Search results for: TEMPERATURE DUALISM OF THE RAYLEIGH NUMBER
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On the differential effect of temperature on the Nusselt-Rayleigh relationship in free convection
PublicationThe aim of and inspiration behind this paper was to explain the reasons, also observed by other researchers, of the discrepancy in the results of experimental free convection, which for small Rayleigh and Nusselt numbers in the initial phase of research can sometimes reach several hundred percent. These discrepancies decrease with increasing heating power and plate surface temperature, in proportion to the increase in Ra and Nu,...
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Method to determine the critical concentration Rayleigh number in isothermal passive membrane transport processes
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Flow structure, heat transfer and scaling analysis in the case of thermo-magnetic convection in a differentially heated cylindrical enclosure
PublicationThe experimental, numerical and scaling analysis in the case of thermo-magnetic convection in a thermosyphon-like enclosure filled with a paramagnetic fluid is presented. Visualization of temperature field together with the numerical simulation gave an information about the flow structure, which indicated “finger-like” structures of hot and cold streams advecting each other. Their number depended on the Rayleigh number and also...
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Effect of Temperature and Nanoparticle Concentration on Free Convective Heat Transfer of Nanofluids
PublicationA theoretical analysis of the influence of temperature and nanoparticle concentration on free convection heat transfer from a horizontal tube immersed in an unbounded nanofluid was presented. The Nusselt (Nu) number and heat transfer coefficient were parameters of the intensity of the convective heat transfer. For free convection, the Nu number was a function of the Rayleigh (Ra) number and Prandtl (Pr) number. The Rayleigh (Ra)...
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Numerical simulation of natural convection of Glycol-Al2O3 nanofluids from a horizontal cylinder
PublicationThis paper deals with natural convection around a circular cylinder with constant heat flux in a cavity using computational fluid dynamics. As fluids ethylene glycol and a mixture of ethylene glycol with Al2O3 nanoparticles (mass concentrations of nanoparticles: 0.1% and 1%) are chosen. Rayleigh number ranges from 3104 to 3105. The nanofluids are modeled with single-phase approach. For the investigated range of nanoparticle concentration, the...
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Free Convection Heat Transfer from Horizontal Cylinders
PublicationThe results of experimental investigation of free convection heat transfer in a rectangular container are presented. The ability of the commonly accepted correlation equations to reproduce present experimental data was tested as well. It was assumed that the examined geometry fulfils the requirement of no-interaction between heated cylinder and bounded surfaces. In order to check this assumption recently published correlation equations...
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Computational analysis of power-law fluids for convective heat transfer in permeable enclosures using Darcy effects
PublicationNatural convection is a complex environmental phenomenon that typically occurs in engineering settings in porous structures. Shear thinning or shear thickening fuids are characteristics of power-law fuids, which are non-Newtonian in nature and fnd wide-ranging uses in various industrial processes. Non-Newtonian fuid fow in porous media is a difcult problem with important consequences for energy systems and heat transfer. In this...
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Natural convection in symmetrically heated vertical channels
PublicationThe study describes natural convection through a vertical channel, open on four sides and bound by two isothermal walls. Both balancing and infrared experimental investigations were performed in air (Pr = 0.71) to estimate the impact of channel width s and wall-to-ambient temperature difference (tw - t∞) on natural convective heat transfer, the formation of air flow patterns and the rate of flow pattern formation. The study was...
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Experimental Investigation of Free Convection Heat Transfer from Horizontal Cylinder to Nanofluids
PublicationThe results of free convection heat transfer investigation from a horizontal, uniformly heated tube immersed in a nanofluid are presented. Experiments were performed with five base fluids, i.e., ethylene glycol (EG), distilled water (W) and the mixtures of EG and water with the ratios of 60/40, 50/50, 40/60 by volume, so the Rayleigh (Ra) number range was 3 104 Ra 1.3 106 and the Prandtl (Pr) number varied from 4.4 to 176....
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Natural convective heat transfer from isothermal cuboids
PublicationThe paper presents results of theoretical and experimental investigations of the convective heat transfer from isothermal cuboid. The analytical solution was performed taking into account complete boundary layer length and the manner of its propagation around isothermal cuboid. It arises at horizontal bottom surface and grows on vertical lateral surface of the block. After changing its direction, the boundary layer occurs above...
