Thin-film Platinum Resistance Thermometer Research Articles

Development of a functional model of the temperature meter

Thin-film platinum resistance thermometers of various designs and performance are widely used in various industries. The temperature measurement range of these sensors is from -200 °C to +600 °C.
 A functional model of a portable digital temperature meter in the range from -50 °C to +300 ℃ based on the L416 sensor type Pt100 is proposed. The optimal circuit solution for connecting the L416 sensor to the Winston measuring bridge was selected. The proposed circuit solution is suitable for power supply from autonomous DC sources, which allows for miniaturization of the device and contributes to energy efficiency.
 The amplification of the output voltage of the amplifier in the entire operating range of the analog-to-digital converter following the operating range of the temperature sensor has been performed, which allows obtaining the maximum resolution of the analog-to-digital conversion when measuring temperature.
 A functional model for converting the resistance of a temperature sensor into a digital code has been developed. The functional model shows that the source code of the analog-to-digital converter does not depend on the supply voltage of the circuit, thus realizing the stability of the function of converting the resistance of the sensor into the value of the code of the analog-to-digital converter.
 The sensor has a normalized characteristic of the dependence of resistance on temperature, so a precision resistance box MSR-60M has been used to calibrate the circuit of the temperature meter. With the help of the resistance box MSR-60M, it is possible to calibrate the circuit of the temperature meter with an uncertainty of 0.07 °C.
 Keywords: temperature meter; RTD; Pt100; Winston bridge; ratiometric power supply.

Stagnation temperature measurement using thin-film platinum resistance sensors

The measurement of stagnation temperature in high-speed flows is an important aspect of gas turbine engine testing. The ongoing requirement to improve the accuracy of such measurements has led to the development of probe systems that use a thin-film platinum resistance thermometer (PRT) as the sensing element. For certain aspects of engine testing this type of sensing device potentially offers superior measurement performance to the thermocouple, the temperature sensor of choice in most gas turbine applications. This paper considers the measurement performance of prototype PRT-based stagnation temperature probes, up to high-subsonic flow conditions, using passively aspirated probe heads. The relatively poor temperature recovery performance of a simply constructed probe has led to the development of a new design that is intended to reduce the impact of thermal conduction within the probe assembly. The performance of this so-called dual-skin probe has been measured through a series of tests at a range of Mach numbers, incidence angles and Reynolds numbers. The data reveal that a high probe recovery factor has been achieved with this device, and that the application of this design to engine tests would yield the measurement performance benefits of the PRT whilst requiring small levels of temperature recovery compensation.

Development of a platinum resistance thermometer on the silicon substrate for phase change studies

Resistance temperature detectors are commonly used measurement sensors in heat transfer studies. In many resistance temperature detectors, the platinum resistance thermometer (PRT) is chemically stable, has a wide temperature measurement range and possesses high measurement accuracy. In phase change studies of carbon nanotubes, bi-porous structures for microelectronic thermal management, 100 nm thick PRTs are developed on silicon substrates with 10 nm titanium adhesive to achieve precise and interface-free temperature measurements. After an annealing at 375 °C, the PRT samples are calibrated at a temperature range from 20 to 180 °C. Measurement hysteresis of temperature appears in thermal cycles. Electrical resistance tends to become low during all heating periods, which establishes the maximum measurement deviation of 10 °C. Experimental results from two different thin-film PRTs indicate that accurate and repeatable temperature measurements can be achieved by either reducing heating speed or using data in the cooling period.

Thermal Hysteresis in Thin-Film Platinum Resistance Thermometers

Thin-film platinum resistance thermometers (PRTs) are generally manufactured using the deposition of a thin platinum film on an alumina substrate and a laser-trimming method. Because of the strong adhesion between the platinum thin film and the alumina substrate, the PRTs inevitably have strain over the operating temperature range. This causes anomalies and instabilities in the resistance versus temperature characteristics (R–T). The most prominent and observable effect of thermally induced strain is the thermal hysteresis in the R–T characteristics. Thermal hysteresis is one of the main uncertainty factors in the calibration of industrial platinum resistance thermometers in laboratories. The thermal hysteresis for 30 thin-film PRTs was measured in the range of 0 °C to 500 °C in 100 °C steps. The thermal hysteresis was measured repeatedly using the same process, and the hysteresis decreased drastically with the repeated measurements. The thermal hysteresis was distributed from 16 mK to 156 mK for all sensors, and the lowest hysteresis was 1 mK to 11 mK in the test temperature range.

A Fast-Response Total temperature Probe For Unsteady compressible Flows

A fast-response probe for the measurement of total temperature in unsteady or fluctuating compressible flows is discussed. The operation of the device is based on the measurement of transient heat flux at different probe operating temperatures. The heat flux gauges used in the present investigation were thin film platinum resistance thermometers painted onto the stagnation region of hemispherical fused quartz probes. The quartz probes had a diameter of approximately 3 mm. Uncertainty estimates indicate that temperature measurements with an accuracy of better than ±3 K are possible. As a demonstration of the accuracy and utility of the device, total temperature and convective heat transfer coefficient measurements were obtained in a number of supersonic nozzle tests and in a compressible turbulent jet experiment.

