Simultaneous velocity profile and temperature profile measurements in microfluidics. (March 2022)

• Record Type: Journal Article
• Authors: Bürkle, Florian; Czarske, Jürgen; Büttner, Lars
• Is Part Of: Flow measurement and instrumentation. Volume 83(2022)
• Publication Date: 2022-03
• Subjects: Optical flow measurement -- Laser Doppler velocimetry -- Laser Doppler velocity profile sensor -- Optical temperature measurement -- Laser-induced fluorescence -- Microfluidics; Fluid dynamic measurements -- Periodicals; Flow meters -- Periodicals; Fluides, Dynamique des -- Mesure -- Périodiques; Débitmètres -- Périodiques; 681.2805
• DOI: 10.1016/j.flowmeasinst.2021.102106
• Languages: English
• ISSNs: 0955-5986

Abstract

Abstract: Simultaneous non-intrusive temperature and velocity measurements in flows are of high technological interest, e. g. to study the heat transfer in microfluidic environments. However, a measurement system that offers a low velocity uncertainty and micrometre spatial resolution as well as highly accurate temperature measurements in a single device has not been demonstrated so far. In this work, this problem is solved by combining a Laser Doppler Velocity Profile Sensor (LDV-PS) with Laser-Induced Fluorescence (LIF). Seeding particles are employed, that contain the fluorescent dyes uranine and rhodamine B. The multiple dye approach eliminates the influence of the droplet size. Relative velocity uncertainties of down to 0.4% and a temperature uncertainty of down to 0.24 ∘ C with a spatial resolution of 10 μ m are achieved in a demonstration air flow experiment. The method has the potential to be optimised for different temperature ranges and uncertainty requirements, making it applicable on a wide range of thermal flows like fuel cells or microbioreactors. A better understanding of heat exchange processes can improve the energy efficiency of microfluidic devices. Highlights: The laser-Doppler profile sensor enables flow measurements on the microscale. Laser-Doppler measurements were combined with laser-induced fluorescence. Simultaneous temperature and velocity profile measurements were performed. The method allows for heat transfer analysis in microfluidic devices.