Simulation Study On Heat And Mass Transfer Properties Of Compound Working Medium

Humid Air Turbine(HAT) cycle is well known for its high efficiency,high specific power, low NOxemissions etc, and is called―cross-centurythermodynamic cycle‖. Combined the advantages of advanced coalgasification technology and efficient humid air turbine cycle, IntegratedGasification Humid Air Turbine (IGHAT) cycle is a coal using powergeneration system of high-efficiency, low-pollution and low-specificinvestment. Both these new thermodynamic cycles have a key process:humidification of working fluid (air or syn-gas) within a saturator. Thesaturator’s performances in heating and humidifying the working fluidhave important impact on the holistic performance of these cycles, andits internal wetting process is a complex gas-liquid two-phase flow withheat and mass transferring.Therefore, it is of great significance to study theproperties of gas-liquid heat and mass transfer.According to the characteristics of the gas-liquid two-phase flow andits heat and mass transfer properties, the complex gas-liquid flow insidethe saturator with bulk packing is simplified to gas-liquid two-phase fallingfilm flow along vertical corrugated plate with the wall equivalent method.A two-dimensional two-phase flow mathematical model using the volumeof fluid (VOF) method is established. The UDF function of the mass andenergy source term working in the film flow are considered. By using thecomputational model, the heat and mass transfer characteristics of air andfuel gas falling film are studiedBased on the simulated results, The influences of various structuralparameters such as amplitude α、wavelength λ、dimensionless parameter α/λ of corrugated plate, inner liquid velocity on the heat and masstransfer properties in gas-liquid two-phase flow are analyzed. Additional,the simulation results between air humidification and syn-gashumidification are compared and analyzed. According to the result, to getrid of liquid film rupture or splashing, the ratio of plate dimensionlessparameter should be within the range of0.02-0.08under given pneumaticcondition; And there is an optimum plate parameter of0.06for air tomaximize its mass transfer, while the value for syn-gas is0.04.