Advanced air dehumidification membranes for energy efficient membrane-based air-cooling process

Space cooling is the most rapidly growing energy consumption in residential and commercial buildings in hot and humid economies with high consumer expectations of thermal comfort. The global annual energy use of space cooling in residential and commercial spaces has exceeded 2000 terawatt.hour in 2016 with 9.3% of the global consumption in the Middle East. Recently, membrane dehumidification is identified by the US Department of Energy as the top alternative to the conventional vapor compression cooling because it has significant potential to increase energy efficiency and reduce the use of environmentally hazardous hydrofluorocarbons. Nonetheless, a viable membrane dehumidification process requires membranes with extremely high water vapor permeability, high water/air selectivity, fouling resistance, good durability, and low cost. Currently there are very limited membrane materials that could provide the necessary water permeation and water/air selectivity at moderate cost. This proposed research aims to develop and test advanced, cost-effective air dehumidification membranes for air conditioning/cooling applications in the Qatar environment. The research team will design, optimize, fabricate, and test two types of nanomaterials-based flexible membranes with water vapor permeance ≥〖7x10〗^(-6) kmol/m^2.s.kPa and water/air selectivity ≥ 〖10〗^4. The first membrane type is mixed matrix membranes (MMMs) that incorporate water-selective nanofillers including graphene oxide (GO), sulfonated GO (SGO), and metal organic framework (MOF) materials into a flexible polymer matrix. In addition to MMMs, graphene-based materials themselves are promising candidates as the next generation of thin film membranes that are expected to provide an unparalleled combination of high selectivity and high permeation rates as well as excellent thermal, chemical, and antifouling properties. Therefore, we will also develop GO and SGO membranes using a new coating method that yields the molecular level control of coating thickness and is capable of continuous deposition and film transfer such that large area membranes can be fabricated commercially. The selection of the polymer matrix/support and the structure of the nanofiller will critically influence the membrane performance. MD simulation will be used to predict the transport properties of water vapor and air through polymeric membranes containing different concentrations of GO, SGO, and MOFs. In addition to the membrane transport properties, the membrane’s long term performance could be affected by mechanical durability and fouling caused by aerosol contaminants. Therefore, these characteristics will be investigated under Qatar environmental conditions to establish the structure-property-performance relationship and the membrane longevity. Finally, the performance of the optimized membranes will be tested in vacuum membrane air-dehumidification process and the results will be used to perform a technoeconomic analysis of the membrane dehumidification cooling process. Successful development of the proposed membranes would accelerate the commercialization of the energy efficient membrane dehumidification process resulting in significant energy saving and reduction in CO2 emission associated with A/C cooling applications. Furthermore, the developed membranes can serve as the basis for other membrane dehydration processes such as dehydration of natural gas and flue gas.

Texas A&M University at Qatar