How can thermocouple and thermal resistance measure temperature accurately?

    Thermocouples and thermal resistances are the most common temperature measurement components, and they are all contact temperature measurement, so the probe must be able to quickly and faithfully reflect the temperature of the object being measured. The measured object may be solid, liquid, colloid, gas, etc.

    Solid temperature measurement: If measuring the temperature of a solid surface, the probe must be fastened to the solid surface with screws or glue. In order to fully contact the solid surface, the probe is generally made into a flat shape; if the internal temperature of the solid is measured, the solid Open the hole, extend the probe into the hole, and then fill in the filler with strong thermal conductivity.

    Liquid, colloid, gas temperature measurement: Because the measured object is flowing, the temperature probe only needs to be hovered tightly inside the substance, so that the substance component can fully wrap the probe. In addition, due to thermal convection inside the measured object, the probe only measures the local temperature. If you want to measure the temperature of the entire measured object, you need to stir the measured object to make the internal temperature as uniform as possible.

    However, the temperature measured by the probe is actually the temperature of the measured object transmitted to the sensor head of the probe, which takes time. If the probe is in poor contact with the measured object, or the sensor head of the probe is poorly assembled, or the probe stays on the measured object for too short a time, it will cause inaccurate measurement.

    In order to protect the sensor head of the probe, we usually put a metal sleeve on the outside of the sensor head. The metal sleeve is to protect the sensor head from damage (impact, wear, corrosion, etc.). In order to make the sensor head reflect more quickly, the metal casing should be made of materials with strong thermal conductivity, and the wall thickness should be as thin as possible under the premise of ensuring the mechanical strength, so as to reduce the thermal inertia of the probe.

    Finally, the wires, connectors, transmitters, collectors, etc. used for the signal transmission of thermocouples and thermal resistances must all use special corresponding models, and can't be mixed and misused.

    (huiputech)