ENERGY AND EXERGY ANALYSIS OF AN ORGANIC RANKINE CYCLE INTEGRATED WITH VAPOUR COMPRESSION REFRIGERATION SYSTEM

An increase in the consumption of fossil fuels in industries has created some serious environmental issues like ozone layer depletion, air pollution, climate change, etc. In the world, around 50% of energy gets wasted in the form of heat from different resources like biomass, solar radiation, etc. To make reuse of this low and medium temperatures waste heat into useful power output, the most reliable and favorable technology is Organic Rankine Cycle (ORC). The maximum obtainable work from a system at any given state and of a given environment is called as exergy. A study reveals that exergy analysis being adapted by engineers for the optimization of any given system. It involves the application of exergy basics, equation balance, and exergy efficiencies to measure and improve system performances. It also helps in the identification of major areas of exergy destruction, which later on subjected to its minimization. In this paper, modelling is done of a vapour compression refrigeration system combined with an ORC to form integrated refrigeration-ORC. The condenser of the cold storage plant with R450A as a refrigerant rejects heat at 70 0C to 75 0C, which has been utilized by implementing ORC. It is followed by the selection of a proper organic fluid among seven different refrigerants considered. An Engineering Equation Solver is used to have thermodynamic modelling of the system. From the energy and exergy investigations, the best combination of R450A and R123 is selected as a fluid pair for the integrated system. The coefficient of performance increases from 3.17 to 3.88 for simple a vapour compression refrigeration system to an integrated system using R123. A power output of 0.296 kW is gained from ORC with 5.70% and 17.97% as thermal and exergy efficiencies respectively.