Comparative analysis of an improved two-stage multi-inter-cooling ejector-expansion trans-critical CO2 refrigeration cycle

• A particular two-stage multi-inter-cooling refrigeration cycle is improved.
• It is improved by including an internal heat exchanger within the cycle.
• Internal heat exchanger improves cycle's COP at low gas cooler pressure operation.
• Internal heat exchanger increases total exergy destruction rate.
• Overall improvement is important from mechanical operation viewpoint.

A new two-stage multi-inter-cooling ejector-expansion system trans-critical CO2 refrigeration cycle has been recently introduced. In the present study, an internal heat exchanger has been included within this cycle for possible improvement in cooling performance. Comparative studies on the COPs of the two cycles at the same operational conditions showed that improved cycle could be more efficient alternative for the original cycle at low gas cooler pressures. Of course, internal heat exchanger increased the total exergy destruction rate, but overall improvement index increased when internal heat exchanger was used within the refrigeration cycle.