Статті в журналах: "Heat transfer intensity"

1

Hu, Gui Chuan, and Jing Hua Liu. "Thermo-Mechanical Couple Analysis of Cylinder Head Joint with Quadratic Contact." Advanced Materials Research 871 (December 2013): 141–44. http://dx.doi.org/10.4028/www.scientific.net/amr.871.141.

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Finite element simulation technology was applied to the steady heat transfer and thermo-mechanical coupling analysis in order to investigate the influence of thermal load on stress intensity and sealing performance. An finite element heat transfer model of cylinder head joint assembly was set up, based on which the steady heat transfer analysis was performed subsequently by applying reasonable boundary conditions and loads. The influence on cylinder head sealing performance due to thermal field under the thermal stress conditions was evaluated by using the finite element method. The results showed that the thermal load increases the bolt tensile force and the gasket pressure, which help to improve the sealing performance. Compared to the mechanical load case, the thermo-mechanical stress of the liner and the cylinder head is obviously increased, so the thermal load is not neglectable when calculating the stress intensity of the cylinder head and the cylinder liner.

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2

Hu, Gui Chuan, and Jing Hua Liu. "The Thermo-Mechanical Couple Analysis Base on Assembly." Applied Mechanics and Materials 467 (December 2013): 416–19. http://dx.doi.org/10.4028/www.scientific.net/amm.467.416.

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Finite element simulation technology was applied to the steady heat transfer and thermo-mechanical coupling analysis in order to investigate the influence of thermal load on stress intensity and sealing performance. An finite element heat transfer model of cylinder head joint assembly was set up, based on which the steady heat transfer analysis was performed subsequently by applying reasonable boundary conditions and loads. The influence on cylinder head sealing performance due to thermal field under the thermal stress conditions was evaluated by using the finite element method. The results showed that the thermal load increases the bolt tensile force and the gasket pressure, which help to improve the sealing performance. Compared to the mechanical load case, the thermo-mechanical stress of the liner and the cylinder head is obviously increased, so the thermal load is not neglect able when calculating the stress intensity of the cylinder head and the cylinder liner.

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3

Kindzera, Diana, Roman Hosovskyi, Volodymyr Atamanyuk, and Dmytro Symak. "Heat Transfer Process During Filtration Drying of Grinded Sunflower Biomass." Chemistry & Chemical Technology 15, no. 1 (February 15, 2021): 118–24. http://dx.doi.org/10.23939/chcht15.01.118.

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Filtration drying of grinded sunflower stems as the unit operation of the technological line for solid biofuel production has been proposed. Theoretical aspects of heat transfer processes during filtration drying have been analyzed. The effect of the drying agent velocity increase from 0.68 to 2.05 m/s on the heat transfer intensity has been established. The values of heat transfer coefficients have been calculated on the basis of the thin-layer experimental data and equation . Calculated coefficients for grinded sunflower stems have been correlated by the dimensionless expression within Reynolds number range of and the equation has been proposed to calculate the heat transfer coefficients, that is important for forecasting the heat energy costs at the filtration drying equipment design stage.

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4

Plotnikov, L. V., Y. M. Brodov, and M. O. Misnik. "Heat transfer intensity of pulsating gas flows in the exhaust system elements of a piston engine." E3S Web of Conferences 124 (2019): 01015. http://dx.doi.org/10.1051/e3sconf/201912401015.

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Internal combustion engines are the most common sources of energy among heat engines. Therefore, the improvement of their design and workflow is an urgent task in the development of world energy. Thermal-mechanical perfection of the exhaust system has a significant impact on the technical and economic performance of piston engines. The article presents the results of experimental studies of gas-dynamics and heat exchange of pulsating gas flows in the exhaust system of a piston engine. Studies were carried out on a full-scale model of a single-cylinder engine. The article describes the instrument-measuring base and methods of experiments. The heat transfer intensity was estimated in different elements of the exhaust system: the exhaust pipe, the channel in the cylinder head, the valve assembly. Heat transfer studies were carried out taking into account the gas-dynamic nonstationarity characteristic of gas exchange processes in engines. The article presents data on the influence of gas-dynamic and regime factors on the heat transfer intensity. It is shown that the restructuring of the gas flow structure in the exhaust system occurs depending on the engine crankshaft speed, this has a significant impact on the local heat transfer coefficient. It has been established that the heat transfer intensity in the valve assembly is 2-3 times lower than in other elements of the exhaust system.

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5

Chernica, I. M., M. K. Bologa, O. V. Motorin, and I. V. Kozhevnikov. "Enhancement of heat transfer at boiling in electrohydrodynamic flow." Journal of Physics: Conference Series 2088, no. 1 (November 1, 2021): 012005. http://dx.doi.org/10.1088/1742-6596/2088/1/012005.

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Abstract The influence of the electric field strength and interelectrode spacing on the heat transfer intensity at boiling in an electrohydrodynamic flow was studied. It was stated that the heat transfer coefficient increases with the increasing of the field strength. The influence of the interelectrode spacing is ambiguous. The efficiency of the action of a electrohydrodynamic flow on the heat transfer intensity at boiling was evaluated using the ratio of the heat transfer coefficient at boiling in the field to the heat transfer coefficient at boiling without the field. The relationships for calculation were obtained that satisfactorily agree with the experimental data.

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6

Wang, Zhao Hui, and Guohua Chen. "Heat and mass transfer during low intensity convection drying." Chemical Engineering Science 54, no. 17 (September 1999): 3899–908. http://dx.doi.org/10.1016/s0009-2509(98)00408-4.

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7

Derevich, I. V., and L. I. Zaichik. "Influence of particles on the turbulent heat-transfer intensity." Journal of Engineering Physics 48, no. 4 (April 1985): 403–8. http://dx.doi.org/10.1007/bf00872062.

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8

Stepanov, Oleg, Boris Aksenov, Natalia Rydalina, and Elena Antonova. "Heat-exchange units with porous inserts." E3S Web of Conferences 140 (2019): 05006. http://dx.doi.org/10.1051/e3sconf/201914005006.

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Currently, porous metals are not used in heat supply systems. Usage of porous materials in heat exchangers increases the heat transfer intensity and makes the heat exchangers more compact. An experimental setup consisting of two circuits was developed in order to study the influence of porous metals on heat transfer intensity. In the first circuit the hot coolant is water, which flows through narrow tubes inside the porous metal. In the second circuit the cold coolant is freon. The purpose of the study is to obtain experimental confirmation of the hypothesis of an increase in the heat transfer intensity when using porous metals. To achieve this goal, experiments were carried out, which showed the increased heat transfer intensity. The standard methods for calculating heat exchangers cannot be applied in this case as the inner pores’ surface is unknown. A mathematical model was compiled allowing engineering calculations for the heat exchangers of this type. The hot water temperature inside the heat exchanger is determined analytically. The resulting equation allows us to determine the cooling degree of the first coolant, i.e. hot water. The obtained deviations between experimental and analytical data are within the acceptable limits, which indicates the reliability of the proposed model.

