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1
Content available Heat transfer investigations in a liquid that is mixed by means of a multi-ribbon mixer
Borowski Tomasz, Sołoducha Dawid, Musik Daniel, Wójcik Krzysztof, Chyla Mariusz, Ziętarska Katarzyna, Friedrich Małgorzata, Kiełbus-Rąpała Anna, Kordas Marian, Konopacki Maciej, Rakoczy Rafał
Polish Journal of Chemical Technology
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2021
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Vol. 23, nr 2
66--72
EN
The objective of this paper is to present the investigations of the heat transfer process carried out by means of the multi-ribbon mixer. It is shown that the heat transfer process for the synergic effect of the mixing process and the flowing liquid through the mixer has significantly higher values of the heat transfer coefficients than the mixer with motionless impellers. The empirical correlations between the heat transfer coefficient and the operational parameters obtained in this work can provide guidance for the design and operation of an apparatus equipped with the multi-ribbon impeller. These empirical correlations can be used to predict the heat transfer coefficient for the multi-ribbon mixer.
2
Content available A non integer order, state space model for one dimensional heat transfer proces
Oprzedkiewicz K., Gawin E.
Archives of Control Sciences
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2016
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Vol. 26, no. 2
261--275
EN
In the paper a new, state space, non integer order model for one dimensional heat transfer process is presented. The model is based on known semigroup model. The derivative with respect to time is described by the non integer order Caputo operator, the spatial derivative is described by integer order operator. The elementary properties of the state operator are proven. The solution of state equation is calculated with the use of Laplace transform. Results of experiments show, that the proposed model is more accurate than analogical integer order model in the sense of square cost function.
3
Content available Computational Fluid Dynamics and Experimental Studies of a New Mixing Element in a Static Mixer as a Heat Exchanger
Konopacki M., Kordas M., Fijałkowski K., Rakoczy R.
Chemical and Process Engineering
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2015
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Vol. 36, nr 1
59--72
EN
The main aim of this work is to study the thermal efficiency of a new type of a static mixer and to analyse the flow and temperature patterns and heat transfer efficiency. The measurements were carried out for the static mixer equipped with a new mixing insert. The heat transfer enhancement was determined by measuring the temperature profiles on each side of the heating pipe as well as the temperature field inside the static mixer. All experiments were carried out with varying operating parameters for four liquids: water, glycerol, transformer oil and an aqueous solution of molasses. Numerical CFD simulations were carried out using the two-equation turbulence k-ω model, provided by ANSYS Workbench 14.5 software. The proposed CFD model was validated by comparing the predicted numerical results against experimental thermal database obtained from the investigations. Local and global convective heat transfer coefficients and Nusselt numbers were detrmined. The relationship between heat transfer process and hydrodynamics in the static mixer was also presented. Moreover, a comparison of the thermal performance between the tested static mixer and a conventional empty tube was carried out. The relative enhancement of heat transfer was characterised by the rate of relative heat transfer intensification.
4
Content available remote An effect of different factors on heat transfer process in an agitated vessel
Major-Godlewska M.
Czasopismo Techniczne. Chemia
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2014
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R. 111, z. 2-Ch
85--94
EN
Heat transfer process depends on many different factors. The type of heating/cooling surface area has an effect on the intensity of the heat transfer process. In the agitated vessel, a jacket or a coil can be used as heating/cooling surface area. When using coil as a heating/cooling surface area, its shape (helical or vertical) and its location in the vessel should be taken into account. The size of the vessel and the type of the agitator and its diameter also have the influence on heat transfer process. Moreover, except for geometrical factors, the fluid type and its physical properties are important in heat transfer process. The aim of the study presented in the paper was to compare intensity of heat transfer process as a function of different factors for the agitated vessel equipped with jacket or coil. This analysis was carried out on the basis of the own experimental results and literature data.
