The examination of available vapor pressure data in the case of the methane, ethane, propane and butane halogenated refrigerants, allowed recommendations of standard equations for this property. In this study, three new models include a general correlation; a substance-dependent correlation and an artificial neural network (ANN) approach have been developed to estimate the saturated vapor press...

In this study, a generalized equation is presented to calculate vapor pressure of pure substances as a function of reduced temperature, critical pressure, and acentric factor. With the presented model, vapor pressures have been calculated and evaluated with NIST data bank for 70 pure substances for about 14000 data points, and the overall average absolute percentage deviation has been only 0.78...

In the vapor phase a solvent-free spectroscopic analysis of dye molecules is applicable [1-3]. For some dye vapors laser action was achieved [1-3]. The dye vapor pressure rises approximately exponentially with temperature. Reasonable vapor pressures (p around 100 Pa = 1 mbar) are obtained for many non-ionic dyes in a temperature region between 200 and 400 °C without considerable thermal decompo...

in this paper, the vapor-liquid equilibrium (vle) properties of polar and nonpolar fluids are modeled by the use of a statistically-based equation of state (eos). the equation of state used in this work is that of ihm-song-mason (ism) eos. an alternative approach is to revise the isothermal integration on liquid. in this respect, a temperature-dependent revision factor b (t) is introduced to th...

Vapor pressures in the range of 256 to 331 K and saturated liquid and vapor densities from 315 to 331 K have been measured for difluoromethane (HFC-32) on the saturation line by means of variable volume and static experimental methods. Our results have been combined with literature values, and on the basis of all the measurements, accurate analytical correlations for saturated liquid and vapor ...

[1] Tropical convective anvil clouds detrain preferentially near 200 hPa. It is argued here that this occurs because clear-sky radiative cooling decreases rapidly near 200 hPa. This rapid decline of clear-sky longwave cooling occurs because radiative emission from water vapor becomes inefficient above 200 hPa. The emission from water vapor becomes less important than the emission from CO2 becau...

A numerical method based on the SIMPLE algorithm has been developed for the analysis of vapor flow in a concentric annular heat pipe. The steady-state response of a concentric annular heat pipe to various heat fluxes in the evaporator and condenser sections are studied. The fluid flow and heat transfer in the annular vapor space are simulated using Navier-Stokes equations. The governing equatio...