scholarly journals Modeling and Thermal Analysis of a Moving Spacecraft Subject to Solar Radiation Effect

Processes ◽  
2019 ◽  
Vol 7 (11) ◽  
pp. 807 ◽  
Author(s):  
Mohamed Gadalla ◽  
Mehdi Ghommem ◽  
George Bourantas ◽  
Karol Miller
Keyword(s):  
Solar Radiation ◽  
Heat Dissipation ◽  
Collocation Point ◽  
Space Vehicle ◽  
Low Earth Orbit ◽  
Operating Conditions ◽  
Cylindrical Shape ◽  
Field Function ◽  
Meshless Collocation ◽  
The Impact

The impact of solar radiation on spacecraft can increase the cooling load, degrade the material properties of the structure and possibly lead to catastrophic failure of their missions. In this paper, we develop a computational model to investigate the effect of the exposure to solar radiation on the thermal distribution of a spacecraft with a cylindrical shape which is traveling in low earth orbit environment. This is obtained by the energy conservation between the heat conduction among the spacecraft, the heating from the solar radiation, and the radiative heat dissipation into the surroundings while accounting for the dynamics of the space vehicle (rotational motion). The model is solved numerically using the meshless collocation point method to evaluate the temperature variations under different operating conditions. The meshless method is based on approximating the unknown field function and their space derivatives, by using a set of nodes, sprinkled over the spatial domain of the spacecraft wall and functions with compact support. Meshless schemes bypass the use of conventional mesh configurations and require only clouds of points, without any prior knowledge on their connectivity. This would relieve the computational burden associated with mesh generation. The simulation results are found in good agreement with those reported in previously-published research works. The numerical results show that spinning the spacecraft at appropriate rates ensures low and uniform temperature distribution on the spacecraft, treated as thick-walled object of different geometries. Therefore, this would extend its lifetime and protect all on-board electronic equipment needed to accomplish its mission.

From Chip to Cooling Tower Data Center Modeling: Chip Leakage Power and its Impact on Cooling Infrastructure Energy Efficiency

2011 ◽  
Author(s):  
Thomas J. Breen ◽  
Ed J. Walsh ◽  
Jeff Punch ◽  
Amip J. Shah ◽  
Cullen E. Bash ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Power Consumption ◽  
Data Center ◽  
Heat Dissipation ◽  
Linear Models ◽  
Operating Temperature ◽  
Leakage Power ◽  
Operating Conditions ◽  
Operating Temperatures ◽  
The Impact

The power consumption of the chip package is known to vary with operating temperature, independently of the workload processing power. This variation is commonly known as chip leakage power, typically accounting for ∼10% of total chip power consumption. The influence of operating temperature on leakage power consumption is a major concern for the IT industry for design optimization where IT system power densities are steadily increasing and leakage power expected to account for up to ∼50% of chip power in the near future associated with the reducing package size. Much attention has been placed on developing models of the chip leakage power as a function of package temperature, ranging from simple linear models to complex super-linear models. This knowledge is crucial for IT system designers to improve chip level energy efficiency and minimize heat dissipation. However, this work has been focused on the component level with little thought given to the impact of chip leakage power on entire data center efficiency. Studies on data center power consumption quote IT system heat dissipation as a constant value without accounting for the variance of chip power with operating temperature due to leakage power. Previous modeling techniques have also omitted this temperature dependent relationship. In this paper we discuss the need for chip leakage power to be included in the analysis of holistic data center performance. A chip leakage power model is defined and its implementation into an existing multi-scale data center energy model is discussed. Parametric studies are conducted over a range of system and environment operating conditions to evaluate the impact of varying degrees of chip leakage power. Possible strategies for mitigating the impact of leakage power are also illustrated in this study. This work illustrates that when including chip leakage power in the data center model, a compromise exists between increasing operating temperatures to improve cooling infrastructure efficiency and the increase in heat load at higher operating temperatures due to leakage power.

