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Tytuł:
Analysis of climate change and its potential influence on energy performance of building and indoor temperatures. Part 2: Energy and thermal simulation
Analiza zmiany klimatu i jego wpływu na charakterystykę energetyczną budynku oraz temperatury wewnętrzne. Część 2: Symulacje energetyczne i środowiska wewnętrznego
Autorzy:
Firląg, Szymon
Miszczuk, Artur
Witkowski, Bartosz
Powiązania:
https://bibliotekanauki.pl/articles/27312126.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
zmiana klimatu
efektywność energetyczna
komfort cieplny
budynek niskoenergetyczny
symulacja energetyczna
climate change
energy efficiency
thermal comfort
low energy building
energy simulation
Opis:
The subject of this paper is the analysis of possible influence of climate change on the energy performance of building and indoor temperatures. The model is based on the Maison Air et Lumière house, which concept was developed as part of the Model Homo 2020 project. It was a low-energy, single family, detached house. The model was divided into three thermal zones and developed by using SketchUp software. The analysis of the climate change was made on the example of the city in Poland - Kielce and described in the first part of the paper. Dynamic calculations of the building model were performed by using the TRNSYS software. The calculations were made for three different scenarios relating to existing technical systems: ventilation, ventilation + heating, ventilation + heating + cooling. Annual energy consumption and rooms air temperature changes were estimated for each variant. The results showed higher risk of summer discomfort and change in energy balance of building what indicates the need to use the cooling system in the future during the summer to reduce the discomfort of overheating. In the variant without the cooling system, the percentage of time with an indoor temperature above 27°C increased from 23.7% to 44.2% in zone 2. The energy demand for heating was reduced by 23.4% compared to the current climate, and the energy consumption for cooling (with the cooling option) increased significantly by 232% compared to the current demand. Summarizing, research indicates that with global warming, the energy demand for heating will decrease and the cooling demand will increase significantly in order to maintain the required user comfort.
Przedmiotem niniejszego artykułu jest analiza możliwego wpływu zmian klimatycznych na charakterystykę energetyczną budynku i temperatury wewnętrzne. Model budynku oparty jest na domu Maison Air et Lumière, którego koncepcja powstała w ramach projektu Model Homo 2020. Jest to niskoenergetyczny, jednorodzinny, wolnostojący dom. Model został podzielony na trzy strefy i stworzony przy użyciu oprogramowania SketchUp. Analiza zmian klimatycznych została przeprowadzona na przykładzie miasta Kielce i opisana w pierwszej części artykułu. Obliczenia symulacyjne przeprowadzono przy użyciu oprogramowania TRNSYS. Wykonano je dla trzech różnych scenariuszy odnoszących się do systemów technicznych - wentylacja, wentylacja + ogrzewanie, wentylacja + ogrzewanie + chłodzenie. Dla każdego wariantu określono roczne zapotrzebowanie energii oraz zmianę temperatury operatywnej w pomieszczeniach. Wyniki wykazały większe ryzyko wystąpienia dyskomfortu w okresie letnim oraz zmianę bilansu energetycznego budynku wraz z ocieplaniem się klimatu. W wariancie bez systemu chłodzenia odsetek czasu z temperaturą wewnętrzną powyżej 27°C wzrósł z 2,6% do 29,0% w strefie 3 oraz z 23,7% do 44,2% w strefie 2. Zapotrzebowanie na energię do ogrzewania zmniejszyło się o 23,4% w stosunku do obecnego klimatu, a zużycie energii do chłodzenia (przy opcji z chłodzeniem) znacznie wzrosło o 232% w stosunku do obecnego zapotrzebowania.
