Estimation of latent heat and physical properties

Increase the liquid stream pressure to the relieving pressure (121% of PRV set pressure). 

Heat the stream further to achieve 5 or 50 mol% vapor, and record the heat input, say, Qj kj/h. 

Estimate the vapor generated at the outlet of the second exchanger, say, Wi kg/h. 

Estimate the increase in sensible heat of the liquid, say, Sj kJ/h. Latent heat = (Qi - S )/kj/kg. 

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The intermolecular interaction energy responsible for the nematic ordering can be estimated from the latent heat of isotropic-nematic phase transition AE 300 cal/mol (= 0.01 eV/molecule (see, for example, G. H. Brown, J. W. Doane, and D. D, Neff, A Review of the Structure and Physical Properties of Liquid Crystals, p. 43, CRC Press, Cleveland, Ohio, 1971). 

Besides having provisions for simulating most of the principal types of process equipment, the more extensive of these programs have routines that generate physical properties of hundreds of chemical species, either from built-in data tables or by using estimation formulas. Included in the stored data are boiling and melting points, liquid densities, critical constants, heat capacities, latent heats, solubilities, and vapor pressures. 

Flash models require heat capacity, latent heat of vaporization data for the pure materials, normal boiling point temperatures, as well as the initial conditions of temperature and presstire. The AIChE/DIPPR physical properties compilation (Danner and Daubert, 1985) is a useful source of temperature dependent properties. For flashing mixtures a commercial process simulator would normally be used. If droplet size is to be determined to allow estimation of settling velocity, the velocity of discharge must be calculated, along with density and surface tension of the liquid and the density of gas. 

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