COP Prediction of an ejector refrigeration cycle combined with a vapour compression cycle for automotive air conditioning

Abstract

This paper presents the COP prediction of an ejector refrigeration cycle combined with a vapour
compression cycle for automotive air conditioning. Using computational fluid dynamics (CFD) technique, the
performance of an ejector was analyzed in term of the entrainment ratio (Rm) and critical back pressure
(CBP). The results from this study were compared with a previous study of combined ejector refrigeration
system for automotive air conditioning application [1] which the entrainment ratio (Rm) were predicted from
one-dimensional (1-D) equation. The performance of an ejector (Rm and CBP) from CFD and onedimensional
method were analyzed and used as database for a mathematical modeling. In order to predict
the COP of the combined system, a set of mathematical equations was developed using EES. The operating
conditions are chosen accordingly as, intercooler temperature between 15 ๐C and 25 ๐C, condenser
temperature equal to 35 ๐C and evaporator temperature equal to 5 ๐C. However, when generator
temperatures are 80 ๐C, 85 ๐C and 90 ๐C, the results showed average relative errors of the COP of an ejector
refrigeration cycle (COPej), between CFD and 1-D are 44.64%, 50.47% and 59.68% respectively, and
between CFD and 1-D NEW are 1.54%, 0.08% and 6.49% respectively.