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1

Analysis of cooling of the exhaust system in a small airplane by applying the ejector effect

Złoty Ł., Łapka P., Furmański P.

Journal of Power Technologies

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2018

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Vol. 98, nr 1

121--126

EN

This paper presents a thermal analysis of elements of the exhaust system of the redesigned airplane I-23. In order to improve the thermal performance of the exhaust system and decrease thermal loads inside the engine bay, modifications of the initial geometry of the cover pipe were proposed. This pipe shields the nacelle interior from thermal interaction and direct contact with the hot exhaust pipe. Several openings were created in its wall to increase the mass flow rate of the cold air sucked in from the nacelle interior to the gap between the exhaust pipe and its cover due to the ejector effect. Then numerical models were developed and simulations for flight conditions were carried out for the original and modified exhaust systems. The results obtained for both geometries were compared, showing that openings in the cover duct resulted in a high mass flow rate flowing through the gap between exhaust pipe and its cover and a lower exhaust pipe temperature. Even though the number, locations and cross-section area of the openings were selected arbitrarily, better thermal performance was obtained for the modified exhaust system.

2

Modelling of a micro-channel heat sink for cooling of high-power laser diode arrays

Furmański P., Thualfaqir K., Łapka P.

Archives of Thermodynamics

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2018

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Vol. 39, no 3

15--27

EN

Micro-channel heat sinks are used in a wide variety of applications, including microelectronic devices, computers and high-energy-laser mirrors. Due to the high power density that is encountered in these devices (the density of delivered electrical power up to a few kW/cm2 ) they require efficient cooling as their temperatures must generally not exceed 100 °C. In the paper a new design for micro-channel heat sink (MCHS) to be used for cooling laser diode arrays (LDA) is considered. It is made from copper and consisting of 37 micro-channels with length of 9.78 mm, width of 190 µm and depth of 180 µm with the deionized water as a cooling medium. Mathematical and numerical models of the proposed design of the heat sink were developed. A series of thermofluid numerical simulations were performed for various volumetric flow rates of the cooling medium, its inlet temperature and different thermal power released in the laser diode. The results show that the LDA temperature could be decreased from 14 to 17% in comparison with earlier proposed design of the heat sink with the further drop in temperature obtained by applying indium instead of gallium arsenide as the soldering material between the LDA and MCHS interface. Moreover, it was found that the maximum temperature, and therefore the thermal resistance of the considered heat sink, could be decreased by increasing the coolant flow rate.

3

Investigation of thermal interactions between elements of propulsion system and selected parts of the airplane skin in small aircrafts

Łapka P., Seredyński M., Furmański P.

Archives of Thermodynamics

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2018

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Vol. 39, no 3

45--61

EN

Development of new or upgrading of existing airplanes requires many different analyses, e.g., thermal, aerodynamical, structural, and safety. Similar studies were performed during re-design of two small aircrafts, which were equipped with new turboprop engines. In this paper thermo-fluid analyses of interactions of new propulsion systems with selected elements of airplane skin were carried out. Commercial software based numerical models were developed. Analyses of heat and fluid flow in the engine bay and nacelle of a single-engine airplane with a power unit in the front part of the fuselage were performed in the first stage. Subsequently, numerical simulations of thermal interactions between the hot exhaust gases, which leave the exhaust system close to the front landing gear, and the bottom part of the fuselage were investigated. Similar studies were carried out for the twin-engine airplane with power units mounted on the wings. In this case thermal interactions between the hot exhaust gases, which were flowing out below the wings, and the wing covers and flaps were studied. Simulations were carried out for different airplane configurations and operating conditions. The aim of these studies was to check if for the assumed airplane skin materials and the initially proposed airplane geometries, the cover destruction due to high temperature is likely. The results of the simulations were used to recommend some modifications of constructions of the considered airplanes.

4

Zastosowanie dwurównaniowego modelu transportu ciepła w skórze do oceny charakterystyk cieplnych ubrań ochronnych

Łapka P., Furmański P.

