Non-intrusive temperature measurement for liquid flow using compensators of pipelines

The article presents the results of a numerical study that aimed to accuracy improvement for non-intrusive measurements of the liquid flow temperatures in standard pipelines compensators. Non-intrusive measuring devices are one of the modern promising and profitable tools that stimulate the improvement of technologies and the involvement of world corporations in this sphere, while the growing intellectualization of measurements positively affects the safety and efficiency of the industry. The numerical study result is consistent with the results of laboratory tests and shows the general regularity of flow velocity effect the error of non-intrusive temperature measurements. Shown that measurements after the upper or lower elbow of the compensator makes possible to reduce the measurement error in the Reynolds (Re) range of about 1000-7000, which is characteristic for the onset of turbulent flow of a liquid. Also shown that gravity negatively affects the accuracy of measurements, so preference should be given to horizontally located compensators. Obtained that the flow in pipeline determines the largest temperature change in the wall region of the pipe for relatively high Re, and along the pipeline axis for small Reynolds numbers. In combination with the flow characteristics in the compensator, it changes temperature distribution and error, depending on the flow velocity in the pipeline. In particular, this effect determines error decreasing for temperature measurement in the compensators at low Re numbers. The existing surface temperature sensors, with correction the surface temperature measurements to the flow temperature, require calibration to work on flows with Re numbers varying over a wide range, and binding these measurements to pipeline compensators can improve the quality of measurements due to smoothing and, fluctuation thermal and hydrodynamic influences.