From Chip to Cooling Tower Data Center Modeling: Chip Leakage Power and Its Impact on Cooling Infrastructure Energy Efficiency

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Thomas J. Breen ◽  
Ed J. Walsh ◽  
Jeff Punch ◽  
Amip J. Shah ◽  
Cullen E. Bash ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Power Consumption ◽  
Data Center ◽  
Heat Dissipation ◽  
Linear Models ◽  
Operating Temperature ◽  
Leakage Power ◽  
Operating Conditions ◽  
Operating Temperatures ◽  
The Impact

The power consumption of the chip package is known to vary with operating temperature, independently of the workload processing power. This variation is commonly known as chip leakage power, typically accounting for ~10% of total chip power consumption. The influence of operating temperature on leakage power consumption is a major concern for the information technology (IT) industry for design optimization where IT system power densities are steadily increasing and leakage power expected to account for up to ~50% of chip power in the near future associated with the reducing package size. Much attention has been placed on developing models of the chip leakage power as a function of package temperature, ranging from simple linear models to complex super-linear models. This knowledge is crucial for IT system designers to improve chip level energy efficiency and minimize heat dissipation. However, this work has been focused on the component level with little thought given to the impact of chip leakage power on entire data center efficiency. Studies on data center power consumption quote IT system heat dissipation as a constant value without accounting for the variance of chip power with operating temperature due to leakage power. Previous modeling techniques have also omitted this temperature dependent relationship. In this paper, we discuss the need for chip leakage power to be included in the analysis of holistic data center performance. A chip leakage power model is defined and its implementation into an existing multiscale data center energy model is discussed. Parametric studies are conducted over a range of system and environment operating conditions to evaluate the impact of varying degrees of chip leakage power. Possible strategies for mitigating the impact of leakage power are also illustrated in this study. This work illustrates that when including chip leakage power in the data center model, a compromise exists between increasing operating temperatures to improve cooling infrastructure efficiency and the increase in heat load at higher operating temperatures due to leakage power.

Truck Tire Operating Temperatures on Flat and Curved Test Surfaces

2005 ◽  
Vol 33 (3) ◽  
pp. 156-178 ◽  
Author(s):  
T. J. LaClair ◽  
C. Zarak
Keyword(s):  
Flat Surface ◽  
Operating Temperature ◽  
Operating Conditions ◽  
Load Pressure ◽  
Truck Tire ◽  
Endurance Testing ◽  
Operating Temperatures ◽  
The Impact ◽  
Tread Rubber ◽  
Cylindrical Test

Abstract Operating temperature is critical to the endurance life of a tire. Fundamental differences between operations of a tire on a flat surface, as experienced in normal highway use, and on a cylindrical test drum may result in a substantially higher tire temperature in the latter case. Nonetheless, cylindrical road wheels are widely used in the industry for tire endurance testing. This paper discusses the important effects of surface curvature on truck tire endurance testing and highlights the impact that curvature has on tire operating temperature. Temperature measurements made during testing on flat and curved surfaces under a range of load, pressure and speed conditions are presented. New tires and re-treaded tires of the same casing construction were evaluated to determine the effect that the tread rubber and pattern have on operating temperatures on the flat and curved test surfaces. The results of this study are used to suggest conditions on a road wheel that provide highway-equivalent operating conditions for truck tire endurance testing.

A NEW WELDING MATERIAL FOR REGENERATION IN THE WELDING TECHNOLOGY BASED ON NICKEL. ANALYSIS OF THE COMPOSITION AND PROPERTIES OF DEFORMABLE HEAT-RESISTANT HIGH-CHROMIUM NICKEL-BASED ALLOYS FOR WELDED PARTS. ANALYSIS OF EXISTING FUELLING STATIONS TYPES AND VEHICLES USING HYDROGEN, HYDROGEN PRODUCTION AND STORING METHODS

2019 ◽  
pp. 43-48
Author(s):  
Ben Nengjun ◽  
Zhou Pengfei ◽  
Oleksandr Labartkava ◽  
Mykhailo Samokhin
Keyword(s):  
Rare Earth ◽  
High Temperature ◽  
Nickel Alloys ◽  
Total Content ◽  
Operating Conditions ◽  
High Temperature Strength ◽  
High Chromium ◽  
Salt Corrosion ◽  
Tcp Phases ◽  
The Impact

