Accuracy in thermal contact conductance experiments - the effect of heat losses to the surroundings

A major source of uncertainty in contact heat transfer experiments is the heat loss from the specimens to the surroundings by convection, conduction and radiation. A detailed analysis is presented comparing the resistance to heat transfer across the joint to the resistance to heat flow from the specimens to the surroundings. It is shown that the heat losses may be reduced by the provision of a shield. It is also shown that, unless the contact pressures are very low or there is large flatness deviation in the contacting surfaces, the vacuums of the order obtained by means of a rotary vane pump may be adequate; otherwise, a diffusion pump may also be necessary.