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Application of shifted Chebyshev polynomial-based Rayleigh–Ritz method and Navier’s technique for vibration analysis of a functionally graded porous beam embedded in Kerr foundation
PublicationPresent study is dealt with the applicability of shifted Chebyshev polynomial based Rayleigh-Ritz method and Navier’s technique on free vibration of Functionally Graded (FG) beam with uniformly distributed porosity along the thickness of the beam. The material properties such as Young’s modulus, mass density, and Poisson’s ratio are also considered to vary along the thickness of the FG beam as per the power-law exponent model....
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Possibility of thermal imaging use in studies of natural convection heat transfer on the example of an isothermal vertical plate.
PublicationA new method of infrared (IR) camera use in convective heat transfer studies has been presented. Until now, IR cameras were utilized for temperature field visualizations of flat heated surfaces of solid objects only. Because liquids and gasses do not emit radiation in the infrared range of wave lengths, detection of temperature field in the air was conducted with the use of plastic mesh, which, after heating by hot air, emits infrared...
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Spatial distribution of CO2, O2, CO, NO and temperature within a biowaste composting pile
Open Research DataThe dataset contains the color-coded isophlets illustrating the spatial distribution of gas concentrations (CO, CO2, O2 and NO) and the temperature in biowaste composting pile during 6 weeks of process. Four cross sections and two longitudinal cross sections (the left and right sides of the pile) were made using Surfer 10 software (Golden Software,...
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Heat Transfer of the Multicolor-Laser-Sources-Irradiated Nanoparticles in Reference to Thermal Processes
PublicationUnlike the standard materials, metallic nanoparticles offer enhancing the heat convertion rate which implies the maximum and average temperature boost significantly in the considered system. The work’s purpose is to examine heat transfer in the metallic nanoparticles which have been deposited on a glassy substrate, enabling the nanostructures thermoablation. Furthermore, the functionalized substrate is irradiated with multicolor-laser-sources,...
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Measurements of the heat of hydration released by concrete specimens cured under adiabatic conditions
Open Research DataThe DataSet contains measurements of heat of hydartion of concrete cubes (150 x 150 x 150 mm) cured under adiabatic conditions. The specimens were moulded from six types of concrete mixtures produced in the laboratory conditions. Mix #1: Portland cement CEM I 42.5R and gravel aggregate, mix #2: CEM I 42.5R and basalt aggregate, mix#3: Portland-composite...
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Measured and predicted freeze-thaw days frequencies in climate change conditions in central Poland
PublicationThe rate of progression of geomorphological phenomena is greatly influenced by freeze-thaw processes. In the face of air temperature increasing over the past few decades, a question of the future impact of these processes arises, notably in the temperate and cold climate zones. Using the mean, maximum and minimum daily air temperature data in the period 1951–2018 obtained from three weather stations located in the vicinity of Jeziorsko...
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Performance of the very high-temperature heat pump with low GWP working fluids
PublicationTraditional heat pumps are a very attractive pro-ecological solutions for a number of applications, including providing of heating or heat recovery from industrial processes. The application range of heat pumps could be greatly enlarged when the operating temperature would be increased to 130-150°C and/or the temperature lift can be increased to 50-100 K. In the paper, the very high temperature vapour-compressor based single stage...
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Theoretical consideration of free convective heat transfer from a round isothermal plate slightly inclined from the vertical
PublicationA semi-analytical solution of simplified Navier-Stokes and Fourier-Kirchhoff equations describing free convective heat transfer from a round isothermal surface slightly inclined from the vertical is presented. The solution is based on the assumption, typical for natural convection, that the velocity component normal to the surface is negligibly small in comparison to the tangential one. Next we neglect the nonlinear inertia force...
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Impact of Temperature and Nanoparticle Concentration on Turbulent Forced Convective Heat Transfer of Nanofluids
PublicationTheoretical analysis of the influence of nanoparticles and temperature on the average Nusselt (Nu) number and the average heat transfer coefficient (HTC) during the turbulent flow of nanofluid in a horizontal, round tube was carried out. The Nu number is a function of the Reynolds (Re) number and the Prandtl (Pr) number, which in turn are functions of the thermophysical properties of the liquid and the flow conditions. On the other...