This work involves an analysis of high-chromium high-temperature deformable wieldable nickel alloys for use in GTE repair assemblies. It is shown that the alloys EP868 (VZh98) and Haynes 230 can be used in welded assemblies with an operating temperature of 800-1100 °C. The alloys Nimonic 81, Nimonic 91, IN 935, IN 939, and Nicrotan 2100 GT also have a high potential for use in welded assemblies. They are characterized by a combination of good weldability, high-temperature strength, and resistance to scaling. There have been conducted studies on high-temperature salt corrosion of model nickel alloys. They allowed establishing the patterns of the impact of base metal alloying with chromium, aluminum, titanium, cobalt, tungsten, molybdenum, niobium, tantalum and rare earth metals on the critical temperature of the start of salt corrosion Tcor and the alloy mass loss. It has been established that alloys with a moderate concentration (13-16%) of chromium can possess satisfactory hightemperature corrosion resistance (HTC resistance) under the operating conditions of ship GTE. The HTC resistance of CrAl-Ti alloys improves upon reaching the ratio Ti/Al ˃ 1. Meanwhile, the ratio Ti/Al ˂ 1 promotes the formation of corrosion products with low protective properties. The positive effect of tantalum on the HTC resistance of alloys is manifested at higher test temperatures than that of titanium, and the total content of molybdenum and tungsten in alloys is limited by the condition 8Mo2 – 2W2 = 89. The presence of refractory elements stabilizes the strengthening phase and prevents formation of the ɳ-phase. However, their excess promotes formation of the embrittling topologically close packed (TCP) phases and boundary carbides of an unfavorable morphology. Based on the studies of the HTC resistance, there has been identified a class of model high-temperature corrosionresistant nickel alloys with a moderate or high chromium content (30%), Ti/Al ˃ 1, and a balanced content of refractory and rare-earth elements.

Application of vacuum belt press filters for cane mud filtration and performance comparison with rotary filters

2014 ◽  
pp. 298-301 ◽  
Author(s):  
Arnaud Petit
Keyword(s):  
Electricity Consumption ◽  
Performance Comparison ◽  
Operating Conditions ◽  
Vacuum Filter ◽  
Sugar Mill ◽  
Belt Press ◽  
Vacuum Belt ◽  
And Performance ◽  
Mud Filtration ◽  
The Impact

Bois-Rouge factory, an 8000 t/d cane Reunionese sugarcane mill, has fully equipped its filtration station with vacuum belt press filters since 2010, the first one being installed in 2009. The present study deals with this 3-year experience and discusses operating conditions, electricity consumption, performance and optimisation. The comparison with the more classical rotary drum vacuum filter station of Le Gol sugar mill highlights advantages of vacuum belt press filters: high filtration efficiency, low filter cake mass and sucrose content, low total solids content in filtrate and low power consumption. However, this technology needs a mud conditioning step and requires a large amount of water to improve mud quality, mixing of flocculant and washing of filter belts. The impact on the energy balance of the sugar mill is significant. At Bois-Rouge mill, studies are underway to reduce the water consumption by recycling low d.s. filtrate and by dry cleaning the filter belts.

Influence of temperature and humidity on the angle of repose of wood bulk materials

2016 ◽  
Author(s):  
И.В. Бачериков ◽  
Б.М. Локштанов
Keyword(s):  
Field Experiments ◽  
Bulk Material ◽  
Average Particle Size ◽  
Operating Conditions ◽  
Angle Of Repose ◽  
Wood Dust ◽  
Average Particle ◽  
Bulk Materials ◽  
Technical Literature ◽  
The Impact

