An ejector-enhanced dual-temperature R290 mechanical dehumidification cycle: Energy consumption, exergy, economic, and carbon footprint evaluation

Currently, the mechanical dehumidification based on the vapor compression is the commonly applied for air dehumidification. However, with the increasingly concerns about refrigerant alternative, using eco-friendly refrigerant such as R290 in the mechanical dehumidification cycle is become more important. Additionally, conventional mechanical dehumidification cycle (CMDC) have large irreversible throttling loss generated by expansion valve. Therefore, a modified ejector-enhanced dual-temperature condensation R290 mechanical dehumidification cycle (EDMDC) is proposed in this study to reduce the throttling loss by employing the ejector. Then, the energy and exergy utilization efficiency, investment cost and carbon footprint of the conventional and modified are analyzed and compared. The results demonstrated that the modified cycle performs better than the conventional cycle. Specifically, the coefficient of performance and volume cooling capacity of the modified cycle are improved by 14.0% and 13.9%, respectively, compared to the conventional cycle. Moreover, because of the applying of ejector, the throttling loss in the modified cycle is significantly reduced, which achieves a 13.6% improvement in exergy efficiency. On the other hand, although using ejector improves the initial investment of modified cycle, it could still achieve a 11.84% improvement in unit energy output cost. The assessment of carbon emissions shows that the modified system using R290 could reduce carbon emissions by 15.6% and 19.7%, respectively, compared to system using R32 and R134a. This proves the outstanding eco-friendly advantages of R290 in replacing high global warming potential refrigerants. Therefore, it is worthwhile to promote the application of R290 refrigerant in the mechanical dehumidification field.