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Experimental investigation of flow boiling instabilities in parallel microchannels.

Number: 0452

Author(s) : HALON S., KROLICKI Z., REVELLIN R., ZAJACZKOWSKI B.

Summary

High-density computing has given impetus to the development of solutions able to dissipate relatively large amounts of heat from small heat transfer areas like CPUs. Heat exchangers that feature flow boiling in microchannels placed on the CPU surface meet the specific requirements imposed by dense computing. However, the process of phase transition promoting intense heat transfer also enables flow instabilities posing a potential threat for CPU safe operation. To prevent instabilities, conditions favouring their manifestation need to be studied. In this paper we focus on the influence of heat flux (qw), mass flux (G) and saturation temperature (Tsat) on instabilities occurrence.
We investigate flow boiling of R245fa in 1 mm wide and 1 mm high microchannels connected in parallel for qw = 30 – 50 kW∙m-2, G = 400 – 1000 kg∙m-2∙s-1 and Tsat = 49 – 82°C and analyse photos from a high-speed camera to identify the type of instability. The instability that we observed is flow stagnation coupled with flow reversal, which in some cases leads to vapour backflow into the inlet manifold of the heat exchanger. Conditions favouring this instability are low mass fluxes and high heat fluxes. Saturation temperature does not have a strongly pronounced impact on its occurrence, but it influences its severity.

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Pages: 11 p.

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Details

  • Original title: Experimental investigation of flow boiling instabilities in parallel microchannels.
  • Record ID : 30031614
  • Languages: English
  • Subject: Technology
  • Source: Proceedings of the 26th IIR International Congress of Refrigeration: Paris , France, August 21-25, 2023.
  • Publication date: 2023/08/21
  • DOI: http://dx.doi.org/10.18462/iir.icr.2023.0452

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