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1

Effect of Trenched Hemispherical Pin Fins on Cooling Performance of Heat Sink

Yousfi Aissa, Bellahcene Lahcene, Alqurashi Faris, Sahel Djamel, Teggar Mohamed, Laouer Abdelghani, Arıcı Müslüm, Kchaou Mohamed

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no 3

33--44

EN

Pin fins have the potential to improve the thermal performance of various engineering devices. Modified pin fins could further increase their thermal performance in a passive way at lower cost. This study is aimed to numerically investigate the thermal performance of trenched hemispherical pin fins heat sink (THPFHS) and the influence of parameters including the trench number (N=1, 3 and 5) and thickness (e =1 to 5 mm). The simulations are performed using a CFD software considering turbulent air flow conditions. Results show that the use of aluminum fins fitted with one trench in the middle of the hemispherical pin fin considerably increases the local heat transfer. Furthermore, all studied configurations show high thermal performance factor (HTPF) compared with the conventional CPFHS (cylindrical pin fins heat sink). For this new configuration (THPFHS), Nu increases by 45% while the thermal resistance reduces by 42%, compared to the baseline case. On the other hand, this improved performance results in 50% pressure drop penalty. Moreover, the obtained results show a significant improvement in the performance mainly at high Re.

2

Design of a CPU Heat Sink with Minichannel-Fins & its Thermal Analysis

Arzutuğ Mehmet Emin

Polish Journal of Chemical Technology

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2023

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Vol. 25, nr 3

89--100

EN

In this paper, the design and the thermal analysis of a tribled microprocessor cooler combining the advantages of strong swirl flow and minichannel-fins and CuO nanofluid, have been presented. It is thought that the results will contribute to the understanding of the effects of parameters on the cooling flux of the heat sink and the decline at the microprocessor temperature, as Reynolds number in the minichannels and CuO % volume fraction. The results have exhibited that the total performance of the heat sink cooled with the mixture of water–CuO-EG nanofluids increases with the increase of Re number and the %load of nanoparticles in the coolant. It has been determined that the energy withdrawn from the microprocessor was 241 times higher than the energy generated for maximum CuO load and Re number conditions. Besides, the highest temperature decrease has been measured at the maximum CuO load value and maximum Re number.

3

Możliwości ograniczenia energii niezbędnej do utrzymania systemów wentylacji mechanicznej i klimatyzacji z odzyskiem ciepła w obiektach szpitalnych

Szczęśniak Sylwia

Ciepłownictwo, Ogrzewnictwo, Wentylacja

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2023

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T. 54, nr 3

10--20

PL

W Polsce brakuje danych dotyczących zapotrzebowania na energię niezbędną do utrzymania systemów wentylacyjnych, grzewczych i chłodniczych. Duże wartości strumieni powietrza wentylującego, wysokie wymagania dotyczące jakości oraz parametrów cieplno-wilgotnościowych powietrza w obiektach szpitalnych i służby zdrowia wpływają na wysokie koszty ich utrzymania. W dobie kryzysu politycznego, energetycznego oraz globalnie zmieniającego się klimatu, każda metoda ograniczania energii niezbędnej do transportu i uzdatniania powietrza musi być rozważona i uwzględniona zarówno w procesie projektowym, remontowo-modernizacyjnym jak i w codziennej eksploatacji budynków. Celem artykułu było wykazanie w jakim stopniu można ograniczyć roczne zapotrzebowanie na energię określone dla 1 m3/s powietrza zarówno w aspekcie jego transportu jak i uzdatniania. Takie jednostkowe określenie energii jest niezależnym wskaźnikiem, który można wykorzystać do każdej wartości strumienia powietrza wentylującego. Do wyznaczenia rocznego zapotrzebowania na energię niezbędną do uzdatniania powietrza przygotowano wykresy t-tz obrazujące roczny cykl pracy urządzenia wentylacyjnego z odzyskiem ciepła z wymiennikiem o sprawności 50% i 80%. Przyjęto 10 różnych profili sterowania pracą urządzeń. Do wyznaczenia możliwości ograniczenia energii niezbędnej do transportu powietrza wykonano obliczenia dla wentylatorów o mocy właściwej określonej zgodnie z Warunkami Technicznymi. W artykule wykazano, że zapotrzebowanie na energię do uzdatniania powietrza jest ściśle zależne od właściwie przyjętej metody sterowania pracą urządzenia oraz przyjętych wartości temperatury powietrza nawiewanego i/lub w pomieszczeniu. Przedstawiono tu także możliwe scenariusze ograniczenia strumienia powietrza wentylującego w wypadku pomieszczeń nieużytkowanych, w których należy zachować przepływ powietrza przez pomieszczenie. Wskazano także konieczność dostosowania cech architektoniczno-budowlanych budynku do maksymalnego ograniczenia zysków i strat ciepła pomieszczeń.

