LAUSR

Abstract This study experimentally investigates the effect of the geometrical parameters of a vertical conically coiled tube-in-tube (CCTIT) evaporator/condenser and their operating conditions on their effectiveness and on the coefficient of performance (COP) of a vapor compression refrigeration system (VCRS). Twelve CCTIT evaporator/condenser of different taper angles (0–135°) and torsions (0.0777–0.1311) are tested for different water Dean numbers in their annuli, while R134a flows in their internal tube in a counter flow configuration. The results show that increasing the evaporator/condenser taper angles and torsions in addition to decreasing their water Dean numbers augment the evaporator/condenser effectiveness and the COP of the VCRS. However, the coils taper angles have the more dominant effect than the other studied parameters. Finally, experimental correlations are developed to predict the COP of the VCRS in addition to the effectiveness of both the evaporator and condenser as functions of the investigated parameters.