A new transient method of the measurement of temperature dependent thermal diffusivity

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Abstract
A new method has been developed which enables thermal diffusivity to be measured as a function of temperature in a single experiment. One-dimensional transient temperature distributions T(x,t) generated in the sample are measured at twenty positions xi at discrete times tj. The values of thermal diffusivity a (Te) at temperatures of local extrema of the temperature distributions Te are obtained from the expression a(Te)=( delta T/ delta t)/( delta 2T/ delta x2)/E using least squares cubic spline approximations to T(xi, tj) to evaluate the derivatives at the extrema E. Thermal diffusivities of water-containing food related materials (ice, two food models, cod and mackerel muscle) were measured in wide temperature ranges. The relative accuracy and precision depended on temperature and on the thermal regime varying from 2 to 8% and 3 to 15% respectively for temperatures outside the interval (-5,0) degrees C.

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