A new method for estimating heat flux in superheater and reheater tubes

Purbolaksono, J.; Khinani, A.; Rashid, Abd; Ali, Ammar A.; Ahmad, J.; Nordin, Norlisa Francis

doi:10.1016/j.nucengdes.2009.05.018

Cited by 11 publications

(4 citation statements)

References 3 publications

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“…The main goal of the computational analysis was to detect the reason for the tube rupture inside the boiler. A new procedure for determining heat flux in superheater and reheater tubes based on the empirical formulas and the finite element modeling is presented by Purbolaksono et al [48]. The finite element simulations were performed by Othman et al [49] to find the main reason for superheater tube deformations.…”

Section: Identification Of Thermal Boundary Conditions In Heat Exchanmentioning

confidence: 99%

Solving Inverse Heat Transfer Problems When Using CFD Modeling

Ludowski¹,

Taler²,

Taler³

2016

Numerical Simulation - From Brain Imaging to Turbulent Flows

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The chapter presents solving steady-state inverse heat transfer problems using Computational Fluid Dynamics (CFD) software. Two examples illustrate the application of the proposed method. As the first inverse problem determining the absorbed heat flux to water walls in furnaces of steam boilers is presented in detail. Three different measurement devices (flux tubes) were designed to identify steady-state boundary conditions in water wall tubes of combustion chambers. The first meter is made of a short eccentric tube in which four thermocouples on the fire side below the inner and outer tube surfaces are installed. The fifth thermocouple is situated at the rear of the tube on the housing side of the water wall tube. The second meter has two longitudinal fins that are welded to the bare eccentric tube. In the third option of the instrument, the fins are attached to the water wall tubes but not to the flux tubes as in the second version of the flux tubes. The first instrument is used to measure the heat flux to water walls made from bare tubes, while another two heat flux tubes are designated for measuring the heat flux to membrane walls. Unlike the existing devices, the flux tube is not attached to neighboring water-wall tubes. The absorbed heat flux on the outer surface and the heat transfer coefficient at the inner surface of the flux tube are determined from temperature measurements at internal points. The thermal conductivity of the flux-tube material is a function of temperature. The nonlinear inverse problem of heat conduction (IHCP) is solved using the least-squares method. Three unknown parameters are determined using the Levenberg-Marquardt method. In each iteration, the temperature distribution in the cross section of the heat flux instrument is determined using the ANSYS/CFX software.Another inverse heat transfer problem will be a CFD simulation carried out for the platen superheater placed in the combustion chamber of the circulating fluidized bed (CFB) boiler. Velocity, pressure, and temperature of the steam, as well as the temperature of the tube wall with the complex cross section, were computed using the ANSYS/ CFX software. The direct and inverse problems were solved. In the first inverse problem, the heat transfer coefficient on the flue-gas side was determined based on the meas- ured steam temperature at the inlet and outlet of the three pass steam superheater. In the second inverse problem, the inlet steam temperature and the heat transfer coefficient on the flue-gas side were estimated using measured steam temperatures at selected locations of the superheater. The Levenberg-Marquardt method was also used to solve the second inverse problem. At every iteration step, a direct conjugate heat transfer problem was solved using the ANSYS/CFX software. The CFX program was called and controlled by an external program written in Python language. The LevenbergMarquardt algorithm was also included in the Python program.

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Section: Identification Of Thermal Boundary Conditions In Heat Exchanmentioning

confidence: 99%

Solving Inverse Heat Transfer Problems When Using CFD Modeling

Ludowski¹,

Taler²,

Taler³

2016

Numerical Simulation - From Brain Imaging to Turbulent Flows

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show abstract

“…Purbolaksono et al presents a new method for estimating heat flux in superheater and reheater tubes based on the empirical formulas and the finite element modeling. [21]. The calculations were performed by Othman et al [22] to identify the possible causes of failure of the deformed superheater tubes.…”

Section: Introductionmentioning

confidence: 99%

Thermal simulation of superheaters taking into account the processes occurring on the side of the steam and flue gas

Trojan

Taler

2015

Fuel

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“…Current studies of the superheater are focuses on the numerical simulation of internal field and strength analysis. Purbolaksono J [1]and Pronobis M [2]applied finite element software to calculate the heat flux distribution under different conditions. Madejski Pawel [3]and Taler D [4]had numerical calculation on the superheater tube wall temperature distribution and analyzed the stress in order to study the causes of over-temperature.…”

Section: Introductionmentioning

confidence: 99%