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9

Saponenko, Dmitry, and Boris Semenov. "A source-sink approach for computation of intensity of low-potential underground heat non-stationary extraction." Energy Safety and Energy Economy 5 (November 2020): 28–36. http://dx.doi.org/10.18635/2071-2219-2020-5-28-36.

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A new methodology for estimation of changing intensity characteristics of non-stationary heat transfer in underground heat extraction by a single-pipe upright heat exchanger is presented in this paper. Major trends in changing of a heat removal volume, linear heat transfer coefficient, linear heat transfer resistance, and heat sink radius have been estimated for specific ground types. Also a generalized one-factor linear semilogarythmic equation has been developed for specific ground types, along with an appropriate approximating function intended to simplify the underground heat extraction intensity estimation methodology.

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10

Li, Zhi, Zhong Min Li, and Jun Guo. "Heat Transfer and Flow Characteristics of Liquid Nitrogen Laminar Fulling Films in Cryogenic Heat Transfer." Applied Mechanics and Materials 148-149 (December 2011): 1514–18. http://dx.doi.org/10.4028/www.scientific.net/amm.148-149.1514.

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This paper studies the characteristics of both the dynamic heat and mass transfer of liquid nitrogen thin film which have vital significance to improve heat transfer efficiency and optimize the cryogenic heat exchanger. Liquid nitrogen laminar film flows in the brazed cryogenic heat exchanger with 2.3mm distance between plates. Relationship between the dimensionless thickness and the coefficient of heat convection of liquid nitrogen film is derived. And the impact of rate of vapor content, intensity of interfacial convection heat transfer and Reynolds numbers are calculated and analyzed.

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11

Ames, F. E. "The Influence of Large-Scale High-Intensity Turbulence on Vane Heat Transfer." Journal of Turbomachinery 119, no. 1 (January 1, 1997): 23–30. http://dx.doi.org/10.1115/1.2841007.

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An experimental research program was undertaken to examine the influence of large-scale high-intensity turbulence on vane heat transfer. The experiment was conducted in a four-vane linear cascade at exit Reynolds numbers of 500,000 and 800,000 based on chord length. Heat transfer measurements were made for four inlet turbulence conditions including a low turbulence case (Tu ≅ 1 percent), a grid turbulence case (Tu ≅ 7.5 percent), and two levels of large-scale turbulence generated with a mock combustor at two upstream locations (Tu ≅ 12 percent and 8 percent). The heat transfer data demonstrated that the length scale, Lu, has a significant effect on stagnation region and pressure surface heat transfer.

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12

Gau, C., W. Y. Sheu, and C. H. Shen. "Impingement Cooling Flow and Heat Transfer Under Acoustic Excitations." Journal of Heat Transfer 119, no. 4 (November 1, 1997): 810–17. http://dx.doi.org/10.1115/1.2824187.

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Experiments are performed to study (a) slot air jet impingement cooling flow and (b) the heat transfer under acoustic excitations. Both flow visualization and spectral energy evolution measurements along the shear layer are made. The acoustic excitation at either inherent or noninherent frequencies can make the upstream shift for both the most unstable waves and the resulting vortex formation and its subsequent pairing processes. At inherent frequencies the most unstable wave can be amplified, which increases the turbulence intensity in both the shear layer and the core and enhances the heat transfer. Both the turbulence intensity and the heat transfer increase with increasing excitation pressure levels Spl until partial breakdown of the vortex occurs. At noninherent frequencies, however, the most unstable wave can be suppressed, which reduces the turbulence intensity and decreases the heat transfer. Both the turbulence intensity and the heat transfer decreases with increasing Spl, but increases with increasing Spl when the excitation frequency becomes dominant. For excitation at high Reynolds number with either inherent or noninherent frequency, a greater excitation pressure level is needed to cause the enhancement or the reduction in heat transfer. During the experiments, the inherent frequencies selected for excitation are Fo/2 and Fo/4, the noninherent frequencies are 0.71 Fo, 0.75 Fo, and 0.8 Fo, the acoustic pressure level varies from 70 dB to 100 dB, and the Reynolds number varies from 5500 to 22,000.

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13

Turmukhambetov, A. Zh. "FRACTAL-STRUCTURAL ANALYSIS OF CONVECTION HEAT TRANSFER IN A TURBULENT MEDIUM." Eurasian Physical Technical Journal 17, no. 2 (December 24, 2020): 61–68. http://dx.doi.org/10.31489/2020no2/61-68.

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The features of convective heat transfer of bodies in a turbulent environment are considered. The results of experimental research by one of the authors are discussed. Experimental data show that the heat transfer of a spherical body is affected by natural convection, the thermo-physical properties of the medium, the tightness of the flow, the turbulent flow regime, etc. Due to these factors, the formula for calculating convective heat transfer, which includes many experimental constants, becomes cumbersome and inconvenient for practical application. The paper presents the results of applying fractal-structural analysis methods to describe experimental data on convective heat exchange of badly streamlined (cylinder and sphere) bodies in a channel. Quantitative relations are obtained that link the intensity of turbulent heat transfer with the criteria for the degree of self-organization.

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14

Nedbailo, O. M., and O. G. Chernyshyn. "Features of heat and mass transfer at drying of ceramic products with overglaze paints." Кераміка: наука і життя, no. 2(51) (June 25, 2021): 7–12. http://dx.doi.org/10.26909/csl.2.2021.1.

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The basic results of researches of process of a heat exchange are instanced and parsed at drying glasour ceramic colors. Character of change of importance number of Rebinder is established at drying colors and dependence of intensity of a heat dissipation on velocity of air is spotted. The main results of researches of heat and mass transfer process at drying of overglaze ceramic paints in a stream of drying agent are resulted and analyzed. The nature of the change in the value of the Rebinder number for drying paints is established and the dependence of the heat transfer intensity on the air velocity is determined. Analysis of the temperature coefficient of drying and Rebinder's number determined the directions of heat consumption in the drying process of overglaze ceramic paints. It is established that the heat flux density depends on the temperature and velocity of the coolant and does not depend on the chemical composition of the paints. It is shown that the heat transfer coefficient depends on the velocity of the coolant. Compared with heat transfer during laminar flow around the plate during drying, the intensity of heat transfer increases by 75%.

