PL
 |
EN
Preferencje help
Polish version English version Język
Widoczny [Schowaj] Abstrakt
Liczba wyników
Powiadomienia systemowe
  • Sesja wygasła!

Znaleziono wyników: 6

Liczba wyników na stronie
first rewind previous Strona / 1 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  inverse heat transfer problem
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 1 next fast forward last
1
Content available remote Identification of thermal properties of hardening concreteby means of evolutionary algorithms
Długosz A., Pokorska I., Glinicki M. A., Jaskulski R.
Computer Assisted Methods in Engineering and Science
|
2017
|
Vol. 24, no. 2
101--111
EN
In this paper, the evolutionary computation procedures for identifying thermophysical properties in hardening massive concrete structures are presented. The heat of cement hydration, thermal conductivity and specific heat are determined for the purpose of modeling temperature evolution in massive concrete elements. Knowledge about temperature fields is very important due to their link with undesirable thermal stresses that can cause a weakening of structures because of thermal cracking. The proposed method is based on point temperature measurements in a cylindrical mould and the numerical solution of the inverse heat transfer problem by means of the finite element method and evolutionary computation.
2
Content available Numerical simulations of hardening and cooling of the early-age concrete
Knor G.
IPPT Reports on Fundamental Technological Research
|
2013
|
nr 4
11-18
EN
The paper presents a new method of control, modeling and identification of thermal fields in concrete structures. The proposed methodology boils down to four interdependent tasks: 1) the determination of a time-dependent intensity of the heat of hardening and other thermophysical properties of concrete by means of the numerical inverse problem solution, which is based on experimental measurements of temperature, 2) numerical modeling of the evolution of the thermal field in the maturing concrete structure, using material properties determined in the first point, 3) experimental verification of a thermal field modeling (point 2) using 2D and 3D concrete samples, 4) the formulation of the problem of optimum design of the cooling system to mitigate thermal stress concentrations during maturing of massive concrete structures.
3
Content available The inverse determination of volume fraction of fibres in reinforced composite with imperfect thermal contact between constituents
Mierzwiczak M., Kołodziej J. A.
Journal of Theoretical and Applied Mechanics
|
2011
|
Vol. 49 nr 4
987-1001
EN
The paper considers the problem of determination of the volume fraction of fibres in an unidirectionally reinforced composite in order to provide the appropriate effective thermal conductivity. The problem formulated in such a way should be treated as an inverse heat transfer problem. The thermal conductivities of constituents (fibres and matrix) and fibres arrangement are known. The calculations are carried out for an imperfect thermal contact between the fibres and matrix.
PL
W pracy rozważa się problem określenia objętościowego udziału włókien w jednokierunkowo wzmocnionym kompozycie w celu uzyskania odpowiedniego efektywnego współczynnika przewodzenia ciepła. Problem sformułowany w ten sposób jest traktowany jako odwrotny problem przewodzenia ciepła. Współczynniki przewodzenia ciepła składników (włókien i matrycy) oraz sposób ułożenia włókien są znane. Obliczenia są wykonane dla niedoskonałego kontaktu termicznego pomiędzy włóknami i matrycą.
4
Content available Inverse heat transfer problem in digital temperature control in plate fin and tube heat exchangers
Taler D., Sury A.
Archives of Thermodynamics
|
2011
|
Vol. 32, no. 4
17-32
EN
The aim of the paper is a steady-state inverse heat transfer problem for plate-fin and tube heat exchangers. The objective of the process control is to adjust the number of fan revolutions per minute so that the water temperature at the heat exchanger outlet is equal to a preset value. Two control techniques were developed. The first is based on the presented mathematical model of the heat exchanger while the second is a digital proportional-integral-derivative (PID) control. The first procedure is very stable. The digital PID controller becomes unstable if the water volumetric flow rate changes significantly. The developed techniques were implemented in digital control system of the water exit temperature in a plate fin and tube heat exchanger. The measured exit temperature of the water was very close to the set value of the temperature if the first method was used. The experiments showed that the PID controller works also well but becomes frequently unstable.
5
Content available remote Control of the rate of heat flow in a compact heat exchanger by changing the speed of fan rotation
Taler D.
Archives of Thermodynamics
|
2009
|
Vol. 30, no. 4
67-80
EN
The aim of the steady-state inverse heat transfer problem for plate-fin and tube heat exchangers is to adjust the number of fan revolutions per minute so that the water temperature at the heat exchanger outlet is equal to a preset value. Since the outlet water temperature is a nonlinear function of the fan revolution number, a nonlinear algebraic equation was solved using the secant or interval searching method. The steady-state outlet water temperature was calculated at every search or iteration step using an analytical mathematical model of the heat exchanger. An analytical model of the plate-fin and tube heat exchanger with two tube rows and two passes allowing for different heat transfer coefficients on each tube row was developed. The procedure developed in the paper was validated by comparing the calculated and measured values of the fan revolutions. The calculated numbers of fan revolutions compare closely with the measured values.
6
Content available remote Transient inverse heat transfer problem in control of plate fin and tube heat exchangers
Taler D.
Archives of Thermodynamics
|
2008
|
Vol. 29, no. 4
185-194
EN
A transient inverse heat transfer problem encountered in control of fluid temperature or heat transfer rate in a plate fin and tube heat exchanger was solved. The objective of the process control is to adjust the speed of fan rotation, measured in number of fan revolutions per minute, so that the water temperature at the heat exchanger outlet is equal to a time-dependent target value (setpoint). The least squares method in conjunction with the first order regularization method was used for sequential determining the number of revolutions per minute. Future time steps are used to stabilize the inverse problem for small time steps. The transient temperature of the water at the outlet of the heat exchanger was calculated at every iteration step using a numerical mathematical model of the heat exchanger. The technique developed in the paper was verified by comparing the calculated and measured number of the fan revolutions. The discrepancies between the calculated and measured revolution numbers are small.
first rewind previous Strona / 1 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.