i meant that d pressure is taken as the lower of the 2 streams ... so what happens to the pressure energy of the higher pressure stream ...is that energy is being taken care of in the mixing calculation?? or is it .... lower of the two pressures and temp at the initial condition ? for exmaple :

if C3 is at 21 kg/cm2 and 35C and C4 is at 10 kg/cm2 and 45C ..then the final mixing result is 10kg/cm2 and 38C .... .. i was thinking that d value should be something like 15kg/cm2 and temp 38C ( these values are just my intuition they are not calculated results by hysys)