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1

Thermal Phenomena Related to Plastic Deformation During Tensile Testing and Their Microscopic Interpretation

Ostromęcka Małgorzata, Siwiec Jakub

Problemy Kolejnictwa

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2022

|

Z. 195

121--128

EN

Thermal phenomena related to plastic deformation can be commonly observed. By simply touching a ruptured or bent sample, it is clear that the temperature has risen at the deformation site. Such observations can be carried out for qualitative or quantitative assessment. This paper serves to qualitatively relate the changes in the structure of the deformed material to the temperature increase observed with an infrared camera.

2

Ag Coated Pa-Based Electro-Conductive Knitted Fabrics for Heat Generation in Compression Supports

Repon Md. Reazuddin, Mikučionienė Daiva, Baltina Ilze, Blūms Juris, Laureckiene Ginta

Autex Research Journal

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2022

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Vol. 22, no. 1

55--63

EN

This work deals with the electrically conductive textiles for heat generation in orthopedic compression supports. This study aimed to develop compression knitted structures with integrated electro-conductive yarns and investigate their heat generation characteristics and temperature changes during the time and under stretch which is required to generate compression. Combined half-Milano rib structured knitted fabrics were made by using silver (Ag) coated PA yarn of linear density of 66 tex and 235 tex, respectively. Six variants of specimens were developed by using different amount of electro-conductive yarns in a pattern repeat. It was found that stretch negatively influences temperature values as well as time in which the required temperature is reached. Therefore, the final wearing conditions have to be summed up during the designing of compression orthopedic heated supports.

3

Experimental investigations of heat generation and microstructure evolution during friction stir processing of SnSbCu alloy

Leszczyńska-Madej Beata, Hrabia-Wiśnios Joanna, Węglowska Aleksandra, Perek-Nowak Małgorzata, Madej Marcin

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 4

art. no. e202, 2022

EN

The paper presents the results of experimental investigations of the heat generation and microstructure evolution during the friction stir processing (FSP) of the SnSb11Cu6 alloy. The Triflute tool was used for modification; the process was carried out using two rotational speeds of the tool: 280 and 560 RPM and a constant linear speed of 355 mm/min. Microstructure studies were performed employing the techniques of light microscopy and scanning electron microscopy along with analysis of the chemical composition of micro-areas. Additionally, the phase composition was investigated by means of the X-ray diffraction method, and electron backscatter diffraction (EBSD) analysis and hardness testing were performed before and after FSP modification. Furthermore, measurements of the temperature directly on the modified surface by means of a thermal imaging camera and the temperature in the modified zone with a thermocouple system were performed. It was proved that using FSP to modify the SnSbCu alloy promotes refinement and homogenization of the microstructure, as well as improvement of the hardness. The hardness of the starting material was 24 HB, and after FSP, the hardness increased and amounted to, respectively, 25 and 27 HB after processing at 280 and 560 RPM. The microstructure in the stir zone is formed by the dynamic recrystallization (DRX) process and consists of almost equiaxed tin-rich matrix grains with a size of approx. 5–30 µm and fine particles of Cu6Sn5 and SnSb phases. The temperature distribution in the FSP zone is not uniform and changes in a gradient manner.

4

Three dimensional MHD Casson fluid flow over a stretching surface with variable thermal conductivity

Ganga B., Charles S., Abdul Hakeem A. K., Nadeem S.

Journal of Applied Mathematics and Computational Mechanics

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2021

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Vol. 20, nr 1

25--36

EN

The three-dimensional magnetohydrodynamic (MHD) boundary layer flow of a Casson fluid over a stretching surface set into a porous medium with variable thermal conductivity and heat generation/absorption has been researched. Conservation laws of mass, momentum and energy are changed into ordinary differential equations, which are numerically dealt with by applying the fourth order Runge-Kutta integration scheme in relationship with shooting procedure. The dimensionless velocity, temperature, skin friction coefficient and the local Nusselt number inside the boundary layer are processed and examined through tables and illustrations for various physical parameters. The numerical outcomes obtained for the specific case are sensible in great concurrence with the existing results. Results indicate that momentum boundary layer reduces for the Hartman number and Casson fluid parameter. Temperature is found as an enlightened function for the heat generation and thermal conductivity parameter.

