127be described by using two OH groups. It was necessary to introduce a special glycol group. Similar "proximity effects" are discussed by Hauthal et al. (1980). Complete tables of Rk and Qk values and group-interaction parameters which include the extensions reported in this work are given in Tables IV and VII. As a result of the revisions and extensions of UNIFAC described in this work, UNIFAC now encompasses 40 different main groups and 76 subgroups. Figure 5 gives an overview of the available group-interaction parameters.The new parameter tables do not include the CCOH alcohol group introduced by Fredenslund et al. (1977). In our experience, the OH alcohol group (group no. 5 of Table VII) yields results which are as good as or better than the CCOH group. SupplementA list of references to the data on which the new UNI-FAC parameters are based and a listing of a subroutine which incorporates the new UNIFAC parameter table in generating activity coefficients may be obtained from the authors. AcknowledgmentThe authors are grateful to Deutsche Bundesministerium fur Forschung and Technologie and the Danish Statens tekniske videnskabelige Forskningsrhd for support of the UNIFAC project. In addition, we thank Professor U. Onken and our many other colleagues who in different ways have contributed to this work. Literature CitedFredenslund, Aa.; Gmehllng, J.; Rasmussen, P. "Vapor-Liquid Equilibria Using UNIFAC"; Elsevler: Amsterdam, 1977a; Chapter 5. Fredenslund, Aa.; Gmehilng. J.; Michelaen. M. L.; Rasmussen, P.; Prausnitz, J. M. Ind. Eng. Chem. Process D e s . D e v . 1977b. 16, 450. Fredenslund, Aa; Jones, R.; Prausnitz. J. M. A I C M J . 1975, 2 1 , 1086. Gmehling, J.; Onken, U.; Arlt, W. "Vapor-Liquid Equlibrlum Data Collectlon"; DECHEMA Chemistry Data Series, Vol. 1 (12 parts): Frankfurt, 1977. Gmehling, J.; Doctorlal Thesis, (Hebllitationsschrlft), University of Dortmund. BRD, under preparation, 1981. Gmehling, J; Rasmussen, P.; Fredenslund, Aa. Chem. Ing. Tech. 1980. 52(9), 724. Hauthai, W. H.; Schmelzer, J.; Qultzsch. K.; Mohle, L.; Figurski, G. 6th Int. Conf . Thermodynamics Merseburg I DDR , 1980. Kato, M. Ind. Eng. Chem. Fundem. 1980. 19, 253. Kemgny, S.; SkJoidJerrgensen, S.; Manczinger, J.; T6th, K. AIChE J . 1981 In press. Kolbe, B.; Gmehllng. J.; Onken, U. I.Chem. E . Symp. Ser. 1979, 56, 1.31 23. Maalore, B.; M. Sc. Thesis, SkjoldJerrgensen, S.; Kolbe. B.; Gmehiing, J.; Rasmussen P. Ind. Eng. Chem. Process D e s . D e v . lS79, 18, 714. Zarkarlan, J. A.; Anderson, F. E.; Boyd, J. A.; Prausnltz, J. M. Ind. Eng.Density, viscosity, and surface tension of coal liquids have been experimentally determined at temperatures up to 850 O F and pressures up to 3200 psia. Measurements were made on liquids produced with the Exxon Donor Solvent process from Illinois and Wyoming coals. Several measurements were also made to determine the effect of dissolved hydrogen on the physical properties of coal liquids. These data were used to investigate the applicability of the existing physical property correlations to coaide...

The volatility of Wyoming coal liquids has been experimentally determined at 700-850 O F and 1950 psia with a flow apparatus to minimlze thermal decomposition effects at high temperatures. Measurements were made on two liquids produced wlth the Exxon Donor Solvent process from Wyomlng coal, in mlxtwes with H, and methane. VLE data measured in this work were analyzed with a modified Chao-Seader correlation and a modified Rediich-Kwong equation of state. Both VLE correlations are shown to be equivalent in the prediction of the volatility of coal liqu'kb-when a new vapor pressure method is used. Comparison of the ME data on Wyoming coal liquids with those on Illinois coal liquids previously published (wnson et al., 1981) indicates that the coal source apparently has little effect on the volatility of coal IiquMs, provided the liquids have a similar boiling-point distrlbution.

Experimental procedure and techniques are described for using differential scanning calorimetry to obtain accurate liquid heat capacities of organic materials, particularly coal liquids, at high temperatures. The heat capacity of coal liquids, produced with the Exxon Donor Solvent process from Illinois and Wyoming coals, has been experimentally determined at temperatures up to 404 °F. Measurements were also made up to 530 °F on the heat capacity of defined compounds found In coal liquids. These data, along with literature data for defined compounds and coal liquids from other processes, were used to investigate the applicability of the Watson-Nelson and API Technical Data Book correlations and to develop modifications of these correlations for predicting the liquid heat capacity of coal liquids. With the modified correlation, the average deviation in predicting the liquid heat capacity of coal liquids was reduced from 8.0 to 3.7%.