Experimental investigation of nozzle geometry effect on two-phase nozzle performance through trilateral flash cycle

This paper aims to elucidate the effect of the divergent geometry of a nozzle on its performance by experimentally estimating the force generated by high speed two-phase fluid leaving the nozzle exit. The experiments are carried out by using the nozzles with two diverging profiles of conical and bell and various divergent angles of 6°, 18° and 30° corresponding to the divergent lengths of 45 mm, 17 mm and 12 mm respectively. The nozzles are examined at inlet temperatures of 50 °C and 60 °C for Isopentane as working fluid. The experimental results are indicative of higher values for thrust force and consequently isentropic efficiency by increasing the inlet temperature from 50 °C to 60 °C for all examined nozzles. It is found through the experiments that the maximum efficiency is about 41% with inlet temperature of 60 °C for the bell shape nozzle with the corresponding divergent angle of 6°. Whereas, the 30° conical and bell nozzles have the least force and efficiency. The pressure measurements along the 6° conical and bell nozzles are indicative of a greater pressure drop after the nozzle throat for bell shape nozzle compared to conical nozzle. This paper presents empirical results that can be used in designing efficient nozzles.