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15

Kocheril, Rajesh, and Jacob Elias. "CFD simulation for evaluation of optimum heat transfer rate in a heat exchanger of an internal combustion engine." International Journal for Simulation and Multidisciplinary Design Optimization 11 (2020): 6. http://dx.doi.org/10.1051/smdo/2019017.

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Heat exchanger is an essential component of an engine cooling system. Radiators are compact heat exchangers used to transfer the heat absorbed from engine to the cooling media. The jacket cooling water gets cooled and re-circulated into system after exchanging the heat with cooling water in a heat exchanger. Conventional fluids like water, oil, ethylene glycol, etc. possess less heat transfer performance; therefore, it is essential to have a compact and effective heat transfer system to obtain the required heat transfer. A reduction in energy consumption is possible by improving the performance of heat exchanging systems and incorporating various heat transfer enhancement techniques. In this paper, the heat transfer rate using nano-sized ferrofluid with and without magnetization is analysed using CFD simulation and compared with the experimental values obtained from a heat exchanger using water as base fluid. The heat transfer rate is measured using different combinations by varying the percentage of nano particles and by introduction of different magnetic intensity (gauss) on to the ferrofluid. The optimum heat transfer rate and efficiency of heat exchanger is calculated with the different combinations and the values are compared with the values of CFD simulation. CFD simulation was undertaken for water alone as cooling media and for water with ferro particle addition from 2% to 5%. The difference in temperature observed to be similar with experimental values. The deviation is within the acceptable limit and therefore the experimental findings are validated. The experiment was conducted on a parallel flow heat exchanger with water alone as cooling media, water with varying percentage of ferro fluid and water with varying magnetic intensity on ferrofluid. Percentage of ferro particles added up to where the optimum temperature difference could be obtained and the magnetic intensity also varied up to the optimum value.

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16

Abed, Akram H., Sergey E. Shcheklein, and Valery M. Pakhaluev. "Heat transfer intensification in emergency cooling heat exchanger and dry cooling towers on nuclear power plant using air-water mist flow." Nuclear Energy and Technology 5, no. 4 (December 10, 2019): 281–87. http://dx.doi.org/10.3897/nucet.5.47972.

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Advanced nuclear power plants are equipped with passive emergency heat removal systems (PEHRS) for removing the decay heat from reactor equipment in accidents accompanied by primary circuit leakage to the final heat absorber (ambient air). Herein, the intensity of heat dissipation to air from the outer surface of the heat exchanger achieved by buoyancy induced natural convection is extremely low, which need to a large heat exchanger surface area, apply different types of heat transfer intensification including (grooves, ribs and extended surfaces, positioning at higher altitudes, etc.). The intensity of heat removal is also strongly dependent on the ambient air temperature (disposable temperature head). Construction of nuclear power plants in countries with high ambient temperatures (Iran, Bangladesh, Egypt, Saudi Arabia, and others) which are characterized by a high level of ambient temperature imposes additional requirements on the increase of the heat exchange surfaces. The experimental investigation results of heat transfer intensification by a low energy ultrasonic which supply a fine liquid droplet (size ~3 µm) in the cooling air are presented in the present paper. In such case, the heat transfer between the surface and cooling flow involves the following three physical effects: convection, conductive heat transfer, and evaporation of water droplets. The last two effects weakly depend on the ambient air temperature and provide an active heat removal in any situation. The investigation was performed using a high-precision calorimeter with a controlled rate of heat supply (between 7800 and 12831 W/m2) imitating heated surface within the range of Reynolds numbers from 2500 to 55000 and liquid (water) flow rates from 23.39 to 111.68 kg·m-2·h-1. The studies demonstrated that the presence of finely dispersed water results in a significant increase in heat transfer compared with the case of using purely air-cooling. With a fixed heat flux, the energy efficiency increases with increasing water concentration, reaching the values over 600 W·m-2·C-1 at 111.68 kg·m-2·h-1, which is 2.8 times higher than for air cooling. With further development of research in order to clarify the optimal areas of intensification, it is possible to use this technology to intensify heat transfer to the air in dry cooling towers of nuclear power plants and thermal power plants used in hot and extreme continental climates.

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17

Long, Ji Bo, Ping Wang, Yu Lou Li, and Si Yi Huang. "Analysis on Heat Transfer Intensity of Bamboo Structure Wall in Warm and Humid Environment." Advanced Materials Research 639-640 (January 2013): 721–26. http://dx.doi.org/10.4028/www.scientific.net/amr.639-640.721.

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Based on the fundamentals of heat and moisture transfer in porous media, characteristics of heat transfer intensity of a bamboo structure wall are analyzed when the moisture content changes under the action of natural warm and humid environment. The results show that: when the moisture content changes, the effective coefficient of heat conductivity and specific heat capacity of bamboo both change, and physical parameters (e.g., heat transfer capacity, heat storage capacity, temperature distribution, attenuation coefficient of temperature wave, delay coefficient of temperature wave) all change accordingly. When the total moisture content of the wall increases, the temperature difference between inside and outside surfaces of the wall is reduced, and attenuation and delay coefficient of temperature wave both increase. All of these improve the thermal comfort of indoor environment, but the heat transfer capacity through the wall increases. If the total moisture content of the wall is constant and the moisture distribution along the thickness direction of the wall changes, the temperature gradient decreases and the heat storage coefficient increases in bamboo layer of high moisture content, and the temperature gradient increases and the heat storage coefficient decreases in bamboo layer of low moisture content.

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18

Rao, V. K., and M. F. Bardon. "Convective Heat Transfer in Reciprocating Engines." Proceedings of the Institution of Mechanical Engineers, Part D: Transport Engineering 199, no. 3 (July 1985): 221–26. http://dx.doi.org/10.1243/pime_proc_1985_199_160_01.

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A formula is presented for computing the instantaneous convective heat transfer coefficient between the charge and the confining walls in a reciprocating engine. The formula is developed from basic considerations of turbulent diffusion and relates the convective heat transfer coefficient directly to the turbulence intensity in the charge. This feature distinguishes it from the existing methods of computing the convective heat transfer coefficient which require a precise specification of the continually changing velocity and length scales of the fluid flow. The proposed formula is therefore expected to be more accurate in heat transfer modelling for new and existing engines, particularly as turbulence measurements in engines progressively improve.

