Supersonic separator (3S) provides submicron separation of liquids from gas streams. The advanced separation is based on adiabatic gas expansion due to attaining supersonic velocities accompanied with creation of huge centrifugal acceleration (500,000g) which is very adequate for separation of water or hydrocarbon condensates from natural gas. Most of the previous works have been assumed isentropic operation. In this article, the effect of process non-isentropicity is investigated on 3S performance. Modeling of 3S is studied using three different approaches: a) the entire system is viewed as an isentropic process, b) isentropic expansion and contraction in nozzle diffuser accompanied with non isentropic shock wave, c) the entire system is viewed as a non-isentropic process. The simulation results clearly indicate that the process nonisentropicity causes a pre-mature shock occurrence. Evidently, the non-isentropic fluid temperature is higher than the isentropic case which leads to lower liquid collection due to less condensation. Hence, total separation efficiency will be decreased in the presence of process nonisentropicity. Furthermore, the effect of various back pressures in three above cases are compared together and it is shown that the process nonisentropicity reduces overall pressure recovery

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