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Effect of the inclination angle of the condenser on the heat transfer coefficient value – experimental study
PublicationWhen considering problem of the condensation of the refrigerant in a flow inside channel, one needs to pay attention to the shape of its cross-section, the hydraulic diameter, the channel length as well as the orientation of the channel axis in space (horizontal, vertical, inclined). This paper presents an experimental study concerning the effect of the inclination angle of the condenser with a single coil pipe on the heat transfer...
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Characterisation of the interfacial heat transfer coefficient in hot stamping of titanium alloys
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Pressure drop and heat transfer during boiling and condensation at subcritical region
PublicationMost of the data presented in the literature relate to saturation temperatures in the range - 20°C to 40°C due to the application in refrigeration technology. There is necessity to extend databases to higher values of saturation temperature due to new applications such as Organic Rankine Cycle and high temperature heat pumps. Only few papers contain data for high reduced pressure for low boiling point liquids. This paper focus...
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Pressure drop related to flow maldistribution in a model minichannel plate heat exchanger
PublicationThe paper describes the issues related to the pressure drop that accompanies the phenomenon of maldistribution of working fluid between the channels of a model minichannel plate heat exchanger. The research concerns a single exchanger's plate containing 51 (in every geometry) parallel rectangular minichannels of hydraulic diameters 461 µm, 571 µm, 750 µm and 823 µm. In addition, the more complex geometry has been investigated,...
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Two-phase optimizing approach to design assessments of long distance heat transportation for CHP systems
PublicationCogeneration or Combined Heat and Power (CHP) for power plants is a method of putting to use waste heat which would be otherwise released to the environment. This allows the increase in thermodynamic efficiency of the plant and can be a source of environmental friendly heat for District Heating (DH). In the paper CHP for Nuclear Power Plant (NPP) is analyzed with the focus on heat transportation. A method for effectivity and feasibility...
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An improved method for flow boiling heat transfer with account of the reduced pressure effect
PublicationIn the paper are presented the results using the authors own model to predict heat transfer coefficient during flow boiling. The model has been tested against a large selection of experimental data to investigate the sensitivity of the in-house developed model. In the work are presented the results of calculations obtained using the semi-empirical model on selected experimental flow boiling data of the refrigerants: R134a, R1234yf,...
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Photovoltaic Roof Tiles: The Influence of Heat Recovery on Overall Performance
PublicationA photovoltaic (PV) roof tile serves both as a roofing material and as an electricity-producing surface. The main aim of the present study was to increase the overall system efficiency of PV tiles by using heat recovery. The chosen strategy was two-fold: determine the operational efficiency of PV tiles and optimize construction to increase the cooling effect when using air as the working medium. A detailed experimental study was...
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High-quality Experiment Dedicated to microGravity Exploration, Heat Flow and Oscillation Measurement from Gdańsk
PublicationIn this paper we propose HEDGEHOG (High-quality Experiment Dedicated to microGravity Exploration, Heat flow and Oscillation measurement from Gdańsk) REXUS experiment to investigate vibrational and heat flow phenomena during the whole (ascent, microgravity phase, descent and recovery) flight of a sounding rocket. First, a proposed system of cantilever beams is discussed to study dynamic behaviour of dummy payload. Dimensioning has...
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Experimental investigation on straight and u-bend double tube heat exchanger with active and passive enhancement methods
PublicationAuthors in this work want to demonstrate the possibility to increase the heat transfer efficiency by using simple wire coil inserts to create turbulent flow in the boundary layer as well as air blowing into the annulus of the pipe. In the study, Wilson plot approach was applied in order to estimate heat transfer coefficients for all heat exchanger (HX) configurations. The study focuses on experimental values of heat transfer coefficient...
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Effect of asymmetric fluid flow distribution on flow boiling in a microchannel heat sink – An experimental investigation
PublicationFlow boiling in microchannels is emerging as an exclusive cooling solution for miniaturized high-power electronic devices alongside having other high heat flux applications. Size miniaturization at microscale strangely increases heat transfer performance as well as flow boiling instabilities. Many flow boiling instabilities are interrelated and result from imperfect hydrodynamic conditions. One of such problems is flow maldistribution among...