Przemysł Chemiczny

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2017

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T. 96, nr 2

343--347

PL

Przedstawiono zaawansowany model matematyczny i numeryczny transportu energii przez ubrania ochronne oraz przez wierzchnie warstwy tkanki. Model uwzględniał przekazywanie ciepła przez przewodzenie oraz promieniowanie w porowatych warstwach tekstylnych o spektralnych właściwościach optycznych oraz szczelinach powietrznych, któremu towarzyszył transport dyfuzyjny wilgoci przez pory i przestrzenie powietrzne oraz procesy sorpcji i desorpcji ciekłej wody przez włókna tkaniny. Z kolei w skórze i mięśniach zasymulowano nierównowagowy transport ciepła pomiędzy tkanką i krwią tętniczą za pomocą modelu dwurównaniowego oraz zmienną prędkość perfuzji krwi. Otrzymane wyniki posłużyły do oceny wpływu wielkości strumienia ciepła oraz czasu ekspozycji na stopień oparzenia skóry oraz właściwości ochronne ubrań.

EN

Energy transfer in protective clothing and in superficial skin tissue was math. and numerically modeled assuming assuming heat conduction and non-gray thermal radiation in the porous textile layers and air gaps accompanied by water vapor diffusion in pores and air spaces as well as sorption and desorption of liq. water from fabric fibers. Non-equil. heat transfer between the tissue and arterial blood as well as variable blood perfusion rate were simulated in the skin and muscle applying two-equation bioheat transfer model. The results were used to access influence of the heat flux changes and exposition time on degree of skin burns and protective performance of garments.

5

Analysis of a hydro-osmotic power plant using a simple mathematical model

Furmański P., Saleh S. A.-A., Łapka P.

Journal of Power Technologies

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2017

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Vol. 97, nr 5

395--405

EN

Osmotic energy created by salinity gradient is a novel energy source. The chemical potential difference of two liquids with dissimilar salinities can be used to generate a flow of water across a semi-permeable membrane. The Pressure-Retarded Osmosis (PRO) concept controls the flow of the water across the membrane and contributes to the production of electrical energy with a hydraulic turbine. This study describes a simple mathematical model for evaluating the effectiveness of application of the PRO process in a hydro-osmotic power plant. The influences of pressures and salt concentrations of the inlet streams as well as the concentration polarization across the membrane on the membrane power density and plant efficiency were investigated. The effects of liquid temperature and membrane characteristics (water and salt permeability) on power plant performance were also studied.

6

Coordination number for random distribution of parallel fibres

Darnowski P., Furmański P., Domanski R.

Archives of Thermodynamics

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2017

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Vol. 38, no. 1

3--26

EN

This paper presents the results of computer simulations carried out to determine coordination numbers for a system of parallel cylindrical fibres distributed at random in a circular matrix according to twodimensional pattern created by random sequential addition scheme. Two different methods to calculate coordination number were utilized and compared. The first method was based on integration of pair distribution function. The second method was the modified sequential analysis. The calculations following from ensemble average approach revealed that these two methods give very close results for the same neighbourhood area irrespective of the wide range of radii used for calculation.

7

Walidacja modelu przepływu ciepła i wilgoci przez ubiór ochronny

Łapka P., Furmański P., Bugaj M. A., Cieślikiewicz Ł., Pietrak K., Kubiś M., Wiśniewski T. S.

