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Performance and Economic Analysis of a Variable Refrigerant Flow ( VRF ) System

This study deals with the exergetic modeling and performance/cost evaluation of a variable refrigerant flow (VRF) air conditioning system. An experimental setup was established to investigate the system performance under cooling conditions. System mainly consists of one outdoor unit and two indoor units. Outdoor unit equipped with two compressors (one variable speed and one constant speed), condenser, and four way valve is connected to two indoor units. Exergy, cost, energy and mass (EXCEM) analysis was applied to this system for the first time to the best of the authors` knowledge. The relations between thermodynamic losses and capital costs were also parametrically investigated. Experimental results show that the greatest irreversibility (exergy destruction) occurs in the condenser, followed by the evaporators. Exergy efficiency of the whole system on the exergetic product/fuel basis was calculated to be 85.84% at a reference state temperature of 25 o C. Exergy efficiency and exergy loss rate were in the range of 85.27-86.55% and 0.919-0.916 MW/USD, respectively, based upon the conditions and parameters considered in the present study.