EN

Poland has no data concerning the energy demand to maintain ventilation, heating, and cooling systems. High values of mechanical ventilation and air-conditioning air flow and high requirements regarding indoor air quality, temperature, and relative humidity in hospital and healthcare facilities result in high maintenance costs. In the time of political and energy crisis and the globally changing climate, any method of reducing the energy demand for transport and air treatment must be considered and included in the design, renovation, and modernisation process as well as in the daily operation of buildings. The aim of the article is to show how to limit the annual energy demand, specified for 1m3/s of airflow volume, both in terms of its transport and treatment. This unitary determination of energy can be an independent indicator that can be used for each value of the ventilation air flow. To determine the annual energy demand for air treatment, t-tz charts were prepared. They show the annual operation cycle of a ventilation unit with heat recovery, with a 50% and 80% efficiency, exchanger. 10 different ventilation system control profiles have been analysed. In order to determine the possibility of reducing the energy demand for air transport, calculations were made for fans with a specific power determined in accordance with the Technical Conditions. The article shows that the energy demand for air heating and cooling is strictly dependent on the properly adopted method of controlling the operation of the device and the assumed values of supply and indoor air temperature. It also presents possible scenarios of limiting the energy demand for air transport with respect to unused rooms, where air flow through the room should be maintained. It was also indicated the need to adjust the architectural and construction features of the building to minimise the heating and cooling loads for the rooms.

4

Photovoltaic panels cooling technologies: Comprehensive review

Ibrahim Osama Abd Al-Munaf, Kadhim Saif Ali, Al-Ghezi Moafaq Kaseim Shiea

Archives of Thermodynamics

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2023

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Vol. 44, no 4

581--617

EN

The solar radiation absorbed by photovoltaic panels is not fully utilized in the production of electricity. When the photovoltaic panels are exposed to solar radiation, part of the energy of the incident radiation is transformed into heat accumulated inside these panels. The heat accumulated inside the photovoltaic panels causes two types of losses. The first type of losses is the increase in the operating temperature of the panels and the deterioration of their efficiency and life span. The second type of losses explains that part of the energy of the incident radiation is transformed into heat inside the panels and does not contribute to the production of electrical energy. There are several cooling systems that have been applied to photovoltaic panels for the purpose of regulating their temperature including air, water, and nanofluid cooling systems, which are mostly done by placing a solar collector in the back side of the photovoltaic panels (PV/T). There is also a recently used system that uses phase change material (PCM) in cooling. This paper provides a comprehensive review of several cooling methods and their improvements that researchers have focused on. Through this review, it is clear that the best improvement in the performance of the photovoltaic panel occurs when using PCM because of the high heat transfer coefficient of these materials. Performance improves more when the addition of nanoparticles to the phase change material (PCM-Np) and also when merging (PCM) with (PV/T).

5

Parametric Optimization for Producing Semi-Solid A383 Alloy using Cooling Slope Casting Process

Rao M. S., Khandelwal Himandshu, Kumar M., Kumar A.

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 1

43--52

EN

Cooling slope casting is a simple technique to produce semi-solid feedstock with a non-dendritic structure. The cooling slope technique depends on various parameters like slope length, slope angle, pouring temperature etc, that has been investigated in the present study. This work presents an extensive study to comprehend the combined effect of slope angle, slope length, pouring temperature, on hardness and microstructure of A383 alloy. Response Surface Methodology was adopted for design of experiments with varying process parameters i.e. slope angle between 15o to 60o, slope length between 400 to 700 mm, and pouring temperature between 560 oC to 600 oC. The response factor hardness was analysed using ANOVA to understand the effect of input parameters and their interactions. The hardness was found to be increasing with increased slope length and pouring temperature; and decreased with slope angle. The empirical relation for response with parameters were established using the regression analysis and are incorporated in an optimization model. The optimum hardness with non-dendritic structure of A383 alloy was obtained at 27o slope angle, 596.5 mm slope length and 596 oC pouring temperature. The results were successfully verified by confirmation experiment, which shows around 2% deviation from the predicted hardness (87.11 BHN).

