Performance evaluation of the transcritical CO₂ heat pump driven liquid desiccant deep dehumidification system using the ionic liquid.

The transcritical CO2 heat pump driven liquid desiccant dehumidification system, which makes use of the environmentally friendly refrigerant and superior heating performance of a CO2 heat pump, is a potentially sustainable and effective air treatment method. Nevertheless, considering limitations such as crystallization and corrosion, traditional salt solutions should be replaced by ionic liquids, which possess non-crystallizing behavior and negligible vapor pressure, making them more suitable for deep dehumidification. In this paper, a transcritical CO2 heat pump driven liquid desiccant deep dehumidification using the ionic liquid is proposed. With the conducted parametric analysis, the multi-objective optimization is further explored. Then, the influences of the indoor and outdoor air parameters are also investigated. The annual performance in the selected city is also presented to show the system’s flexibility. The multi-objective optimization results show that with designed supply air moisture content of 3.0g/kg, the optimal coefficient of performance and number of mass transfer units are respectively 1.57 and 2.0. Moreover, the maximum annual performance factor is 2.32 in the selected city Nanjing.