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19

Wang, Hui, and Hai Bo Yang. "6063 Aluminum Alloy Online Quenching Surface Heat Transfer Coefficient and the Temperature Field Simulation." Applied Mechanics and Materials 446-447 (November 2013): 146–50. http://dx.doi.org/10.4028/www.scientific.net/amm.446-447.146.

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For the 6063 aluminum alloy spray quenching process, respectively establish finite element model of upper, lower nozzle jet impact and water area and meshing in the Gambit. Import into fluent software for cooling numerical simulation, getting the upper and lower nozzle’s pressure contours , velocity contours , heat transfer coefficient curve and water area’s velocity contours and heat transfer coefficient curves. Analysis the various contours and the heat transfer coefficient along the aluminum plate surface radial distribution: upper nozzle’s heat transfer intensity is not in stationary point and near its both sides; Lower nozzle’s contours and heat transfer coefficient has a certain similarity with the upper nozzle, but the maximum heat transfer intensity is at stagnation point; Water area‘s heat transfer coefficient fall faster at the entrance and maintained at a constant value finally. Put heat transfer coefficient as a boundary condition into the ansys software to simulate the three dimensional temperature field of quenching process and analysis the temperature field contours in different time: the biggest speed is 36°C/s during the process of quenching, appearing in the high temperature range, namely deformation sensitive areas, therefore it most likely to occur deformation at the beginning of the quenching profiles.

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20

Plotnikov, L. V., B. P. Zhilkin, Yu M. Brodov, and L. E. Osipov. "Computational and experimental evaluation of heat transfer intensity in channels of complex configuration for gas flow with different levels of turbulence." Journal of Physics: Conference Series 2119, no. 1 (December 1, 2021): 012007. http://dx.doi.org/10.1088/1742-6596/2119/1/012007.

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Abstract Disclosure of the physical mechanism of the influence of the turbulence intensity of gas flows on the heat transfer level in pipes of different configurations is an urgent task in the field of heat and power engineering. A brief overview of the literature on this topic is given in the article. A description of the boundary conditions for modeling is presented. The main characteristics of the experimental stand and measuring instruments are described. The purpose of this study is to study the effect of the initial turbulence level of a stationary gas flow on the heat transfer intensity in long pipes with different cross sections. The study is carried out using numerical simulation. The simulation results are qualitatively confirmed using experimental data. The values of the local heat transfer coefficient are shown to increase from 5 to 17% with increasing turbulence intensity (from 2 to 10%) in pipes with different cross sections. The heat transfer intensity in a triangular pipe is found to increase up to 30% compared to a round pipe. It is revealed that there is an up to 15% suppression of heat transfer in a square pipe compared to a round pipe. The data obtained may be useful for the design of flow paths and gas exchange systems for power machines and installations.

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21

Voinov, Nikolay Aleksandrovich, Denis Andreyevich Zemtsov, Anastasiya Viktorovna Bogatkova, and Nina Vladimirovna Deryagina. "INTENSIFICATION OF HEAT EXCHANGE IN DIABATIC RECTIFICATION COLUMNS." chemistry of plant raw material, no. 4 (December 21, 2020): 511–18. http://dx.doi.org/10.14258/jcprm.2020048580.

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The heat exchange in a diabatic column was investigated during the rectification of an ethanol-water mixture, in which partial condensation of rising vapors on the surface of vertical heat exchange tubes installed vertically along the height of the installation was carried out, as well as the evaporation of intermediate condensate on the surface of horizontal plates. Based on the review of diabatic columns, it is shown that they can reduce the cost of conducting the rectification process. Heat-exchange devices placed on trays of rectification units are considered and ways to intensify heat transfer in them are proposed. It has been established that the most efficient heat removal in heat exchangers of diabatic columns is achieved when using a film flow of a coolant on a heat transfer surface. Heat transfer in a diabatic column is investigated during gravitational flow of surfaces of heat exchange tubes, as well as when organizing an ascending and descending co-current film flow, both in the case of heating and boiling of the coolant. To intensify heat transfer in the coolant film, a helical artificial roughness was installed on the surface of the pipes, made in the form of a wire spiral tightly mounted on the heat transfer surface. The geometric parameters of the helical roughness, such as the distance between the turns of the spiral and the height of the wire, which have the greatest influence on the intensity of heat transfer, have been established. Dependences for determining the value of the heat transfer coefficient are presented and an estimate of the value of the specific heat flux in the diabatic column is given.

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22

Dullenkopf, K., and R. E. Mayle. "Darryl E. Metzger Memorial Session Paper: An Account of Free-Stream-Turbulence Length Scale on Laminar Heat Transfer." Journal of Turbomachinery 117, no. 3 (July 1, 1995): 401–6. http://dx.doi.org/10.1115/1.2835675.

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The effect of length scale in free-stream turbulence is considered for heat transfer in laminar boundary layers. A model is proposed that accounts for an “effective” intensity of turbulence based on a dominant frequency for a laminar boundary layer. Assuming a standard turbulence spectral distribution, a new turbulence parameter that accounts for both turbulence level and length scale is obtained and used to correlate heat transfer data for laminar stagnation flows. The result indicates that the heat transfer for these flows is linearly dependent on the “effective” free-stream turbulence intensity.

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23

Li, Qun Song, Qian Yang, Zhi Song Li, and Tian Lan Yu. "3D Numerical Simulation of Fluid Flow and Heat Transfer in Tube with Spiral-Flange Insert." Advanced Materials Research 236-238 (May 2011): 1508–15. http://dx.doi.org/10.4028/www.scientific.net/amr.236-238.1508.

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With the help of Fluent 6.2 and supporting software, 3D numerical simulation of fluid flow and heat transfer enhancement of plastic spiral tubes were performed on computer, and the velocity, turbulence intensity and improvement of convective heat transfer coefficient distribution in plastic spiral tubes were analyzed and compared with those in smooth tubes, and characteristics of fluid flow and heat transfer were obtained. The results showed that there were obvious axial, tangential and radial velocities in spiral space, and they were bigger than those in smooth tubes. The turbulence intensity was also increased greatly because of the existence of spiral channels. The dirt production was prevented and the tube's convection heat transfer was effectively strengthened. Its surface average heat transfer coefficient had been enhanced by about 20% compared with the smooth tubes; The pressure drop caused by plastic spiral flange was in the permissible range of engineering application. It was suitable for the heat exchanger at a flow velocity lower than 0.8m/s.

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24

Kudritskii, G. R., and I. A. Krivolapov. "Effect of Vibrational Mixing of a Heat-Carrier on Heat-Transfer Intensity in Boiling." Heat Transfer Research 28, no. 4-6 (1997): 340–43. http://dx.doi.org/10.1615/heattransres.v28.i4-6.170.

