A fine needle probe for determining the thermal conductivity of penetrablematerials

A fine needle probe for determining the thermal conductivity of penetrable materials such as fluids, fruit and animal flesh has been developed. The pr esent probe is constructed by inserting twenty strands of copper wire with electrical insulation coating into a fine stainless steel needle. The coppe r wire serves both as a heating unit and as an electrical resistance thermo meter. The effects on the thermal conductivity measurement caused by the th in needle wall have been analysed. It is found that the effects can be negl igibly small if the instruments and the measurement procedure are adequatel y designed. The usability of the as-constructed apparatus for penetrable ma terials has been tested to measure the thermal conductivities of liquid, fr uit and animal flesh. The accuracy of the present measurement was estimated to be within +/- 3%.