Źródło:
Archives of Civil Engineering; 2023, 69, 2; 195--209
1230-2945
Pojawia się w:
Archives of Civil Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exergetic performance analysis of solar air heater with inverted L-shape ribs as roughness element
Autorzy:
Chaudhari, Manmohan
Sharma, Sohan Lal
Debbarma, Ajoy
Powiązania:
https://bibliotekanauki.pl/articles/27312231.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
solar air heater
heat transfer
exergy loss
exergy efficiency
thermal efficiency
Opis:
Improvement in the exegetic efficiency of a solar air heater (SAH) can be done by enhancing the rate of heat transfer. In this work, the exergetic efficiency optimization of an artificially roughened solar air heater having an inverted L-shape rib has been performed. The numerical analysis of the exergetic performance of the solar air heater was carried out at a constant heat flux of 1000 W/m2 . The study was conducted to investigate the effect of different relative roughness pitch (7.14–17.86) on the exergy losses, under the Reynolds number range of 3000 to 18 000. The roughness parameter of this geometry has been optimized and found to be among functional operating parameters like average solar intensity and temperature rise across the collector. The optimized value of relative roughness pitch is 17.86 at the isolation of 1000 W/m2 , and the parameter of temperature rise ranges from 0.005 to 0.04.
Źródło:
Archives of Thermodynamics; 2023, 44, 3; 241--267
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigations on the Microstructure and Corrosion Performance of Different WC-Based Cermet Coatings Deposited by High Velocity Oxy Fuel Process onto Magnesium Alloy Substrate
Autorzy:
Jonda, Ewa
Łatka, Leszek
Maciej, Artur
Khozhanov, Aleksandr
Powiązania:
https://bibliotekanauki.pl/articles/2201928.pdf
Data publikacji:
2023
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
AZ91 magnesium alloy
HVOF
thermal spraying
metal matrix composite coatings
microstructure
electrochemical corrosion
Opis:
In the field of surface engineering, thermal spraying is very wide adopted in many branches of the industry. The main reasons of such situation are its flexibility as well as cost effectiveness. Among others, High Velocity Oxy Fuel (HVOF) technique is dedicated for spraying hardmetal and cermet coatings, especially for wear- and corrosion resistance. Such type of coating could be a promising candidate as protective layer for magnesium alloys elements. These materials need a strong improvement in the corrosion protection as well as on the field of wear resistance in order to be widely used in the industry. In this work, different WC-based coatings, namely: (i) WC-Co, (ii) WC-Co-Cr and (iii) WC-Cr3C2-Ni manufactured by HVOF spraying, were investigated. The form of all feedstock materials was agglomerated and sintered powder. All coatings were sprayed with the same technological parameters, especially spray distance which was equal to 400 mm on the AZ91 magnesium alloy substrate. The main aim of the studies was to investigate the influence of the powder material on the corrosion resistance of obtained coatings. The manufactured coatings were examined in terms of its microstructure, using scanning electron microscope (SEM) and corrosion performance, which was assessed in the electrochemical corrosion investigations in 3.5% NaCl solution by Tafel method. The study showed that the corrosion resistance increasing in such order: AZ91 < WC-Cr3C2-Ni < WC-Co < WC-Co-Cr. It should be stressed that WC-Cr3C2-Ni coating exhibits very low corrosion performance, which could be effected by relatively high porosity (c.a. 3 vol.%) and because of that the more complex composition promotes creation of many corrosion cells.
