Analysis of a novel refrigeration Carnot-type cycle based on isothermal vapour compression

A novel Carnot-type cycle is proposed to reach high performances for sub-critical and trans-critical applications. Two natural fluids, ammonia and carbon dioxide each one corresponding to one of the application, were chosen. Compared to conventional cycles, the Carnot-type cycle leads to COP increase by 4-70% depending on the application. For the most suitable case (CO2), a simpler design resulting from a trade-off between complexity and performances still exhibits high performances (92.5% Of COPcarnot vs. 95.4% for Carnot-type cycle). Compared to conventional one, this simpler design appears to be more sensitive to the expander efficiency but still achieves higher performances: 80% vs. 50% of COPcarnot. The impact of the compression cooling efficiency was explored too. with a temperature pinch equal to 20 K, the performances are still better than those of the conventional one (+21% of COP) despite a decrease by 24% of the COP. (C) 2008 Elsevier Ltd and IIR. All rights reserved.