Liquid-to-air-membrane energy exchangers (LAMEEs) are constructed with micro-porous semi-permeable membranes and transfer heat and water vapor between two separate fluids (air and liquid desiccant). Over the last decade, research has shown that LAMEEs can significantly reduce the energy consumption of HVAC systems. In this paper, a novel 3-fluid LAMEE prototype is designed and tested. The main objective of the proposed 3-fluid LAMEE is to enhance the performance (i.e. sensible, latent, and total effectivenesses, moisture removal rate, and sensible cooling capacity) of regular 2-fluid LAMEEs. The major difference between the proposed 3-fluid LAMEE and a 2-fluid flat-plate LAMEE is that, refrigeration tubes are placed inside the desiccant solution channels to enhance the cooling capacity and control the temperature of the desiccant solution along the length of the 3-fluid LAMEE. Water is used as the refrigerant in the current work. The main contribution of this paper is that it shows that the inlet temperature and mass flow rate of the cooling water have significant influences on the steady-state performance of the 3-fluid LAMEE. Compared to a 2-fluid LAMEE with the same design parameters, the sensible, latent, and total effectivenesses, moisture removal rate, and sensible cooling capacity of the 3-fluid LAMEE are improved by up to 69%, 28%, 39%, 54%, and 140% respectively, depending on the inlet temperature and mass flow rate of the cooling water. (C) 2015 Elsevier Ltd. All rights reserved.