Analysis of a novel pressurized dehumidification air conditioning system for urban underground space

Abstract

Underground urban space (UUS), which represents the future development of cities can effectively alleviate land shortage and improve urban elasticity. To create a suitable living environment, dehumidification in the air conditioning of UUS must be considered. A novel pressurized dehumidification air conditioning system (PDACS) is proposed in this study. The PDACS adopts an air cycle refrigerator and desiccant wheel (DW) simultaneously to adjust the air temperature and humidity to the desired level, this effectively reduces the dehumidification load on the DW. The thermal performance and thermodynamic characteristics of PDACS are analyzed using enthalpy method and endoreversible thermodynamic analysis model, respectively. The results show that the proposed system can achieve efficient dehumidification under a wide range of ambient temperature and humidity. A case study shows that under the condition of ambient temperature of 25 °C and relative humidity of 80%, the coefficient of performance of the system can be increased from 0.257 to 0.582, and the dehumidification capacity of DW can be reduced from 9.22 g/kgdry air to 4.05 g/kgdry air. Thus, we validated the effectiveness of our humidity and temperature control method. The comparative analysis shows that PDACS improves the integration of the system. We then conducted a complete thermal analysis, and obtained the system thermal–moisture–power conversion mechanism to provide strong technical support for the proposed air conditioning design. The PDACS scheme and analysis results proposed in this study will provide new ideas for the design of underground buildings.