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25

Revathy, P., V. Sadasivam, and T. Ajith Bosco Raj. "Intensity Based Simulation of the Temperature Prediction in the Focal Region of Liver Using MRI-Guided High Intensity Focused Ultrasound (HIFU)." Journal of Computational and Theoretical Nanoscience 13, no. 10 (October 1, 2016): 6728–32. http://dx.doi.org/10.1166/jctn.2016.5620.

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In this research paper a new temperature prediction method is proposed to predict the temperature in liver during thermal ablation which also takes in to account the blood flow cooling. The proposed method suggest a modification of Pennes bioheat transfer equation (PBHTE) inorder to more accurately predict the treatment temperature. The temperature elevation by the proposed heat transfer model is compared with the PBHTE model and the other two heat continuum models by Wulff and Klinger. Appropriate temperature prediction is useful in treatment planning. This may reduce the recurrence level of cancer. Further the reduction in treatment time increases patient safety.

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26

Zvereva, E. N., and Yu A. Taran. "EVALUATION OF VARIABLE INTENSITY OF HEAT REMOVAL FROM THE SURFACE OF FALLING AND CRYSTALLIZING MELT DROPLETS IN THE PROCESS OF THEIR PRILLING." Fine Chemical Technologies 12, no. 1 (February 28, 2017): 45–49. http://dx.doi.org/10.32362/2410-6593-2017-12-2-45-49.

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The method of calculation of the intensity of heat removal from the surface of the crystallizing melt droplets is presented. A comparison with the experimental fixed values representing the intensity of the heat transfer between the surface of the resulting pellet and cooling agent is carried out. The influence of heat transfer coefficient on the surface of the pellet changes on complete crystallization time, and therefore on the size of the granulation tower, is analyzed. Conditions defining the heat transfer between the granule surface and surrounding coolant, while full crystallization in conjunction with the dependence of the rate of nucleation and growth of the granules determine mechanical properties of ammonia fertilizer granules.

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27

Radchenko1, Mykola I., Tadeusz Bohdal2, Andrii M. Radchenko1, Eugeniy I. Trushliakov1, Volodymyr Y. Labay3, and Veniamin S. Tkachenko1. "Innovative air conditioning system with rational distribution of thermal load." Joupnal of New Technologies in Environmental Science 5, no. 3 (September 30, 2020): 62–79. http://dx.doi.org/10.30540/jntes-2020-3.5.

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The efficiency of air conditioning (AC) systems depends on the operation of their air coolers at varying heat loads in response to current changeable climatic conditions. The intensity of heat transfer of refrigerant, evaporated inside air coils, drops at the final stage of evaporation, that is caused by drying out the inner wall surface. This results in lowering the overall heat transfer coefficient and reduction of air cooler efficiency in the whole. The concept of overfilling air coils that leads to excluding a dry-out of their inner surface and falling the overall heat transfer intensity at variation of refrigerant flows in response to change of current thermal load on air coolers is developed.

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28

Ponomarev, Konstantin O., Geniy V. Kuznetsov, Dmitry V. Feoktistov, Evgenia G. Orlova, and Vyacheslav I. Maksimov. "On heat transfer mechanism in coolant layer on bottom cover of a two-phase closed thermosyphon." Tyumen State University Herald. Physical and Mathematical Modeling. Oil, Gas, Energy 6, no. 1 (2020): 65–86. http://dx.doi.org/10.21684/2411-7978-2020-6-1-65-86.

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The authors hypothesize that the intensity of all thermophysical and hydrodynamic processes in a thermosyphon depends, first of all, on the intensity of heat transfer in the coolant layer on the bottom cover and on the free surface of this layer. Based on the experimentally obtained temperature fields in a two phase closed thermosyphon, the authors have formulated a mathematical model of heat transfer in such heat exchangers which differs from the known models by accounting for conduction and convection only in the coolant layer on the bottom cover and conduction in the evaporation section of the thermosyphon. The calculated temperatures in characteristic points of the coolant layer comply with the readings of thermocouples. The results of numerical simulation provide grounds for concluding that the thermogravitational convection in the coolant layer on the bottom cover plays a dominant role in controlling the intensity of heat transfer in the thermosyphon.

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29

Nebuchinov, A. S. "Experimental study of heat transfer of impinging swirling jets and jets with chevrons." Journal of Physics: Conference Series 2119, no. 1 (December 1, 2021): 012023. http://dx.doi.org/10.1088/1742-6596/2119/1/012023.

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Abstract The aim of this work is to study the effect of different forms of passive change in the shape of the flow on the intensity of heat transfer in the impact jet. In this work, a cycle of experiments was performed to investigate an axisymmetric jet flowing normally onto a heated surface. The jet was located both in natural conditions and during swirling of the flow (S = 0.4; 0.7; 1.0). It is shown that the intensity of heat transfer on a heated target in the case of a chevrons jet has little effect on the character, but significantly intensifies heat transfer. In the case of a swirling jet, the intensity distribution on the wall changes its character and locally increases at small distances between the nozzle and the heater.

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30

Mehendale, A. B., J. C. Han, and S. Ou. "Influence of High Mainstream Turbulence on Leading Edge Heat Transfer." Journal of Heat Transfer 113, no. 4 (November 1, 1991): 843–50. http://dx.doi.org/10.1115/1.2911212.

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The influence of high mainstream turbulence on leading edge heat transfer was studied. High mainstream turbulence was produced by a bar grid (Tu = 3.3–5.1 percent), passive grid (Tu = 7.6–9.7 percent), and jet grid (Tu = 12.9–15.2 percent). Experiments were performed using a blunt body with a semicylinder leading edge and flat sidewalls. The mainstream Reynolds numbers based on leading edge diameter were 25,000, 40,000, and 100,000. Spanwise and streamwise distributions of local heat transfer coefficients on the leading edge and flat sidewall were obtained. The results indicate that the leading edge heat transfer increases significantly with increasing mainstream turbulence intensity, but the effect diminishes at the end of the flat sidewall because of turbulence decay. Stagnation point heat transfer results for high turbulence intensity flows agree with the Lowery and Vachon correlation, but the overall heat transfer results for the leading edge quarter-cylinder region are higher than their overall correlation for the entire circular cylinder region. High mainstream turbulence tends not to shift the location of the separation-reattachment region. The reattachment heat transfer results are about the same regardless of mainstream turbulence levels and are much higher than the turbulent flat plate correlation.

