Process fluid temperature estimation using improved heat flow sensor

A process temperature estimation system comprising:

• a mounting assembly configured to mount the process temperature estimation system to an external surface of a process fluid conduit having a temperature as high as 600 degrees Celsius;
• a sensor capsule having an end cap configured to contact the external surface of the process fluid conduit, the sensor capsule defining a sensor capsule chamber therein;
• a resistance temperature device (RTD) positioned within the sensor capsule chamber, the RTD having a pair of connection points;
• a first copper conductor electrically connected to the first connection point of the RTD;
• a second copper conductor electrically connected to the first connection point of the RTD;
• a third copper conductor electrically connected to the second connection point of the RTD;
• a fourth copper conductor;
• a first thermocouple junction formed by a junction of the third copper conductor and a thermocouple wire, the first thermocouple junction being disposed within the sensor capsule chamber proximate the RTD;
• a second thermocouple junction formed by a junction of the fourth copper conductor and the thermocouple wire, the second thermocouple junction being disposed within the sensor capsule and attached to the end cap;
• measurement circuitry coupled to the first and second thermocouple junctions by the third and fourth copper conductors and configured to detect an emf of the first and second thermocouple junctions, the measurement circuitry being coupled to the RTD by the first, second and third copper conductors, the measurement circuitry being configured to measure a resistance of the RTD that varies with temperature of the second thermocouple junction and provide sensor temperature information;
• and
• a controller coupled to the measurement circuitry, the controller being configured to measure a reference temperature based on the resistance of the RTD and employ a heat transfer calculation with the reference temperature, the emf of the first and second thermocouple junctions and known thermal conductivity of the process fluid conduit to generate an estimated process temperature output.