Prediction of Fluid Temperatures From Measurements of Outside Wall Temperatures in Pipes

1994 ◽  
Vol 116 (2) ◽  
pp. 179-187 ◽  
Author(s):  
M. Guyette
Keyword(s):  
Temperature Measurement ◽  
Wall Temperature ◽  
Industrial Application ◽  
Thermal Stratification ◽  
Transfer Functions ◽  
Fluid Temperature ◽  
Convolution Integral ◽  
Thermal Transients ◽  
Points Of Interest ◽  
Piping Systems

The monitoring of the fatigue induced by thermal transients in thick-walled structures becomes more and more currently performed, mainly on equipment the failure of which could present severe implications on the environment. The easiest way of performing this monitoring is by use of Green’s functions in a convolution integral of the measured fluid temperatures to assess the stresses at the points of interest. Numerous cases, however, exist where the fluid temperatures are not available and only an outside wall temperature measurement is feasible. This paper describes the development and the industrial application of the so-called “inverse” transfer functions to predict the evolution of the fluid temperature from measurements of the metal temperature either at the outside or in the wall of the considered equipment. Some applications are shown for the particular case of the thermal stratification in piping systems.

Development and Validation of Inverse Analysis of Heat Conduction and Thermal Stress for Elbow: Part II

2013 ◽  
Author(s):  
Kiminobu Hojo ◽  
Mayumi Ochi ◽  
Seiji Ioka ◽  
Shiro Kubo
Keyword(s):  
Heat Conduction ◽  
Thermal Stress ◽  
Outer Surface ◽  
Thermal Stratification ◽  
Inverse Method ◽  
Transfer Functions ◽  
Estimation Accuracy ◽  
Fluid Temperature ◽  
Time Data ◽  
Data Points

A heat conduction inverse method for piping elbow was developed to estimate the temperature and stress distribution on the inner surface by measuring the outer surface temperature. In the Part I paper, the derivation and verification of the heat conduction inverse method were described. In the Part II paper, the accuracy for the thermal stress calculation was confirmed by assuming several thermal stratification patters and comparing with the reference results from normal FE heat conduction and thermal stress analyses. As a result, in the case of the measured-basis fluid temperature input from a high temperature-pressure test, the inverse method estimated the maximum stress change by 7% conservative comparing the normal FE analyses. For the assumed temperature change pattern the estimation accuracy was conservatively improved by attaching the additional thermocouples on the outer surface adjacent to the thermal stratification phase. The developed method is practically useful because of short calculate time of 1–2 seconds for 500 time data points after providing the transfer functions.

Fatigue Crack Initiation and Growth Observation for 316 Stainless Steel Subjected to Equi-Biaxial Cyclic Loading

2015 ◽  
Author(s):  
Satoshi Iida ◽  
Shigeki Abe ◽  
Takao Nakamura ◽  
Masayuki Kamaya
Keyword(s):  
Fatigue Crack ◽  
Crack Growth ◽  
Fatigue Damage ◽  
Equivalent Stress ◽  
Fatigue Crack Initiation ◽  
Biaxial Stress ◽  
Fluid Temperature ◽  
Plant Design ◽  
Cracking Behavior ◽  
Thermal Transients

Fatigue accumulation is one of the ageing phenomena considered in the plant design and maintenance. The degree of fatigue damage is evaluated by cumulative usage factor using design fatigue curve, which is determined from results of uniaxial fatigue tests. The stress caused by thermal transients is generally equibiaxial, not uniaxial. Fluid temperature fluctuation due to changes in plant conditions, such as plant start-up and shutdown, is the primary cause of fatigue damage. For accurate fatigue damage evaluation, it is important to be conducted under equi-biaxial condition. In this study, pressurized disc fatigue test was conducted in order to simulate the cyclic equi-biaxial stress. In order to clarify how the crack initiates and grows under the equi-biaxial stress condition. Cracking behavior was examined by replica observation method. The crack growth rates were identified by the change in the crack length. It was shown that the fatigue crack growth rate under equi-biaxial stress was faster than that under uniaxial stress for the same equivalent stress intensify factor. It was concluded that the reduction in the fatigue life under equi-biaxial stress was brought about by the accelerated crack growth.

Thermal Fatigue of Pwr Coolant System Loop Drain Lines Due to Outflow Activities

2021 ◽  
Author(s):  
Yue Zou ◽  
Brian Derreberry
Keyword(s):  
Thermal Fatigue ◽  
Operating Experience ◽  
Fatigue Cracking ◽  
Screening Methods ◽  
Primary Coolant ◽  
Pressurized Water ◽  
Thermal Transients ◽  
Piping Systems ◽  
Class 1 ◽  
Coolant System