Zeszyty Naukowe SGSP / Szkoła Główna Służby Pożarniczej

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2016

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Nr 58 (tom 2) (2)

231--251

PL

W artykule przedstawiono zaawansowany model matematyczny i numeryczny transportu ciepła i masy w wielowarstwowych ubraniach ochronnych, które były poddane działaniu wysokiej temperatury otoczenia lub dużych radiacyjnych strumieni ciepła emitowanych przez gorące ciała. Zaproponowany model uwzględniał przewodzenie ciepła i promieniowanie cieplne w warstwach tkaniny o spektralnych właściwościach optycznych i w szczelinach powietrznych oraz transport energii związany z dyfuzją wilgoci przez ubranie ochronne oraz z procesami sorpcji i desorpcji wody w włóknach tkaniny. Dodatkowo do modelu włączono złożone warunki bilansu energii i masy oraz warunki optyczne na granicach warstw tkaniny. Do rozwiązania równań modelowych opracowano autorski iteracyjny algorytm numeryczny, który bazował na metodzie objętości kontrolnych. Następnie przeprowadzono analizę walidacyjną zaproponowanego modelu obliczeniowego poprzez porównanie otrzymanych wyników z wynikami pomiarów eksperymentalnych dla wybranego pakietu ubrania ochronnego ogrzewanego przez krótki czas radiacyjnym strumieniem ciepła emitowanym przez promiennik podczerwieni, a następnie chłodzonego w otoczeniu. Otrzymano dobrą zgodność czasowych przebiegów temperatury, co potwierdziło wiarygodność zaproponowanego modelu.

EN

An advanced mathematical and numerical model of heat and mass transfer in the multi-layer protective clothing, which was exposed to either high temperature environment or to high incident radiative heat flux emitted by hot objects was presented in this paper. The developed model accounted for heat conduction and thermal radiation in a non -grey layers of the protective garment. Additionally, heat transport associated with water vapour diffusion through the protective clothing and with sorption and desorption of liquid water in the fabric fibres were included. Complex energy and mass balances as well as optical conditions at the external and internal interfaces between clothing layers were formulated and incorporated into the model. A novel iterative numerical algorithm which was based on the Finite Volume Method was developed to solve the system of governing equations. Finally, the validation analysis of the model was carried out for selected multi-layer clothing which was exposed for a short time to radiative heat flux emitted by an infrared emitter and then cooled down in the surroundings. The simulated and experimentally measured time variations of temperatures were in good agreement, therefore the accuracy of the proposed model was validated.

8

Badanie wpływu rodzaju ubioru na jego właściwości ochronne

Furmański P., Łapka P.

Zeszyty Naukowe SGSP / Szkoła Główna Służby Pożarniczej

|

2016

|

Nr 58 (tom 2) (2)

207--230

PL

W artykule omówiono kryteria oceny właściwości ochronnych ubiorów strażackich oparte o przewidywany stopień oparzenia i wykorzystanie temperatury powierzchniowych warstw skóry. Przedstawiono metody oceny tych właściwości bazujące na pomiarach temperatury przeprowadzanych na manekinach i specjalnie zaprojektowanych stanowiskach pomiarowych wykorzystujących próbki ubiorów ochronnych. Szczególną uwagę zwrócono na metodę opartą o symulację numeryczna procesów wymiany ciepła i wilgoci w ubiorach ochronnych warstwach powietrznych oddzielających jego poszczególne warstwy oraz w skórze. Omówiono zalety i wady zarówno metod eksperymentalnych, jak i teoretycznej oceny właściwości ochronnych ubioru. Krótko streszczono rodzaje materiałów stosowanych na warstwy ubioru ochronnego i ich właściwości cieplne, radiacyjne i dyfuzyjne. Na podstawie symulacji numerycznej różnych sposobów wymiany ciepła w ubiorze ochronnym wykazano, że największą rolę odgrywa w niej przewodzenie ciepła i promieniowanie cieplne. Przeprowadzano symulacje numeryczne przepływu ciepła przez trzy ubiory ochronne wykonane z warstw różnych materiałów. Wykazano, że ubiory te różnią się, przy zadanym obciążeniu cieplnym, zarówno przewidywanym wzrostem temperatury przypowierzchniowych warstw skóry jak stopniem oparzenia. Zbadano również wpływ grubości szczelin powietrznych między warstwami ubioru oraz między wewnętrzną powierzchnią ubioru i skórą wykazując istotny wpływ tej ostatniej szczeliny na przewidywany stopień oparzenia.

