Investigation on drying performance and alternative analysis of different liquid desiccants in compressed air drying system

Highlights: • The mixed solution is cheaper than LiCl solution without affecting drying performance. • Water vapor pressure can be selected as an indicative factor to evaluate substitute of LiCl solution. • Using waste heat from air compressor for desiccant regeneration is verified by experiments. • The novel system can get the compressed air with dew point temperature of −7.7 °C (0.8 MPa). Drying performance of a novel compressed air drying method using different liquid desiccants, including LiCl solution, LiBr solution and mixed solutions (LiCl/CaCl₂), is compared by experiments. It is found that drying performance of LiCl solution is better than that of LiBr solution. Besides, drying performance of three mixed solutions (44%, 46% and 49%) selected is similar to that of 40% LiCl solution, verifying the feasibility of substituting single solution with much cheaper mixed solution. The water vapor pressure of mixed solutions and LiCl solution is same in experiments, therefore it can be selected as an indicative factor to evaluate substitute of LiCl solution. Moreover, the cost of the three mixed solutions is 18% cheaper than that of 40% LiCl solution at least, which shows significant economization in application. Finally, system performance of the compressed air drying system is analyzed. The dew point of outlet compressed air could reach −7.7 °C at operating pressure of 0.8 MPa, indicating the dryness can satisfy requirement of various industrial applications which used typical electricity-driven cooling-drying method. The solution temperature of regeneration could reach 70 °C, validating that it is feasible to use waste heat recycled from the air compressor to drive solution regeneration.