Źródło:
Advances in Science and Technology. Research Journal; 2023, 17, 2; 25--35
2299-8624
Pojawia się w:
Advances in Science and Technology. Research Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Performance investigation of hybrid photovoltaic thermal-heat with mini-channels for application in electric vehicles
Autorzy:
Strąk, Dariusz
Powiązania:
https://bibliotekanauki.pl/articles/24200857.pdf
Data publikacji:
2023
Wydawca:
Sieć Badawcza Łukasiewicz. Przemysłowy Instytut Motoryzacji
Tematy:
mini-channels
numerical simulations
one-dimensional model
autonomous car system with PVT
vehicle battery heat exchanger
Opis:
The first autonomous car was developed in the 1980s, but it wasn't until the early 2010s that the technology began to gain significant attention and investment. In 2010, Google began testing self-driving cars on public roads, and since then, many other companies have joined the race to develop fully autonomous vehicles. Hybrid PVT (Photovoltaic Thermal) heat exchangers cooled with mini-channels find application in autonomous vehicles as a solution that enables efficient cooling of the vehicle's electronics and batteries. The solution involves using photovoltaic panels to generate electricity and removing the heat produced during the process using mini-channels is removed by mini-channels. Hybrid PVT heat exchangers cooled with mini-channels can help maintain appropriate temperatures inside autonomous vehicles that generate large amounts of heat from electronic systems and sensors. The setup can improve the performance and reliability of autonomous systems, increase energy efficiency, and reduce energy demands. The experimental setup includes two parallel mini-channel systems separated by a smooth copper plate. The study aims to determine local heat-transfer coefficients, with a cooled solar cell efficiency range of 10% to 14% compared to other research. The cooled PV temperature range achieved was from 19.6 to 22.4 degrees Celsius, which is favorable for photovoltaic panels' operation under approximate light intensity for Poland's latitude. Heat-transfer from hot surfaces to cold fluids is analyzed during single-phase convection using two calculation methods: one-dimensional and numerical simulations using Simcenter STAR CCM+. Cooling photovoltaic modules is critical for the photovoltaic and autonomous vehicle systems sector, making this research significant both theoretically and practically. The research and methods presented in the article on mini-channel cooling of photovoltaic systems and autonomous vehicle systems are innovative at a global scale, and are crucial for further development of sustainable energy systems and reduction of greenhouse gas emissions.
Źródło:
Archiwum Motoryzacji; 2023, 100, 2; 5--30
1234-754X
2084-476X
Pojawia się w:
Archiwum Motoryzacji
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on performance of a green hydrogen production system integrated with the thermally activated cooling
Autorzy:
Moulebe, Laince Pierre
Touati, Abdelwahed
Obar, Akpoviroro Eric
Rabbah, Nabila
Powiązania:
https://bibliotekanauki.pl/articles/2201974.pdf
Data publikacji:
2023
Wydawca:
Centrum Badań i Innowacji Pro-Akademia
Tematy:
thermal energy
green hydrogen
trigeneration
energy transition
cooling
energia termiczna
zielony wodór
trigeneracja
transformacja energetyczna
chłodzenie
Opis:
The energy transition is at the centre of research and development activities with the aim to fight against the effects of global warming. Today, renewable energies play a significant role in the electricity supply to the World and their use increases day after day. Because of the intermittency of a large-scale production system generates the need to develop clean energy storage systems. Hence, energy storage systems play is one of key elements in the energy transition. In this perspective, a green hydrogen is defined as an energy carrier thanks to its high energy density in relation to its negligible mass, not to mention its abundance in our environment, and its extraction, which does not contribute to any greenhouse gases. However, the production cost is not negligible. Hence, this work shows a numerical modelling of the heat balance from a green hydrogen production system using a thermal storage in a Metal Hydride (MH) tank for an electrification by Proton Exchange Membrane (PEM) fuel cell integrated into the production of heating, cooling and sanitary hot water (SHW) through the recovery of the heat released by the whole system combined with the technology of thermally activated cooling of an adsorber. This allows demonstrating that the green hydrogen can be an interesting solution according in the hydrogen production chain and in the tertiary sectors.
Źródło:
Acta Innovations; 2023, 47; 5--19
2300-5599
Pojawia się w:
Acta Innovations
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal performance of the thermal storage energy with phase change material
Autorzy:
Bałon, Paweł
Kiełbasa, Bartłomiej
Kowalski, Łukasz
Smusz, Robert
Powiązania:
https://bibliotekanauki.pl/articles/2204648.pdf
Data publikacji:
2023
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
energy storage
phase change material
PCM
heat accumulation
Opis:
Values of energy supply and demand vary within the same timeframe and are not equal. Consequently, to minimise the amount of energy wasted, there is a need to use various types of energy storing systems. Recently, one can observe a trend in which phase change materials (PCM) have gained popularity as materials that can store an excess of heat energy. In this research, the authors ana-lysed paraffin wax (cheese wax)’s capability as a PCM energy storing material for a low temperature energy-storage device. Due to the relatively low thermal conductivity of wax, the authors also analysed open-cell ceramic Al2O3/SiC composite foams’ (in which the PCM was dispersed) influence on heat exchange process. Thermal analysis on paraffin wax was performed, determining its specific heat in liquid and solid state, latent heat (LH) of melting, melting temperature and thermal conductivity. Thermal tests were also performed on thermal energy container (with built-in PCM and ceramic foams) for transient heat transfer. Heat transfer coefficient and value of accumulated energy amount were determined.