Abstract Thermal cycling induced fatigue is widely recognized as one of the major contributors to the damage of nuclear plant piping systems, especially at locations where turbulent mixing of flows with different temperature occurs. Thermal fatigue caused by swirl penetration interaction with normally stagnant water layers has been identified as a mechanism that can lead to cracking in dead-ended branch lines attached to pressurized water reactor (PWR) primary coolant system. EPRI has developed screening methods, derived from extensive testing and analysis, to determine which lines are potentially affected as well as evaluation methods to perform evaluations of this thermal fatigue mechanism for the U.S. PWR plants. However, recent industry operating experience (OE) indicate that the model used to predict thermal fatigue due to swirl penetration is not fully understood. In addition, cumulative effects from other thermal transients, such as outflow activities, may also contribute to the failure of the RCS branch lines. In this paper, we report direct OE from one of our PWR units where thermal fatigue cracking is observed at the RCS loop drain line close to the welded region of the elbow. A conservative analytical approach that takes into account the influence of thermal stratification, in accordance with ASME Class 1 piping stress method, is also proposed to evaluate the severity of fatigue damage to the RCS drain line, as a result of transients from outflow activities. Finally, recommendations are made for future operation and inspection based on results of the evaluation.

scholarly journals Estimating uncertainty of temperature measurements for studies of flow boiling heat transfer in minichannels

2019 ◽  
Vol 213 ◽  
pp. 02059
Author(s):  
Dariusz Michalski ◽  
Kinga Strąk ◽  
Magdalena Piasecka
Keyword(s):  
Heat Transfer ◽  
Temperature Measurement ◽  
Boiling Heat Transfer ◽  
Experimental Error ◽  
Flow Boiling ◽  
Mean Value ◽  
Temperature Measurements ◽  
Fluid Temperature ◽  
Flow Boiling Heat Transfer ◽  
Characteristic Points

This paper presents the method of estimating the uncertainty of temperature measurements conducted using K-type thermocouples in the study of flow boiling heat transfer in minichannels. During heat transfer experiments. the fluid temperature at the inlet and outlet of the minichannel is measured with thermocouples connected to a DaqLab 2005 data acquisition station. The major part of the experimental setup for calibration of temperature measurement included a calibrator of thermocouples. The thermocouples were manufactured by Czaki Thermo-Product. Poland. The temperatures recorded with the thermocouples were compared statistically while measuring the temperature of demineralised water at several characteristic points at liquid phase change or using the reference temperature known from the calibrator. The experimental error of the temperature measurement method was determined according to the principles of statistical analysis. Estimates of the mean value and the experimental standard deviation of the experimental error as well as the confidence interval for a single experimental error and the measurement accuracy were presented. The uncertainty of the difference in temperature was also calculated

Numerical Investigations of Arched Vortex Characteristics Generated at T-Junction Piping Systems

2004 ◽  
Author(s):  
Toshiharu Muramatsu
Keyword(s):  
Stokes Equations ◽  
Velocity Ratio ◽  
Navier Stokes ◽  
Fluid Temperature ◽  
Simulation Code ◽  
Navier Stokes Equations ◽  
Downstream Region ◽  
Piping Systems ◽  
Frequency Components ◽  
Thermal Striping

Thermohydraulic analyses for a fundamental water experiment simulating thermal striping phenomena at T-junction piping systems were carried out using a quasi-direct numerical simulation code DINUS-3, which is represented by instantaneous Navier-Stokes equations and deals with a modified third-order upwind scheme for convection terms. Calculated results were compared with experimental results on the flow patterns in the downstream region of the systems, the arched vortex structures under a deflecting jet condition, the generation frequency of the arched vortex, etc. in the various conditions; i.e., diameter ratio α, flow velocity ratio β and Reynolds number Re. From the comparisons, it was confirmed that (1) the DINUS-3 code is applicable to the flow pattern classifications in the downstream region of the T-junction piping systems, (2) the arched vortex characteristics with lower frequency components and their generation possibilities can be estimated numerically by the DINUS-3 code, and (3) special attentions should be paid to the arched vortex generations with lower frequency components of fluid temperature fluctuations in the design of T-junction systems from the viewpoints of the avoidances for the thermal striping.

Transfer Functions and Input Impedances of Pressurized Piping Systems

1967 ◽  
Vol 89 (2) ◽  
pp. 440-443
Author(s):  
B. L. Johnson ◽  
D. E. Wandling
Keyword(s):  
Transfer Function ◽  
Input Impedance ◽  
Transfer Functions ◽  
Block Diagram ◽  
Single Line ◽  
Piping System ◽  
Feedback Model ◽  
Distributed Parameters ◽  
Piping Systems

This paper presents a method to determine the transfer function and input impedance of a pressurized fluid piping system. Distributed parameters are used to arrive at a transfer function of a single line, and then block-diagram feedback methods are used to model the system. The input impedance is derived from the feedback model, and methods are presented for finding the flow and pressure at any point in the system.

Nozzle tube-wall temperature measurement by radiometric techniques.

1966 ◽  
Vol 3 (7) ◽  
pp. 1144-1146
Author(s):  
E. L. GEERY ◽  
W. R. THOMPSON ◽  
J. H. BEVERIDGE ◽  
W. J. HELM
Keyword(s):  
Temperature Measurement ◽  
Wall Temperature ◽  
Tube Wall ◽  
Tube Wall Temperature
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