Research Papers: Operations, Applications & Components

Influence of a Variable in Time Heat Transfer Coefficient on Stresses in Model of Power Plant Components

[+] Author and Article Information
Jerzy Okrajni

Silesian University of Technology,
ul. Krasińskiego 8,
Katowice 40-019, Poland
e-mail: jerzy.okrajni@polsl.pl

Mariusz Twardawa

ul. Łąkowa 33,
Racibórz 47-400, Poland
e-mail: mariusz.twardawa@rafako.com.pl

1Corresponding author.

Contributed by the Pressure Vessel and Piping Division of ASME for publication in the JOURNAL OF PRESSURE VESSEL TECHNOLOGY. Manuscript received August 8, 2013; final manuscript received January 30, 2014; published online April 15, 2014. Assoc. Editor: Haofeng Chen.

J. Pressure Vessel Technol 136(4), 041602 (Apr 15, 2014) (6 pages) Paper No: PVT-13-1133; doi: 10.1115/1.4026799 History: Received August 08, 2013; Revised January 30, 2014

The paper discusses the issue of the modelling of strains and stresses resulting from heating and cooling processes of components in power plants. The main purpose of the work is to determine the mechanical behavior of power plant components operating under mechanical and thermal loading. The finite element method (FEM) has been used to evaluate the temperature and stresses changes in components as a function of time. Temperature fields in the components of power plants are dependent, among parameters, on variable heat-transfer conditions between components and the fluid medium, that may change its condition, flowing inside them. For this reason, an evaluation of the temperature field and the consequent stress fields requires the use of heat-transfer coefficients as time-dependent variables and techniques for determining appropriate values for these coefficients should be used. The methodology that combines computer modelling of the temperature fields with its measurements performed at selected points of the pipelines may be used in this case. The graphs of stress changes as a function of time have been determined for the chosen plant components. The influence of the heat transfer conditions on the temperature fields and mechanical behavior of components in question have been discussed.

Copyright © 2014 by ASME
Your Session has timed out. Please sign back in to continue.


BS 7910, 1994, Guide on Methods for Assessing the Acceptability of Flows in Structures (replacing PD 6493 and PD 6539), British Standards Institution, London.
Nuclear Electric Ltd, 1997, Assessment Procedure for the High Temperature Response of Structure, Proc. R5 Issue 2, UK.
Webster, S., and Bannister, A., 2000, Structural Integrity Assessment Procedure for Europe—of the SINTAP Programme Overview, Engineering Fracture Mechanics, Elsevier Science, Vol. 67, pp. 481–514.
Project European Thematic Network FITNET FFS-GIRT-CT-2001-05071.
Bressers, J., and Remy, L., eds., 1996, Fatigue under Thermal and Mechanical loading, Kluwer Academic Publishers, Netherlands.
Hähner, P., et al. ., 2008, “Research and Development into a European Code-of-Practice for Strain-Controlled Thermo-Mechanical Fatigue Testing,” Int. J. Fatigue, 30(2), pp. 372–381. [CrossRef]
Sehitoglu, H., 1996, “Thermal and Thermo-Mechanical Fatigue of Structural Alloys,” Fatigue Fracture, 19, pp. 527–556.
Manson, S. S., 1966, Thermal Stress and Low Cycle Fatigue, McGraw-Hill, New York.
Okrajni, J., Mutwil, K., and Cieśla, M., 2007, “Steam Pipelines' Effort and Durability,” J. Achievements Mater. Manuf. Eng., 22(2), pp. 63–66.
Renowicz, D., Hernas, A., Cieśla, M., and Mutwil, K., 2006, “Degradation of the Cast Steel Parts Working in Power Plant Pipelines,” 15th Scientific International Conference AMME’2006, Gliwice, Vol. 18, pp. 219–222.
Orłoś, Z., eds., 1991, Naprężenia cieplne (Thermal stresses), Wydawnictwo Naukowe, PWN, Warszawa (in Polish).
Standards EN 12952-3:2001 (E), EN 12952-4:2000.


Grahic Jump Location
Fig. 1

Model of the main steam pipeline Y-junction

Grahic Jump Location
Fig. 2

Steam temperature fluctuations close to the boiler as functions of time; (a) hot starting, (b) cold starting (cold start-up—the steam temperature at the beginning of process is lower than 200 °C)

Grahic Jump Location
Fig. 3

Temperature versus time diagrams for the shallow point; experimental data and computational results for heat transfer coefficient of 1000 W/m2 °C; (a) hot starting, (b) cold starting

Grahic Jump Location
Fig. 4

Diagram of changes of the heat transfer coefficient with time; (a) hot starting, (b) cold starting

Grahic Jump Location
Fig. 5

Temperature versus time diagrams for the model and experimental results; characteristics determined for the selected point—located shallow under the outer surface (a) hot starting, (b) cold starting

Grahic Jump Location
Fig. 6

Temperature versus time diagrams for the model and experimental results; characteristics determined for the selected point—located deep under the outer surface (a) hot starting, (b) cold starting

Grahic Jump Location
Fig. 12

σzz stress changes with time at a selected points—O and In (see Fig. 10) of the Y-junction surfaces for mechanical and thermal loading

Grahic Jump Location
Fig. 11

Von-Mises stress changes with time at a selected point C (see Fig. 10) of the Y-junction surface for different types of loading

Grahic Jump Location
Fig. 10

Locations of the point at which the stresses with time have been determined

Grahic Jump Location
Fig. 9

Steam pressure fluctuations close to the boiler as functions of time

Grahic Jump Location
Fig. 8

Cyclic stress–strain curves of P91 steel as results of isothermal tests at temperature: 200 °C, 500 °C, 620 °C

Grahic Jump Location
Fig. 7

Difference of the temperature of points located “deep” and “shallow” fluctuations as functions of time; operation conditions—measurements and FEM model



Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In