This paper reports on a robust technique for the measurement of temperature at multiple heights (levels). This technique uses a bank of straight ultrasonic waveguide temperature sensors attached to a single ultrasonic pulser-receiver instrument. Since the ultrasonic waveguide does not use a junction, the robustness of the sensor is expected to be more for field applications. The measurements have been made by using the L(0,1) ultrasonic guided wave mode end reflection as the signal of interest. The changes in the time-of-flight (DTOF) of this signal as the measurement were related to the local changes temperature of the surrounding medium. Several waveguide configurations were studied and the thickness of the waveguide was optimized to provide a reliable calibration curve. Data was collected and analyzed in a laboratory furnace from 45°C to 1100°C, and the multi-level temperature measurement was demonstrated both in the laboratory as well as in a waste treatment vitrification facility. © 2014 Elsevier Ltd. All rights reserved.

Krishnan Balasubramaniam

Department of Mechanical Engineering

Suresh Periyannan

Curve fitting

Guided electromagnetic wave propagation

temperature measurement

ULTRASONIC SENSORS

VITRIFICATION

Waste treatment

Waveguides

Calibration curves

Field application

Measurement of temperature

Signal of interests

ultrasonic guided wave

ULTRASONIC PULSER RECEIVERS

VITRIFICATION MELTER

WAVEGUIDE CONFIGURATIONS

Ultrasonic applications

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Measurement: Journal of the International Measurement Confederation

This paper reports the feasibility of using an ultrasonic waveguide sensor for distributed temperature measurement in two different case studies, that is: 1) skin temperature of a solid structure (pipe) and 2) fluid (water). This technique improves upon the conventional multiple thermocouples approach for multi-level temperature measurements. The range of temperatures is from room temperature to maximum utility temperature for the two case studies (85 °C for water and 200 °C for pipe). Using the interaction of the propagating ultrasonic waves in a thin rodlike waveguide with intentionally designed geometric discontinuities (bends, axisymmetric, non-axisymmetric notches, and so on), the localized information on the temperature is extracted. An ultrasonic technique for accurate temperature measurement by tracking the time-of-flight of reflected guided wave modes from appropriately spaced notch reflectors is therefore proposed here, while using the reflection from a bend is used as a reference. Using a finite element model approach, the notch size and/or the bend radius were selected in order to reduce mode conversion effects as well as to obtain uniform amplitudes of the reflected signals from these designed discontinuities. The numerical results were experimentally validated for the L(0,1) wave mode using a stainless steel waveguide sensor. This paper is of interest to industrial applications including mould cooling jacket temperature monitoring during the steel manufacturing process as well as for furnace wall temperature measurements in petrochemical industries. © 2001-2012 IEEE.

IEEE Sensors Journal

Ultrasonic waveguide-based multi-level temperature sensor for confined space measurements

This paper studies the propagation of ultrasound in spiral waveguides, towards distributed temperature measurements on a plane. Finite Element (FE) approach was used for understanding the velocity behaviour and consequently designing the spiral waveguide. Temperature measurements were experimentally carried out on planar surface inside a hot chamber. Transduction was performed using a piezo-electric crystal that is attached to one end of the waveguide. Lower order axisymmetric guided ultrasonic modes L(0,1) and T(0,1) were employed. Notches were introduced along the waveguide to obtain ultrasonic wave reflections. Time of fight (TOF) differences between the pre-defined reflectors (notches) located on the waveguides were used to infer local temperatures. The ultrasonic temperature measurements were compared with commercially available thermocouples. © 2017 Author(s).

Fulltext

AIP Advances

Multiple temperature sensors embedded in an ultrasonic “spiral-like” waveguide

This paper describes novel techniques for simultaneous measurement of temperatures at multiple locations using two configurations (a) a single transducer attached to multiple waveguides of different lengths (each with a single bend) and (b) single waveguide with multiple bends connected to single transducer. These techniques improve upon the earlier reported studies using straight waveguides, where the non-consideration of the effect of temperature gradients was found to be a major limitation. The range of temperature measurement is from room temperature to maximum utility temperature of the waveguide material. The time of flight difference of reflected ultrasonic longitudinal guided wave modes (L(0, 1)) from the bend, which is the reference signal, and another signal from the end of the waveguide, is utilized to measure the local temperature of the surrounding media. Finite element simulations were employed to obtain the appropriate dimensions and other design features of the multiple bent waveguide. This work is of interest to several industrial applications involving melters and furnaces. © 2016