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31

Łapiński, Adam, Kamil Śmierciew, Huiming Zou, and Dariusz Butrymowicz. "Measurement of Heat Transfer and Flow Resistance for a Packed Bed of Horticultural Products with the Implementation of a Single Blow Technique." Processes 9, no. 12 (November 28, 2021): 2151. http://dx.doi.org/10.3390/pr9122151.

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This paper provides the practical implementation of the single blow technique as an effective approach of average convective heat transfer coefficient measurement for a packed bed of horticultural products. The measurement approach was positively validated for the case of a packed bed of balls. The presented results cover heat transfer coefficient results for carrots stored in packed beds for two various arrangements (regular and irregular) and bed of apples under conditions of various turbulent intensity at the inlet to the bed. The turbulent intensity (defined as the ratio of the root mean square of the turbulent fluctuation of the air velocity to the mean air velocity) varied from 0.02 to 0.14. The applied velocity ranges for the tests refers to the conventional storage conditions. The heat transfer correlations were proposed based on the obtained results for each arrangement. It was demonstrated that due to flow laminarization inside the bed, the turbulence intensity has no significant effect on heat transfer inside the bed. Heat transfer enhancement of up to 25% was demonstrated for the case of the irregular carrot arrangement in the tested bed. The flow resistance correlations were additionally proposed for the tested beds. It was demonstrated that the product arrangement does not produce an important effect on the pressure drop.

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32

Madi, Arous. "Heat transfer prediction in a shallow cavity effect of incoming flow characteristics." Thermal Science 20, no. 5 (2016): 1519–32. http://dx.doi.org/10.2298/tsci140119093m.

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This study deals numerically with a heat transfer in a turbulent flow over a shallow cavity. Two different configurations of the incoming flow are considered: a boundary layer flow and a plane wall jet flow, in order to examine the wall jet outer layer effect on the heat transfer. This layer is an important additional turbulence source in the wall jet flow. Reynolds number and turbulence intensity effects were investigated in the boundary layer incoming flow case. The cavity depth to nozzle height ratio effect was examined in the wall jet incoming flow case. The numerical approach is based on k-? standard turbulence model. This study reveals that the heat transfer is very sensitive to the incoming flow characteristics. The turbulence intensity increase accelerates the reattachment of the shear layer at the cavity floor and enhances the heat transfer. The reattachment phenomenon seems to be less affected by the Reynolds number. However, an increase in this parameter ameliorates the heat transfer. It was also observed a heat transfer enhancement in the wall jet incoming flow case as compared to that of a boundary layer. Likewise, it was found that the augmentation of the cavity depth to the jet nozzle height ratio improves even more the heat transfer. The maximum heat transfer occurs upstream of the reattachment.

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33

Zhang, Y. M., W. Z. Gu, and J. C. Han. "Heat Transfer and Friction in Rectangular Channels With Ribbed or Ribbed-Grooved Walls." Journal of Heat Transfer 116, no. 1 (February 1, 1994): 58–65. http://dx.doi.org/10.1115/1.2910884.

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The effect of compound turbulators on friction factors and heat transfer coefficients in rectangular channels with two opposite ribbed-grooved walls was determined for a Reynolds number range of 10,000 to 50,000. The channel width-to-height ratio was 10. The fully developed heat transfer coefficients and friction factors on the ribbed-grooved and smooth side walls of each test channel were measured for six rib-groove spacings (p/e = 8, 10, 15, 20, 25, and 30). The fully developed friction and heat transfer in similar aspect ratio rectangular channels with two opposite ribbed walls with two rib spacings (p/e = 8.5 and 11.5) was also measured for comparison. The results show that the heat transfer performance of the rib-groove roughened duct is much better than the rib roughened duct. The rib-groove roughened wall enhances the heat transfer 3.4 times and pays 6 times the pressure drop penalty, whereas the rib roughened wall, with similar rib height and rib spacing, enhances the heat transfer 2.4 times and pays about the same pressure drop penalty. Semi-empirical friction and heat transfer correlations were obtained. Flow measurements show that the roughened ducts have flatter velocity profiles than the smooth duct and rib-groove roughened duct produces higher turbulence intensity than the rib roughened duct. The flatter velocity profile and higher turbulence intensity are responsible for producing higher heat transfer.

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34

Ma, Ke, Yu Can Fu, Hong Jun Xu, and Jun He. "Effect of Processing Parameters on Heat Transfer Performance of the Heat-Pipe Grinding Wheel." Applied Mechanics and Materials 217-219 (November 2012): 2480–83. http://dx.doi.org/10.4028/www.scientific.net/amm.217-219.2480.

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Heat transfer performance of the heat-pipe grinding wheel (HPGW) is mainly depended on the heat pipe in the wheel. In this paper, a basal body of HPGW was developed and a heat transfer experiment was performed to study the effect of the parameters of the heat pipe such as liquid filling ratio and rotating speed on the heat transfer performance of the HPGW. Results show that the heat transfer performance decreases if the liquid filling rate is too large or too small under the same heat source intensity and the optimal liquid filling rate is about 35% of the volume inside the heat pipe. The heat transfer performance of the HPGW is enhanced with the increasing of the rotating speed. The analysis of the results also shows that the heat pipe in the HPGW can play a great role on enhancing the heat transfer in the grinding zone with suitable processing parameters.

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35

Wang, Fude, and Rusen Hou. "Numerical study of nano-particle composite paraffin phase change heat storage capsule." Journal of Physics: Conference Series 2194, no. 1 (February 1, 2022): 012011. http://dx.doi.org/10.1088/1742-6596/2194/1/012011.

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Abstract The heat exchange characteristics of traditional heat exchange fluids such as water and oil in phase change heat storage can no longer meet the ever-increasing heat exchange requirements. The researchers found that by adding nano-scale particles to the basic phase change material (pure PCM) in a certain proportion to form a composite phase change material, the heat transfer characteristics of the material can be improved. In this paper, a model study of the phase change heat storage characteristics of the nano-particle composite paraffin wax phase change capsule with holes is carried out, and the effects of thermal disturbance, natural convection heat transfer and external convection heat transfer on the phase change heat storage are mainly studied. It is found that when nanoparticles are added to the phase change heat storage capsule, the composite phase change heat storage capsule formed by the phase change heat storage, the internal natural convection intensity increases, and with the increase of the particle share, the heat storage rate increases, and the heat exchange intensity increases.

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36

Hu, Ke-Qi, Yi-Fan Xia, Yao Zheng, and Gao-Feng Wang. "Effects of inlet turbulence intensity on wall heat transfer in a turbine guide vane." International Journal of Modern Physics B 34, no. 14n16 (May 30, 2020): 2040082. http://dx.doi.org/10.1142/s0217979220400822.

