Characterisation and evaluation of a new phase change enhanced working solution for liquid desiccant cooling systems

Desiccant solutions play an essential role in desiccant cooling systems to absorb moisture from the process air. This paper presents the characterisation of a new working solution for liquid desiccant cooling systems. The new working solution was prepared through dispersion of micro-encapsulated phase change materials (MPCMs) into lithium chloride (LiCl) desiccant solutions to ensure that the dehumidification process was achieved under a low temperature condition and to improve thermal capacity and moisture removal efficiency of the mixture. The properties of the new solution, including density, enthalpy-temperature relationship, particle size distribution, thermal conductivity, and vapour pressure were characterised through either experimental tests or theoretical analysis. It was shown that the density and thermal conductivity of the new working solution slightly decreased with the increase of the mass fraction of the MPCMs in the mixture. The thermal capacity of the new working solution substantially increased in the melting temperature range of the MPCMs used. The vapour pressure of the new working solution decreased due to the existence of the MPCM particles. It is expected that the dehumidification efficiency of adiabatic dehumidifiers can be potentially improved when using this new working solution due to the decreased vapour pressure and increased thermal capacity of the phase change enhanced desiccant solution.