5

A numerical examination of an unsteady nonlinear MHD flow in the presence of thermal radiation and heat generation

Agbaje T. M., Leach P. G. L.

International Journal of Applied Mechanics and Engineering

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2021

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Vol. 26, no. 1

1--17

EN

In this study, the spectral perturbation method and the spectral relaxation method are used to solve the nonlinear differential equations of an unsteady nonlinear MHD flow in the presence of thermal radiation and heat generation. The SPM is mainly based on series expansion, generating series approximation coupled with the Chebyshev spectral method. The numerical results generated using the spectral perturbation method were compared with those found in the literature, and the two results were in good agreement.

6

Management of Solid Biomass in Medium Power Boiler Plants

Rybak-Wilusz Elżbieta, Proszak-Miąsik Danuta, Kuliński Bartosz

Journal of Ecological Engineering

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2020

|

Vol. 21, nr 1

106--112

EN

Solid biomass plays a leading role in the development and dissemination of technologies pertaining to the usage of renewable raw materials. The biomass processed into solid biofuel requires special logistic operations. Distribution from the place of production, handling and storage of biofuel are basic and necessary elements of the chain of fuel supply to the energy source. Solid biofuels for energy use occur in different forms which affect the costs of logistic operations. Rational heat generation requires choosing a specific type and form of biofuel, assessing the availability of raw materials, integrating fuel management with energy source technology and, above all, determining the cost of energy generation. The cost of energy generation includes the cost of fuel and logistic operations, which depend mainly on a type and form of fuel. Currently, the commonly used biofuels are wood chips, straw and pellets. This paper presents a comparison of heat demand of 400 kW, 600 kW and 1 MW boiler plants generating heat for the purpose of heating buildings and water. The analysis took into account three forms of biofuels: compressed, crushed and granulated forms resulting from different types of biomass (straw, woodchips, pellets). The cost of heat generation in the aspect of biofuel management and the share of particular cost components in heat production were determined. It was shown that in medium power boiler plants, the granulated fuel has the lowest cost of biomass distribution, whereas wood chips have the lowest cost of heat production.

7

Thermal analysis of longitudinal a porous fin with temperature-dependent internal heat generation using the variation of parameters method

Güngör Osman, Arslantürk Cihat

Journal of Applied Mathematics and Computational Mechanics

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2020

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Vol. 19, nr 3

5--16

EN

The present study investigates the thermal performance of longitudinal a porous fin with temperature-dependent internal heat generation. The Darcy model is utilized to obtain the differential form of the governing equation that solves the nonlinear temperature distribution equation using the method of variation of parameters. Although this method is applied to solve both linear and nonlinear differential equations, there exist rare applications of this method to solve nonlinear heat transfer problems. In the present study, we applied the method to estimate the thermal analysis of the porous fin exposed to convection. The heat generation is assumed as a function of temperature. The effects of the convection parameter Nc, internal heat generation ɛ, porosity Sh, and generation number G parameter on the dimensionless temperature distribution are discussed in detail. The accuracy of the variation of parameters method is verified through comparison with homotopy perturbation method and the Matlab bvp4c solver (NUM). The results have disclosed that the variation of parameters method can be used as a very effective and practical approach for further studies of the porous medium.

8

Influence of heat generation/absorption on mixed convection flow behaviour in the presence of Lorentz forces in a vertical micro circular duct having time periodic boundary conditions: steady periodic regime

Aina B., Isa S.

International Journal of Applied Mechanics and Engineering

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2020

|

Vol. 25, no. 4

1--21

EN

The problem of mixed convection flow of a heat generating/absorbing fluid in the presence existence of Lorentz forces in a vertical micro circular subjected to a periodic sinusoidal temperature change at the surface has been studied taking the first-order slip and jump effects into consideration. The research analysis is carried out by considering a fully developed parallel flow and steady periodic regime. The governing equations, together with the constraint equations which arise from the definition of mean velocity and temperature, are written in a dimensionless form and mapped into equations in the complex domain. One obtains two independent boundary value problems, which provide the mean value and the oscillating term of the velocity and temperature distributions. These boundary value problems are solved analytically. A parametric study of some of the physical parameters involved in the problem is conducted. The results of this research revealed that the magnetic field has a damping impact on the flow and results in decreases in fluid velocity for both air and water. Furthermore, the presence of the heat generation parameter is seen to enhance the temperature distribution and this is reflected as an increase in the magnitude of the oscillation dimensionless velocity, whereas in the presence of heat absorption a reversed trend occurs.