PL
Wymiana ciepła zależy od wielu różnych czynników. Na intensywność wnikania ciepła ma wpływ rodzaj zastosowanej podczas wymiany ciepła powierzchni grzejnej/chłodzącej, która w mieszalniku może być zabudowana w formie płaszcza bądź wężownicy. Używając wężownicy jako powierzchni grzejnej/ chłodzącej, należy brać pod uwagę jej kształt oraz rozmieszczenie w zbiorniku. Również wielkość zbiornika oraz rodzaj i średnica mieszadła mają wpływ na wymianę ciepła. Poza czynnikami geometrycznymi na wartość współczynnika wnikania ciepła może mieć wpływ rodzaj cieczy użytej podczas procesu mieszania oraz jej właściwości fizyczne. Celem studiów prezentowanych w pracy było, na podstawie danych dostępnych w literaturze przedmiotu oraz wyników badań własnych, porównanie intensywności wnikania ciepła w funkcji różnych czynników dla zbiornika wyposażonego w płaszcz lub wężownicę.
5
Content available remote Mathematical modelling of the steady state heat transfer processes in the convectional elements of passive solar heating systems
Piotrowski J. Z., Stroy A., Olenets M.
Archives of Civil and Mechanical Engineering
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2013
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Vol. 13, no. 3
394--400
EN
This paper presents the developed mathematical models of the steady state heat transfer processes in the convectional elements of passive solar heating systems as well as the numerical results of these processes’ simulation. The influence of the adjustable radiant barrier installation on the solar heat gain through the convectional elements of a building’s solar passive heating system has also been analyzed.
6
Temperature recovery method. New aspects and applications
Mochnacki B., Lara S., Freus S.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
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2005
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z. 86
71-74
EN
In the paper the certain problems connected with the temperature recovery method application in numerical modelling of solidification are discussed. The method can be a base of very effective numerical procedure supplementing the boundary element method algorithm for the Fourier equation determining the heat transfer processes in the domain of solid body. In this way the basic version of the BEM can be used for the simulation of solidification process. In the final part the example of applications is presented.
7
Shape sensitivity analysis in 2D heat transfer
Majchrzak E., Kałuża G.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
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2004
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z. 78
229-234
EN
In the paper the 2D model of heat transfer process (steady state) is considered and the sensitivity analysis of this process with respect to the geometrical parameters is presented. On the stage of numerical computations the boundary element method is used. In the final part of the paper the results obtained are shown.
8
Application of the Thiessen polygons in numerical modelling of heat transfer
Mochnacki B.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
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2004
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z. 78
241-244
EN
In the paper the control volume method is applied for numerical modelling of solidification and cooling processes proceeding in the 2D domain. In particular the control volumes corresponding to the Thiessen polygons (TP) are introduced [1, 2, 3]. The geometrical properties of TP assure the possibility of good approximation of the energy balances being the base for CVM equations construction. In the final part of the paper the example of computations is shown.
9
Content available remote Sensitivity analysis of temperature field in the tissue with a tumor
Majchrzak E., Paruch M., Drozdek J.
Prace Naukowe Instytutu Matematyki i Informatyki Politechniki Częstochowskiej
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2003
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Vol. 2, nr 1
93--98
EN
The numerical algorithm based on the boundary element method is used for the temperature field computations in the non-homogeneous domain of healthy tissue and the tumor region. Thermophysical parameters of tumor region, in particular the perfusion coefficient and the metabolic heat source are essentially bigger than for healthy tissue. The values of these parameters are assumed to be constant. From the mathematical point of view the problem is described by the system of two Poisson’s equations supplemented by the adequate boundary conditions. The main subject of the paper is the sensitivity analysis of temperature distribution with respect to the constant source functions in the sub-domains considered. In the final part the examples of computations are shown.
10
The Hybrid Numerical Model of Heat and Mass Transfer in Domain of Casting
Mochnacki B., Prażmowski M., Suchy J.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
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2002
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z. 75
137-140
EN
In the paper the numerical model of solidification and segregation processes proceeding in the casting domain is discussed. The thermal processes described by the Fourier equation and the adequate physical, geometrical and boundary-initial conditions are simulated using the control volume method, while the segregation model bases on the collocation method described in (1). The coupling of the both algorithms results from the solidification rate (the heat transfer model) and changing solidification point (the segregation one). In the final part of the paper the example of numerical realization is shown.
11
Estimation of Time Dependent Boundary Heat Flux Using Sensitivity Coefficients
Majchrzak E., Mendakiewicz J., Janisz D.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
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2002
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z. 75
141-144
EN
In the paper the method of time dependent boundary heat flux estimation is presented. The algorithm is constructed on the basis of the boundary element method and the least squares criterion in which the sensitivity coefficients are introduced. The theoretical considerations are supplemented by the example of computations.
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