N2 - The following paper presents the method for solving one-dimensional inverse boundary heat conduction problems. The method is used to estimate the unknown thermal boundary condition on inner surface of a thick-walled Y-branch. Solution is based on measured temperature transients at two points inside the element's wall thickness. Y-branch is installed in a fresh steam pipeline in a power plant in Poland. Determination of an unknown boundary condition allows for the calculation of transient temperature distribution in the whole element. Next, stresses caused by non-uniform transient temperature distribution and by steam pressure inside a Y-branch are calculated using the finite element method. The proposed algorithm can be used for thermal-strength state monitoring in similar elements, when it is not possible to determine a 3-D thermal boundary condition. The calculated temperature and stress transients can be used for the calculation of element durability. More accurate temperature and stress monitoring will contribute to a substantial decrease of maximal stresses that occur during transient start-up and shut-down processes. L1 - http://journals.pan.pl/Content/94260/PDF/13_paper.pdf L2 - http://journals.pan.pl/Content/94260 PY - 2011 IS - No 3 December EP - 200 DO - 10.2478/v10173-011-0022-4 KW - heat transfer coefficient KW - inverse method KW - Transient temperature KW - Stress distribution A1 - Grądziel, Sławomir PB - The Committee of Thermodynamics and Combustion of the Polish Academy of Sciences and The Institute of Fluid-Flow Machinery Polish Academy of Sciences DA - 2011 T1 - Determination of temperature and thermal stresses distribution in power boiler elements with use inverse heat conduction method SP - 191 UR - http://journals.pan.pl/dlibra/publication/edition/94260 T2 - Archives of Thermodynamics