Dr. Fenglei Niu is a pioneering researcher in nuclear thermal hydraulics. He was a former dean and professor of the School of Nuclear Science and Engineering, North China Electric Power University, and a member of the American Nuclear Society. Dr. Niu has multiple registered patents to his credit. He obtained his Ph.D. in Nuclear Engineering from the University of California, Berkeley, in 2003, and his BEng and MEng from Tsinghua University in 1994 and 1997, respectively.
Temperature is one of the seven base units of the physical world, and the temperature sensors have wide applications in the lives, research, and industries. This chapter presents a brief introduction on four classic types of temperature sensors, including thermometers, thermocouples, resistance temperature detectors (RTD), and thermistors. These traditional temperature sensors have some limitations and are not suitable for dynamic measurements. To meet the demand for temperature measurement under various extreme and complex conditions, four advanced types of temperature sensors are introduced. The optical temperature sensors, including the infrared thermal imaging and laser temperature sensor, utilize the thermal radiation and are capable of measuring high-temperature objects without direct contact. The small and flexible fiber optic temperature sensors take advantage of the fact that the temperature plays a significant role in the optical transmission characteristics of the optical fiber, and it can be used in point, quasi-distributed, or distributed form. Acoustic temperature sensors measure the speed and frequency of the sound wave under different temperatures to obtain the temperature, and it is commonly used for health monitoring of complex structures. Furthermore, micro/nano temperature sensors are ideal for specific applications due to their small size, high sensitivity, and rapid response time.
Part of the book: Wireless Sensor Networks
In nuclear energy research, the precise measurement of coolant temperature under extreme conditions of high temperature, high pressure, and intense radiation is a critical parameter for evaluating nuclear safety design and ensuring reactor efficiency. This section introduces methods for precise temperature measurement in such demanding environments, covering both the essential hardware and the sophisticated software components of modern temperature sensing systems. Specific coolants discussed include advanced options like liquid metals and supercritical carbon dioxide, each posing unique measurement challenges due to their distinct thermophysical and chemical properties. The advanced measurement techniques employed to address these challenges involve specially designed radiation-hardened armored thermocouples, immune fiber-optic temperature sensors, and robust thermistor-based detection systems. The following analysis compares and evaluates the measurement accuracy, long-term stability, and specific installation requirements of these sensor types under intense radiation conditions, noting the distinct advantages and practical considerations of each type—such as the ruggedness of thermocouples versus the electromagnetic immunity of fiber optics. Finally, typical integrated measurement solutions are provided for key operational parameters; these include strategies for measuring the central temperature of reactor fuel elements and for monitoring the coolant temperature at the core inlet and outlet with high reliability. Collectively, these advanced application cases and technological comparisons offer valuable insights and practical references for temperature measurement in nuclear energy research, directly supporting the ongoing safety design and thermal-hydraulic optimization of current and next-generation nuclear systems.
Part of the book: Principle, Application, and Advancement of Temperature and Humidity Sensors