THERMODYNAMIC ANALYSIS AND OPTIMIZATION OF A JET EJECTOR REFRIGERATION CYCLE USED TO COOL DOWN THE INTAKE AIR IN AN IC ENGINE

Abstract The present paper evaluates a jet ejector refrigeration system intended to cool down diesel engine intake below ambient conditions. Performance is assessed by means of 1D thermodynamic model of the cycle fed with ejector maps obtained with CFD code using R134a as working fluid. In the first study, no particular ejector geometry is fixed thus allowing the genetic algorithm to adapt the cycle to different engine conditions. Following this approach engine intake temperatures close to 0  ∘ C can be attained in those engine operating points in which exhaust thermal power is sufficient to drive the jet-ejector refrigeration system. In the second evaluation, ejection cycle configuration which provided best results for the most frequent operating point in a standard driving, designated as 2000 rpm and 50% load, is selected. With this particular configuration the rest of engine operating points are reassessed. In this study performance degradation is found away from the design point showing that ejector size is a limiting factor.