EN

Criteria for evaluation of protective properties of firefighters clothing were presented in the paper. They were based on a degree of predicted skin burns and determination of temperature of the skin surface layers. Methods of the skin temperature measurements using mannequins and specially designed experimental stands containing samples of the protective clothing were described. Special attention was directed toward numerical simulation of heat and moisture transfer across layers of the protective clothing as well as via the air spaces separating them and the human skin. Advantages and disadvantages of the experimental and theoretical methods were briefly discussed. Types of textiles used for the separate layers of the protective clothing together with their thermal radiative and diffusive properties were presented. Numerical simulations indicate that heat conduction and thermal radiation play the most important role in heat transfer across the protective clothing. The numerical simulations were also carried out for three kinds of the protective clothing made from layers of different textiles. It was shown that these clothing differ in the predicted skin temperature values and burn degree for the same thermal load applied. Effect of changing thickness of the air spaces between textile layers and the skin on the burn degree was also studied. It was proved that the latter air space exerts significant influence on the predicted burn degree.

9

Micro-macro model for prediction of local temperature distribution in heterogeneous and two-phase media

Furmański P., Seredyński M., Łapka P., Banaszek J.

Archives of Thermodynamics

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2014

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Vol. 35, no. 3

81--103

EN

Heat flow in heterogeneous media with complex microstructure follows tortuous path and therefore determination of temperature distribution in them is a challenging task. Two-scales, micro-macro model of heat conduction with phase change in such media was considered in the paper. A relation between temperature distribution on the microscopic level, i.e., on the level of details of microstructure, and the temperature distribution on the macroscopic level, i.e., on the level where the properties were homogenized and treated as effective, was derived. The expansion applied to this relation allowed to obtain its more simplified, approximate form corresponding to separation of micro- and macro-scales. Then the validity of this model was checked by performing calculations for 2D microstructure of a composite made of two constituents. The range of application of the proposed micro-macro model was considered in transient states of heat conduction both for the case when the phase change in the material is present and when it is absent. Variation of the effective thermal conductivity with time was considered and a criterion was found for which application of the considered model is justified.

10

Prediction of thermal conductivities of dry granular media using artificial neural networks

Grabarczyk M., Furmański P.

Journal of Power Technologies

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2013

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Vol. 93, nr 2

59--66

EN

Thermal conductivity of heterogeneous materials is a complex function not only of properties and amounts of constituents but also of many structural factors. Therefore it is difficult to predict. An attempt to predict thermal conductivity of granular media using the Artificial Neural Network (ANN) model is undertaken in the paper. It was assumed that it is a function of a ratio of thermal conductivities of the constituents, medium porosity as well as the coordination number describing the mean number of the nearest neighbours to each grain. Several configurations of the ANNs were tested while developing the optimal model. As a measure of prediction accuracy the coefficient of linear regression and the mean squared error were used. The optimal model of ANN was found to consist of three hidden layers with eight neurons in each layer for both types of media. Some problems associated with application of ANN were pointed out. The predicted values of thermal conductivity obtained with ANN were compared with values calculated from an analytical formula. It was found that the ANN predictions show identical trends and similar values as the analytical formula for all factors affecting thermal conductivities of the granular media.

11

Detection of moisture in porous materials through infrared methods

Furmański P., Wiśniewski T., Wyszyńska E.

Archives of Thermodynamics

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2008

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Vol. 29, no. 1

19-39

EN

Presence of liquid water is one of the agents responsible for damage of materials. A study on determination of the liquid water content in porous materials was carried out in the paper. At first a review of methods for moisture detection was performed. Then a new quantitative method, based on IR observation of variation in the surface temperature of the moist sample in the humid environment, is proposed. The mathematical model for the method was based on the fundamental assumption that the liquid phase appears in thermodynamic equilibrium with the water vapour in pores of the material. Analysis of the simplified solutions of the mathematical model is carried out for a common, red brick and relations between the water content and experimentally measurable parameters are presented. Finally, preliminary measurements on the moist material are done on a specially designed experimental stand using the infrared camera. It follows that the transient part of the surface temperature response is most suitable for determination of the water content in the porous material.