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Analysis of Organic Rankine Cycle efficiency and vapor generator heat transfer surface in function of the reduced pressure
PublicationIn the paper presented is analysis of the influence of reduced pressure on efficiency and heat transfer area of vapor generator of Organic Rankine Cycle (ORC) in case of subcritical and supercritical parameters of operation. Compared are two cases of subcritical and supercritical ORC featuring a similar arrangement of heat source supply and heat removal, that is featuring the same temperatures of working fluid before the turbine,...
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Experiment-Based Study of Heat Dissipation from the Power Cable in a Casing Pipe
PublicationThe paper deals with the important challenges in terms of electricity transmission by means of underground cable lines. The power cable’s performance is characterized by an ampacity that represents its maximum electric current-carrying capacity. The ampacity of power cables depends on their ability to diffuse the heat generated by the current flow into the environment. In the performed research, the analysis of the efficiency of...
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Thermal and economic investigation of straight and U-bend double tube heat exchanger with coiled wire turbulator
PublicationExperimental research has been carried out for four individual heat exchanger constructions, i.e., plain double tube, turbulized double tube, plain U-bend and U-bend with turbulator. Tests were made for the water-water system. The study covered a wide measuring range, i.e., Re = 800–9000 – on the shell side, for a constant cold water temperature of 9 ◦C and hot water of 50 ◦C. The heat exchangers were made from copper tubes with...
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Turbulent heat transfer in thin liquid films at low and high heat fluxes
PublicationW pracy przedstawiono rozważania turbulentnej wymiany ciepła w cienkich filmach cieczowych powstałych w wyniku uderzenia strugi przy małych i dużych strumieniach ciepła. W ostatnim przypadku może dojść do wrzenia filmu cieczowego. Oba zjawiska zamodelowano i uzyskano odpowiednie rozkłady temperatury i pedkosci.
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Prediction of flow boiling heat transfer coefficient for carbon dioxide in minichannels and conventional channels
PublicationIn the paper presented are the results of calculations using authors own model to predict heat transfer coefficient during flow boiling of carbon dioxide. The experimental data from various resea rches were collected. Calculations were conducted for a full range of quality variation and a wide range of mass velocity. The aim of the study was to test the sensitivity of the in-house model. The results show the importance of taking into...
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Analysis of possibility and purposefulness of application of waste-heat boilers to trailing suction hopper dredgers
PublicationThis paper presents an analysis of possibility and purposefulness of application of waste-heat boilers to trailing suction hopper dredgers. Using results of own operational research on dredgers this author determined thermal power demand for six hypothetical trailing suction hopper dredgers of various size, at accounting for a type of power system and kind of fuel combusted by dredger's power plant. By means of basic indices of...
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Experimental Investigation of Free Convection Heat Transfer from Horizontal Cylinder to Nanofluids
PublicationThe results of free convection heat transfer investigation from a horizontal, uniformly heated tube immersed in a nanofluid are presented. Experiments were performed with five base fluids, i.e., ethylene glycol (EG), distilled water (W) and the mixtures of EG and water with the ratios of 60/40, 50/50, 40/60 by volume, so the Rayleigh (Ra) number range was 3 104 Ra 1.3 106 and the Prandtl (Pr) number varied from 4.4 to 176....
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A new method for determination of flow boiling heat transfer coefficient in conventional diameter channels and minichannels
PublicationW pracy przedstawiono rozważania związane z modelowaniem wrzenia w przepływie w kanałach o średnicach konwencjonalnych, małych i minikanałach. Przedstawiono przegląd podejść do modelowania wymiany ciepła i w tym świetle przedstawiono oryginalne podejście autora. W przeciwieństwie do innych podejść metoda autora ma zastosowanie zarówno do kanałów o średnicach konwencjonalnych i minikanałach. Przedstawiono zadowalające porównania...
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Promising Nanoparticle-Based Heat Transfer Fluids—Environmental and Techno-Economic Analysis Compared to Conventional Fluids
PublicationProviding optimal operating conditions is one of the major challenges for effective heating or cooling systems. Moreover, proper adjustment of the heat transfer fluid is also important from the viewpoint of the correct operation, maintenance, and cost efficiency of these systems. Therefore, in this paper, a detailed review of recent work on the subject of conventional and novel heat transfer fluid applications is presented. Particular...