9

Navier slip condition on time-dependent radiating Nanofluid with the soret effect

Suneetha Sangapatnam, Subbarayudu Ketineni, Wahidunnisa Lalahamed, Reddy Polu Bala Anki

Engineering Transactions

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2020

|

Vol. 68, iss. 2

177--198

EN

This work concentrates on the study of the two-dimensional hydromagnetic flow of nanofluids over an suddenly started nonlinear stretching sheet in the presence of radiation and dissipation. The Soret effect and heat generation are also taken into consideration. The transformed ordinary differential equations (ODEs) are solved numerically via the MATLAB RK4S approach bvp4c solver with the assistance of similarity variables. The effects of various parameters are explored and shown in graphs and tables. It is noted that the concentration increases as the Soret number increases within the boundary layer. An increase in velocity slip decreases the velocity and a reverse effect is observed for temperature. This model has significance in different areas such as polymer chemical and metallurgical industries, and other fields that use the latest technology and thermo-processed materials such as metallic and glass sheets.

10

Obieg kogeneracyjny w wodnych kotłach ciepłowniczych

Ostrowski Piotr, Pronobis Marek, Świątkowski Tomasz

Nowa Energia

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2019

|

nr 1

21--28

PL

Kogeneracja - wspólne wytwarzanie energii elektrycznej i ciepła przynosi oszczędności w zużyciu paliw pierwotnych. W związku z tym przyczynia się do redukcji emisji szkodliwych substancji do atmosfery (CO2), co również oznacza zmniejszenie kosztów zewnętrznych wytwarzania energii i ciepła. Do tej pory cykle kogeneracyjne nie były stosowane w ciepłowniach wyposażonych w kotły wodne (wodno-rurowe lub płomienicowo-płomieniówkowe). W artykule przedstawiono koncepcję innowacyjnego obiegu kogeneracji, który współpracuje z wodnym kotłem ciepłowniczym lub przemysłowym, a instalacja kogeneracji nie zmienia zatwierdzenia parametrów technicznych kotła i nie ogranicza zakresu jego użytkowania. Przedstawiono opracowane obiegi porównawcze w układach h-s i T-s, pasmowy wykres energii Sankey'a oraz wykresy wybranych wskaźników kogeneracji. Ponadto przedstawiono wskaźniki ekonomiczne kogeneracji dla kotłów wodnych.

11

Nanofluid motion past a shrinking sheet in porous media under the impact of radiation and heat source/sink

Sharma R. P., Jha A. K., Gaur P. K., Mishra S. R.

International Journal of Applied Mechanics and Engineering

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2019

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Vol. 24, no. 4

183--199

EN

An investigation has been carried out for the MHD 3-dimensional flow of nanofluid over a shrinking sweet saturating a porous media in the presence of thermal radiation and heat generation. Convective boundary conditions for the flow phenomena are used in the present analysis. The governing equations are reduced to ODEs employing suitable similarity transformations. The solutions of formulated differential equations have been attained mathematically by fourth order R-K technique along with the shooting method. The impact of the governing constraints on momentum, heat, and local Nusselt number, are explored. It is noticed that the momentum and heat decrease with raise in the porosity variable, temperature reduces with an enhance in the thermal radiation variable, and temperature enhances with an enhance in the heat source/sink parameter.

12

Transient free convective radiative flow between vertical parallel plates heated/cooled asymmetrically with heat generation and slip condition

Gaur P. K., Sharma R. P., Jha A. K.

International Journal of Applied Mechanics and Engineering

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2018

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Vol. 23, no. 2

365--384

EN

Investigation of an MHD convective flow of viscous, incompressible and electrically conducting fluid through a porous medium bounded by two infinite vertical parallel porous plates is carried out. Forchheimer-Brinkman extended Darcy model is assumed to simulate momentum transfer within the porous medium. A magnetic field of uniform strength is applied normal to the plates. The analytical results are evaluated numerically and the presented graphically to discuss in detail the effects of different parameter entering into the problem.

13

Entropy generation on MHD slip flow over a stretching cylinder with heat generation/absorption

Jain S., Bohra S.