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Heat transfer is an important phenomenon that exists in many industrial applications, especially for gas turbines, aeronautical engines. In this work, two different turbulence models ([Formula: see text] and SAS model) are used to investigate the effects of inlet turbulence on wall heat transfer and the characteristics of flow field in a well-known turbine guide vane (LS89). In order to handle the transition, Menter’s [Formula: see text] transition model is used. The simulations show that the inlet turbulence has an apparent effect on the wall heat transfer of the vane. Not only the maximum wall heat transfer coefficient is increased, the distribution of wall heat flux at the suction side is also modified. The isentropic Mach number along the vane surface is insensitive to the variance of inlet turbulence intensity. Besides, a shock appears in the throat and a laminar-to-turbulence transition position moves forward after the main flow turbulence is enhanced. Moreover, the results indicate that SAS model is capable of capturing more flow structures such as reflecting pressure waves and shedding vortexes while the [Formula: see text] model misses them due to the dissipation.

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37

Zhou, Guo Fa, and Ting Peng. "Heat Transfer Enhancement of Viscoelastic Fluid in the Rectangle Microchannel with Constant Heat Fluxes." Applied Mechanics and Materials 117-119 (October 2011): 574–81. http://dx.doi.org/10.4028/www.scientific.net/amm.117-119.574.

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It has been found that viscoelastic fluid has evident heat transfer enhancement function in macro scale. But in micro scale, viscoelastic fluid’s flow and heat transfer characteristics are still unknown. In this paper, the heat transfer process of viscoelastic fluid in the microchannel is studied by numerical simulation method. The simulation results show that the maximum heat transfer enhancement of viscoelastic fluid is up to 800%, compared with pure viscous fluid. The viscoelastic fluid has such obvious heat transfer enhancement function because of its strong secondary flow. Laminar sub-layer can be damaged by the strong secondary flow, and thus radial flow generates in laminar sub-layer. The radial flow can increase the interference and mixing effect, and enhances fluid’s turbulence and convection which can enhance heat transfer as a result. So the heat transfer enhancement depends on the intensity of secondary flow which is caused by the second normal stress difference, and it will increase with the raise of the flow rate.

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38

Кравець, Володимир Юрійович, Валерий Иванович Коньшин, and Наталья Сергеевна Ванеева. "Heat transfer intensity in the evaporation zone of two-phase thermosyphons." Eastern-European Journal of Enterprise Technologies 2, no. 5(68) (April 15, 2014): 45. http://dx.doi.org/10.15587/1729-4061.2014.9717.

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39

Epik, Eleonora Ya. "Local Heat Transfer Downstream of a Turbulent Separation of Any Intensity." Heat Transfer Research 33, no. 1-2 (2002): 8. http://dx.doi.org/10.1615/heattransres.v33.i1-2.10.

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40

Paist, A., A. Poobus, and T. Tiikma. "Probes for measuring heat transfer parameters and fouling intensity in boilers." Fuel 81, no. 14 (September 2002): 1811–18. http://dx.doi.org/10.1016/s0016-2361(02)00114-x.

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41

Kirakosyan, V. A., A. P. Baskakov, E. Yu Lavrovskaya, and Yu A. Popov. "Heat-transfer intensity from swirling disperse flow to cyclone-chamber wall." Journal of Engineering Physics 59, no. 4 (October 1990): 1291–97. http://dx.doi.org/10.1007/bf00878061.

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42

Shablovskii, O. N. "The study of nonlinear problems of high-intensity nonstationary heat transfer." Journal of Engineering Physics 52, no. 2 (February 1987): 237–43. http://dx.doi.org/10.1007/bf00870774.

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43

Sun, Difu, Junqiang Song, Hongze Leng, Kaijun Ren, and Xiaoyong Li. "Impacts of Air-Sea Energy Transfer on Typhoon Modelling." Advances in Meteorology 2021 (April 15, 2021): 1–14. http://dx.doi.org/10.1155/2021/5567717.

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The Coupled Ocean-Atmosphere-Wave-Sediment Transport model has been used to simulate Super Typhoon Yutu (2018). The impacts of four momentum transfer parameterization schemes (COARE, TY, OT, and DN) and three heat transfer parameterization schemes (COARE, GR, and ZK) on typhoon modelling have been studied by means of the track, intensity, and radial structure of typhoon. The results show that the track of Yutu is not sensitive to the choice of parameterization scheme, while the combinations of different parameterization schemes affect the intensity of Yutu. Among the four momentum flux parameterization schemes, three wave-state-based schemes (TY, OT, and DN) provide better intensity results than the wind-speed-based COARE scheme, but the differences between the three wave-state-based schemes are not obvious. Among the three heat flux parameterization schemes, the results of the GR scheme are slightly better than those of the COARE scheme, and both the GR and COARE schemes are significantly better than the ZK scheme, from which the intensity of Yutu is underpredicted obviously. The influence of the combination of different parameterization schemes on the intensity of the typhoon is also reflected in the radial structure of the typhoon, and the radial structure of the typhoon simulated by experiments with stronger typhoon intensity also develops faster. Differences of intensity between experiments are due mainly to the differences in sea surface heat flux, the enthalpy transferred from sea surface to the atmosphere has a significant impact on the bottom atmosphere wind field, and there is a strong correspondence between the distribution of enthalpy flux and the bottom wind field.

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44

Zhang, L., and J. C. Han. "Combined Effect of Free-Stream Turbulence and Unsteady Wake on Heat Transfer Coefficients From a Gas Turbine Blade." Journal of Heat Transfer 117, no. 2 (May 1, 1995): 296–302. http://dx.doi.org/10.1115/1.2822520.

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The combined effect of free-stream turbulence and unsteady wakes on turbine blade surface heat transfer was studied. The experiments used a five-blade linear cascade in a low-speed wind tunnel facility. A turbulence grid and spoked-wheel type wake generator produced the free-stream turbulence and unsteady wakes. The mainstream Reynolds numbers based on the cascade inlet mean velocity and blade chord length were 100,000, 200,000, and 300,000. Results show that the blade time-averaged heat transfer coefficient depends on the mean turbulence intensity, regardless of whether this mean turbulence intensity is from unsteady wake only, turbulence grid only, or a wake and grid combination. The higher mean turbulence promotes earlier boundary layer transition and causes much higher heat transfer coefficients on the suction surface. It also significantly enhances the heat transfer coefficients on the pressure surface. The unsteady wake greatly affects blade heat transfer for low oncoming free-stream turbulence; however, the wake effect diminishes for high oncoming turbulence. The free-stream turbulence also strongly affects blade heat transfer for a low wake passing frequency, but the oncoming turbulence effect diminishes for a high unsteady wake condition.

