Systematic analysis of heat and mass transfer processes will help researchers better understand the characteristics of heat and mass transfer and improve the design of HVAC systems and equipment. Throughout the heat and mass transfer process, thermal and humid exergy destruction are separated, which illuminates the relationship of heat transfer and mass transfer. Exergy destruction caused by the inlet parameters of humid air and water and by the flow rate ratio of air to water will not be eliminated by increasing heat/mass transfer area. A parameter unmatched coefficient can be defined to evaluate the influence of inlet parameters quantitatively. Exergy destruction decreases if humid air entering the air-water contact module is close to the saturated line, when the parameter unmatched coefficient is close to 0. The parameter unmatched coefficient was applied to illustration examples of a humidifier and an indirect evaporative cooling tower. Flow paths show better performance when the parameter unmatched coefficient is small. (C) 2015 Elsevier Ltd. All rights reserved.