Numerical study on effective thermal conductivity of the compacted superconducting magnet

•A numerical model to calculate the effective thermal conductivity (ETC) of superconducting coil is proposed.•The thermal conductivity of insulation layer has a linear effect on the radial and axial ETC.•The specific residual resistivity ratio (RRR) of the copper matrix is positively correlated with the circumferential ETC.•The increase of the circumferential ETC is obvious as the Cu-to-nbti ratio increases, but become unconspicuous when the ratio exceeds 10.