Match properties of heat transfer and coupled heat and mass transfer processes in air-conditioning system

Sensible heat exchangers and coupled heat and mass transfer devices between humid air and water/desiccant are commonly used devices in air-conditioning systems. This paper focuses on the match properties of sensible heat transfer processes and coupled heat and mass transfer processes in an effort to understand the reasons for performance limitations in order to optimize system performance. Limited heat transfer capability and flow mismatching resulted in heat resistance of the sensible heat transfer process. Losses occurred during the heat and mass transfer processes due to limited transfer capability, flow mismatching, and parameter mismatching. Flow matching was achieved when the heat capacities of the fluids were identical, and parameter matching could only be reached along the saturation line in air–water systems or the iso-concentration line in air–desiccant systems. Analytical solutions of heat transfer resistance and mass transfer resistance were then derived. The heat and mass transfer process close to the saturation line is recommended, and heating sprayed water resulted in better humidification performance than heating inlet air in the air humidifier.

► Investigates match properties of heat or mass transfer processes in HVAC system.
► Losses are caused by limited transfer ability, flow and parameter mismatching.
► Condition of flow matching is the same heat capacity of the fluids.
► Parameter matching is only reached along the saturation line in air–water system.
► Analytical solutions of heat and mass transfer resistance are derived.