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1

Optymalizacja nagrzewania ciśnieniowych zbiorników grubościernych z otworami

Dzierwa P.

Energetyka

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2012

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nr 5

258-261

PL

Przedstawiona metoda optymalizacji nagrzewania może znaleźć zastosowanie do wyznaczania optymalnych przebiegów temperatury czynnika podczas nagrzewania walczaków kotłów parowych oraz zbiorników ciśnieniowych reaktorów jądrowych. Ze względu na wysokie naprężenia cieplne występujące w punkcie P2 na brzegu otworu, tj. w punkcie leżącym na brzegu otworu w przekroju poprzecznym walczaka, naprężenia te decydują o przebiegu nagrzewania optymalnego. Ściskające naprężenia cieplne w tym punkcie są w małym stopniu kompensowane przez naprężenia rozciągające pochodzące od ciśnienia. Dopuszczalne zmiany temperatury czynnika w czasie nagrzewania zbiorników grubościennych powinny być wyznaczane z uwagi na naprężenia w punkcie P2.

EN

Presented is a method for determining time-optimum medium temperature changes. The heating of pressure elements will be conducted in such way, that the circumferential stresses caused by pressure and fluid temperature variations at the edge of the opening and the point of stress concentration would not exceed the allowable values. The optimum fluid temperature changes assume a ramp form. It is possible to increase the fluid temperature stepwise at the beginning of the heating process and then increase the fluid temperature with the constant rate. Allowing stepwise fluid temperature increase at the beginning of heating ensures that heating time of a thick-walled component is shorter than the heating time resulting from calculations according to the EN 12952-3 European Standard.

2

Optimum heating of cylindrical pressure components weakened by holes

Dzierwa P., Taler J.

Archives of Thermodynamics

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2012

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Vol. 33, no. 3

111-121

EN

A method for determining time-optimum medium temperature changes is presented. The heating of the pressure elements will be conducted so that the circumferential stress caused by pressure and fluid temperature variations at the edge of the opening at the point of stress concentration, do not exceed the allowable value. In contrast to present standards, two points at the edge of the opening are taken into consideration. The first point, P[1], is located at the cross section and the second, P[2], at the longitudinal section of the vessel. It will be shown that the optimum temperature courses should be determined with respect to the total circumferential stress at the point P[2], and not, as in the existing standards due to the stress at the point P[1]. Optimum fluid temperature changes are assumed in the form of simple time functions. For practical reasons the optimum temperature in the ramp form is preferred. It is possible to increase the fluid temperature stepwise at the beginning of the heating process and then increase the fluid temperature with the constant rate. Allowing stepwise fluid temperature increase at the beginning of heating ensures that the heating time of a thick-walled component is shorter than heating time resulting from the calculations according to EN 12952-3 European Standard. @eng

3

A new method of drum heating determination during start-up of steam boilers

Taler D., Dzierwa P.

Archives of Thermodynamics

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2009

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Vol. 30, no. 4

81-95

EN

A method for determining time-optimum medium temperature changes is presented. Heating and cooling of pressure exposed elements will be conducted in such way, that the circumferential stresses caused by pressure and fluid temperature variations at the edge of the opening and at the point of stress concentration, do not exceed the allowable values. How-ever, the calculated optimum temperature changes are difficult to follow in practice in the initial stage of heating. It is however possible to in-crease the fluid temperature stepwise to the minimum value and then heat the pressure component according to the determined optimum temperature changes. Allowing stepwise fluid temperature increase at the beginning of heating ensures that the heating time of a thick-walled component is shorter, than heating time resulting from the calculations according to EN 12952-3 European Standard or TRD 301 regulations.

4

Identification of transient thermal boundary conditions in complex-shape bodies

Duda P.

Archives of Thermodynamics

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2005

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Vol. 26, no. 1

17-33

EN

The following paper presents a method for solving one- and multidimensional inverse boundary heat conduction problems. The method is used to estimate an unknown thermal boundary condition on an inner surface of complex-shape elements. Next, the Finite Element Method can be used to calculate thermal stresses caused by other loads such as, for instance, internal pressure. The developed method is tested using the measured temperatures generated from a direct solution. Transient temperature distribution obtained from method presented below is compared with the values obtained from the direct solution. Next, method is used to estimate an unknown thermal boundary condition on an inner surface of a thick-walled Y-branch. Solution is based on measured temperature transients at two points inside the elementary wall thickness.