6

Influence of winding and shaft cooling on the thermal characteristics of a traction machine for heavy-duty distribution transport

Groschup Benedikt, Butterweck Daniel, Hameyer Kay

Archives of Electrical Engineering

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2023

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Vol. 72, nr 3

769--784

EN

This paper studies the influence of different cooling technologies on the power density of a traction machine for heavy-duty distribution transport. A prototype induction machine is built with a housing cooling jacket, potted end-windings, entire winding cooling, and shaft cooling. Electromagnetic finite element and thermal lumped-parameter models are parameterized and verified using test bench measurements. The influence of each thermal resistance along the heat paths is studied and discussed. The results are used for studying different cooling technologies. The results indicate an improvement of the continuous power density up to 108% using shaft cooling and up to 15.6% using entire winding cooling.

7

Study on performance of a green hydrogen production system integrated with the thermally activated cooling

Moulebe Laince Pierre, Touati Abdelwahed, Obar Akpoviroro Eric, Rabbah Nabila

Acta Innovations

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2023

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no. 47

5--19

EN

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.

8

Cysty Dinoflagellata z górnego kampanu i najniższego mastrychtu (górna kreda) profilu środkowej Wisły : stratygrafia i paleoekologia

Nechwedowicz Mariusz

Przegląd Geologiczny

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2022

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Vol. 70, nr 10

751--760

EN

Among the rich dinoflagellate cyst assemblages recovered from the upper Campanian-lowermost Maastrichtian succession of the Middle Vistula River section (central Poland), four taxa (Callaiosphaeridium bicoronatum, Odontochitina dilatata, Oligosphaeridium araneum and Samlandia paucitabulata) have been described as new. An analysis of the distribution of particular dinoflagellate cyst taxa enabled the development of a highly resolved biostratigraphic framework, calibrated against other biozonal schemes (based, among others, on inoceramid bivalves, ammonites and belemnites), formerly established for the succession. A comparison of the Middle Vistula River record with the dinoflagellate cyst ranges documented in other European successions enabled correlations with selected sections in Belgium, the Netherlands, southern Germany and northern Italy, and with the Campanian/Maastrichtian boundary stratotype section in Tercis les Bains, southwest France. A palaeoecological analysis of the dino- flagellate cyst assemblages and of other components of phytoplankton communities revealed a well-defined trend in sea-level fluctuations (likely of eustatic origin), and palaeoclimatic changes probably related to the latest Cretaceous cooling episode, as observed elsewhere.

9

Pompy ciepła dla ogrzewania i chłodzenia w aspekcie obniżenia emisji ditlenku węgla

Szczechowiak Edward

Przegląd Budowlany

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2022

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R. 93, nr 7-8

160--166

PL

Dyrektywy Unii Europejskiej oraz przepisy krajowe wyraźnie wskazują na rozwój budownictwa niemal zeroenergetycznego i o niskiej emisji ditlenku węgla. Artykuł zawiera informacje o tym, jak można zrealizować ten cel poprzez zastosowanie pomp ciepła i to zarówno dla potrzeb ogrzewania, jak i chłodzenia. Omówiono pompy ciepła stosowane w budownictwie, wykorzystujące energię niskopotencjalną: powietrze zewnętrzne, grunt, wodę, ścieki i inne ciepło odpadowe do konwersji na ciepło o potencjale użytkowym: do ogrzewania, podgrzewania ciepłej wody, ale również do chłodzenia pomieszczeń. Podano przykłady rozwiązań dla różnej wielkości budynków i pokazano korzyści wynikające z zastosowania pomp ciepła w aspekcie energetyczno-ekologicznym. Pompy ciepła bardzo dobrze wpisują się w tendencje przyszłościowe i pozwalają na znaczne obniżenie śladu węglowego budynków.