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3D printed ABS thermoplastic vs. steel. Dry sliding wear test in constant load & velocity ring on flat configuration. Test parameters: print layer thickness and orientation. Test symbol: 009_v_2
Open Research DataData gathered in sliding ring-on-block (flat contact) tribological experiment. Materials: alloy steel (heat treated) vs. ABS plastic.
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3D printed ABS thermoplastic vs. steel. Dry sliding wear test in constant load & velocity ring on flat configuration. Test parameters: print layer thickness and orientation. Test symbol: 009_v_3
Open Research DataData gathered in sliding ring-on-block (flat contact) tribological experiment. Materials: alloy steel (heat treated) vs. ABS plastic.
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3D printed ABS thermoplastic vs. steel. Dry sliding wear test in constant load & velocity ring on flat configuration. Test parameters: print layer thickness and orientation. Test symbol: 009_h_3
Open Research DataData gathered in sliding ring-on-block (flat contact) tribological experiment. Materials: alloy steel (heat treated) vs. ABS plastic.
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3D printed ABS thermoplastic vs. steel. Dry sliding wear test in constant load & velocity ring on flat configuration. Test parameters: print layer thickness and orientation. Test symbol: 019_v_5
Open Research DataData gathered in sliding ring-on-block (flat contact) tribological experiment. Materials: alloy steel (heat treated) vs. ABS plastic.
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3D printed ABS thermoplastic vs. steel. Dry sliding wear test in constant load & velocity ring on flat configuration. Test parameters: print layer thickness and orientation. Test symbol: 009_h_5
Open Research DataData gathered in sliding ring-on-block (flat contact) tribological experiment. Materials: alloy steel (heat treated) vs. ABS plastic.
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3D printed ABS thermoplastic vs. steel. Dry sliding wear test in constant load & velocity ring on flat configuration. Test parameters: print layer thickness and orientation. Test symbol: 009_h_4
Open Research DataData gathered in sliding ring-on-block (flat contact) tribological experiment. Materials: alloy steel (heat treated) vs. ABS plastic.
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3D printed ABS thermoplastic vs. steel. Dry sliding wear test in constant load & velocity ring on flat configuration. Test parameters: print layer thickness and orientation. Test symbol: 039_h_4
Open Research DataData gathered in sliding ring-on-block (flat contact) tribological experiment. Materials: alloy steel (heat treated) vs. ABS plastic.
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3D printed ABS thermoplastic vs. steel. Dry sliding wear test in constant load & velocity ring on flat configuration. Test parameters: print layer thickness and orientation. Test symbol: 019_v_4
Open Research DataData gathered in sliding ring-on-block (flat contact) tribological experiment. Materials: alloy steel (heat treated) vs. ABS plastic.
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3D printed ABS thermoplastic vs. steel. Dry sliding wear test in constant load & velocity ring on flat configuration. Test parameters: print layer thickness and orientation. Test symbol: 019_h_5
Open Research DataData gathered in sliding ring-on-block (flat contact) tribological experiment. Materials: alloy steel (heat treated) vs. ABS plastic.
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3D printed ABS thermoplastic vs. steel. Dry sliding wear test in constant load & velocity ring on flat configuration. Test parameters: print layer thickness and orientation. Test symbol: 039_v_4
Open Research DataData gathered in sliding ring-on-block (flat contact) tribological experiment. Materials: alloy steel (heat treated) vs. ABS plastic.
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3D printed ABS thermoplastic vs. steel. Dry sliding wear test in constant load & velocity ring on flat configuration. Test parameters: print layer thickness and orientation. Test symbol: 009_v_4
Open Research DataData gathered in sliding ring-on-block (flat contact) tribological experiment. Materials: alloy steel (heat treated) vs. ABS plastic.
