Review of secondary loop refrigeration systems

Due to the environmental damage caused by HFC refrigerants, there is an increasing universal interest to research environmentally friendly fluids in refrigerants and alternative approaches to the traditional DX refrigeration system. These refrigerants include ammonia, carbon dioxide, hydrocarbon, R152a and HFO1234yf. Major drawbacks of these refrigerants are their potential flammability and safety hazards. One way to overcome this issue is to use the new refrigerants in conjunction with a secondary loop refrigeration system. Additional benefits of the secondary loop refrigeration system are refrigerant charges, leakage reduction, potential maintenance simplification, and low operating cost. This article presents a comprehensive review of the secondary loop refrigeration systems. Furthermore, this review covers the performance and risk assessment of flammable refrigerants, secondary refrigerants and components of the secondary loop refrigeration system within the following applications: commercial refrigeration, residential air conditioning/heat pumping, and mobile air conditioning.