International Journal of Applied Mechanics and Engineering

|

2018

|

Vol. 23, no. 2

413--428

EN

In the present study, we have investigated entropy generation on a magnetohydrodynamic fluid flow and heat transfer over a stretching cylinder with a porous medium in slip flow regime. A uniform heat source and radiation is also considered. Similarity transformation has been applied for making an ordinary differential equation from nonlinear governing partial differential equations. The numerical solution for the set of nonlinear ordinary differential equations has been obtained by using the fourth-order Runge-Kutta scheme together with the shooting method. The effects of pertinent parameters such as the magnetic field parameter, permeability parameter, slip parameter, Prandtl number and radiation parameter on the fluid velocity distribution, temperature distribution, entropy generation and Bejan number are discussed graphically.

14

Unsteady MHD mixed convection flow of a micropolar fluid over a vertical wedge

Roy N. C., Gorla R. S. R.

International Journal of Applied Mechanics and Engineering

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2017

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Vol. 22, no. 2

363--391

EN

An analysis is presented to investigate the unsteady magnetohydrodynamic (MHD) mixed convection boundary-layer flow of a micropolar fluid over a vertical wedge in the presence of thermal radiation and heat generation or absorption. The free-stream velocity and surface temperature are assumed to be oscillating in magnitude but not in the direction of the oncoming flow velocity. The governing equations have been solved by two distinct methods, namely, the finite difference method for the entire frequency range, and the series solution for low frequency range and the asymptotic series expansion method for the high frequency range. Numerical solutions provide a good agreement with the series solutions. The amplitudes of skin friction and couple stress coefficients are found to be strongly dependent on the Richardson number and the vortex viscosity parameter. The Prandtl number, the conduction-radiation parameter, the surface temperature parameter and the pressure gradient parameter significantly affect the amplitudes of skin friction, couple stress and surface heat transfer rates. However, the amplitudes of skin friction coefficient are considerably affected by the magnetic field parameter, whereas the amplitudes of heat transfer rate are appreciably changed with the heat generation or absorption parameter. In addition, results are presented for the transient skin friction, couple stress and heat transfer rate with the variations of the Richardson number, the vortex viscosity parameter, the pressure gradient parameter and the magnetic field parameter.

15

Modelling of thermoelastic transient contact interaction for binary bearing taking into account convection

Kolesnikov I., Danilchenko S., Kolosova E., Chebakov M., Lyapin A.

Transport Problems

|

2016

|

T. 11, z. 4

73--81

EN

Serviceability of metal-polymeric "dry-friction" sliding bearings depends on many parameters, including the rotational speed, friction coefficient, thermal and mechanical properties of the bearing system and, as a result, the value of contact temperature. The objective of this study is to develop a computational model for the metallic-polymer bearing, determination on the basis of this model temperature distribution, equivalent and contact stresses for elements of the bearing arrangement and selection of the optimal parameters for the bearing system to achieve thermal balance. Static problem for the combined sliding bearing with the account of heat generation due to friction has been studied in [1]; the dynamic thermoelastic problem of the shaft rotation in a single and double layer bronze bearings were investigated in [2, 3].

RU

Работоспособность полимерных подшипников скольжения «сухого трения» зависит от многих параметров, включающих в себя скорость вращения вала, коэффициент трения, термо-механические свойства элементов подшипниковой системы и, как следствие, величины результирующих контактных температур. Целью данного исследования является разработка расчётной модели работы бинарного подшипника скольжения «сухого трения» с полимерными цилиндрическими вставками, определения на ее основе распределения температур, эквивалентных и контактных напряжений в элементах подшипниковой системы и подбор оптимальных параметров подшипниковой системы, при которых достигается тепловой баланс. Статическая задача для комбинированного подшипника скольжения с учётом тепловыделения от трения была исследована в работе [1], динамическая термоупругая задача о вращении вала в однослойном подшипнике из бронзы была исследована в работе [2], двухслойного с антифрикционным покрытием в.

16

Computational and experimental model of electroporation for human aorta

Filipovic N., Saveljic I., Jovicic N., Tanaskovic I., Zdravkovic N.