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Influence of Cement Replacement with Sewage Sludge Ash (SSA) on the Heat of Hydration of Cement Mortar
PublicationThe amount of fly ash from the incineration of sewage sludge is increasing all over the world, and its utilization is becoming a serious environmental problem. In the study, a type of sewage sludge ash (SSA) collected directly from the municipal sewage treatment plant was used. Five levels of cement replacement (2.5%, 5%, 7.5%, 10% and 20%) and unchanged water-to-binder (w/b) ratio (0.55) were used. The purpose of the study was...
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A semi-empirical model for flow boiling heat transfer with account of the reduced pressure effect
PublicationIn the present study the attention was focused on the influence of reduced pressure on the predictions of heat transfer during flow boiling at the extensive range of pressures. The results of calculations were to test the sensitivity of the in-house flow boiling model with respect to the selection of the appropriate two-phase flow multiplier, which is one of the distinctive elements of that model. For this purpose a few two-phase...
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Heat recovery from the hybrid photovoltaic tile – experimental studies with the solar light simulator
PublicationConsidering the current development of micro-cogeneration energy sources, supported by the national prosumer policy and the act on the renewable energy sources, there is a great demand for the effective solar technologies. In this area, the photovoltaic cells with a combined conversion of the solar radiation energy into the electrical and thermal energy (PV/T cells) seem to be attractive. They are already widely available and treated...
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Improved finite element method for flow, heat and solute transport of Prandtl liquid via heated plate
PublicationIn the current study, a vertical, 3D-heated plate is used to replicate the generation of heat energy and concentration into Prandtl liquid. We discuss how Dufour and Soret theories relate to the equations for concentration and energy. In order to see how efectively particles, interact with heat and a solvent, hybrid nanoparticles are used. It does away with the phenomena of viscous dissipation and changing magnetic felds. The motivation...
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Comparison of heat transfer characteristics in surface cooling using microjets with water, ethanol and HFE7100 as test fluids
PublicationAccurate control of cooling parameters is required in ever wider range of technical applications. It is known that reducing the dimensions of the size of nozzle leads to an increase in the economy of cooling and improves its quality. Present study describes research related to the design and construction of the nozzles and microjet study, which may be applied in many technical applications such as in metallurgy, electronics, etc....
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Effect of tube bundle arrangement on performance of shell-and-tube latent heat storage system
PublicationThis work presents the results of experimental investigation on charging and discharging of latent heat storage systems (LHSS) in the form of shell-and-tube heat exchangers with a variable arrays of the tube bundles. The tests included two tube arrangements – in-line and triangular (staggered), a variable number of tubes in a bundle, two pitch ratios, and different tube positions in a bundle. Three commercial products (LTP56, RT54HC,...
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Numerical analysis of permeability and Darcy effect in heat transfer of pyramid-shaped structure
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Heat transfer intensification by jet impingement – numerical analysis using RANS approach
PublicationJet impingement is a method of the heat transfer enhancement applied in the engineering systems. The idea is to generate fast-flow fluid jet which impinge on the heated (or cooled) surface, causing significantly higher heat transfer rate. Although some flat surface jet impingement cases are described in the literature, the validated data is still limited. The reason is coming from the fact, that these flows are hydrodynamically...
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Influence of nanoparticle concentration on convective heat transfer of water-Al2O3 nanofluids inside horizontal tubes
PublicationNanofluids came to be seen as a new generation of coolants, especially in single-phase systems. Conducted experiments indicate that the increase in thermal conductivity is not the only reason for the intensification of heat transfer when using nanofluids. Preliminary results of the experimental investigation of the forced convection heat transfer of water-Al2O3 nanofluids inside stainless steel tube with 8 mm internal diameter...
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Experimental study of boiling heat transfer in the stagnation point of water microjet
PublicationIn the paper presented is a comparison of computational model with experimental data. Numerical model of liquid film with phase change in the stagnation zone due to impingement of the microjet is more widely presented in authors previous work. The radius on which theevaporation process is taking place can be determined from the energy balance on the element of the plate. That radius has also been confirmed experimentally in the...
