Modelling and parametric analysis of heat and mass transfer performance of refrigerant cooled liquid desiccant absorbers

A detailed mathematical model is developed to predict the heat and mass transfer performance of a vapour compression/liquid desiccant hybrid cooling and dehumidification absorber referred to as RCLDA system in this work. An RCLDA system uses a desiccant loop to bring the humidity within the comfort range along with a sensible cooling loop to bring the temperature within the comfort range. In an attempt to increase both the COP of the desiccant as well as the cooling system, the RCLDA system combines a desiccant cycle operating in its most efficient range along with a cooling cycle operating at higher evaporator temperatures. Governing equations describing the steady-state, two-dimensional heat and mass transfer in an RCLDA system are developed to study its cooling and dehumidification performance. A numerical scheme based on a control volume analysis is used to solve these differential equations. A parametric analysis is conducted to help understand and optimize the performance of this RCLDA system. The analytical model is also used to develop heat and mass transfer performance maps for partial load performance estimation of the RCLDA system. A knowledge of the partial load performance is required for the yearly performance estimation. It is found from this study that the performance of the RCLDA system is a strong function of refrigerant and air side NTU, evaporator temperature, carry-over regenerator load and refrigerant and air mass flow rates. The mass flow rate of desiccant solution in the absorber did not have any significant impact on the performance of the absorber. © 1998 John Wiley & Sons, Ltd.