAIN FLOW IN A MINI-CHANNEL

Volume 5, Numéro 1-4, 2014, pp. 103-110
DOI: 10.1615/HeatPipeScieTech.v5.i1-4.80
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RÉSUMÉ

An experimental study has been carried out to understand the heat transfer characteristics of pulsating Taylor bubble-train flow in a square mini-channel of 3 mm × 3 mm (Bond number Bo ≈ 1.1 based on water-air flow), heated from one side. Taylor bubble-train has been formed by mixing dry air and de-ionized, de-gassed water at a T-junction which is located far upstream from the heated zone. The parameters of study are total superficial velocity (Jtot) achieved by varying water flow rate keeping the air flow rate constant and the pulsating frequency. Total superficial velocity is varied from 0.11 m/s to 0.15 m/s. Flow is pulsated at two different imposed frequencies of 1 Hz and 3.125 Hz. Experiments are performed at two stages. At the first stage, continuous Taylor bubble-train is passed through the heated channel and heat transfer is determined. While at the second stage, pulsatile air-water slug flow (pulsating Taylor bubble-train flow) is injected inside the heated channel to estimate the heat transfer coefficient. Infra-Red Thermography (IRT) has been employed to measure the wall temperature, while local fluid temperature is measured at the inlet and outlet cross-sections by a K-type thermocouples. Based upon these temperature measurements, local heat transfer co-efficient is determined. High-speed videography is also used for visualization of liquid slugs and air bubbles in continuous and pulsating Taylor bubble-train flow. It has been observed that augmentation/deterioration of heat transfer due to externally applied frequency on continuous Taylor bubble-train flow is not monotonous.

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