Research On Heat And Mass Transfer Of Membrane Contactor For Air Humidity Conditioning

Air humidity conditioning not only has a direct impact on people’s life and production,but also has an important significance of energy saving in building energy consumptions.Usually air humidity conditioning includes humidification and dehumidification. For airhumidification, it can be realized by the heat source, the ultrasonic vibration system and so on.For air dehumidification, it can be made by the cooling coil, liquid absorption and othermethods. Whether air humidification or dehumidification, these methods either consumehigh-grade energy or will cause the droplet drift and other deficiencies.So a method based on membrane contactors for air humidity conditioning, is used tosolve these problems. The biggest of the contactors is that the two fluids are separated by theselectively permeable membranes. Under the difference of the water vapor pressure, onlywater vapor is allowed to exchange through the membrane to realize air humidityconditioning. Unlike conventional heat exchangers, the boundary conditions of contactors areformed by coupling between the gas-liquid fluid and the membrane. Therefore, it’s required toinvestigate heat and mass transfer mechanisms during membrane process.In this paper, new quasi-counter flow parallel-plate contactor and counter flow hollowfiber contactor are designed and fabricated. Then the experimental platforms are established.The performance of membrane contactors are investigated under various operating conditions,such as air flow, solution temperature. It’s found that air flow and liquid flow have greatinfluence on parallel-plate contactor’s flow channel. While in the hollow fiber membranecontactor, the flow field distribution on the shell side plays an important role on heat and masstransfer. At last, a mathematical model of hollow fiber membrane contactor (in-line andstaggered) for air dehumidification is proposed and solved. It’s found that for the air stream,the Nusselt and Sherwood numbers decrease with an increase in the packing fraction. Andthey are larger than NuHfor a sparsely populated tube bank.