In this paper

non-condensable gas (N2) was added to CO2 transcritical refrigeration cycle as additive. And the the effect on refrigerant performance is studied by theoretical analysis and computer simulation. The major thermophysical parameters of CO2 and N2 are analysed. The addition of N2 results in the change of the thermophysical parameters of CO2. The calculated results have shown that additives can increase saturation pressure and liquid specific heat of CO2

but reduce viscosity coefficient

surface tension

the liquid/vapor density ratio and coefficient of thermal conductivity of CO2. N2 can increase gas nucleus in evaporator

and leads to heterogeneous nucleating process in liquid. So the nucleation temperature decreases and heat transfer coefficientis increases. Moreover

the discharge temperature and specific power of compressor are reduced and refrigeration efficiency improves. The more the N2 is added in the system

the more the refrigeration system performance coefficient increases. The paper provides theoretical basis for the research on highly efficient application of CO2 refrigeration system.