Experimental modeling of heat transfer in Taylor flow in mini-scale tubing

Alrbee, Khalifa B. (2020) Experimental modeling of heat transfer in Taylor flow in mini-scale tubing. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

Heat transfer enhancement in mini / micro scale channels is desired in most compacted devices. Typically, these devices experience a high heat generation. In this regard several approaches were invented to increase heat dissipation rates. Taylor flow provides a promising technique to enhance heat transfer within mini / micro scale channels. Taylor flow parameters and channel geometries are experimentally and theoretically studied to improve the thermal performance of mini / micro channels. The present dissertation aims to investigate heat transfer enhancement using the Taylor flows of gas-liquid and liquid-liquid flows in straight and curved tubes. The influence of the liquid slug length on heat transfer is examined when the isothermal boundary condition is applied to the heat transfer surface. This study also examines the effect of nanoparticle inclusion in the continuous and Taylor flows as new achievement in this regard. This dissertation will address heat transfer enhancement in the mini scale tubes over eight chapters as follows. The first chapter provides a brief introduction and shows the originality, novelty, and importance of using the Taylor flows in the heat transfer enhancement. The second chapter summarizes a survey on the past attempts to investigate heat transfer of Taylor flows. The third and fourth chapters are devoted to study heat transfer in Taylor flows of gas-liquid and liquid-liquid in mini scale straight tubes. These experiments examine the effect of the liquid slug length on the thermal behavior of the Taylor / slug flows. In the fifth and sixth chapters, the thermal behavior of Taylor flows inside curved / coiled geometry are experimentally studied, and new empirical models were developed using the experimental data. The experiments considered the effects of three parameters, tube curvatures, liquid slug ratios, and Prandtl numbers. The seventh chapter addresses the heat transfer enhancement of nanofluids and compares with the conventional liquids. The study demonstrated the effect of nanoparticle concentration on heat transfer in continuous and Taylor flows. The last chapter provides a summary and conclusion of the present study. Recommendations for the future studies are also stated to highlight the important aspects for further investigation.

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