EN

European Union directives and national regulations clearly indicate the development of nearly zero-energy and low-carbon construction. The article provides information on how to achieve this goal by using heat pumps for both heating and cooling. Discussed heat pumps used I construction, using low-potential energy: outdoor air, soil, water, sewage and other waste heat for conversion into heat with a useful potential for heating, hot water, but also for cooling rooms. Examples of solutions for different sizes of buildings are given and the benefits of using heat pumps in terms of energy and ecology are shown. Heat pumps fit very well into the trends of the future and allow for a significant reduction in the carbon footprint of buildings.

10

Investigation into Increasing the Motor-Drivable Current Using a Thermoelectric Cooling Module

Morikawa Kazuma, Katsura Seiichiro

Power Electronics and Drives

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2022

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Vol. 7 (42)

279--289

EN

To enhance the performance of humanoids, mobile robots and manipulators, motors are desired to be able to provide high torque without relying on gears. To be able to drive joint motors with high output, the current value that can flow needs to be increased. However, the heat generated by the high current drive can cause motor failure, so cooling is necessary. We used thermoelectric cooling as a new cooling method for high-power drive of motors. By developing a thermoelectric cooling module for motors and conducting experiments, the effectiveness of thermoelectric cooling was verified. In the experiment, the motor was kept running at a high current for a long period of time. The comparison with the motor alone or with water cooling showed that the thermoelectric cooling module can significantly reduce the rise in temperature of the motor. Furthermore, based on the results of the voltage value measurements, it was expected that the increase in coil resistance due to higher coil temperatures would be kept lower than in other cases. The effect on rise in internal temperature was also considered to be greater than that of water cooling. These experimental results show that the thermoelectric cooling module can be used to increase the upper limit of the current at which the motor is continuously driven.

11

The efficiency of waste hot water utilisation to improve the temperature conditions for growing plants

Turcheniuk Vasil, Rokochinskiy Anatoliy, Kuzmych Lyudmyla, Volk Pavlo, Koptyuk Roman, Romanyuk Ivan, Voropay Galyna

Journal of Water and Land Development

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2022

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no. 54

94--100

EN

One of the rational ways of energy saving is to use the heat of wastewater from energy companies for open ground heating and cultivation crops. The most significant sources of heat are thermal and nuclear power plants that produce low-thermal waters of 28-35°C. Heating of the ground with the use of circulating warm water allows to increase temperature at all points of the soil profile. The maximum thermal effect from heating ground is observed at the depth of pipe heaters (7.3- 11.1°C). Ground heating allows to extend the growing season for crops by 3-4 weeks, which can expedite harvesting and thus maximise the harvest. In natural moisture conditions, ground heating does not lead to significant reduction of moisture reserves in the active layer throughout the growing period. There is a redistribution of moisture in a soil profile. It decreases in the zone of pipe heaters and redistributes toward the top. The formation of the nutrient regime changes, the content of mobile phosphorus and potassium, and nitrate nitrogen increases, whereas the content of ammonia nitrogen is reduced. Ground heating is a new special heat reclamation technique. It allows not only to control temperature of the agricultural crop environment, but also to dissipate heat in the ground, and promote the utilisation of waste heat and the stabilisation of the environment.

12

The analysis of the rolls cooling at push bench in rolling mill plant ŽP A.S.

Kán Michal, Turňa Ján, Mojžiš Milan, Patin Ľubomír, Kotrbáček Petr, Bellerová Hana

Journal of Metallic Materials

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2022

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Vol. 74, no. 1

4--8

EN

This article deals with a comprehensive analysis at roll cooling of push bench on a rolling mill during the rolling process of semi-finished products used for the production of seamless tubes. An important issue that we deal with in this issue is the influence of the cooling parameters using special programmable nozzles of various types with the required flow and water pressure on the final surface temperature of the extruder rollers, at finish quality of shell. The experiment will address the problem of determining the cooling efficiency of different types of nozzles on an experimental device for testing the heat transfer coefficient during cylinder cooling. During experiments maintains development of deformation processes in stands of push bench.

