Energy, exergy, exergoeconomic and enviroeconomic (4E) assessment on a liquid desiccant air-conditioning system using green deep eutectic solvent of ethaline

Abstract

Despite the recognition of its energy-saving potential, the promotion of liquid desiccant air-conditioning system is limited by the drawbacks of existing desiccants in long-term or large-scale use. Deep eutectic solvent with good bio- and eco- friendliness has not yet been tested for systematic study in air-conditioning system. In this paper, a deep eutectic solvent, ethaline, is utilized in a heat pump driven liquid desiccant air-conditioning system, whose energy, exergy, exergoeconomic and enviroeconomic performances are studied. Under basic condition of ambient temperature of 35 ℃ and relative humidity of 80%, its systematic coefficient of performance reaches 1.406 with exergy efficiency of 32.65%. Meanwhile, 52.36% CO2 emission can be reduced compared with conventional condensation dehumidification air-conditioning system. The payback period of such system at basic condition with 20 kW cooling load is 14.4 years, and it can be significantly reduced in applications with larger cooling load. Parametric analyses for different requirements and environments are conducted as well. The energy and environmental superiority of ethaline is more significant under more latent loads, higher supply air flow rate and lower fresh air ratio. Under ambient temperature ranging from 28 ℃ to 40 ℃, the effect of CO2 emission reduction for ethaline reaches to extents of more than 38%. The advantages of ethaline are further illustrated in comparison with other potential desiccant candidates, in aspects of toxicity, price and corrosiveness. The potential performance improvement approach for ethaline used as liquid desiccant is also proposed and discussed. The results in this paper demonstrate the promising prospect of ethaline quantitatively, and provide enlightening for exploration of new liquid desiccant. In pace with the broadening application of air-conditioning system, liquid desiccant air-conditioning system using such green desiccants can be promoted, which brings out great prospects in energy saving and CO2 emission reduction.