Guidelines to do Line sizing and pressure drop calculation for two phase fluid flowing through a horizontal pipe.http://checalc.com/guide/line_two_phase.htmlCriterion for Line size selection is generally pressure drop expressed as P per 100 feet or meters of pipe. There are different type of two phase pressure drop correlations determined by viscosity ratio and mass flux.L / GMass Flux, G (kg/m.sec)Correlation

< 1000AllFriedel

> 1000> 100Chisolm - Baroczy

> 1000< 100Lockhart - Martinelli

Step 1Obtain Process Parameters Select a pipe and estimate inner diameter (D) based on pipe schedule. Obtain important properties for both Gas and Liquid like flowrate, density (), viscosity () and surface tension ().

Step 2Calculate two phase line sizing properties Density, velocity and viscosity are averaged for the combined phases in fluid flow and two-phase Reynolds number is calculated.(average) = ( QG + QL )/( QG / G + QL / L ) V(average) = ( QG + QL )/( average * (D/4) ) (average) = ( QG + QL )/( QG / G + QL / L ) Re(average) = 4*( QG + QL )/( * D * average ) where,QG , QL: Gas and Liquid mass flowrate.G , L: Gas and Liquid density.G , L: Gas and Liquid viscosity.

Step 3Chisolm - Baroczy method Pressure drop for each of the phases are calculated assuming that the total mixture flows as either liquid or gas based on procedure provided for single phase flow.G = Q G + Q L (P/L)Go = function(G, D, G, G, ) (P/L)Lo = function(G, D, L, L, ) A pressure ratio is calculated :Y = (P/L)Go / (P/L)Lo Based on pressure ratio, a constant is calculated:B = 55 / G 0.5, 0 < Y < 9.5 = 520 / YG 0.5, 9.5 < Y < 28 = 15,000 / Y 2G 0.5, 28 < Y Two phase correction factor is calculated as following:Lo = 1 + (Y - 1)[ BX (2-n)/2(1 - X) (2-n)/2 + X 2-n ] where,n: 0.25X: mass fraction gasTwo phase pressure drop is calculated as following:(P/L)TP = Lo (P/L)Lo

Lockhart - Martinelli method Pressure drop for each of the phases are calculated explicitly assuming that either liquid or gas is flowing through the pipe based on procedure provided for single phase flow.(P/L)G = function(QG, D, G, G, ) (P/L)L = function(QL, D, L, L, ) A pressure ratio is calculated :X = (P/L)L / (P/L)G A pressure correction factor for each phase is calculated using following chart:

A separate pressure drop is calculated for each phase :(P/L)L1 = L (P/L)L (P/L)G1 = G (P/L)G Estimated two phase pressure drop is maximum of these(P/L)TP = Max( (P/L)L1, (P/L)G1 )

Friedel method Calculate Froude and Weber number using mass flux of the total mass flowing in pipe:Fr = G / ( gcDaverage ) We = GD / ( average ) where,gc : Gravitational constantFriction factor for each of the phases are calculated assuming that the total mixture flows as either liquid or gas based on procedure provided for single phase flow.fGo = function(G, D, G, G, ) fLo = function(G, D, L, L, ) Following constants are calculated :E = (1 - X) + X LfGo / (GfLo) H = (L / G)0.91 (G / L)0.19 (1 - G / L)0.7 F = X 0.78 (1 -X) 0.24 Two phase correction factor is calculated as following:Lo = E + 3.24 FH / (Fr 0.045 We 0.035) where,X: mass fraction gasTwo phase pressure drop is calculated as following:(P/L)TP = Lo (P/L)Lo References1. Chemical Process Equipment: Selection and Design 2. Pressure Drop, Two Phase Flow at Thermopedia.com3. Horizontal 2-Phase Flow Correlations at Cheresources.com4. Article on Two Phase Flow at rivercityeng.comVisitCalculation Spreadsheet