Conference paper

Publication year: 2007

Pages: 834-841

Journal: Heat Transfer Engineering

Volume number: 28

Issue number: 10

ISSN: 0145-7632

eISSN: 1521-0537

DOI Link: https://doi.org/10.1080/01457630701378242

Conference: 6th International Conference on Boiling Heat Transfer

Publisher: Taylor and Francis Group

Abstract: 
Visualization by high- speed videography and infrared surface thermography was used to compare the spatial and temporal maldistribution of flow, manifesting itself in pulsation and hot spot formation, respectively, in water evaporators consisting of either a single metallic foil with an array of mechanically micromachined microchannels or of several such foils assembled into an electrically powered micro heat exchanger. In the single layer devices examined by high- speed videography, pulsation in the frequency range below 20 Hz was found to be dominated by the generation of large bubbles in the inlet plenum. A redesign of the inlet with microchannels instead of a large plenum eliminated the pulsation at sub- audio frequencies, at the expense of a significantly increased pressure drop across the device. Infrared thermography of an electrically powered micro heat exchanger operated as an evaporator showed the formation of metastable hot spots as the result of maldistribution among different microchannel array layers. The formation of these hot spots could be eliminated by operating the device under heater cartridge temperature control conditions instead of constant power conditions.

Harvard Citation style: Henning, T., Brandner, J., Schubert, K., Lorenzini, M. and Morini, G. (2007) Low-frequency instabilities in the operation of metallic multi-microchannel evaporators, Heat Transfer Engineering, 28(10), pp. 834-841. https://doi.org/10.1080/01457630701378242

APA Citation style: Henning, T., Brandner, J., Schubert, K., Lorenzini, M., & Morini, G. (2007). Low-frequency instabilities in the operation of metallic multi-microchannel evaporators. Heat Transfer Engineering. 28(10), 834-841. https://doi.org/10.1080/01457630701378242