Problems in calculating the steam and water resistance of header boxes
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In the section on the local resistance coefficient of single-phase fluids in JB/Z 201-83, \"Hydrodynamic Calculation Methods for Hot Water Boilers\", under \"Resistance Coefficient of the Header\": 1. The \"resistance coefficient of the header calculated based on the flow velocities at the inlet (distribution header) and outlet (collection header) of the pipes in the header system\" refers to: for the distribution header, the resistance coefficient of the header is calculated based on the average flow velocity in the pipes that originate from it； For the collector box, the box resistance coefficient is calculated based on the average flow velocity in the pipes entering it. Is this the correct way to understand it? 2. For the parameter n in the formula, it holds that \"when introducing or leading out at a single-sided end or end side, n is the number of tubes in the header system\" ； When introducing or leading out from the middle of the manifold, it is expressed as n = number of tubes / 2 times the number of introduction or leading-out tubes. In this sentence, do “tubes”, “introduction” and “leading in (tubes)” carry the meanings of “heating surface tubes” and “connection tubes”? Or does it only refer to the pipes or connecting tubes that \"enter\" the header or \"leave\" the header? It’s really troubling; I hope everyone will kindly help me understand this.
Let’s learn together*. For question 2, in my own calculations, I understood it as a comparison of the number of inlet and outlet pipe fittings on the manifold, with no relation to whether it is exposed to heat.
JB/Z201-1983 \"Hydrodynamic Calculation Method for Power Station Boilers\" has been repealed, and there is no alternative standard. The standard title for the \"Method for hydrodynamic calculation of hot water boilers\" is JBT8659-1997. Books on other specialties (industrial boilers): \"Hydrodynamics of Boilers and Heat Transfer Inside Boilers\", 1982 edition; \"Hydrodynamics of Boilers and Equipment Inside Boilers\", 1988 edition; \"Hydrodynamic Calculations for Boilers\", 2009 edition.