Numerical investigation on optimization of ejector primary nozzle geometries with fixed/varied nozzle exit position

In this paper, an ejector-based multi-evaporator refrigeration cycle was proposed to focus on its application in the tropical region refrigerated truck refrigeration systems. For this application, numerical investigations on optimization of ejector primary nozzle geometries with fixed and varied nozzle exit position (NXP) by using Computational Fluid Dynamics techniques were performed by the authors. The main contribution of this paper is: (1) optimal primary nozzle throat diameter was determined with considering the demanding cooling load of both air-conditioning and freezer chambers at given operating conditions; (2) for the fixed NXP, the detailed effects of converging portion angle and length of two types of nozzle as well as diverging portion angle and length of converging-diverting nozzle on the ejector performance and relevant optimizations on these geometries were conducted, optimum converging portion geometries of both converging and converging-diverging nozzles are A(c1) = 8 degrees and L-c1 = 16 mm, and optimum for the diverging portion geometries are A(d2) = 6 degrees and L-d2 = 2 mm, respectively; (3) the reason to the performance difference of the two types of nozzle with fixed NXP was analyzed on the first try; and (4) specific study on seeking optimized primary nozzle geometries of two types of primary nozzle with varied NXP was completed for the first time.