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3D printed ABS thermoplastic vs. steel. Dry sliding wear test in constant load & velocity ring on flat configuration. Test parameters: print layer thickness and orientation. Test symbol: 039_v_3
Open Research DataData gathered in sliding ring-on-block (flat contact) tribological experiment. Materials: alloy steel (heat treated) vs. ABS plastic.
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3D printed ABS thermoplastic vs. steel. Dry sliding wear test in constant load & velocity ring on flat configuration. Test parameters: print layer thickness and orientation. Test symbol: 019_v_3
Open Research DataData gathered in sliding ring-on-block (flat contact) tribological experiment. Materials: alloy steel (heat treated) vs. ABS plastic.
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3D printed ABS thermoplastic vs. steel. Dry sliding wear test in constant load & velocity ring on flat configuration. Test parameters: print layer thickness and orientation. Test symbol: 019_h_3
Open Research DataData gathered in sliding ring-on-block (flat contact) tribological experiment. Materials: alloy steel (heat treated) vs. ABS plastic.
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3D printed ABS thermoplastic vs. steel. Dry sliding wear test in constant load & velocity ring on flat configuration. Test parameters: print layer thickness and orientation. Test symbol: 039_h_5
Open Research DataData gathered in sliding ring-on-block (flat contact) tribological experiment. Materials: alloy steel (heat treated) vs. ABS plastic.
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3D printed ABS thermoplastic vs. steel. Dry sliding wear test in constant load & velocity ring on flat configuration. Test parameters: print layer thickness and orientation. Test symbol: 019_h_4
Open Research DataData gathered in sliding ring-on-block (flat contact) tribological experiment. Materials: alloy steel (heat treated) vs. ABS plastic.
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3D printed ABS thermoplastic vs. steel. Dry sliding wear test in constant load & velocity ring on flat configuration. Test parameters: print layer thickness and orientation. Test symbol: 039_v_2
Open Research DataData gathered in sliding ring-on-block (flat contact) tribological experiment. Materials: alloy steel (heat treated) vs. ABS plastic.
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3D printed ABS thermoplastic vs. steel. Dry sliding wear test in constant load & velocity ring on flat configuration. Test parameters: print layer thickness and orientation. Test symbol: 039_h_3
Open Research DataData gathered in sliding ring-on-block (flat contact) tribological experiment. Materials: alloy steel (heat treated) vs. ABS plastic.
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An inclination in Thermal Energy Using Nanoparticles with Casson Liquid Past an Expanding Porous Surface
PublicationPhysical aspects of inclined MHD nanofluid towards a stretching sheet embedded in a porous medium are visualized. Two types of nanoparticles are used named as copper and alumna dioxide with water as base fluid. Similarity transformations are used to convert the partial differential equations into the set of ordinary differential equation. Closed solutions are found to examine the velocity and the temperature profiles. It is examined...
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Field investigation of low-temperature cracking and stiffness moduli on selected roads with conventional and high modulus asphalt concrete
PublicationHigh Modulus Asphalt Concrete (HMAC) was introduced in Poland as a one of the solutions to the problem of rutting, type of deterioration common in the 1990s. After first encouraging trials in 2002 HMAC was widely used for heavily loaded national roads and motorways. However some concerns were raised about low-temperature cracking of HMAC. This was the main reason of the studies presented in this article were started. The article...
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Thermal visualization of Ostwald-de Waele liquid in wavy trapezoidal cavity: Effect of undulation and amplitude
PublicationThe present study is concerned with the numerical simulations of Ostwald-de Waele fluid flow in a wavy trapezoidal cavity in the presence of a heated cylinder situated at the center of the cavity. The work consists in characterizing the mixed convection as a function of the intensity of heat flow. The flow behaviour and temperature distribution in a cavity are the main focus of this study. The lower wall of the cavity is fixed...
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Field Evaluation of High Modulus Asphalt Concrete Resistance to Low-Temperature Cracking
PublicationHigh-modulus asphalt concrete has numerous advantages in comparison to conventional asphalt concrete, including increased resistance to permanent deformations and increased pavement fatigue life. However, previous studies have shown that the construction of road pavements with High Modulus Asphalt Concrete (HMAC) may significantly increase the risk of low-temperature cracking. Those observations were the motivation for the research...