PL

W artykule przedstawiono kompleksową analizę procesu chłodzenia walców walcarki przepychowej w walcowni podczas procesu walcowania półproduktów wykorzystywanych do produkcji rur bez szwu. Ważnym zagadnieniem w tym temacie jest wpływ parametrów chłodzenia za pomocą specjalnych programowalnych dysz różnego typu o wymaganym przepływie i ciśnieniu wody na końcową temperaturę powierzchni walców walcarki przepychowej, co wiąże się z końcową jakością tulei. Eksperyment będzie dotyczył problemu wyznaczania wydajności chłodzenia różnych typów dysz na urządzeniu doświadczalnym do badania współczynnika przenikania ciepła podczas chłodzenia rolek. Podczas wszystkich eksperymentów zachowano przebieg procesów odkształcania w klatkach walcarki przepychowej.

13

Experimental Study of Temperature Influence on the Performance of PV/T Cell under Jordan Climate Conditions

Al-Odat Mohammed Qassim

Journal of Ecological Engineering

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2022

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Vol. 23, nr 10

80--88

EN

The electrical performance and the productivity of PV module depend on two main parameters, i.e. the radiation intensity and the cell operating temperature. The module electrical efficiency and productivity are significantly reduced as its temperature increases. Accordingly, cooling of PV modules is one of the most effective techniques to obtain higher efficiency and productivity as well as to reduce the degradation modes of PV modules due to high temperatures. This research work presents an experimental study carried out to investigate the effect of PV module cooling on the performance of PV module under Irbid city (Jordan) climate conditions. It was found that the electrical efficiency and the productivity of the PV modules were approximately enhanced by 14%. Therefore, water cooling of the PV modules is essential to enhance their performance.

14

Żywność chłodzona i mrożona - wady i zalety

Hać-Szymańczuk Elżbieta, Cegiełka Aneta, Lipińska Edyta

Chłodnictwo : organ Naczelnej Organizacji Technicznej

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2022

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R. 57, nr 5

2--5

PL

W artykule omówiono możliwości zastosowania niskiej temperatury do utrwalania żywności. Omówiono również wybrane zmiany fizyczne i biochemiczne powstające w żywności poddanej działaniu niskiej temperatury – chłodzenie i mrożenie. Wskazano również drobnoustroje występujących w żywności chłodzonej i mrożonej, które mogą być przyczyną niekorzystnych zmian tego segmentu produkcji spożywczej.

EN

The article discusses the possibilities of using low temperature for food preservation. Selected physical and biochemical changes occurring in food subjected to low temperature – cooling and freezing are also discussed. The microorganisms present in chilled and frozen food, which may cause unfavorable changes in this segment of food production, were also indicated.

15

Ocena schładzania zapraw cementowych narażonych na działanie wysokiej temperatury za pomocą piany gaśniczej

Dinler Ebru

Cement Wapno Beton

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2022

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R. 27, nr 6

427--437

PL

Celem niniejszej pracy było zbadanie efektów szybkiego chłodzenia zapraw z cementu portlandzkiego poddanych działaniu wysokiej temperatury, syntetyczną lekką pianą gaśniczą. W niniejszym badaniu próbki zaprawy z cementu portlandzkiego CEM I 42,5R, piasku Rilem-Cembureau i wody wodociągowej poddano najpierw dojrzewaniu w wodzie przez 28, 90 i 180 dni, a następnie poddano działaniu temperatury odpowiednio 20°C, 150°C, 300°C, 500°C i 700°C przez 3 godziny. Zaprawy cementowe wystawione na działanie wysokiej temperatury schładzano syntetyczną pianą gaśniczą lekką, a następnie oceniano wytrzymałość na zginanie i ściskanie w zależności od czasu hydratacji i temperatury, na której działanie były wystawione. Następnie 180-dniowe zaprawy cementowe wystawione na działanie wysokiej temperatury schładzano różnymi metodami: powietrzem, wodą i pianą. Stwierdzono, że przy zastosowaniu metody chłodzenia powietrzem uzyskano większą wytrzymałość na ściskanie, niż przy chłodzeniu wodą lub pianą. W dalszej kolejności dokonano analizy wytrzymałości na zginanie, wytrzymałości na ściskanie, szybkości przejścia fali ultradźwiękowej oraz procentowego ubytku masy, próbek zapraw otrzymanych w wyniku zastosowania różnych temperatur oraz metod chłodzenia. Stwierdzono, że próbki poddane działaniu temperatury 500°C, chłodzone pianą gaśniczą dały o 9% większą wytrzymałość na ściskanie, w porównaniu do chłodzenia wodą. Uzyskano i przeanalizowano obrazy mikrostruktury 180-dniowych zapraw z cementu portlandzkiego poddanych działaniu temperatury 20°C, 300°C i 700°C, a następnie schładzanych odpowiednio powietrzem, wodą i pianą.