Źródło:
Acta Mechanica et Automatica; 2023, 17, 1; 76--84
1898-4088
2300-5319
Pojawia się w:
Acta Mechanica et Automatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A comparative study for double pass solar air collector utilizing medial glass panel
Autorzy:
Salih, Hussein M.
Powiązania:
https://bibliotekanauki.pl/articles/27309858.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
solar air collector
double-pass
CFD
finite volume
thermal performance
kolektor powietrza słonecznego
skończona objętość
wydajność cieplna
Opis:
A numerical investigation of thermal prediction of double-pass solar air heater of-counter flow is developed in the present study. The main idea of the current study is that the collector consists of two layers of glass so that the middle layer is glass instead of the usual metal plate. The performance of double-pass solar air heater is studied for a wide range of solar radiation intensities (600, 750 and 900 W/m 2). A FORTRAN-90 program is built to simulate the mathematical model of double-pass solar air heater based on solving steady state two-dimensional Navier-Stokes equations and energy equation based on finite volume method. Turbulence effect is simulated by two equations k-ε module. The results are compared with the results of a previous experimental study and a good agreement was found. From compression calculating efficiency of the present and traditional collector for each solar intensity, it was found that the efficiency of the current collector is higher than that of the traditional one, where the efficiency of the current collector at the solar intensity of (600, 750 and 900) W/m 2 are (0.529, 0.514 and 0.503), respectively, while those of the traditional collector (0.508, 0.492 and 0.481), respectively. In addition to this, the effect of the mass flow rate on the temperature difference of the current proposed collector was studied. Three values of the mass flow rate were studied (0.009,0.018, and 0.027) kg/s at solar intensity of 750 W/m 2. From this it was found that the temperature difference decreases with increasing mass flow rate. Accordingly, the efficiency decreases
Źródło:
Archive of Mechanical Engineering; 2022, LXIX, 4; 729--747
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Air bottoming combined cycle performance analyses by the combined effect of variable parameters
Autorzy:
Khan, Mohammad N
Alzafiri, Dhare
Powiązania:
https://bibliotekanauki.pl/articles/27309845.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
topping cycle
air bottoming cycle
net power output
thermal efficiency
total exergy
destruction
exergetic efficiency
cykl uzupełniania
cykl opadania powietrza
moc wyjściowa netto
wydajność termiczna
całkowita egzergia
zniszczenie
efektywność egzergetyczna
Opis:
To meet the continuous demand for energy of industrial as well as commercial sectors, researchers focus on increasing the power generating capacity of gas turbine power plants. In this regard, the combined cycle is a better solution in terms of environmental aspects and power generation as compared to a simple gas turbine power plant. The present study is the thermodynamic investigation of five possible air bottoming combined cycles in which the topping cycle is a simple gas turbine cycle, regenerative gas turbine cycle, inter-cool gas turbine cycle, reheat gas turbine cycle, and intercool-reheat gas turbine cycle. The effect of pressure ratio of the topping cycle, the turbine inlet temperature of topping cycle, and ambient temperature on net power output, thermal efficiency, total exergy destruction, and exergetic efficiency of the combined cycle have been analyzed. The ratio of the net power output of the combined cycle to that of the topping cycle is maximal in the case when the topping cycle is a simple gas turbine cycle. The ratio of net power output and the total exergy destruction of the combined cycle to those of the topping cycle decrease with pressure ratio for all the combinations under study except for the case when the topping cycle is the regenerative gas turbine cycle.
Źródło:
Archive of Mechanical Engineering; 2022, LXIX, 3; 497--517
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An effect of binary fluid on the thermal performance of pulsation heat pipe
Autorzy:
Barrak, Anwar S.
