A heat flux sensor with both fast response and high sensitivity

Area of Science:

• Thermodynamics and Heat Transfer
• Sensor Technology
• Materials Science

Background:

• Heat flux sensors are crucial for heat transfer analysis.
• Existing sensors face limitations in balancing sensitivity and response time due to thermal resistance and junction count.
• High-accuracy, rapid heat flux measurement remains a challenge.

Purpose of the Study:

• To design and develop a novel heat flux sensor with enhanced sensitivity and rapid response.
• To overcome the limitations of conventional heat flux sensors.
• To enable accurate measurement of high-temperature and transient heat transfer processes.

Main Methods:

• Designed a thermopile array utilizing a hexagonal dense arrangement to maximize junctions within a limited area.
• Incorporated films with distinct functions at hot and cold junctions to amplify temperature differences.
• Conducted tests to evaluate sensor performance across various heat flux ranges and conditions.

Main Results:

• Achieved a coefficient of determination (R²) > 0.999 for quadratic fits between sensor output and heat flux (0-207 kW/m²).
• Demonstrated a maximum heat flux sensitivity of 91.13 μV/(kW/m²) in the linear operating range (114-201 kW/m²).
• Exhibited response times faster than 2.85 ms under varying laser powers and durations, with good responses to respiration, flame, and hot air.

Conclusions:

• The developed heat flux sensor effectively combines high sensitivity and fast response times.
• The hexagonal thermopile array and differential film design enhance measurement accuracy and speed.
• The sensor shows significant potential for applications involving high-temperature and rapidly changing heat transfer measurements.