The influence of gas pressure on the effective thermal conductivity of nano-porous material

Thermal conductivities of gas in free space and in nano-porous materials were theoretical investigated. The Hot Disk thermal constant analyzer based on the transient plane source method was adopted to measure the effective thermal conductivity of nano-porous materials within a gas pressure range from 0.01 Pa to 1 MPa. The influence of temperature and gas pressure on the effective thermal conductivity of nano-porous materials was investigated experimentally. The contribution of gas heat conduction to the effective thermal conductivity of nano-porous materials was decomposed from the experiment result. The effective thermal conductivity of nano-porous materials increases rapidly with the increases of gas pressure. The decomposed contribution of gas heat conduction is higher than the gas thermal conductivity in nano-porous materials and the difference increases with the increment of pressure and even higher than the gas thermal conductivity in free space at 1 MPa. The influence of temperature on the gas heat conduction becomes apparent at gas pressure higher than 400 kPa.