Performance of compression type refrigerator using natural working fluid

Refrigeration system influences the environment. The discovery of ozone-depleting effects and global warming potential of CFCs and HCFCs, led to the Montreal Protocol and the UN Framework Convention on Climate Change and its Kyoto Protocol. It documents clear and persuasive scientific  proof of the interconnections of climate change and stratospheric ozone depletion. An alternative to CFCs as well as HCFCs is the use of naturally occurring substances (refrigerants). The majority of natural working fluids have been well known for a long time. Their low cost and minimum environmental impact make them attractive alternatives to the environmental harmful material such as CFCs and HCFCs. Much research works have been conducted to explore the new applications of natural working fluids. Carbon dioxide (CO2) is one of the few natural refrigerants, which is neither flammable nor toxic. It is inexpensive, widely available and does not affect the global environment as many other refrigerants. The most important issues are to enhance the energy efficiency and reduce cost of the systems to an acceptable level. The compressor of a refrigerant compression process is the component with the major influence on the efficiency and reliability of the entire system. In this paper the effects on the efficiency of the compression process of a CO2– compressor are discussed and evaluated. Choosing operative conditions, experimental test have been done. Transcritical and subcritical carbon dioxide vapour compression cycle were considered and the COP was estimate.