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High-temperature heat pumps – new devices for heat recovery and production of technological steam
PublicationIn the paper, the original high temperature compressor based heat pump with a dry working fluid, i.e. the one in which the slope of saturated vapour line is positive, was presented. The objective of the paper is to investigate the possibility of preparation of technological steam with tempperature 120 C from the waste heat resource at temperature of 50 C. Single comppression cycles as well as cascade systems have been considered...
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Electromagnetic Control and Dynamics of Generalized Burgers’ Nanoliquid Flow Containing Motile Microorganisms with Cattaneo–Christov Relations: Galerkin Finite Element Mechanism
PublicationIn our research work, we have developed a model describing the characteristics of the bio-convection and moving microorganisms in the flows of a magnetized generalized Burgers’ nanoliquid with Fourier’s and Fick’s laws in a stretchable sheet. Considerations have been made to Cattaneo–Christov mass and heat diffusion theory. According to the Cattaneo–Christov relation, the Buongiorno phenomenon for the motion of a nanoliquid in...
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Theoretical examination of the fracture behavior of BC3 polycrystalline nanosheets: Effect of crack size and temperature
Publication2D carbon graphene nanostructures are elements of advanced materials and systems. This theoretical survey provides explanation to the mechanical and fracture behavior of mono- and polycrystalline BC3 nanosheets (denoted as MC- and PCBC3NS, respectively) as a function of temperature and the type of crack defects. The mechanical performance of PCBC3NS at elevated temperatures was monitored varying the number of grain boundaries (the...
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Spectroscopic study of atmospheric pressure 915 MHz microwave plasma at high argon flow rate
PublicationIn this paper results of optical emission spectroscopic (OES) study of atmospheric pressure microwave 915 MHz argon plasma are presented. The plasma was generated in microwave plasma source (MPS) cavity- resonant type. The aim of research was determination of electron excitation temperature Texc gas temperature Tg and electron number density ne. All experimental tests were performed with a gas flow rate of 100 and 200 l/min and...
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ATTEMPTS OF THERMAL IMAGING CAMERA USAGE IN ESTIMATIONS OF THE CONVECTIVE HEAT LOSS FROM A VERTICAL PLATE
PublicationIn this paper a new method for determining heat transfer coefficients using a gradient method has been developed. To verify accuracy of the proposed method vertical isothermal heating plate with natural convection mechanism has been examined. This configuration was deliberately chosen, because of the fact that such case is historically the earliest and most thoroughly studied and its rich scientific documentation - the most reliable....
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Pressure drop and heat transfer during boiling and condensation at subcritical region
PublicationMost of the data presented in the literature relate to saturation temperatures in the range - 20°C to 40°C due to the application in refrigeration technology. There is necessity to extend databases to higher values of saturation temperature due to new applications such as Organic Rankine Cycle and high temperature heat pumps. Only few papers contain data for high reduced pressure for low boiling point liquids. This paper focus...
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Taguchi sensors under temperature modulation
PublicationSemiconductor gas sensors are widely used in gas- analyzing applications for various gas species determination due to their low cost and possibility to detect number of different gases. However, one of the main problems with such sensors is their lack of selectivity. To overcome this issue different ap- proaches can be used. One of them is the operation with sensor temperature modulation combined with dedicated data process- ing...
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Natural convective heat transfer from isothermalconic
PublicationTheoretical considerations on convective heat transfer from isothermal upward conicalsurfaces have been presented. The physical model of this phenomenon consists of an isothermalcone of inclination angle (φ) between the cone generating line (X) and the radius (R) of the cone base. The angle is a parameter of conical surface which varied from (φ = 0−circular horizontal plate) to (φ = π/2—vertical cylinder) . Onthe basis of Navier–Stokes...
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Steady magnetohydrodynamic flow in a diverging channel with suction or blowing
PublicationAn analysis is made of steady two-dimensional divergent flow of an electrically conducting incompressible viscous fluid in a channel formed by two non-parallel walls, the flow being caused by a source of fluid volume at the intersection of the walls. The fluid is permeated by a magnetic field produced by an electric current along the line of intersection of the channel walls. The walls are porous and subjected to either suction...