Conceptualization and Analysis of a Membrane-Assisted Condensation Dehumidifier

Given air conditioning's significant contribution to global energy consumption, there is a need to develop more efficient and cost-effective methods of cooling and dehumidification. Separate sensible and latent cooling systems have been proposed as a potential means of improving air conditioning efficiency. Many of these proposed systems use water-selective membranes to create separate streams of dry air and water vapor, after which they use some means of rejecting the water vapor to the outdoor space. However, certain system architectures have proven challenging to realize in practice, including the dual-module water vapor compressor-based “humidity pump”. In this work, we describe a similar system that instead uses a vapor compression refrigeration cycle to condense the permeate water vapor and pump the liquid to atmospheric pressure. This subverts the challenge of developing an efficient, compact, and inexpensive water vapor compressor by replacing the compressor with a refrigeration cycle (a mature technology). It also eliminates the outdoor membrane module completely. Our numerical model of the system reveals 100,000 as the target membrane module selectivity; at this value, the system would achieve an MRE of 8 - 10 kg/kWh and an exergetic efficiency of 8 - 10% for the conditions analyzed in this work.