12

Parallel solution of two-dimensional conjugated radiative-conductive heat transfer problem

Łapka P., Furmański P.

Turbulence : international journal

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2007

|

Vol. 12

149-168

EN

In this paper a two-dimensional conjugated heat transfer both by radiation and conduction in the thermal lightweight insulation layer was investigated. It was assumed that the radiation might be emitted, absorbed and isotropically scattered inside the gray medium. Its walls were opaque, absorbing, emitting and reflecting diffusively. The Alternating Direction Implicit Method and the Finite Volume Method were used for solution of heat conduction equation and radiative transfer equation, respectively. At first the problem was solved sequentially and then by applying the Domain Decomposition Method. Parallel calculations were carried out for two and four sub-domains. Influence of different factors on differences between the results obtained from the parallel computing and from the sequential calculations, on parallel computing efficiency as well as on number of iterations required for heat conduction equation to be effectively solved were studied in this paper.

13

Badania współczynnika przewodzenia ciepła izolacji kadłuba turbiny oraz analiza jego wpływu na pola temperatury i naprężeń

Wiśniewski T., Łapka P., Miścicki M., Seredyński M., Furmański P.

Prace Naukowe Politechniki Warszawskiej. Konferencje

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2007

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T. 2, z. 25

679-686

PL

W pracy przedstawiono wyniki badań współczynnika przewodzenia ciepła wełny mineralnej zastosowanej do izolacji kadłuba WP turbiny parowej. Przeprowadzono również obliczenia numeryczne pól temperatury kadłuba i izolacji oraz pola naprężeń i wartości wydłużeń kadłuba WP turbiny parowej o mocy 25 MW, badając wpływ zmiany współczynnika przewodzenia ciepła na te pola. Pomiary współczynnika przewodzenia ciepła prowadzono przy użyciu układu pomiarowego skonstruowanego w Zakładzie Termodynamiki Instytutu Techniki Cieplnej Politechniki Warszawskiej, będącym implementacją jednopłytowego aparatu Poensgena. Specjalna konstrukcja układu pozwala na pomiar przy zadanej zawartości wilgoci w próbce. Przeprowadzono badania współczynnika przewodzenia ciepła w funkcji objętościowej zawartości wilgoci w izolacji; od O do 10%. Współczynnik całkowicie suchej badanej izolacji (o średniej gęstości 216 kg/m3) wynosił lambda20 =0,072 W/(m-K). Obecność wilgoci - w postaci ciekłej - znacznie pogorszyła właściwości izolacyjne badanej wełny mineralnej (w temperaturze 20°C) - do ponad 0,11 W/(m-K) - przy udziale objętościowym wody 10%. Przeprowadzono analizę zmian współczynnika przewodzenia ciepła izolacji kadłuba turbiny podczas jej rozruchu. W średniej temperaturze pracy izolacji równej 230°C współczynnik przewodzenia ciepła wełny o gęstości 100 kg/m3 wynosi 0,071 W/(m-K), natomiast współczynnik przewodzenia ciepła wełny o gęstości 216 kg/m3 wynosi 0,121 W/(m-K). Obecność pary wodnej zamiast powietrza nieznacznie zmniejsza współczynnik przewodzenia ciepła badanej izolacji. Obecność fazy ciekłej wyraźnie zwiększa współczynnik przewodzenia ciepła izolacji, ale ma to mieć miejsce sporadycznie w stanach awaryjnych. Istotny wpływ na współczynnik przewodzenia ciepła izolacji ma jej gęstość. Stosowanie granulatu wełny mineralnej może powodować w praktyce znaczne zwiększenie jej gęstości w stosunku do wartości projektowanej i istotny wzrost współczynnika przewodzenia ciepła.

