ИСТИНА

Here we report on membrane humidification, heat exchange and desalination processes using nanoporous gas-liquid membrane contactors. Porous polypropylene hollow fibers with diameter of 320 mkm and pore sizes of 100 × 500 nm were used in the design of counterflow divergent-convergent modules with an active surface area of 0.75 - 4 m2 and packing density of up to 300 m2/m3. Evaporative heat exchange and air humidification test revealed effective water evaporation performance of the modules up to 2 kg/m2/h and an ultimate cooling capacity attaining 1 MW/m3. The general tendencies of heat transfer coefficients on Reynolds numbers, air humidity, flows and temperature conditions were experimentally established. Evaporative heat transfer from membrane surface allowed to increase heat transfer coefficient to ambient gas to 200 W/m2/K and heat exchange power over 2500 W/m2 at Reynolds numbers >100. An ability for liquid cooling ~10-15° below the input temperature of gas and liquid was also established with evaporative heat exchanger. Further, the nanoporous membrane modules were applied in air gap membrane desalination with condensation on a hollow fiber heat exchanger. The permeate purified water flux of 2 kg/m2/h and thermal efficiency over 90% were achieved with proposed strategy using hot brine temperature of <80 °C and 5% wt salts content.