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Modelling study of flow boiling heat transfer of perspective fluids for refrigeration technology
PublicationThere is a gap of knowledge on flow boiling at high saturation temperatures and higher values of reduced pressure. Thus far, the in-house developed semi-empirical model for flow boiling and flow condensation showed a satisfactory accuracy for calculations for various refrigeration fluids for a wide scope of reduced pressures. This study presents results of calculations of heat transfer coefficient of perspective refrigeration fluids,...
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Computational analysis of power-law fluids for convective heat transfer in permeable enclosures using Darcy effects
PublicationNatural convection is a complex environmental phenomenon that typically occurs in engineering settings in porous structures. Shear thinning or shear thickening fuids are characteristics of power-law fuids, which are non-Newtonian in nature and fnd wide-ranging uses in various industrial processes. Non-Newtonian fuid fow in porous media is a difcult problem with important consequences for energy systems and heat transfer. In this...
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Impact of Temperature and Nanoparticle Concentration on Turbulent Forced Convective Heat Transfer of Nanofluids
PublicationTheoretical analysis of the influence of nanoparticles and temperature on the average Nusselt (Nu) number and the average heat transfer coefficient (HTC) during the turbulent flow of nanofluid in a horizontal, round tube was carried out. The Nu number is a function of the Reynolds (Re) number and the Prandtl (Pr) number, which in turn are functions of the thermophysical properties of the liquid and the flow conditions. On the other...
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Impact of the inclination angle of the condenser with refrigerant R410A on heat transfer coefficient – experimental study
PublicationIn the paper the authors present results of a laboratory test of the condenser with refrigerant R410A. The effect of the inclination of this condenser on the heat transfer coefficient value has been considered. The test has proved that there is an optimal inclination angle of the condenser which gives maximal value of this coefficient.
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Additive Manufacturing as a Solution to Challenges Associated with Heat Pipe Production
PublicationThe aim of this review is to present the recent developments in heat pipe production, which respond to the current technical problems related to the wide implementation of this technology. A novel approach in HP manufacturing is to utilise hi-tech additive manufacturing techniques where the most complicated geometries are fabricated layer-by-layer directly from a digital file. This technology might be a solution to various challenges...
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Effect of Tube Bundle Arrangement on the Performance of PCM Heat Storage Units
PublicationThe results of comprehensive study on charging and discharging of latent heat storage systems (LHSS) are presented. The multi tube shell-and-tube unit with a variable layouts of the tube bundles are examined. Two tube arrangements – in-line and staggered are tested. A variable number of tubes and different tube positions in a bundle are investigated. Moreover, two pitch ratios are studied. Three commercially available substances...
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Heat generation by impulse ultrasound.
PublicationOryginalna metoda zastosowana dla wyprowadzenia równaniaewolucyjnego dla ogrzewania środowiska przez falę akustycznądowolnej natury, w tym nieokresowej. Przedstawiono przykłady obliczeń numerycznych.
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The effect of reduced pressure on carbon dioxide flow boiling heat transfer in minichannels
Publication. In the paper presented are the results of the study on the effect of reduced pressure on flow boiling heat transfer data in minichannels as well as conventional ones. That effect renders that most of heat transfer correlations fail to return appropriate results of predictions. Mostly they have been developed for the reduced pressures from the range 0.1-0.3. The special correction has been postulated to the in-house model of flow...
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Study of the Influence of Heat Convection Coefficient on Predicted Performance of a Large Tilting-Pad Thrust Bearing
PublicationPart of the heat generated by the shearing of the lubricating film during operation of a hydrodynamic bearing is transferred to the bearing components. In the case of the pad, which is usually fully submerged in the lubricating oil, heat is further transferred at the pad free walls to the oil by convection. This mechanism causes a thermal gradient in a pad and, consequently, its thermal deflection. In large hydrodynamic thrust...
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Comparitive study of heat transfer and pressure drop during flow boiling and flow condensation in minichannels
PublicationIn the paper a method developed earlier by authors is applied to calculations of pressure drop and heat transfer coefficient for flow boiling and also flow condensation for some recent data collected from literature for such fluids as R404a, R600a, R290, R32,R134a, R1234yf and other. The modification of interface shear stresses between flow boiling and flow condensation in annular flow structure are considered through incorporation...