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45

Michaletz, S. T., and E. A. Johnson. "A heat transfer model of crown scorch in forest fires." Canadian Journal of Forest Research 36, no. 11 (November 1, 2006): 2839–51. http://dx.doi.org/10.1139/x06-158.

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The Van Wagner crown scorch model is widely used to estimate crown component necroses in surface fires. The model is based on buoyant plume theory but accounts for crown heat transfer processes using an empirical proportionality factor k. Crown scorch estimates have used k values for foliage, but k varies with heat transfer characteristics, and branch and bud necroses are more relevant to tree mortality. This paper derives and validates a more physically complete model of crown scorch in surface fires (I ≤ 2500 kW·m–1). The model links a buoyant plume model with a lumped capacitance heat transfer analysis applicable to branches, buds, and foliage (~1 cm maximum diameter). The lumped capacitance analysis is validated with vegetative-bud heating experiments, and the entire heat transfer model of crown scorch is validated with fireline intensity and foliage necrosis data. The model is more general than the Van Wagner model and is independent of experimental fire data. Predictions require measurements of fireline intensity, residence time, ambient temperature, and five thermophysical properties of crown components. The model predicts differences between bud and foliage necrosis heights, and illustrates why heat transfer processes should be considered in crown scorch models.

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46

Avramenko, А., M. Kovetskaya, A. Tyrinov, and Yu Kovetska. "Characteristics of supercritical heat transfer during filmboiling of nanofluids on a vertical heated wall." Nuclear and Radiation Safety, no. 4(80) (December 3, 2018): 29–35. http://dx.doi.org/10.32918/nrs.2018.4(80).05.

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Nanofluid using for intensification of heat transfer during boiling are analyzed. The using boiling nanofluids for cooling high-temperature surfaces allows significantly intensify heat transfer process by increasing the heat transfer coefficient of a nanofluid in comparison with a pure liquid. The properties of nanoparticles, their concentration in the liquid, the underheating of the liquid to the saturation temperature have significant effect on the rate of heat transfer during boiling of the nanofluid. Increasing critical heat flux during boiling of nanofluids is associated with the formation of deposition layer of nanoparticles on heated surface, which contributes changing in the microcharacteristics of heat exchange surface. An increase in the critical heat flux during boiling of nanofluids is associated with the formation of a layer of deposition of nanoparticles on the surface, which contributes to a change in the microcharacteristics of the heat transfer of the surface. Mathematical model and results of calculation of film boiling characteristics of nanofluid on vertical heated wall are presented. It is shown that the greatest influence on the processes of heat and mass transfer during film boiling of the nanofluid is exerted by wall overheating, the ratio of temperature and Brownian diffusion and the concentration of nanoparticles in the liquid. The mathematical model does not take into account the effect changing structure of the heated surface on heat transfer processes but it allows to evaluate the effect of various thermophysical parameters on intensity of deposition of nanoparticles on heated wall. The obtained results allow to evaluate the effect of nanofluid physical properties on heat and mass transfer at cooling of high-temperature surfaces. The using nanofluids as cooling liquids for heat transfer equipment in the regime of supercritical heat transfer promotes an increase in heat transfer and accelerates the cooling process of high-temperature surfaces. Because of low thermal conductivity of vapor in comparison with the thermal conductivity of the liquid, an increase in the concentration of nanoparticles in the vapor contributes to greater growth in heat transfer in the case of supercritical heat transfer.

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47

NIKITIN, Maxim N. "STUDY OF HEAT TRANSFER OF A HEATER FOR VARIOUS INSTALLATION METHODS." Urban construction and architecture 9, no. 1 (March 15, 2019): 33–37. http://dx.doi.org/10.17673/vestnik.2019.01.6.

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Analysis of numerically simulated convective heat transfer for a variety of heater installations is presented. A critical review of the existing method of energy effi ciency assessment, which is based on empirical coeffi cients, is given. Numerically verifi ed nondimensional heat transfer coeffi cients for eight installations of the heater are presented. The results were validated with the adopted experimental data. Sensitivity analysis of heat transfer intensity towards heat carrier temperature for a variety of heater installations is presented.

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48

Zudin, Yu B. "Averaging of the heat-transfer coefficient in the processes of heat exchange with periodic intensity." Journal of Engineering Physics and Thermophysics 73, no. 3 (May 2000): 643–47. http://dx.doi.org/10.1007/bf02681810.

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49

Flamant, G., J. D. Lu, and B. Variot. "Radiation Heat Transfer in Fluidized Beds: A Comparison of Exact and Simplified Approaches." Journal of Heat Transfer 116, no. 3 (August 1, 1994): 652–59. http://dx.doi.org/10.1115/1.2910919.

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Radiation heat transfer at heat exchanger walls in fluidized beds has never been examined through a complete formulation of the problem. In this paper a wall-to-bed heat transfer model is proposed to account for particle convection, gas convection, and radiation exchange in a variable porosity medium. Momentum, energy, and intensity equations are solved in order to determine the velocity, temperature, radiative heat flux profiles and heat transfer coefficients. The discrete-ordinates method is used to compute the radiative intensity equation and the radiative flux divergence in the energy equation. Both the gray and the non-gray assumptions are considered, as well as dependent and independent scattering. The exact solution obtained is compared with several simplified approaches. Large differences are shown for small particles at high temperature but the simplified solutions are valid for large particle beds. The dependency of radiative contribution on controlling parameters is discussed.

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50

Van Fossen, G. J., R. J. Simoneau, and C. Y. Ching. "Influence of Turbulence Parameters, Reynolds Number, and Body Shape on Stagnation-Region Heat Transfer." Journal of Heat Transfer 117, no. 3 (August 1, 1995): 597–603. http://dx.doi.org/10.1115/1.2822619.

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This experiment investigated the effects of free-stream turbulence intensity, length scale, Reynolds number, and leading-edge velocity gradient on stagnation-region heat transfer. Heat transfer was measured in the stagnation region of four models with elliptical leading edges downstream of five turbulence-generating grids. Stagnation-region heat transfer augmentation increased with decreasing length scale but ann optimum scale was not found. A correlation was developed that fit heat transfer data for isotropic turbulence to within ±4 percent but did not predict data for anisotropic turbulence. Stagnation heat transfer augmentation caused by turbulence was unaffected by the velocity gradient. The data of other researchers compared well with the correlation. A method of predicting heat transfer downstream of the stagnation point was developed.

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