Temperature measurement under vacuum conditions

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This post was last edited by ljy3033 on 2018-8-17 at 15:05. As shown in the diagram below, the material is dried using a dryer under reduced pressure (under normal operation, the pressure gauge on the dryer indicates -0.1 Mpa). The dryer has an external jacket through which circulating hot water flows; there is also a remote temperature sensor on the dryer itself, which measures the temperature inside the dryer’s interior, not the temperature of the fluid in the jacket. What I would like to know is the principle behind how this thermometer measures temperature, and whether its reading accurately reflects the temperature of the material being dried. There are three basic ways of heat transfer: conduction, convection, and thermal radiation. Under normal operation, since the operating conditions are close to absolute vacuum, I believe thermal convection does not occur; thermal radiation is present, but I’m not sure about thermal conduction. Heat conduction is defined as the transfer of heat that occurs when there is no relative movement between different parts of a substance, and it is caused solely by the thermal motion of microscopic particles such as molecules, atomic nuclei, and free electrons. Does heat conduction still occur in a vacuum environment? If heat conduction occurs, is the amount of heat transferred to the thermometer through heat conduction greater than the amount of heat transferred to the thermometer through thermal radiation? By extension, how is the temperature of the environment measured in outer space?