Thin film platinum resistance thermometers: calibration and mathematical description of T(R) function

Thin film platinum resistance thermometers with three different dimensions are investigated. Mathematical descriptions of the results in the temperature range 77–300 K are presented. The optimum number of terms is determined for the two types of polynomials which are used for analytical presentation of the experimental data.

A prospective thermomagnetic temperature transducer

The possibilities of measuring the temperature of seawater as a continuous medium are analysed. It is shown that contemporary thin-film platinum resistance thermometers are inadequate for seawater temperature measurements because of their lag and resolution. The following shortcomings of these thermometers are indicated: heat dissipation by the terminals and the need for them to be hermetically sealed. A prospective improved design is suggested for a thermomagnetic temperature transducer, which provides for the minimal possible lag for the required resolution.

磁場中の比熱計測技術の開発 （１） 高い再現性を持つ白金薄膜抵抗温度計ＰＴＦ‐７の磁気抵抗とその異方性

The magneto-resistance of a thin film platinum resistance thermometer, PTF-7, was measured between 20 and 200K under magnetic fields of up to 8T. It showed a high stability during the thermal cycles between room temperature and liquid nitrogen temperature. The variation among the resistance values at 20, 50, 100 cycles was <1mK in terms of temperature for 8 of 10 sensors. Its magneto-resistance, ε, was well fit by an empirical formula ε=D(T)B2/(1+E(T)B) with two fitting parameters, D(T) and E(T). The variation of the magneto-resistance among the sensors was found to be 5%, which is 30 times as large as that of new-JIS fine wire platinum resistance thermometers, GR 0705. The anisotropy of the magneto-resistance was also measured and found to be as large as 50% depending on the direction of the field applied to the sensors.

Thin film platinum resistance thermometer for measurements in high magnetic fields

The resistivity of thin platinum films at high magnetic fields (up to 140 kOe) was measured at 30 and 77 K. The films were deposited by magnetron sputtering on an Al 2O 3 substrate. A Chebyshev type polynomial description is also given, at zero magnetic field, of the function R( T) in the temperature range 10–300 K. The first derivative of this function is compared with that of a wire thermometer, model PT-103, offered by Lake Shore Cryotronics. It was determined that the sensitivity of the new sensors was better at temperatures below 100 K.

Thin-film platinum resistance thermometer for use at low temperatures and in high magnetic fields

A thin-film platinum resistance thermometer (SDT101A, Tama Electric Work Company, Japan), which is available commercially, has useful characteristics for thermometry in the range of 20 to 300 K and in high magnetic fields up to 5 T. The Z function-table of this platinum resistance thermometer (PRT) was obtained experimentally. It was confirmed that SDT101A PRT would be useful in the temperature range of 20 to 300 K within a precision of ± 0.1 K. This confirmation was achieved by using a two-point calibration method with the Zfunction. The magnetoresistance of this PRT at 30 K is ≈ 1.5% for a magnetic field of 5 T, whose value is one order of magnitude smaller than that of a standard type PRT.

白金薄膜温度素子の低温・強磁場中における特性

A thin-film platinum resistance thermometer (SDT101A, Tama Electric Work Company), which is available commercially, has useful characteristics for thermometry in the range of 20 to 300K and in high magnetic fields up to 5T. The Z function-table of this platinum resistance thermometer (PRT) was obtained experimentally. We comfirmed a possibility of the two point calibration with a precision of ±0.1K above 30K.The magnetoresistance of this PRT at 30K is about 1.5% for a magnetic field of 5T, whose value is one order of magnitude smaller than that of a precision type PRT.

Characteristics of Steam Injection Heating. II. Downstream Temperature Variations Within Fluid Stream After Steam Injection

Summary Five steam injectors were tested to determine the extent of high-frequency temperature variations in the fluid downstream from the point of steam injection. The injectors were of three basic design types: tangential, venturi, and nozzle. They were tested with water and, in addition, two were tested with whole milk. The magnitude and period of temperature fluctuations were obtained with a thin-film platinum resistance thermometer. The variations were recorded on 35 mm film from a temperature trace displayed on a high-gain oscilloscope. Periodic temperature variations occurred in the downstream holding sections of steam injection heaters and varied with the type of injector. A tangential injector with a single steam port showed the most downstream temperature variation with water. The venturi design showed the least variation. Temperature fluctuations within the fluid stream decreased rapidly along the downstream holding sections and were nearly constant at approximately 20 in. from the point of steam injections. Whole milk showed lower temperature variations than water.