Improving the flow uniformity in compact parallel-flow heat exchangers manifold using porous distributors

• The present study deals with the numerical simulation of turbulent flow in a Z-type manifold in which the fluid is distributed via nine distribution tubes. One of the major drawbacks of such devices is the mal-distribution of flow within these tubes. The flow rates are usually low in the first tubes close to the header entrance and increase in the other tubes. To address this problem and achieve a more uniform flow distribution inside the manifold, a novel solution is introduced in the present study, which includes the insertion of thin layers of porous media at the inlet of distribution tubes. In addition, a parametric study is conducted to evaluate the effect of porous media geometrical parameters such as pore diameter, porosity, and porous layer thickness on flow distributions among the tubes. The results demonstrate that the proposed approach increases the uniformity of flow distribution specifically when a porous media with higher resistance against the fluid flow is inserted uniformly within the manifold. In this case, a standard deviation as small as Phi=0.0067 could be reached showing the high level of flow uniformity within the manifold. Also, a maximum pressure drop of 12.557 kPa is observed which is approximately 38% larger than that calculated in the manifold without porous insertions. Moreover, several non-uniform distributions of porous media are also investigated to further improve the flow uniformity and decrease the pressure drop. An improvement in the standard deviation of Phi=0.0043 is obtained in the case of #E3 with a non-uniform porous distribution with a 5% reduction in pressure drop compared to the pressure drop calculated in the corresponding uniform case #E1. The results reveal the effectiveness of the approach presented here to reach a more uniform flow distribution within the manifold without the need for re-designing and altering the manifold geometry which is usually proposed in the literature.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Kemiteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Chemical Engineering (hsv//eng)

Nyckelord

Flow distribution

Z-type manifold

Porous media

Pressure drop

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