A measurement system exploiting non-linearity of thermocouples for cold junction compensation

Thermocouples are very popular sensors for temperature measurements. Since, in practical applications, they need accurate fixed temperatures or the cold junction compensation with other sensors, they can be considered "non-independent" sensors. This paper introduces an innovative technique that exploits the non-linearity of thermocouples to perform a cold junction compensation. The temperature is derived by comparing the voltage of two different types of thermocouples. In this way, the measurement needs neither other types of sensors nor ice baths. The theoretical background of the proposed technique is thoroughly analyzed and some numerical methods are verified. A complete temperature measurement system was developed, in order to apply the presented algorithms.