Ali, Nawfal M
Ali, Hussein Hayder Mohammed
Powiązania:
https://bibliotekanauki.pl/articles/2174164.pdf
Data publikacji:
2022
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
rura cieplna
przepływ dwufazowy
przepływ ciepła
binary fluid
oscillation heat pipe
two phase flow
thermal resistance
heat transfer
Opis:
A pulsation heat pipe is an efficient heat pipe used in many engineering applications. This study aims to test the effect of working fluids on the thermal performance of pulsation heat pipe. Seven turned pulsation heat pipes were designed and manufactured from a copper pipe with a 3.5 mm inner diameter. The lengths of an evaporation part, an adiabatic passage, and a condenser part were 300 mm, 210 mm, and 300 mm, respectively. In this study, three different fluids were used as the working fluid: distilled water, methanol, and binary fluid (a mixture of water and methanol) with a 50% filling ratio. Compared to water, the experimental results suggested that methanol had a better thermal performance when used as a working fluid in the PHP. On the other hand, a binary fluid enhanced the lower thermal performance of water (29% reduction in the thermal resistance and a 20% increase in the effective thermal conductivity of the PHP).
Źródło:
International Journal of Applied Mechanics and Engineering; 2022, 27, 1; 21--34
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An overview of heat transfer enhancement based upon nanoparticles influenced by induced magnetic field with slip condition via finite element strategy
Autorzy:
Hafeez, Muhammad B.
Krawczuk, Marek
Shahzad, Hasan
Powiązania:
https://bibliotekanauki.pl/articles/2105987.pdf
Data publikacji:
2022
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
magnetohydrodynamic flow
porous medium
nanofluids
heat transfer
thermal performance
convective boundary conditions
FEM
Opis:
The mathematical model of heat generation and dissipation during thermal energy transmission employing nanoparticles in a Newtonian medium is investigated. Dimensionless boundary layer equations with correlations for titanium dioxide, copper oxide, and aluminium oxide are solved by the finite element method. Parameters are varied to analyze their impact on the flow fields. Various numerical experiments are performed consecutively to explore the phenomenon of thermal performance of the combination fluid. A remarkable enhancement in thermal performance is noticed when solid structures are dispersed in the working fluid. The Biot number determines the convective nature of the boundary. When the Biot number is increased, the fluid temperature decreases significantly. Among copper oxide, aluminium oxide, and titanium oxide nanoparticles, copper oxide nanoparticles are found to be the most effective thermal enhancers.
Źródło:
Acta Mechanica et Automatica; 2022, 16, 3; 200--206
1898-4088
2300-5319
Pojawia się w:
Acta Mechanica et Automatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Czerń w architekturze w aspekcie zrównoważonego rozwoju - Część 1
Black in architecture in the aspect of sustainable development - Part 1
Autorzy:
Gerlic, Krzysztof
Powiązania:
https://bibliotekanauki.pl/articles/2064143.pdf
Data publikacji:
2022
Wydawca:
PWB MEDIA Zdziebłowski
Tematy:
projektowanie architektoniczne
rozwój zrównoważony
dach chłodny
nawierzchnia chłodna
albedo
materiał budowlany
właściwości cieplne
pochłanianie promieniowania
barwa
projektowanie ekologiczne
architectural design
sustainable development
cool roof
cool pavement
building material
thermal performance
radiation absorption
colour
ecological design
Opis:
Artykuł jest wprowadzeniem do badań dotyczących wpływu zastosowania materiałów budowlanych o ciemnych barwach w architekturze. Obecnie projektowanie architektoniczne kieruje się m.in. doktryną zrównoważonego rozwoju. Troska o zmiany klimatyczne zaleca kształtowanie środowiska zbudowanego tak, aby zapewnić najlepsze warunki dla osób przebywających w nim obecnie i w przyszłości. Badania środowiskowe potwierdzają wpływ materiałów budowlanych na mikroklimat przestrzeni zbudowanej i dlatego stanowią inspirację do analizy ich właściwości, a zwłaszcza współczynników odbicia i pochłaniania promieniowania słonecznego. Istotne jest również, dlaczego podejmowane są decyzje o stosowaniu bardzo ciemnych materiałów. Czy kreacja twórcy może to pomijać?