Ultrasonics

Ultrasonic bent waveguides approach for distributed temperature measurement

Distributed temperature sensing has important applications in the long term monitoring of critical enclosures such as containment vessels, flue gas stacks, furnaces, underground storage tanks and buildings for fire risk. This paper presents novel techniques for such measurements, using wire in a spiral configuration and having special embodiments such a notch for obtaining wave reflections from desired locations. Transduction is performed using commercially available Piezo-electric crystal that is bonded to one end of the waveguide. Lower order axisymmetric guided ultrasonic modes were employed. Time of fight (TOF) differences between predefined reflectors located on the waveguides are used to infer temperature profile in a chamber with different temperatures. The L(0,1) wave mode (pulse echo approach) was generated/received in a spiral waveguide at different temperatures for this work. The ultrasonic measurements were compared with commercially available thermocouples. © 2017 Author(s).

AIP Conference Proceedings

Distributed temperature sensing using a SPIRAL configuration ultrasonic waveguide

This paper introduces an ultrasonic torsional mode based technique, configured in the form of a helical "spring-like" waveguide, for multi-level temperature measurement. The multiple sensing levels can be repositioned by stretching or collapsing the spring to provide simultaneous measurements at different desired spacing in a given area/volume. The transduction is performed using piezo-electric crystals that generate and receive T(0,1) mode in a pulse echo mode. The gage lengths and positions of measurements are based on machining multiple reflector notches in the waveguide at required positions. The time of fight (TOF) measurements between the reflected signals from the notches provide local temperatures that compare well with co-located thermocouples. © 2016 Author(s).

Torsional mode ultrasonic helical waveguide sensor for re-configurable temperature measurement

The paper presents an attempt to find the possibility of measuring high temperature properties of mould powder slags such as viscosity, break temperature, liquidus temperature during heating as well as solidification start and solidification end temperatures during cooing using ultrasonics. These powders are used in continuous casting of steel and the abnormality in their properties can impact the productivity and quality of the steel products. These properties are in general measured by high temperature rotational viscometers, hot stage microscopes and DTA instruments. Here, the fundamental flexural guided wave mode F(1,1) in a ceramic buffer rod was employed in experiments. The results show the possibility of measuring all the above properties in single experiment by measuring ultrasonic reflection factors during continuous heating and cooling of the mould powders. The advantage of the ultrasonic system is that it can be installed in the plant for online monitoring of these properties. The ultrasonically measured properties of the mould powders supplied by five different suppliers were compared with those measured by rotational viscometers and estimated by mathematical models. © 2011.

Ironmaking and Steelmaking

Measurement of viscosity and melting characteristics of mould powder slags by ultrasonics

This paper describes an experimental procedure using ultrasonic waves propagating in a rod to simultaneously measure the viscosity and temperature of melts at high temperatures using a very small amount of sample and without any mechanical rotating equipment. This method has applications in laboratory tests as well as for process monitoring in industries. A refractory material is used as buffer rod in the experiment to transfer the ultrasonic vibrations from a piezoelectric transducer into the melt, which is water cooled to protect the transducer from high temperatures. The sensor is based on the effect of melt viscosity on ultrasonic guided wave reflections from the solid-fluid interface. The difference in the time of flight of the ultrasonic wave in the buffer rod at two different temperatures is used to measure the temperature. The results from the measurement of melt viscosity using the proposed method, on three different glass samples, are in agreement with the values provided by the National Institute of Standards and Technology, USA. This method offers advantages in reduction in the amount of sample, cost, complexity in experiments, experimental time. © 2008 Elsevier B.V. All rights reserved.

Journal of Materials Processing Technology

Viscosity measurements of melts at high temperatures using ultrasonic guided waves

Metallurgical and Materials Transactions A

Glassy Wasteforms for Nuclear Waste Immobilization

Journal of High Energy Physics

F-theory, GUTs, and the weak scale

Measurement Science and Technology

An ultrasonic air temperature measurement system with self-correction function for humidity

Multi-level temperature measurements using ultrasonic waveguides

Journal	Data powered by TypesetMeasurement: Journal of the International Measurement Confederation
Publisher	Data powered by TypesetElsevier B.V.
ISSN	02632241
Open Access	No