METHODOLOGY LIQUID MIXTURE PROPERTIES The mixing calculations are done on the composite blend mixture. The properties of this blend mixture are calculated from the properties of two liquid phases by the mixing rules given below. The method assumes that the two liquid phases are completely miscible. In the following equations the properties of the Bulk fluid is denoted by the letter B. The properties of the Disperse phase uses the letter D. and the Mix phase uses the letter M. MIXTURE VOLUME The volume of the mix phase is determined by adding the volume of the Bulk and the Disperse phase. Mvol = Bvol + Dvol MIXTURE DENSITY The density of the mixed phase is determined by the volumetric average of the density of the two phases. Mden = (Bvol*Bden + Dvol*Dden)/ Mvol MIXTURE VISCOSITY The mixture viscosity is calculated by an computerized adaptation of the ASTM method using blending indexes. The viscosity of the mixture if calculated by hand would follow the method shown in J.B. Maxwell's Data Book on Hydrocarbons Section 9 using ASTM standard Viscosity-Temperature Charts for liquid Petroleum Products (D341-39) Charts C and D. The Blending Index for each fraction is determined from its viscosity at the mix temperature. The blending indexes are additive by volume fractions, and the resulting sum may be converted to the viscosity of the mixture by referring to the blending chart again. The computerized adaption of this method uses the following relationships, derived from the chart. Visc = 10^(10.22602 - 5.81024 log BI) for viscosity > 10cp Visc = 10^(6.55958 - 3.50779 log BI ) for viscosity < 10 cp MIXTURE HEAT CAPACITY The heat capacity of the mixture is calculated by a weight average of the heat capacity of the bulk and disperse phase. MIXTURE THERMAL CONDUCTIVITY The mixture thermal conducitivity is calculated by a weight average of the thermal conductivities of the bulk and disperse phases. This the API recommended procedure No 12A2.1 MIXTURE SURFACE TENSION The mixture surface tension is calcuated by taking a volume average of the bulk and disperse phases. The method of Morgan and Griggs referred to in the API data book and in the JOURNAL OF AM CHEM SOC 39,2261(1917) recommends calculating the surface tension from a molal average. Other methods using Parachlors and group contributions also exist. Probably none are very accurate.