Simplified effectiveness and number of transfer unit model for a vacuum membrane dehumidifier applied to air conditioning

Abstract

• A simplfied prediction model for a vacuum-based membrane dehumidifier is proposed. • Proposed model was validated via numerical simulation and experimental data. • Model dehumidification performance exhibits error bounds below 20%. • Model consumes 42.4% lower vacuum pump energy than existing control method. This paper purposed to develop a simplified model for a vacuum membrane dehumidifier in an air conditioning system. The proposed model is a gray model that uses mathematical equations that are deducted from the effectiveness and number of the transfer unit of the heat exchanger and a regression equation for the ratio of humidity capacities (X factor) analogous to the heat capacities ratio of heat exchangers. The applicability of the simplified effectiveness and number of transfer unit methods to vacuum-based membrane dehumidifiers in air conditioning systems has been validated via numerical simulation and experimental data. The error bound for the validation of the numerical simulation and experimental data for dehumidification performance (i.e., outlet humidity ratio and dehumidification effectiveness) was 20%. In addition, an operation example using the simplified model was performed to control the vacuum pressure of the vacuum-based membrane dehumidifier in the air-conditioning system. The results show that the proposed algorithm using the simplified model exhibits an energy-saving potential of 42.4% compared to the conventional vacuum-based membrane dehumidification operated in a variable air volume system.