Thermal resistance network model for thermal conductivity of normal liquid helium-4 and helium-3.

Liquid heliums are intriguing substances. Superfluid states below certain critical temperatures, notably liquid helium-4 and helium-3 exhibit ultra-high thermal conductivity in the superfluid phase. However, the microscopic origin of the thermal conductivity of liquid heliums in the normal phase remains unclear. In this work, we employ the thermal resistance network model to calculate the thermal conductivities of normal liquid helium-4 (He I) and helium-3. Predicted values are not only in good agreement with the measurements but also reproduce the experimental trend of thermal conductivity increasing with temperature and pressure.