EN

The results of nwestigations of thermal conductivity of steam turbine insulation are presented. The conductivity of mineral wool samples (density 216 kg/m3), with volumetric water contents increased from 0 to 10%, was measured in special experimental stand. It was found, that the conductivity increased from lambda20 = 0,072 W/(m-K) to lambda20 = 0,11 W/(m-K). Thermal conductivity of the insulation at 230°C, i.e. average temperature of the insulation during operation of the turbine was calculated as lambda230= 0,07 W/(m-K) for density 100 kg/m3 and lambda230= 0,12 W/(m-K) for density 216 kg/m3. Presence of steam in the mineral wool - instead of air - slightly decreases thermal conductivity. Numerical analysis of the influence of thermal conductivity of insulation on temperature, stress and displacement fields in the 25 MW steam turbine body are presented. FLUENT and ANSYS codes were used for calculations. It was found that increase in thermal conductivity of insulation (from 0,07 to 0,12 W/(m-K)) does not affect displacement and stress field. Temperature of external surface of insulation increases by 8°C.

14

Sygnalizator opromieniowania radiolokacyjnego SO4-0818

Furmański P.

Biuletyn Wojskowej Akademii Technicznej

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2007

|

Vol. 56, nr sp.2

143-148

PL

W artykule przedstawiony jest opracowany przez Oddział Wrocławski Przemysłowego Instytutu Telekomunikacji sygnalizator opromieniowania radarowego SO4-0818 przeznaczony do instalacji na zautomatyzowanym wozie dowodzenia na podwoziu specjalnym HMMWV. Zadaniem tego urządzenia jest ostrzeżenie załogi o opromieniowaniu pojazdu przez źródło emisji radarowej i umożliwienie powzięcia odpowiednich środków zaradczych. Przedstawiona została budowa, zasada działania, proponowane zastosowania sygnalizatora opromieniowania radiolokacyjnego oraz możliwości dalszego rozwoju systemu.

EN

In this paper, the SO4-0818 Radar Warning Receiver designed by the Telecommunications Research Institute Wroclaw Division is presented. The device significantly enhances the survivability of a platform and its crew, improving situational awareness. The warning receiver is designed for general ground vehicles for example HMMWV. The device detects the radio emission of the radar systems. This system is capable of classifying the source of the radar type (pulsed or continuous wave). Detected emission (pulsed or CW) from airborne or on-board other ground-based emitters are displayed on one of the eight LEDs bar. The device can switch on external alarm systems or can send warning command to other warning systems. This warning system consists of two independent parts: antenna unit and visual display. Antenna unit has four independent microwave detection blocks. Each of them consists of wideband spiral antenna, band pass filter, power limiter, microwave power detector, and control unit which send a detected signal to a display unit. Visual display has eight LEDs bar, which turns on when radar emission in any sector is detected. Each sector can be also turned off by an operator. The device presented in this paper has sensitivity regulation capability. The SO4-0818 Radar Warning Receiver is a simple, light-weight, low power consumption and cost-effective set. The total system weight is 4.5 kg. The device passed all environmental and electromagnetic compatibility test according to demand of proper military norms.

15

Detection of structural defects in materials through infrared methods

Furmański P., Łapka P., Wiśniewski T.

Archives of Thermodynamics

|

2007

|

Vol. 28, no. 4

19-40

EN

A review of infrared methods used for non-destructive testing of material defects is presented. Some experimental studies with the long wavelength IR camera are carried out when the pulse heating is used. Then the thorough theoretical analysis of the defect detectability with the use of the pulse thermography is performed. A sample with a two-dimensional defect with a rectangular cross-section is considered. Influence of different way of sample heating on thermal contrast is investigated for two materials with widely varying thermal properties.

