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Flow maldistribution and its mitigation in mini heat exchangers

Abstract

In the present paper, a detailed numerical investigation has been carried out to analyze the flow maldistribution in 50 parallel 1 mm x 1 mm rectangular minichannels and 1 mm depth minigap section with rectangular, trapezoidal, triangular or concave mani-folds in Z-type flow configuration (16 different cases). The working medium was ethanol and the mass flow rate was 5×10-4 kg/s. Both sections was heated from the bottom side. Heat flux of 10 000 W/m2 and 5 000 W/m2 was applied to the minichannel and minigap section respectively. It provides an equal heat flow rate of about 50 W for both types of the sections. A novel approach for the mitigation of non-uniformity has been proposed introducing threshold at the entrance of the minigeometry section. The maldistribution coefficient can be reduced about twice in the minigap section or about three times in the minichannel section with the 0.5 mm threshold as compared to the conventional arrangement without threshold. Authors analyzed velocity profile and temperature profile over the heat exchanger’s surface. Reduction of maldistribution results in lower maximum temperature over the surface. The distribution is more uniform in minichannel section than in minigap section. This is due to a two-dimensional flow over a minigap in comparison to one-dimensional flow in channels. To obtain uniform distribution of fluid and hence uniform temperature profile, flow should be stabilized al-ready at the inlet manifold, at the entrance to the minichannel or minigap section.

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Details

Category:
Monographic publication
Type:
rozdział, artykuł w książce - dziele zbiorowym /podręczniku w języku o zasięgu międzynarodowym
Title of issue:
Contemporary Issues of Heat and Mass Transfer strony 83 - 109
Language:
Polish
Publication year:
2019
Bibliographic description:
Dąbrowski P., Klugmann M., Mikielewicz D.: Flow maldistribution and its mitigation in mini heat exchangers// Contemporary Issues of Heat and Mass Transfer/ Koszalin: Publishing House of the Koszalin University of Technology, 2019, s.83-109
Sources of funding:
  • Narodowe Centrum Nauki, projekt Nr 2017/27/N/ST8/02785 na lata 2018-2020.
Verified by:
Gdańsk University of Technology

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