The article is an introduction to research on the influence of the use of dark-colored building materials in architecture. Currently, architectural design is guided, among others, by the doctrine of sustainable development. Concern for climate change recommends shaping the built environment to provide the best conditions for people living now and in the future. Environmental research confirms the influence of building materials on the microclimate of the built space, hence the analysis of their properties, in particular the reflectivity and absorption of solar radiation. It is also important why decisions are made to use very dark materials. Can the designer creation skip this?
Źródło:
Builder; 2022, 26, 3; 18--21
1896-0642
Pojawia się w:
Builder
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dependence between nominal power deterioration and thermal efficiency of gas turbines due to fouling
Autorzy:
Herdzik, Jerzy
Powiązania:
https://bibliotekanauki.pl/articles/24202511.pdf
Data publikacji:
2022
Wydawca:
Akademia Morska w Szczecinie. Wydawnictwo AMSz
Tematy:
gas turbine
gas turbine deterioration
reasons of fouling
thermal efficiency
performance
fuel consumption
Opis:
Deterioration in the performance of gas turbines is a well-known phenomenon occurring during their operation. The most important form is a decrease in the internal efficiency of the compressor and turbine due to fouling, which is the most significant deterioration problem for an operator. This article presents the effect of gas turbine fouling as a drop in airflow, pressure ratio, and compressor efficiency resulting in a reduction in power output and thermal efficiency. This resulted in a decrease in the nominal power of a gas turbine and an increase in the fuel consumption (heat rate). The fouling effects were described using the example of the MT30 marine gas turbine with a nominal power of 36 MW. The estimated profit loss during the operation of the gas turbine was within the range of 1–10% of the total fuel consumption cost. A 2% deterioration in the output of a gas turbine accounted for US$ 10,000–20,000 per year and 1 MW of gas turbine nominal power (according to marine fuel prices in 2019–2020) – this means at least US$ 300,000 annually for an MT30. Due to the low accuracy of fuel consumption measurements, another possibility was provided. The correlation between the gas turbine power deterioration and thermal efficiency was presented, which made it possible to estimate the increase in the specific and total fuel consumption when the nominal power deterioration is known. Two linear approximations were proposed to calculate increases in the annual operating costs for an MT30 due to fouling.
Źródło:
Zeszyty Naukowe Akademii Morskiej w Szczecinie; 2022, 69 (141); 45--53
1733-8670
2392-0378
Pojawia się w:
Zeszyty Naukowe Akademii Morskiej w Szczecinie
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of serrated circular rings on heat transfer augmentation of circular tube heat exchanger
Autorzy:
Kharkwal, Himanshi
Singh, Satyendra
Powiązania:
https://bibliotekanauki.pl/articles/2091375.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
heat transfer rate
friction factor
thermal performance factor
serrated circular ring
Opis:
Limiting energy resources has led researchers to find new innovative ways to enhance heat exchanging devices thermal performance in power generating systems. Thus, the present paper analyzes passive techniques of enhancing the thermal performance of a single tube heat exchanger. Experimental and numerical investigation on heat transfer enhancement using aserrated circular ring with twisted tape is carried out. The work incorporates the determination of Nusselt number, friction factor, thermal performance factor for serrated circular ring with twisted tape with variation in diameter ratio (0.8 and 0.85) and pitch ratio (2 and 3). Air is used as a working fluid with Reynolds number 6000–24000. The experiment is conducted by providing a constant wall heat flux of 1000 W/m2 to the system and thereby taking results at a steady state. The experimental and computational findings obtained for the smooth tube case are compared with the standard correlations of Dittus–Boelter and Blasius. Based on experimental and numerical investigation, there is 5.16 times augmentation in heat transfer and 3.05 times improvement in thermal performance factor over the smooth tube heat exchanger. In addition, the study of entropy generation rate for every geometrical parameter has been conducted, and their influence on the system’s thermal behaviour is presented. The results obtained in the present study may help the researchers of the same research area to find similar inserts and new ways of enhancing the thermal performance of heat exchangers.
