Electromagnetic Acoustic Transducers Applied to High Temperature Plates for Potential Use in the Solar Thermal Industry

Maria Kogia,Wamadeva Balachandran,Abbas Mohimi,Liang Cheng,Tat-Hean Gan,Vassilios Kappatos,Cem Selcuk

doi:10.3390/app5041715

Abstract

Concentrated Solar Plants (CSPs) are used in solar thermal industry for collecting and converting sunlight into electricity. Parabolic trough CSPs are the most widely used type of CSP and an absorber tube is an essential part of them. The hostile operating environment of the absorber tubes, such as high temperatures (400–550 °C), contraction/expansion, and vibrations, may lead them to suffer from creep, thermo-mechanical fatigue, and hot corrosion. Hence, their condition monitoring is of crucial importance and a very challenging task as well. Electromagnetic Acoustic Transducers (EMATs) are a promising, non-contact technology of transducers that has the potential to be used for the inspection of large structures at high temperatures by exciting Guided Waves. In this paper, a study regarding the potential use of EMATs in this application and their performance at high temperature is presented. A Periodic Permanent Magnet (PPM) EMAT with a racetrack coil, designed to excite Shear Horizontal waves (SH0), has been theoretically and experimentally evaluated at both room and high temperatures.

Highlights

Solar thermal industry is an environmentally friendly means of power generation, converting solar energy into electricity
Four case studies were investigated; the Electromagnetic Acoustic Transducers (EMATs) were employed in both a defect-free and a defective area, with and without common ground connection with the specimen
The connection/interaction between the EMAT and the specimen is differential, since the specimen induces to the EMAT coil an alternating, differential mode current

Summary

Introduction

Solar thermal industry is an environmentally friendly means of power generation, converting solar energy into electricity. Concentrated Solar Plants (CSPs) are employed in the solar thermal industry for collecting sunlight and converting it firstly into heat and later into electricity. Their entire surface should be exposed to sunlight and there are few access points for any extra hardware to be attached to them. Inside the tubes, working fluid, either water/molten salt or synthetic oil, is flowing, absorbing the heat of the sunlight and transmitting it into heat/steam engines for the final stages of the power generation procedure

Methods

Results

Conclusion