16

Parallel computation of conjugated radiative-conductive heat transfer in thermal insulation layer

Łapka P., Furmański P.

Archives of Thermodynamics

|

2006

|

Vol. 27, no. 2

55-80

EN

In this paper the parallel computing of conjugated heat transfer both by radiation and conduction in a two-dimensional lightweight thermal insulation layer was analysed. It was assumed that the medium can emit, absorb and isotropically scatter radiation. Its walls were opaque, absorbing, emitting and reflecting diffusively. At first, the problem was numerically solved by carrying out the sequential calculations. The radiative transfer equation was discretised by the Finite Volume Method. For the heat conduction equation the Alternating Direction Implicit Method was applied. Next the Domain Decomposition Method was used to perform the parallel calculations by dividing the whole domain into two and four sub-domains. Influence of different factors on differences between the results obtained from the parallel computing and from the sequential calculations were studied. Finally, the parallel computing speed up and efficiency were analysed together with factors affecting them.

17

Theoretical and technical aspects of thermochemical conversion of concentrated solar energy

Amhalhel G., Furmański P.

Biuletyn Instytutu Techniki Cieplnej Politechniki Warszawskiej

|

2004

|

nr 89/90

25--58

EN

This paper presents an up-to-date overview of the theoretical and technical aspects of thermo-chemical energy conversion (TCEC) systems of concentrated solar energy. The conventional methods of thermal energy conversion and TCEC systems are presented and their merits and demerits are summarized. The different types of TCEC systems and the main elements of the TCEC system are described. Problems associated with the application of these systems, with special emphasis on the receiver/reactor system, are discussed. The industrial importance of the TCEC process is also demonstrated. The state of the art and problems associated with the mathematical and experimental modeling of the TCEC process have also been discussed in more detail. Finally, suggestions as to further development of mathematical and experimental modeling of the TCEC process of concentrated solar energy are presented.

PL

W pracy przedstawiono przegląd teoretycznych i technicznych aspektów termochemicznej konwersji energii skoncentrowanego promieniowania słonecznego (TCEC). Omówiono i porównano klasyczne metody konwersji energii promieniowania słonecznego oraz układy oparte na TCEC. Opisano różne typy układów TCEC oraz ich poszczególne elementy składowe. Przedyskutowano różne problemy związane z zastosowaniem tych systemów ze szczególnym uwzględnieniem układu odbiornik promieniowania/reaktor chemiczny. Wskazano na potencjalne znaczenie TCEC w przemyśle. Szczegółowo omówiono również stopień zaawansowania modelowania matematycznego i badań eksperymentalnych tych układów oraz wskazano na kierunki dalszych badań.

18

Energy analysis of different design concepts of receivers/reactors for thermochemical conversion of cocncentrated solar energy

Amhalhel G. A., Furmański P.

Biuletyn Instytutu Techniki Cieplnej Politechniki Warszawskiej

|

2004

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nr 89/90

85--104

EN

In this paper, exergy analysis of the different design concepts of receivers/reactors utilized for the Thermochemical Energy Conversion process (TCEC) of the concentrated solar energy is presented. The analysis considers all the exergy interactions taking place during the TCEC process. The proposed model has been used to compare the general thermochemical behavior of the three general types of receivers/reactors used for the TCEC process operated in both continuous and discontinuous flow regimes. Comparison of the thermal characteristics of the TCEC process with other Sensible Thermal Energy and Phase Change Thermal Energy Conversion processes has also been presented.

PL

W pracy przedstawiono analizę egzergetyczną różnych typów odbiorników promieniowania/reaktorów chemicznych wykorzystywanych w układach do termochemicznej konwersji energii skoncentrowanego promieniowania słonecznego (TCEC). Analiza uwzględnia wszelkiego rodzaju oddziaływania występujące podczas procesu TCEC. Przy jej pomocy dokonano porównania trzech różnych typów odbiorników promieniowania/reaktorów pracujących zarówno w przypadku przepływu reagentów, jak i jego braku. Przeprowadzono również porównanie sprawności egzerge-tycznej procesu TCEC z innymi procesami konwesji energii promieniowania słonecznego.