Acta of Bioengineering and Biomechanics

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2016

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Vol. 18, no. 4

15--20

EN

Purpose: In this study the computational and experimental electroporation model with human aorta tissue is made in order to examine the reduction of smooth muscle cells. Methods. The segments in native state of the aorta are treated by electroporation method through a series of electrical impulses from 50 V/cm to 2500 V/cm. For each patient we analyzed one sample with and one sample without electroporation as a control. In the computational study, electrical field distribution is solved by the Laplace equation. The Pennes Bioheat equation without metabolism and blood perfusion heating is used to solve heat transfer problems. Different conductivity values are used in order to fit the experimental results. Results: Experimental histology has shown us that there are a smaller number of vascular smooth muscle cells (VSMC) nuclei at the tunica media, while the elastic fibre morphology is maintained 24 h after electroporation. In the computational model, heat generation coupled with electrical field is included. The fitting procedure is applied for conductivity values in order to make material properties of the aorta tissue. The fitting procedure gives tissue conductivity of 0.44 [S/m] for applied electrical field of 2500 V/cm. Conclusions: Future studies are necessary for investigation of a new device for in-vivo ablation with electroporation of plaque stenosis. It will open up a new avenue for stenosis treatment without stent implantation.

17

Efektywne rozmieszczenie płaskich kolektorów słonecznych na płaskiej powierzchni kwadratowej

Dziedzic J., Olczak P., Kryzia D.

Logistyka

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2015

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nr 4

8832--8840, CD3

PL

W artykule przedstawiono sposób rozmieszczenia płaskich kolektorów słonecznych na ograniczonej, płaskiej i kwadratowej powierzchni. Problem efektywnego rozmieszczenia kolektorów słonecznych wynika z występowania efektu zasłaniania się kolejnych rzędów kolektorów słonecznych przez rzędy poprzedzające. Ustalenie odpowiedniej odległości pomiędzy rzędami nie jest łatwe, gdyż determinuje ją wiele czynników. Przeprowadzona w pracy analiza zwraca uwagę na kluczowe dla wyników rozważań czynniki, określając ich znaczenie dla efektywnego rozmieszczenia płaskich kolektorów słonecznych. Praca w ten sposób wskazuje istniejące problemy logistyczne, a uzyskane wyniki dają wskazówki, jaką odległość pomiędzy poszczególnymi rzędami kolektorów należy przyjąć, w zależności od istniejących uwarunkowań.

EN

The article presents method of localization of plate solar collectors on a limited, flat and square surfaces. Major problem of effective deployment of mentioned devices is effect of overlaying successive rows of solar collectors by rows preceding. Determining appropriate distance between rows is not easy because it determined by many factors. Presented paper shows analysis of key factors determining it importance for the effective distribution of solar collectors. Our work in this manner indicates existing research problems and the results give hints about what distance between rows of collectors should be adopted depending on prevailing conditions.

18

Meshing strategies in FEM simulation of the machining process

Niesłony P., Grzesik W., Chudy R., Habrat W.

Archives of Civil and Mechanical Engineering

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2015

|

Vol. 15, no. 1

62--70

EN

This paper presents some methods of mesh smoothing when using cutting tool inserts with complex geometry of the cutting edge and the rake face. Several sets of meshing parameters are proposed and their influences on the performance of FEM simulation of the cutting process are presented. In addition, both mechanical and thermal characteristics of the cutting process are compared for four groups of meshing parameters. The simulations were carried out for a Ti6Al4V alloy using TiAlN coated carbide commercial cutting tool insert. It was documented that accurate representation of the tool micro-geometry influences the simulation results.

19

Dobór mocy (liczby) kolektorów słonecznych w zależności od charakterystyki energetycznej budynku i zastosowanych źródeł ciepła

Kryzia K., Olczak P.

