Calculating Two-Phase Pressure Drop

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Chemical Processing, 2000 Fluid Flow 1 of 8Calculating Two-Phase Pressure DropScott S. Haraburda, PE Engineer, GE Plastics, Mt. Vernon, INAndSteve Chafin Process Engineer, River City Engineering, Lawrence, KSFluid flow concerns are quite prevalent among systems that handle chemicals, either inthe liquid or the vapor state. An important parameter for characterizing the energy of thefluid flowing within a contained system, such as pipes, is Pressure . This pressurebecomes important for designing pipe sizes, determining pump requirements, andaddressing safety concerns. Often the fluid is flowing as both liquid and TypeThe flow type of Two-Phase liquid-gas flow can be characterized into one of seven typesshown in Figure 1. These types could be predicted using the following processparameters:Gas density ratio (gas ratio) = (gas) / (air)Liquid density ratio (liquid ratio) = (liquid) / (water)Viscosity ratio (ratio) = (liquid) / (water)Surface tension ratio (ratio) = (liquid) / (water)Mass FluxMF (liquid or gas) = F(liquid or gas) / (3600*AR)To determine which type of flow exists, use the following coefficients in Figure 1, whichis a flow-pattern (lb/sec ft2) = MF(gas) / [ (gas ratio) * (liquid ratio)] = MF(liquid) * [ (gas ratio) * (liquid ratio)] * (ratio) / [MF(gas) * (ratio) 3 * (liquid ratio) 2]5-Step Pressure D

Chemical Processing, 2000 Fluid Flow Annual http://www.chemicalprocessing.com Page 1 of 8 Calculating Two-Phase Pressure Drop Scott S. Haraburda, PE (scott.haraburda@gepex.ge.com)

  Phases, Pressure, Calculating, Drop, Calculating two phase pressure drop