Liquid-to-air membrane energy exchangers (LAMEEs)are used to transfer heat and moisture between air and desiccantsolution streams. LAMEEs use semipermeablemembranes to prevent the penetration of desiccant droplets tothe airstream.When a LAMEE is used for air cooling and dehumidifying,the energy of phase change is released as the desiccantsolution absorbs moisture from the humid airstream.Consequently, the temperature of the desiccant solutionincreases as it flows along the exchanger, which decreases theLAMEE’s performance. A three-fluid LAMEE is a novel typeof LAMEE that includes a refrigerant circuit to cool/heat thedesiccant solution along the exchanger. The main contributionof this paper is that it shows, for the first time, the effects of theenergy of phase change released in liquid desiccant energyexchangers on the temperatures of the air and desiccant solutionstreams under air-cooling and dehumidifying operatingconditions. The effects of phase-change energy on the performancesof a two-fluid LAMEE and a three-fluid LAMEE areexperimentally investigated and compared under air-coolingand dehumidifying operating conditions. Also tested are theeffects of inlet air humidity ratio and desiccant solution flowrate on the performances of the two-fluid LAMEE and threefluidLAMEE.