Effectiveness of temperature and humidity treatment processes: Unified expression and thermodynamic analysis

Abstract

Temperature control and humidity control are the two main objectives of the heating, ventilation, and air conditioning (HVAC) system. Previous studies have mainly focused on analyzing one or more existing configurations with regular indoor conditions of public and residential buildings. In this study, a unified expression is derived to evaluate the thermodynamic effectiveness from the ideal temperature and humidity treatment processes to the actual cooling and dehumidification systems, and it is modified by progressively rejecting the “ideality” assumptions. It is indicated that the thermodynamic effectiveness of the ideal temperature and humidity treatment process only depends on the initial state, the final state, and the flow rate of the air streams, and the process with the highest COPth for dehumidification is coupled with the cooling process. Based on the illustrative non-ideality characteristics in the actual cooling and dehumidification systems, the exergy performances of multiple system configurations are investigated. The results also elucidate that the liquid desiccant systems attain less irreversible loss and has a relatively high thermodynamic effectiveness, but the desiccant wheel system also shows great potential for deep dehumidification applications. This research provides a theoretical guide and illustrates the potential paths for the future design of exergy efficient cooling and dehumidification systems.