При проектировании открытых и закрытых хранилищ измельченных сыпучих материалов древесных материалов, таких как щепа и опилки, большое значение имеет угол естественного откоса (статический и динамический) этих материалов. В технической литературе приводятся противоречивые сведения о величине этих углов, что приводит к ошибкам при проектировании складов. В справочных данных не учитываются условия, в которых эксплуатируются емкости для хранения сыпучих материалов, свойства и состояние этих сыпучих материалов. В свою очередь, ошибки при проектировании приводят к проблемам (зависание, сводообразование, «затопление» и т. д.) и авариям при эксплуатации бункеров и силосов на производстве. В статье представлены сведения, посвященные влиянию влажности и температуры на угол естественного откоса сыпучих материалов. На основании лабораторных и натурных экспериментов, проведенных с помощью специально разработанных методик и установок, была скорректирована формула для определения углов естественного откоса (статического и динамического) для измельченных древесных материалов в зависимости от их фракционного и породного состава, влажности (абсолютной и относительной) и температуры. При помощи скорректированной формулы можно определить угол естественного откоса древесных сыпучих материалов со среднегеометрическим размером частицы от 0,5 мм до 15 мм (от древесной пыли до технологической щепы) в различных производственных условиях. Статья может быть полезна проектировщикам при расчете угла наклона граней выпускающей воронки бункеров и силосов предприятий лесной отрасли и целлюлозо-бумажной промышленности. In the design of open and closed storage warehouses chopped wood materials for bulk materials such as wood chips and sawdust, great importance has an angle of repose (static and dynamic) of these materials. In the technical literature are conflicting reports about the magnitude of these angles, which leads to errors in the design of warehouses. In the referencesdoes not take into account the conditions under which operated capacities for storage of bulk materials, and properties and condition of the bulk material. The design errors lead to problems (hanging, arching, «flooding», etc.) and accidents in the operation of hoppers and silos at the mills. The article provides information on the impact of humidity and temperature on the angle of repose of granular materials. On the basis of laboratory and field experiments, conducted with the help of specially developed techniques and facilities has been adjusted formula for determining the angle of repose (static and dynamic) for the shredded wood materials depending on their fractional and species composition, humidity (absolute and relative) and temperature. It is possible, by using the corrected formula, to determine the angle of repose of loose wood materials with average particle size of from 0.5 mm to 15 mm (wood dust to pulpchips) in various operating conditions. The article can be helpful to designers in the calculation of the angle of inclination of the funnel faces produces bunkers and silos forest industries and pulp and paper industry.

scholarly journals Tanning Wastewater Treatment by Ultrafiltration: Process Efficiency and Fouling Behavior

Membranes ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 461
Author(s):  
Fu Yang ◽  
Zhengkun Huang ◽  
Jun Huang ◽  
Chongde Wu ◽  
Rongqing Zhou ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Shear Rate ◽  
Membrane Surface ◽  
Filtration Efficiency ◽  
Operating Conditions ◽  
Process Efficiency ◽  
Transmembrane Pressure ◽  
Leather Industry ◽  
Pore Blocking ◽  
The Impact

Ultrafiltration is a promising, environment-friendly alternative to the current physicochemical-based tannery wastewater treatment. In this work, ultrafiltration was employed to treat the tanning wastewater as an upstream process of the Zero Liquid Discharge (ZLD) system in the leather industry. The filtration efficiency and fouling behaviors were analyzed to assess the impact of membrane material and operating conditions (shear rate on the membrane surface and transmembrane pressure). The models of resistance-in-series, fouling propensity, and pore blocking were used to provide a comprehensive analysis of such a process. The results show that the process efficiency is strongly dependent on the operating conditions, while the membranes of either PES or PVDF showed similar filtration performance and fouling behavior. Reversible resistance was the main obstacle for such process. Cake formation was the main pore blocking mechanism during such process, which was independent on the operating conditions and membrane materials. The increase in shear rate significantly increased the steady-state permeation flux, thus, the filtration efficiency was improved, which resulted from both the reduction in reversible resistance and the slow-down of fouling layer accumulate rate. This is the first time that the fouling behaviors of tanning wastewater ultrafiltration were comprehensively evaluated, thus providing crucial guidance for further scientific investigation and industrial application.

scholarly journals Ethanol/Gasoline Blends as Alternative Fuel in Last Generation Spark-Ignition Engines: A Review on CO and HC Engine Out Emissions

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 4034
Author(s):  
Paolo Iodice ◽  
Massimo Cardone
Keyword(s):  
Physicochemical Properties ◽  
Alternative Fuels ◽  
Experimental Studies ◽  
Alternative Fuel ◽  
Exhaust Emissions ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Spark Ignition Engines ◽  
The Impact

