Inconel thermal conductivity

Adequate predictions of thermal conductivity for pure metals can be made by means of the Wiedemann-Franz law, which states that the ratio of the thermal conductivity to the product of the electrical conductivity and the absolute temperature is a constant. High-purity aluminum and copper exhibit peaks in thermal conductivity between 20 and 50 K, but these peaks are rapidly suppressed with increased impurity levels and cold work of the metal. The aluminum alloys Inconel, Monel, and stainless steel show a steady decrease in thermal conductivity with a decrease in temperature. This behavior makes these structural materials useful in any cryogenic service that requires low thermal conductivity over an extended temperature range. 

In 1962, Wendlandt (32) described a more robust EGD-DTA system in which the furnace system was constructed of nickel or stainless steel. The sample and reference substances were placed in small Inconel cups, which seated directly onto the differential thermojunctions, as shown in Figure 8.4. Helium was used as the carrier gas and the evolved gases were detected with a thermistor thermal conductivity cell. 

J. G. Hust and L. L. Sparks, Thermal Conductivity, Electrical Resistivity, and Thermopower of Aerospace Alloys from 4 to 300 K III. Annealed Inconel 718, unpublished NBS Report (1970). 

The catalytic activity of the prepared catalysts for methane combustion was tested in a flow reactor unit. Bottled methane (99.995 % purity from AGA, Sweden) and air were fed to the system using mass flow controllers, giving a methane concentration of 2 vol%. The space velocity in all experiments was 50,000 h". The catalysts were placed in a vertical tubular Inconel reactor situated in a tubular furnace. The exiting gases were analyzed by gas chromatography using a Packard model 427 GC, equiped with a Poraplot Q fused silica capillary column and a thermal conductivity detector. The temperature in the furnace was controlled to give a linear temperature ramp of 2 °C/min in all experiments. Hence, the conversion of methane to carbon dioxide and water was determined as a function of the gas inlet temperature. 

The variability of thermal conductivity to impurity and cold work and the suppression of the maximum is shown clearly in Fig. 3.19. Inconel, Monel, and stainless steel are structural alloys that also exhibit these properties and thus are useful in any cryogenic service that requires low thermal conductivity over the entire temperature range. Experimental thermal conductivity values for most materials used in low-temperature design are not only quite extensive but readily available in the literature. ... 

Comparison of Thermal Conductivity Values for INOR-8 AND Inconel at Several Temperatures... 

Titanium shell and tube design were found to be lower mass flian the Inconel designs studied. The Inconel shell and tube design utilizes thinner walled tubes with slightly higher thermal conductivity, allowing reduction of the overall tube length. 

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