Radiation effects with the transient line source measurement of fluid thermal conductivity

The apparent thermal conductivities of fluids, particularly organic liquids, measured by the transient line source technique are known to be higher than the real values. A modified integral method is proposed for analyzing this problem under specified assumptions. Attention is given to a theoretical demonstration of the process and mechanism by which radiation heat transfer brings about higher apparent thermal conductivity. The ratio of the apparent thermal conductivity and real thermal conductivity is discussed in dimensionless form, and correction factors for the measured values are given. Comparison with measured values for toluene shows good agreement.