Abstract: Based on the study with air- water and air-#0 diesel oil in heat exchanger, results on the effects of fluid properties on void fraction and frictional pressure drop in the shell-side two-phase flow with air - 30% (by weight) water glycerine solution was presented. The results showed that the void fraction increases with the increase of liquid viscosity when the mass fraction and mass velocity are maintained unaltered. Surface tension has also effect on the void fraction. Combining these two effects, a void fraction correlation is obtained which can be used in different air-liquid systems. The experimental results show that the data of frictional multiplier increases with the increase of liquid viscosity. A comparison between the data of air - glycerine water solution and air - water system shows that different frictional multipliers approach to 1 as the value of Martinelli number increases. A new two-phase frictional drop correlation is presented. The average error is about 15% .