19

Comparison between different design concepts of receivers/reactors for thermochemical conversion of concentrated solar energy

Amhalhel G. A., Furmański P.

Biuletyn Instytutu Techniki Cieplnej Politechniki Warszawskiej

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2004

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nr 89/90

59--83

EN

In this paper, a zero-order mathematical model based on first law analysis of the Thermochemical Energy Conversion (TCEC) process of concentrated solar energy have been developed. The model assumptions consider the general case for which the receiver/reactor is the direct volumetric absorption and/or indirect receiver/reactor. The thermal decomposition of a single chemical species and endothermic reversible chemical reaction is considered as the reaction system. A qualitative comparison of the model results gave a satisfactory agreement with selected experimental results. The proposed model was used to compare the general thermochemical behavior of the three general types of receivers/reactors proposed for the TCEC process operating in both continuous and in the discontinuous flow regimes. Comparison of the thermal characteristics of the TCEC process with other traditional conversion processes was also performed. Finally, conclusions were drawn to assist any further development and understanding of the TCEC process.

PL

W artykule zaproponowano zerowymiarowy model układu odbiornik promieniowania/reaktor chemiczny umożliwiający analizę energetyczną termochemicznej konwersji energii (TCEC) promieniowania słonecznego. Model ten opisuje ogólny przypadek, gdy pochłanianie promieniowania słonecznego odbywa się na powierzchni lub w objętości odbiornika/reaktora. W reaktorze zachodzi endotermiczna, odwracalna reakcja chemiczna związana z rozkładem pojedynczej substancji. Jakościowe porównanie wyników otrzymanych z modelu z wynikami wybranych badań doświadczalnych, zamieszczonych w literaturze, dało zadawalający rezultat. Następnie wykorzystano opracowany model do analizy porównawczej zachowania trzech typów układu odbiornik promieniowania/reaktor zaproponowanych do realizacji procesu TCEC i pracujących przy ciągłym przepływie czynnika roboczego przez reaktor oraz przy braku przepływu czynnika. Dokonano porównania charkterystyk cieplnych procesu TCEC z innymi klasycznymi procesami konwersji energii promieniowania słonecznego. Pracę zakończono wnioskami dotyczącymi dalszego rozwoju i rozumienia procesu termochemicznej konwersji energii promieniowania słonecznego.

20

Eulerian equilibrium and non-equlibrium macroscopic modelling of binary system solidification

Banaszek J., Furmański P., Browne D.

Archives of Thermodynamics

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2003

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Vol. 24, no 1

37-57

EN

Two models of macroscopic computer simulation of binary system solidification on a fixed grid are discussed. First, it is shown that the single-domain enthalpy-porous medium model not only provides complete information on the evoluation of macroscopic entities, but also enables a detailed analysis of the role of the mushy zone properties in the progress of solidification. In this context, the results of FEM calculations for aqueous ammonium chloride solutions are presented showing the importance of anisotropy of permeability and thermal conductivityof the mushy zone. Next, to account for non-equilibrium phenomenon of the constitutional undercooling a new front tracking technique on a fixed grid, which is based on the kinetics of dendritic growth, (see a companion paper [13]), is used. The model is compared with the enthalpy approach showing its superiority in the detection of the undercooled zone in front of dendrite tips and, thus, in modelling of columnar /equiaxed grain structures. It is, then, further used to address the question of the influence of alloy composition on the size of the undercooled liquid zone in front of columnar dendrite tips during solidification of Al-Cu alloys driven by conduction in a square mould. Eventually, a possible scenario of the coupling of both models, in order to develop a comprehensive computer simulation of binary alloys solidification driven by both conduction and natural convection, is outlined.