Performance of a novel climate-adaptive temperature and humidity independent control system based on zeotropic mixture R32/R236fa

Abstract

• A climate-adaptive temperature and humidity independent control system (CATHICS) is proposed. • Heat and humidity ratio ( ε ) of CATHICS is adjustable to afford the changing heat and moisture. • Temperature glide of non-isothermal cooling sources change with the concentration of zeotropic mixture. • Effect of outdoor meteorological parameters and indoor personnel fluctuation on ε is analyzed. • The affordable ε of the CATHICS varies from 3500 to 4700 kJ/kg. A climate-adaptive temperature and humidity independent control system (CATHICS) is proposed, of which heat and humidity ratio ( ε ) is adjustable to afford the changing indoor heat and humidity load. Zeotropic mixture R32/R236fa is employed due to its characteristic of temperature glide during phase change. A module for composition regulation is incorporated based on boiling point difference of zeotropic mixture. High/low boiling point component increasing modes are operated when indoor air state deviates from the accuracy standard. Temperature glide regions of non-isothermal cooling sources change with the concentration of zeotropic mixture, which conforms to cascade utilization for moisture and heat load removal. The cooling and dehumidifying capacity of the chiller is regulated correspondingly. The models of evaporation temperature glide, affordable ε , cooling and dehumidification efficiency are established. The effects on the affordable ε are analyzed with the changing outdoor meteorological parameters and indoor personnel fluctuation. The relationship between mass concentration of working fluid and sliding temperature regions is revealed. The affordable ε varies from 3500 to 4700 kJ/kg, which illustrates that the CATHICS can totally afford changing heat and humidity load. The cooling and dehumidification efficiency are approximately 3.2 and 1.2. The vapor quality of the working fluid from the condenser is analyzed. The highly-integrated CATHICS is suitable for realizing individualized thermal comfort in residential buildings.