Źródło:
Archives of Thermodynamics; 2022, 43, 2; 129--155
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Waste Fines and Fibers on the Strength and Durability Performance of Silica Fume Based Reactive Powder Concrete
Autorzy:
Renisha, M.
Sakthieswaran, N.
Powiązania:
https://bibliotekanauki.pl/articles/2056305.pdf
Data publikacji:
2022
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Biopolimerów i Włókien Chemicznych
Tematy:
coal bottom ash
waste concrete powder
silica fume
steel fibre
reactive powder concrete
thermal curing
mechanical properties
durability
performance
Opis:
The demand and consumption of conventional concrete materials is increasing day by day, which in turn leads to the extinction of natural resources. Certain researchers tend to draw a circle to solve this global problem by finding alternative materials satisfying all aspects, mainly efficiency, eco-friendly and economical. The present research work aimed to study the combined use of coal bottom ash (CBA) and waste concrete powder (WCP) in silica fume based reactive powder concrete (SF-RPC) subjected to thermal curing. The replacement of cement by silica fume was limited to 20% and the fine aggregate quartz sand replaced by CBA and WCP varied from 5% to 25% each. The material composition of SF-RPC involves the exclusion of coarse aggregates and the inclusion of finer materials with micro-steel fibers. The steel fibers played a significant role in order to obtain a ductile and stable product of SF-RPC. The experimental investigation on SF-RPC comprised of the determination of fresh concrete properties such as slump flow and the compaction factor, as well as mechanical properties like compressive strength, flexural strength and split-tensile strength. The study was also extended to investigate durability properties such as water absorption, sorptivity and resistance to acid attack. The results showed that silica fume proves to be a feasible alternative to partially replace cement and also that optimum incorporation of pre-treated and processed CBA and WCP attains better mechanical and durability performance without compromising the necessary qualities.
Źródło:
Fibres & Textiles in Eastern Europe; 2022, 1 (151); 43--49
1230-3666
2300-7354
Pojawia się w:
Fibres & Textiles in Eastern Europe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electromagnetic analysis, efficiency map and thermal analysis of an 80-kW IPM motor with distributed and concentrated winding for electric vehicle applications
Autorzy:
Młot, Adrian
Korkosz, Mariusz
Lechowicz, Andrzej
Podhajecki, Jerzy
Rawicki, Stanisław
Powiązania:
https://bibliotekanauki.pl/articles/2172808.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
AC losses
concentrated winding
distributed winding
motor performance
radial flux permanent magnet motor
slot fill factor
thermal analysis
Opis:
This paper presents a comparison of an AC radial flux interior permanent magnet (IPM) motor with the distributed winding (DW) and concentrated winding (CW). From time to time, manufacturers of electric vehicles change the design of electric motors, such changes may include changing the DW into CW and vice versa. A change to the winding in a radial permanent magnet synchronous motor may lead to a change in motor parameters during motor operation and /or change in the distribution of the magnetic field and thermal circuit of the electrical machine. The electromagnetic analysis, efficiency map, mechanical stress, and thermal analysis of the machine with the DW and CW are presented in this paper. This article describes the advantages and disadvantages of selected stator winding designs and helps understand manufacturers’ designers how the DW and CW play a key role in achieving the designed motor’s operational parameters such as continuous performance. Analyzing the performance of both machines will help identify their advantages and disadvantages with regard to thermal phenomena, magnetic field and operational parameters of the presented IPM prototypes. Both prototypes are based on commonly used topologies such as 12/8 (slot/pole) and 30/8 (slot/pole) IPM motors consisting of magnets arranged in a V-shape. The AC IPM motor was designed for an 80 kW propulsion system to achieve 170 N·m at a base speed of 4 500 rpm. Modern CAD tools are utilized throughout the numerical computations based on 2-D finite element methods. Selected test data are used to verify and validate the accuracy of finite element models.
Źródło:
Archives of Electrical Engineering; 2022, 71, 4; 981--1002
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł

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