(628g) Development of a Discrete Transport Model for Membrane-Based Advanced HVAC Systems

Authors: 
Smith, K. D. - Presenter, United Technologies Research Center
Ma, Z. - Presenter, United Technologies Research Center
Kandil, S. M. - Presenter, United Technologies Research Center
Ranjan, R. - Presenter, United Technologies Research Center
Wagner, T. C. - Presenter, United Technologies Research Center


A discrete model of heat and mass transport has been developed for use in designing a membrane-based liquid desiccant and vapor compression air conditioner for use in warm and humid climates.  The implementation of a membrane-based liquid desiccant system should overcome desiccant carryover problems, where the desiccant is transported into the air stream.  This paper describes the modeling of the overall heat and mass transfer sorption processes within the membrane contactor.  The air-liquid desiccant system is modeled using discrete nodes of coupled heat and mass transfer in the Engineering Equation Solver (EES) package.  The inclusion of discrete nodes through the contactor is shown to be necessary to accurately predict transport processes within the membrane contactors.  Additionally, the sensitivity of the water flux through the membrane with respect to the mass and heat transfer parameters and the overall membrane parameters are investigated.  The relationship between the residence time in the contactor and the parameters of the membrane system are shown to be related to the water flux through the membrane.  The operation of contactor in counter-flow, cross-flow and a combination is evaluated for influences on the membrane water flux.