Minimum flow area per GB151
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GB151, page 18, 5.2.2 b): The inner depth of multi-layer tube boxes shall ensure that the minimum flow area between two layers is not less than 1.3 times the flow area of the heat exchange tubes in each layer. How is the minimum flow area here calculated? How should the parameters be set? I think when calculating the area, one of the values is the inner depth, and the other is the height of the longitudinal cross-section of the tube box; but should this height be the maximum value or the average value? Because the height direction is an arc surface. Please ask an expert to answer!
1 The minimum flow area refers to the flow area of each heat exchange tube per pass； 2 It shall be ensured that the minimum flow area between the two passes is not less than 1.3 times the flow area of the heat exchange tubes in each pass; the flow area in question should be understood as the maximum cross-sectional area between the tube banks where the fluid flows vertically.
For reference only: The minimum flow area is generally required to be no less than 1.3 times the flow area within a single tube section； The average area of the cross-section in the vertical flow direction between the two stages is considered during calculation.