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The Use of Liquid Crystal Thermography an Image Processing in Heat and Fluid-Flow Research
PublicationLiquid crystal thermography (LCT) have been used in many technical, industrial and biomedical applications [1]. During over 20 years it has been successfully applied in Department of Energy and Industrial Apparatus at Gdansk University of Technology for visualization of steady-state and transient temperature fields. In order to demonstrate feasibility of LCT techniques in practical heat transfer contexts, the authors have performed...
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Preliminary results from HEDGEHOG REXUS project – A sounding rocket experiment on accelerations, vibrations and heat flow
PublicationDuring flight, a sounding rocket is subject to a unique environment - severe vibrations and substantial heat flux. In order to design payloads, precise measurement of these conditions is required. This paper presents preliminary results from HEDGEHOG REXUS Project, whose scientific goal was to characterise the thermal and dynamic environment of REXUS sounding rockets. For this purpose, two new sensors have been designed - mechanical...
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Comparison of traditional district heating with low temperature district heating systems featuring organic Rankine cycle and heat pump
PublicationPaper presents a comparison between a traditional district heating system with conventional boilers as a source of heat and electricity purchases from power utilities and a low temperature DH system incorporating the CHP with organic Rankine Cycle providing electricity and local heat pump raising the temperature of the DH fluid to the required temperature in the dwelling, meaning that both heat and electricity are produced within...
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Numerical solution analysis of fractional point kinetics and heat exchange in nuclear reactor
PublicationThe paper presents the neutron point kinetics and heat exchange models for the nuclear reactor. The models consist of a nonlinear system of fractional ordinary differential and algebraic equations. Two numerical algorithms are used to solve them. The first algorithm is application of discrete Grünwald-Letnikov definition of the fractional derivative in the model. The second involves building an analog scheme in the FOMCON Toolbox...
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Numerical simulation of temperature distribution of heat flow on reservoir tanks connected in a series
PublicationThe flow of temperature distribution through a medium in thermodynamic studies plays an important role in understanding physical phenomena in chemical science and petroleum engineering, while temperature distribution indicates the degree of reaction that must be undergone to obtain the final product. Therefore, this paper aims to present and apply the exponential matrix algorithm (EMA), differential transformation algorithm (DTA),...
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Numerical analysis of the two‐phase steam‐air heat transfer flow induced in smooth and corrugated channel using the VOF model
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Double-stage ORC system based on various temperature waste heat sources of the negative CO2 power plant
PublicationAnalysed is the modification of the thermodynamic cycle with the negative CO2 power plant concept by its combination with the organic Rankine cycle. The analysed power plant operates on a gas produced from the gasification of sewage sludge. The negative emission term comes from the aggregated CO2 balance resulting from the capture of the CO2, while the sewage sludge is one of the inevitable environmental sources of CO2 to be avoided....
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Utilisation of bleed steam heat to increase the upper heat source temperature in low-temperature ORC
PublicationW pracy przedstawiono możliwość dogrzewu obiegu ORC za pomocą pary upustowej.
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Liquid crystal technique application for heat transfer investigation in afin-tube heat exchanger element
PublicationPublikacja przedstawia rezultaty prac autorów w zakresie wykorzystania termografii ciekłokrystalicznej w badaniach wymiany ciepła dla różnych elementów wymienników ciepła. Technika ta z powodzeniem została zastosowana do analizy zabudowy wymiennika na jego efektywność.
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Liquid crystal technique application for heat transfer investigation inafin-tube heat exchanger element
PublicationPublikacja przedstawia rezultaty prac autorów w zakresie wykorzystania techniki ciekłokrystalicznej w badaniach wymiany ciepła dla elementów wymiennika ciepła. Technika ta z powodzeniem została zastosowana do analizy sposobu zabudowy wymiennika na jego efektywność.
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A model of combined heat and power generating plant with urban heat distribution network for production scheduling
PublicationPoruszono zagadnienie związane z pracowaniem harmonogramu produkcji elektrociepłowni. Uwzględniony został wpływ zachowania się miejskiej sieci ciepłowniczej na pracę elektrociepłowni. Możliwe jest również modelowanie współpracy ze zbiornikiem ciepła.