EN

The purpose of this study was to investigate the effects of cooling Portland cement mortars exposed to high temperature, with synthetic high-expansion firefighting foam. In this experimental study, mortar samples produced with Portland cement CEM I 42,5R, Rilem-Cembureau sand and tap water were first subjected to water curing for 28, 90 and 180 days and then exposed to 20°C, 150°C, 300°C, 500°C and 700°C for 3 hours, respectively. Cement mortars exposed to high temperatures were cooled with high expansion firefighting foam and the resulting flexural strength and compressive strengths were evaluated according to hydration period and temperature parameters. Subsequently, 180-day cement mortar samples exposed to high temperature were cooled using air, water, and foam cooling methods. It was determined that the air cooling method resulted in a higher compressive strength than water or foam cooling. The flexural strength, compressive strength, ultrasonic pulse velocity, and mass loss percentage values, obtained by the different cooling methods and exposure temperatures employed, were then analysed. It was determined that samples exposed to 500°C, cooling with firefighting foam, yielded a compressive strength of 9% higher, compared to water cooling. SEM images of 180-day Portland cement mortars exposed to 20°C, 300°C and 700°C and subsequently air, water and foam cooled, respectively, were obtained and analysed.

16

A Technological System for Using Waste Warm Water from Energy Facilities for Effective Agriculture

Turcheniuk Vasil, Rokochinskiy Anatoliy, Kuzmych Lyudmyla, Volk Pavlo, Koptyuk Roman

Archives of Hydro-Engineering and Environmental Mechanics

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2022

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Vol. 69, nr 1

13--25

EN

The waste warm waters from power plants, owing to their temperature regime (25–38°C) and the volumes of discharge, allow for their use for heating of open ground areas in agriculture. Underground heating by such water is a new, special heat and irrigation method which enables not only purposeful regulation of temperature conditions of the crop growing environment, but also dissipates heat in the soil, thus cooling the water for its reuse. This makes it possible to reduce the thermal pollution of water sources.

17

Influence of conductive particle contaminationon the insulation system of rotating electrical machines with direct oil cooling

Yang Liguo, Pauli Florian, Zhang Shimin, Hambrecht Fabian, Hameyer Kay

Archives of Electrical Engineering

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2022

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Vol. 71, nr 3

789--804

EN

An integration of the electrical machine and the gearbox is attracting particular attention for the design of modern electric and hybrid drive trains, since it saves overall space and subsequently increases the power density. Another benefit of a high level of integration is that it enables a combined application of oils as both cooling fluid for the electrical machine and as lubrication fluid for the transmission system. In this way, the power density of the integrated drive train can be further increased. During the oil cycling, conductive contaminations may be introduced and subsequently have an influence on the function of the insulation system of the electrical machine. In the present work, the influences of the cooling oil and its conductive contaminations, conductive particles as well as their combination with humidity, on the electrical and dielectric properties of the insulation system are studied. The results show that by application of the cooling oil, the partial discharge inception voltage (PDIV) of the winding insulation increases significantly so that an electrical breakdown is prone to happen before a partial discharge (PD) occurs. With increasing particle contamination, the PDIV of the insulation system decreases significantly, while the capacitance increases. Besides, conductive particles and humidity decrease the surface resistance and surface breakdown voltage of the insulation papers significantly. The results indicate that the conductive particle contaminations can play an important role for the electrical degradation of the insulation system.

