A noncontact method for measuring thermal conductivity and thermal diffusivity of anisotropic materials

A noricont:tct method Ibr measuring the thermal conducti,.ity and thermal dilliisivity of anisotropic materials is r~roposcd. This method is bused on the lhct that the stlrl,lcC temperature variation with time depends on the thermal propertics of the material when its surlʹacc is heated locally. The three-dimensional transient heat conduction equation in the material is solved numerically. Tile dinlcnsionlcss average stlrftlcc tClllrtcrtlttllC variations arc obtuincd along each principal axis: that is. the .v and .v axes. Tile rdation between the dimensionless temperature and the l:ourier number is expressed by a r~olynomia] equation and used us a master plot. which is a basic rchltion to bc compared with measured temperature variation. In the experiments, the material surl,lcc is heated with a hlscr beam and the surlhcc tCnllʹ)cr;.ittlrc profiles tire mc;.isurcd by an infrared thcrnlOlllCtCr. Tile illGiStlrcd ICnll)Cl;.ltUlC variations with tinlc UlʹC COlllptlrcd with the Master plots to yield the thcrnlul conductivity 2, and thcrnlal dif Ihsivity :% in the .v direction and the thermal conductivity ratio E,,I =2,. 2,) simultaneously. To conlirnL the applicability and the accuracy of the present method, mcasurcnlcnts were performed on muhilaycrcd kent-paper, vinyl chloride, and polyethylene resin l]lnl, whose thermal properties are known. From numerical simuhltions, it is found that the present method can measure the thcrmophysical properties .;.,. :x, and E,, within errors of _+6. _+22, and _+ 50,. respectively, when the measuring errors of tile pcuk Ileal I]ux. the heating radius, and the surface temperature rise arc assumed to be within +2. + 3 ~ and _+ 0.2 K, respectively. This method could be applied to the measurement of thcrmophysical properties of biological materials.