High Conductance Thermal Radiometer with Dual Sensor for Temperature Compensation
Thermal radiometer, thermoresistive sensors, feedback linearization, proportional integral control.
This work proposes the development of a high thermal conductance radiometer. It is used for irradiance detection and features ambient temperature compensation using a dual sensor. An analysis of heat transfer mechanisms through conduction and convection is conducted to determine the contribution of each transfer mode to the compensation technique. Additionally, the effect of these mechanisms on the sensitivity and dynamics of the radiometer is evaluated. To achieve this, a representative high-level model for SPICE simulations is developed. It allows the assessment of various operating conditions, such as how ambient temperature disturbances affect the system response and the contribution of the protective dome used for sensor protection.
The model's response shows agreement with results from existing literature. The proposed nonlinear model for the thermistor incorporates the contribution of the protective dome and is used in the linearization strategy for temperature controller design. In this setup, both the main thermistor and the compensation thermistor operate at a constant temperature using the designed controller. The thermistor's dynamics are altered by a conductance created by the connection between the thermistor and a point at ambient temperature outside the dome. An experimental setup is designed to demonstrate this alteration. Sensitivity is evaluated based on thermistor parameters and the additional thermal conductance due to the thermal link.