18

Różne wymiary chłodzenia

Świat Obrabiarek i Narzędzi

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2021

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R. 16, nr 3

28

19

Problemy konstrukcji współczesnych urządzeń elektronicznych

Leśniewicz Marek, Rachwalik Tomasz, Zabłocki Janusz, Sierpiński Wiesław, Sokołowski Krzysztof

Przegląd Elektrotechniczny

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2021

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R. 97, nr 8

15--22

PL

Przedmiotem pracy jest analiza możliwości jednoczesnego spełnienia różnych wymagań eksploatacyjnych, jakie stawia się przed współczesnymi, wojskowymi urządzeniami elektronicznymi. Omówiono najważniejsze z tych wymagań i przedstawiono problemy, jakie sprawia ich spełnienie. Opisano autorskie metody zapewnienia optymalnych warunków pracy urządzeń w skrajnych warunkach klimatycznych. Metody te zostały praktycznie zweryfikowane w urządzeniach opracowanych i seryjnie produkowanych w WIŁ.

EN

The subject of the work is the analysis of the possibility of simultaneous fulfillment of various operational requirements that are set for modern military electronic devices. The most important of these requirements are discussed and the problems that their fulfillment causes. Proprietary methods of ensuring optimal working conditions for devices in extreme climatic conditions are described. These methods have been practically verified in devices developed and mass-produced at MCI.

20

Wybór rodzaju chłodzenia dla przetaktowanego procesora mikrokomputera Raspberry Pi 4B pracującego w warunkach maksymalnego obciążenia

Machowski Jakub, Dzieńkowski Mariusz

Journal of Computer Sciences Institute

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2021

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Vol. 18

55--60

EN

The Raspberry Pi is a computer platform that is widely used in education, has a very large user community and exten-sive documentation. Therefore, it can be a good and cheap alternative to a traditional computer, a TV streaming device or a console for less demanding games. In the case of observing a lower efficiency of the microcomputer, one of many possibilities of improvement which this device offers is overclocking the processor. It is associated with a proper selection of parameters (voltage, clocking) and software in order to achieve the highest possible performance of the dedicated Raspbian system. However, increasing the work efficiency causes the temperature rise up to the limit values. Therefore, an appropriate, i.e. effective, kind of cooling should be applied. Taking all these circumstances into account, an experiment was developed in which temperature measurements were taken during the maximum processor load on all cores at the clock setting that enabled reaching the highest performance. During the research three cases were considered: without the use of cooling, with passive cooling and with active cooling. The obtained results showed that only the use of active cooling noticeably improves the operating conditions of the device, due to lowering the temperature by about 15°C compared to the situation without cooling or with the use of a passive radiator.

PL

Raspberry Pi jest platformą komputerową, która ma szerokie zastosowanie w edukacji, posiada bardzo dużą społecz-ność użytkowników i bogatą dokumentację. W związku z tym może być dobrą i tanią alternatywą dla tradycyjnego komputera, przystawki do telewizora czy konsoli dla mało wymagających gier. W przypadku odczucia mniejszej wy-dajności pracy mikrokomputera, jedną z wielu możliwości poprawy tego stanu, które oferuje urządzenie jest przetaktowanie (ang. overclocking) procesora. Wiąże się ono z odpowiednim doborem parametrów pracy (napięcia, taktowania) i oprogramowania dla uzyskania jak najwyższej wydajności działania dedykowanego systemu Raspbian. Jednak zwiększanie wydajności pracy urządzenia powoduje wzrost temperatury aż do osiągnięcia wartości granicznych. W związku z tym należy zastosować odpowiedni, tzn. skuteczny, rodzaj chłodzenia. Uwzględniając wszystkie wymienione okoliczności, opracowano eksperyment, w którym dokonano pomiarów temperatury podczas maksymalnego obciążenia procesora na wszystkich rdzeniach przy ustawieniu taktowania, które umożliwiło uzyskanie największej wydajności Podczas badań rozpatrywano 3 przypadki: bez użycia chłodzenia, z chłodzeniem pasywnym oraz chłodzeniem aktywnym. Na podstawie uzyskanych wyników okazało się, że tylko zastosowanie chłodzenia aktywnego wyraźnie poprawia warunki pracy urządzenia, za sprawą obniżenia temperatury o około 15°C w stosunku do sytuacji bez chłodzenia czy z zastosowaniem radiatora pasywnego.