Logistyka

|

2014

|

nr 4

4584--4590, CD6

PL

Kolektory słoneczne są coraz powszechniej wykorzystywane w gospodarstwach domowych do przygotowania ciepłej wody użytkowej. Nie pracują one jednak samodzielnie, lecz są częścią układów grzewczych składających się zwykle z dwóch źródeł energii, którymi są: kolektory słoneczne oraz inne źródło najczęściej wytwarzające energię w procesie spalania paliw. O wydajności tych układów decyduje kompozycja ich elementów, dlatego duży nacisk kładzie się na optymalizowanie mocy źródeł z punktu widzenia zapotrzebowania na energię i istniejące ograniczenia natury technicznej i środowiskowej. Dotychczas wypracowano proste metody doboru mocy kolektorów w zależności od zapotrzebowania na energię. Zaniedbują one jednak pewną pozornie mało istotną kwestię, jaką jest rodzaj drugiego, obok kolektorów, źródła energii, która ma zasadnicze znaczenie dla logistyki przygotowania ciepłej wody użytkowej. W pracy pokazano, jaki wpływ na dobór liczby, a tym samym mocy kolektorów ma rodzaj źródła energii na przykładzie kotłów opalanych biomasą i kotłów gazowych. Zrealizowano to poszukując najefektywniejszej ekonomicznie kombinacji dwóch źródeł ciepła w tym kolektorów słonecznych w zależności od zapotrzebowania ujętego w charakterystyce energetycznej budynku. Wyniki badań mają wartość praktyczną gdyż pozwalają ustalić, o ile należy skorygować moc kolektorów wyznaczoną na podstawie zapotrzebowania na energię w zależności od rodzaju zastosowanego kotła.

EN

Solar panels are increasingly being used in households to prepare hot water. However they do not work alone, but are part of the heating systems usually consist of two energy sources, which are: solar panels and other source producing energy in process of fuel combustion. Composition of the elements determines performance of these systems, for this reason so much emphasis is placed on optimizing power sources from standpoint of energy demand and existing restrictions technical and environmental. So far developed a simple method for selecting collector power depending on the demand for energy. However they neglect a seemingly very important issue, which is kind of second (in addition to solar panels) energy sources, which is essential in logistics preparation of hot water. The study shows what impact on selection of power of solar panels has type of energy sources for example biomass-fired boilers and gas boilers. This was done, searching for the most effective economically combination of two heat sources (including solar collectors) depending on demand of heating, included in the energy performance of the building. Test results have practical value.

20

Kogeneracja w wytwarzaniu energii cieplnej

Urbanik M., Tchórzewska-Cieślak B.

Czasopismo Inżynierii Lądowej, Środowiska i Architektury / Journal of Civil Engineering, Environment and Architecture

|

2014

|

z. 61, nr 4

293--301

PL

Coraz większe zanieczyszczenie powietrza i ciągły wzrost cen paliw sprawiają, że ekologia oraz ekonomia stanowią kluczowe kwestie przy wytwarzaniu energii. Poszukiwane są takie technologie, które pozwolą zmniejszyć emisję spalin przy zmniejszeniu zużycia paliwa. Rozwój gospodarczy w Polsce sprawił, że w najbliższych latach będzie się odnotowywało ciągły wzrost zapotrzebowania na energię elektryczną i cieplną. Dlatego też już teraz do wytwarzania energii należy wprowadzać takie technologie, które pozwolą na obniżenie zużycia paliwa oraz redukcję emisji spalin do atmosfery. Znane technologie odnawialnych źródeł energii nie są w stanie pokryć pełnego zapotrzebowania na energię oraz są stosunkowo drogie. Trzeba więc znaleźć taką technologię, która będzie pomostem pomiędzy technologią obecnie stosowaną a odnawialnymi źródłami energii. Okazuje się, że takie wymagania spełnia produkcja energii elektrycznej i cieplnej w kogeneracji. Układy te odznaczają się wysoką sprawnością, co pozytywnie wpływa na aspekt ekonomiczny i ekologiczny. Mogą być one stosowane do produkcji ciepła, które jest przesyłane do sieci ciepłowniczej. W pracy dokonano ogólnej charakterystyki polskiego rynku produkcji ciepła. Omówiono również główne elementy układu wytwarzania energii w kogeneracji oraz zasady jego działania.

EN

Growing air pollution and fuel prices make the ecology and economy are key issues in energy production. Are searched such technologies that will reduce emissions by reducing fuel consumption. Economic development in Poland made in the coming years, the demand for electricity and heat will increase, therefore, now to produce energy should be introduced such technologies, which allow for lower fuel consumption and reduced emissions to the atmosphere. Known today, renewable energy technologies are not able to cover the full demand for energy and are relatively expensive. We must therefore find the technology that will be a bridge between the technology used today and renewable energy sources. It turns out that this requirement meets the production of electricity and heat in cogeneration. These systems are characterized by high efficiency, which positively affects the economic and ecological aspects. They can be used in the production of heat that is transferred to the district heating network. This article presents the general characteristics of the Polish market of heat production. It also discusses the main elements of the energy production in cogeneration and the principle of its operation.