具有多孔光热蒸发层的微通道内热质传输特性研究

The evaporation driven concentration by photothermal effect holds promising features including non-contact manipulation and simple structure of the devices, which exhibits great potential in microfluidic analysis and detection. Aiming at the present problems in the evaporation driven concentration by photothermal effect such as poor vapor transport, incontrollable interface and low evaporation efficiency, this project proposes an in-channel microfludic concentration technology with photothermal porous evaporation layer for efficient continuous-flow sample concentration. This technology involves multi-physical processes including photothermal conversion, two-phase flow, vapor transport, heat and mass transfer. Among which the two-phase flow and heat mass transfer in the microchannels and porous evaporation layer dominate the efficiency of the evaporation driven concentration. To address this critical thermophysical issue, systematical researches are directed. Firstly, the photothermal conversion property and the evaporation characters of the porous photothermal evaporation layer will be investigated. Then the two-phase flow and heat transfer characters in the porous layer and microchannels will be studied. Finally, investigation of the two-phase flow and heat-mass transfer of multi-components in the porous layer and microchannels will be carried out. Effects of the pore structure of the porous layer, geometric structure of the microchannels, light intensity, flow rate of the liquid and gas phase on the performance of the concentration will be investigated. Theoretical model considering the two-phase flow and heat mass transfer in the porous layer and microchannels will also be developed. The implementation of the project will lay theoretical foundation to the development of microfluidic concentration technologies by photothermally induced evaporation.

基于光热效应的蒸发浓缩具有非接触式操控、结构简单等优点，在微流控分析检测领域极具应用潜力。针对现有光热蒸发浓缩技术所面临的蒸汽传输受限、界面不可控、蒸发效率低等问题，本项目提出一种具有多孔光热蒸发层的微通道内蒸发浓缩技术，用于样品高效连续浓缩。该技术涉及多孔层与微通道内光热转换、两相流动传热、蒸汽传输、物质输运等多物理过程，其中多孔层与微通道内两相流动与热质传递对蒸发浓缩性能至关重要。本项目围绕这一关键热物理问题开展系统研究工作，首先研究多孔蒸发层光热转换及蒸发特性，随后对微通道及多孔蒸发层内两相流动传热特性进行研究，最后对微通道及多孔蒸发层内两相流动与多组分热质传递耦合进行研究，获得多孔层孔隙结构、微通道几何结构、入射光功率、气液相流量等结构与运行参数对蒸发浓缩性能的影响规律，构建具有多孔光热蒸发层及微通道内两相流动热质输运模型，为微流控芯片中光热蒸发浓缩技术开发与应用奠定理论基础。

基于光热效应的蒸发浓缩具有非接触式操控、结构简单等优点，在微流控分析检测领域极具应用潜力。针对现有光热蒸发浓缩技术所面临的蒸汽传输受限、界面不可控、蒸发效率低等问题，本项目提出一种具有多孔光热蒸发层的微通道内蒸发浓缩技术，用于样品高效连续浓缩。该技术涉及多孔层与微通道内光热转换、两相流动传热、蒸汽传输、物质输运等多物理过程，其中多孔层与微通道内两相流动与热质传递对蒸发浓缩性能至关重要。本项目围绕这一关键热物理问题开展系统研究工作，首先制备了易加工、可兼容微流控装置的光热多孔材料，并探究了其光热转换及蒸发特性。随后构建了具有光热多孔网络流道结构的微流控芯片，对多孔网络流道内光热效应驱动的两相流动传热特性进行研究，最后设计加工了具有光热多孔蒸发层的微流控芯片，实现了样品溶液的在线连续浓缩，获得了蒸发模式、工质种类、运行工况等参数对蒸发浓缩性能的影响规律。本项目结合实验研究与数值模拟，构建了孔隙-多孔网络流道-微流控装置内两相流动热质输运模型，为微流控芯片中光热蒸发浓缩技术开发与应用奠定理论基础。