A temperature sensor developed by researchers at the University of Cambridge could improve the efficiency, control, and safety of high-temperature engines. The sensor minimizes drift -- degradation of the sensor that results in faulty temperature readings and reduces the longevity of engine components.
The new sensor, or thermocouple, has been shown to reduce drift by 80 percent at temperatures of 1200 degrees Celsius, and by 90 per cent at 1300 degrees Celsius, potentially doubling the lifespan of engine components.
Modern jet engines can reach temperatures as high as 1500 degrees, but drift in the nickel-based thermocouples used to measure temperature increases to unacceptable levels at temperatures above 1000 degrees. Therefore, the thermocouple is placed away from the hottest part of the engine, and the maximum temperature is extrapolated from that point.
The inaccuracy resulting from this form of measurement means that the engine temperature, and therefore efficiency, has to be set below maximum in order to leave a safety margin for the survival of engine components. Thermocouples with increased temperature capabilities can be placed closer to the combustion chamber, increasing the accuracy with which the peak temperature is estimated, and decreasing the required safety margin.
The thermocouple both withstands oxidization and minimizes any contamination to the wires from the metallic sheath. The thermocouple is made of an outer wall of a conventional oxidization-resistant nickel alloy that can withstand high temperatures, and an inner wall of a different, impurity-free nickel alloy that prevents contamination while reducing drift.