Abstract: A fine needle probe for determining the thermal conductivity of penetrable materials such as fluids, fruit, animal fresh has been developed. The present probe is constructed by inserting twenty strands of copper wire with electrical insulation coating into a fine stainless steel needle. The copper wire serves both as a heating unit and as an electrical resistance thermometer. The effects on the thermal conductivity measurement caused by the thin needle wall has been analyzed. It is found that the effects can be negligibly small if the instruments and the measurement procedure is adequately designed. The usability of the as-constructed apparatus for the penetrable materials has been tested to measure the thermal conductivity of liquid, fruit and animal fresh. The accuracy of the measurement was estimated to be ±3%.

Key words: thermal conductivity, thermal probe