Study Of Heat Transfer Characteristics Of Mathane/Hydrogen Mixture At Supercritical Pressure

The heat transfer characteristics of methane/hydrogen mixture whencooling at supercritical pressure is crucial to the liquefaction of syntheticnatural gas. The investigation of the cooling process will contribute to theconstruction of the liquefaction process as well as the design of heatexchangers. In this paper, numerical simulation of cooling heat transfer tosupercritical methane and methane/hydrogen mixture with standard k-εturbulent model in a horizontal circular tube is presented. Influences ofmass flux, heat flux and inlet pressure on heat transfer coefficient arestudied. Results show that heat transfer coefficient grows with theincrease of mass flux and the decrease of inlet pressure. No obviouschanges of heat transfer coefficient are observed with the variation of heatflux. With the increase of hydrogen proportion, temperature of mixturewhen maximum heat transfer coefficient occurs declines.A new set of experimental apparatus is designed and establishedwith the designing principle illustrated and schematics introduced. Apart from fittings, equipment, precooling and test section, this paper gives adescription of experimental procedure and data acquisition system. Forthe data obtained in the experiment, the paper presents the dataprocessing scheme and the result analysis methods.Heat transfer characteristic of the mixture is investigatedexperimentally at different pressures, mass flux and inlet temperatures.By comparing the experimental data with that of simulation, it is foundthat both of the results present the same trend. Through the supercriticalregion, heat transfer coefficient of the mixture increases as thetemperature rises, reaches the peak and declines afterwards, which can beexplained by the rapid change of heat capacity, density, viscosity andthermal conductivity at the critical point. According to dimensional theory,cooling heat transfer correlations of methane/hydrogen are developed.