Thermodynamic Analysis of the Air-Cooled Transcritical Rankine Cycle Using CO2/R161 Mixture Based on Natural Draft Dry Cooling Towers

Heat rejection in the hot-arid area is of concern to power cycles, especially for the transcritical Rankine cycle using CO2 as the working fluid in harvesting the low-grade energy. Usually, water is employed as the cooling substance in Rankine cycles. In this paper, the transcritical Rankine cycle with CO2/R161 mixture and dry air cooling systems had been proposed to be used in arid areas with water shortage. A design and rating model for mixture-air cooling process were developed based on small-scale natural draft dry cooling towers. The influence of key parameters on the system’s thermodynamic performance was tested. The results suggested that the thermal efficiency of the proposed system was decreased with the increases in the turbine inlet pressure and the ambient temperature, with the given thermal power as the heat source. Additionally, the cooling performance of natural draft dry cooling tower was found to be affected by the ambient temperature and the turbine exhaust temperature.