The single horizontal tube evaporator we used for investigation

being described in a preceeding paper[1]

was modified with a vacuum system in order to operate the boiling experiments under diminished pressures. Binary liquid mixtures employed are:- (1) Water-ethanol; (2) Benzene-toluene. Range of experiments:- (1) Heat load

4 = 4

000 40

000 kcal/m2:hr:(C) (2) Operating pressure

p = 200 760 mm. Hg. (3) Compositions of binary liquid mixtures. A) Benzene % in benzene-toluene system:- 0%

12%

25%

50%

75%

88%

100%

B) Ethanol % in vvater-ethanol system:- 5%

25%

60%

91.8%. The boiling beat transfer coefficients of water under various pressures were examined as preliminary experiments

the results may be correlated as follows:- a=4.0 p0.2 q0.69 For pure benzene

we obtained the following-empirical formula

- and for pure toluene

- The heat transfer coefficients of boiling mixtures of different compositions

and under different pressures were correlated with dimensionless groups suggested by ; we propose that his original equation

can be used for binary liquid mixtures in the following modified form

- with error less than ±10%. We also correlated our experimental results with C. C.equation

- for binary liquid mixtures

we propose the following modified form

with error around (+)10%.