Mechanical Engineering - Heat Transfer, Refrigeration and Air Conditioning - Discussion

Thermal conductivity increase with increase in temperature only for water.

Same happens when we heat water, as the temperature increases the water expands making atoms move more freely enabling to transfer heat at increased speed (the resistance between atom decreaed) so the thermal conductivity increase with increase temprature.

The thermal conductivity of water may increase or decrease with the temperature because, for a certain temperature range, the conductivity will increase (up to a certain temperature only) if the temperature goes beyond that the molecules move vigorously then the conductivity will decrease rapidly.

Hope it helps.