Investigation On The Fluid Flow And Heat Transfer Characteristics Of Microcapillaries In Plastics Film

Micro Capillary Film (MCF) is a novel microstructured film with an array of embedded hollow microcapillaries, which has the advantages of unique structure, large surface area to volume ratio, low cost and easy-to-manufacture. There is a broad range of potential applications in the fields of micro heat exchangers, micro-pumps, microfluidic chip, micro-reactors as well as anti-counterfeiting technology with its unique structure and properties. The MCFs with different capillary diameters were produced by the extrusion line. The LLDPE MCFs with 28 capillaries were about 14-^-22mm wide and 0.6-0.9mm thick, and the diameters of 28 capillaries were 50-300μm. The influence of geometric parameters of microcapillaries on the fluid flow and heat transfer performance of MCFs was investigated experimentally, providing a theoretical reference in the applications of micro heat exchangers, anti-counterfeiting technology and so on. The main work carried out as follows:Firstly, the physical model of microcapillaries has been established, theoretical studies numerical simulation research on the fluid flow and heat transfer performance of MCFs was carried out based on the physical model of microcapillaries. Mathematical models of the drag coefficient, pressure drop, velocity profile and convective Nusselt number (Nu) was established, respectively. Numerical simulation on the fluid flow and heat transfer performance of MCFs with different ellipse aspect ratios and hydraulic diameters was carried out. The results showed that with the increase of ellipse aspect ratios in the same Reynolds numbers, the drag coefficient increased, and the Nu numbers decreased; drag coefficient decreased and Nu number increased with the increase of hydraulic diameters.Secondly, an experiment platform was developed to investigate the fluid flow and heat transfer performance of MCFs experimentally, taking deionized water as the flow fluid. The influence of MCF’s geometry on press drop, friction coefficient, the convective heat transfer coefficient and Nu number was carried out, and compare simulation and experiment results with theoretical predictions. The deviation was analyzed to correct theory calculation of flow and heat transfer parameters, providing a theoretical reference in the applications of plastic micro heat exchangers.Finally, a novel anti-counterfeit packaging method was put forward based on MCF to expand its applications. An experiment platform was developed to investigate flow characteristics of UV fluorescent inks in the capillaries of MCFs. The results showed microcapillary length, the hydraulic diameter, the viscosities of liquids were key factors in forcing UV inks into MCFs.