Pressure and temperature dependence of excess enthalpies of methanol plus tetraethylene glycol dimethyl ether and methanol plus polyethylene glycol dimethyl ether 250

The excess molar enthalpies at 323.15 K, 373.15 K, and 423.15 K, at 8 MPa, are reported for the binary mixtures methanol + tetraethylene glycol dimeth yl ether (TEGDME) and methanol + poly(ethylene glycol) dimethyl ether 250 ( PEGDME 250). Excess molar enthalpies were determined with a Setaram C-80 ca lorimeter equipped with a flow mixing cell. For both systems, the excess en thalpies are positive over the whole composition range, increasing with tem perature. The H-E(x) curves are slightly asymmetrical, and their maxima are skewed toward the methanol-rich region. The excess enthalpies slightly cha nge with the pressure, the sign of this change being composition-dependent. In the case of mixtures with TEGDME, the experimental H-E values have been compared with those predicted with the Gmehling et al. version of UNIFAC ( Dortmund) and the Nitta-Chao and DISQUAC group contribution models.