Estimating The Thermal Parameters Of The Porous Medium By CGM

Heat transfer of porous medium has extensive applications in energy, materials,environmental science, chemical engineering, bionics, biotechnology, medical andagricultural engineering disciplines and new technology field. The inverse problem isthe inverse process of all kinds of direct question, which is an interdisciplinary subjectrelated to many technology fields. It can get unknown parameters by studyingtemperature information of one or more points of object interior or boundary, such asunknown parts of the boundary conditions, thermal conductivity, strength of internalheat source and geometry conditions of the object. Because of the complex internalstructure of porous medium and thermal properties parameters which are not easilymeasured, the study of the inverse problem of porous media has a realistic significance.The inversion of thermal properties parameters of porous medium in verticalannular space using conjugate gradient method (CGM) was studied in this paper. Thestudy mainly included:1) The mathematical model of the direct problem of porous medium heat transferin vertical annular space was established and had dimensionless treatment. Discretizedthe above-mentioned governing non-dimensional model by the finite volume method, adiscrete algebraic equation can be formed to obtain temperature field of heat transfercharacteristics of porous media and velocity field of fluid by SIMPLE algorithm.2) Combined with the mathematical model of the direct problem of porous mediumheat transfer in vertical annular space, the inversion model of multi-variables thermalproperties parameters of porous medium in vertical annular space, which based on thebasic parameters ε and the criterion numerals Da of properties of porous medium, wasestablished using conjugate gradient method (CGM).3) The thermal properties parameters of porous medium in vertical annular spacewere inverted by simulation experiment. The effects of initial predicted values, theamount of temperature measuring set and temperature measuring error on the inversionresults of thermal properties parameters were discussed.The studies results indicated that single variable and multi-variables thermalproperties parameters of porous medium in vertical annular space were effectivelyinversed using CGM methods and temperature information measuring. When theamount of temperature measuring set were properly reduced and measuring results had certain error, the inversion method was also obtained good inversion results. The effectof initial predicted values on the inversion results of thermal properties parameters wasinsignificant.