Among the alternative fuels existing for spark-ignition engines, ethanol is considered worldwide as an important renewable fuel when mixed with pure gasoline because of its favorable physicochemical properties. An in-depth and updated investigation on the issue of CO and HC engine out emissions related to use of ethanol/gasoline fuels in spark-ignition engines is therefore necessary. Starting from our experimental studies on engine out emissions of a last generation spark-ignition engine fueled with ethanol/gasoline fuels, the aim of this new investigation is to offer a complete literature review on the present state of ethanol combustion in last generation spark-ignition engines under real working conditions to clarify the possible change in CO and HC emissions. In the first section of this paper, a comparison between physicochemical properties of ethanol and gasoline is examined to assess the practicability of using ethanol as an alternative fuel for spark-ignition engines and to investigate the effect on engine out emissions and combustion efficiency. In the next section, this article focuses on the impact of ethanol/gasoline fuels on CO and HC formation. Many studies related to combustion characteristics and exhaust emissions in spark-ignition engines fueled with ethanol/gasoline fuels are thus discussed in detail. Most of these experimental investigations conclude that the addition of ethanol with gasoline fuel mixtures can really decrease the CO and HC exhaust emissions of last generation spark-ignition engines in several operating conditions.

scholarly journals Modeling Bacterial Regrowth and Trihalomethane Formation in Water Distribution Systems

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 463
Author(s):  
Gopinathan R. Abhijith ◽  
Leonid Kadinski ◽  
Avi Ostfeld
Keyword(s):  
Distribution Systems ◽  
Water Distribution ◽  
Mechanistic Model ◽  
Water Distribution Systems ◽  
Sensitivity Study ◽  
Operating Conditions ◽  
Growth Rate Constant ◽  
Model Parameters ◽  
Bacterial Regrowth ◽  
The Impact

The formation of bacterial regrowth and disinfection by-products is ubiquitous in chlorinated water distribution systems (WDSs) operated with organic loads. A generic, easy-to-use mechanistic model describing the fundamental processes governing the interrelationship between chlorine, total organic carbon (TOC), and bacteria to analyze the spatiotemporal water quality variations in WDSs was developed using EPANET-MSX. The representation of multispecies reactions was simplified to minimize the interdependent model parameters. The physicochemical/biological processes that cannot be experimentally determined were neglected. The effects of source water characteristics and water residence time on controlling bacterial regrowth and Trihalomethane (THM) formation in two well-tested systems under chlorinated and non-chlorinated conditions were analyzed by applying the model. The results established that a 100% increase in the free chlorine concentration and a 50% reduction in the TOC at the source effectuated a 5.87 log scale decrement in the bacteriological activity at the expense of a 60% increase in THM formation. The sensitivity study showed the impact of the operating conditions and the network characteristics in determining parameter sensitivities to model outputs. The maximum specific growth rate constant for bulk phase bacteria was found to be the most sensitive parameter to the predicted bacterial regrowth.

scholarly journals A New Method to Determine the Impact of Individual Field Quantities on Cycle-to-Cycle Variations in a Spark-Ignited Gas Engine

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4136
Author(s):  
Clemens Gößnitzer ◽  
Shawn Givler
Keyword(s):  
Kinetic Energy ◽  
Flow Field ◽  
Turbulent Kinetic Energy ◽  
Negative Impact ◽  
Operating Conditions ◽  
Engine Operation ◽  
Gas Engine ◽  
Cycle Simulation ◽  
Simulation Results ◽  
The Impact

Cycle-to-cycle variations (CCV) in spark-ignited (SI) engines impose performance limitations and in the extreme limit can lead to very strong, potentially damaging cycles. Thus, CCV force sub-optimal engine operating conditions. A deeper understanding of CCV is key to enabling control strategies, improving engine design and reducing the negative impact of CCV on engine operation. This paper presents a new simulation strategy which allows investigation of the impact of individual physical quantities (e.g., flow field or turbulence quantities) on CCV separately. As a first step, multi-cycle unsteady Reynolds-averaged Navier–Stokes (uRANS) computational fluid dynamics (CFD) simulations of a spark-ignited natural gas engine are performed. For each cycle, simulation results just prior to each spark timing are taken. Next, simulation results from different cycles are combined: one quantity, e.g., the flow field, is extracted from a snapshot of one given cycle, and all other quantities are taken from a snapshot from a different cycle. Such a combination yields a new snapshot. With the combined snapshot, the simulation is continued until the end of combustion. The results obtained with combined snapshots show that the velocity field seems to have the highest impact on CCV. Turbulence intensity, quantified by the turbulent kinetic energy and turbulent kinetic energy dissipation rate, has a similar value for all snapshots. Thus, their impact on CCV is small compared to the flow field. This novel methodology is very flexible and allows investigation of the sources of CCV which have been difficult to investigate in the past.

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