Surface Temperature Of Cylinder Research Articles

Collecting Particulate Matter and Particle-Bound Polycyclic Aromatic Hydrocarbons Using a Cylindrical Thermal Precipitator

Thermophoresis has been used to develop various thermal precipitators; however, their collection performance for ambient particulate matter (PM) with an aerodynamic diameter less than 10 μm (PM10) has been rarely reported, and the effect of the temperature gradient adopted in the precipitator on the evaporation loss of the organic fraction of collected particles has not been discussed to the authors’ knowledge. In this study, a cylindrical thermal precipitator consisting of two coaxially aligned cylinders with an annular space of 0.51 mm and a two-inlet impactor was designed for collecting PM10. The effects of the sampling flow rate and temperature gradient on the collection efficiency were examined. The precipitator was also tested for its collection efficiency for particle-bound polycyclic aromatic hydrocarbons (PAHs). At a temperature gradient of 72.6°C/mm and a flow rate of 7.74 L/min, the collection efficiency could reach 100% for PM with an electrical mobility diameter (Dp)<0.5 μm and decreased gradually to 70% as Dp increased from 0.5 to 1.0 μm. For PM with Dp>1.0 μm, the collection efficiency increased due to impaction at the inlet. The collection efficiency increased with an increase in the temperature gradient or a decrease in the inlet flow rate. The semiempirical model could reasonably fit the collection efficiency curve of the precipitator. No significant evaporation loss of PAHs was found when the temperature of the cold cylinder surface was approximately 0°C. It was concluded that the thermal precipitator could be used to collect ambient fine PM with a size less than 0.5 μm, and the inlet impactor design could improve the collection efficiency for coarse particles.

Numerical simulation of the flow of a gas-liquid medium in a circular channel at cooling a high-temperature metal cylinder with a variable cross-section

The numerical simulation results of the flow of a gas-liquid medium over the high-temperature metal cylinder surface in a circular channel are presented. The flow over the solid metal cylinder with a variable cross-section by a gas-liquid medium is considered. Based on the mathematical model taking into account the cooling-media-flow axial symmetry relative to the cylinder longitudinal axis, the results of the numerical simulation of the process of solving the two-dimensional nonstationary problem of the coupled heat exchange of the gas-liquid medium flow and metal cylinder are obtained. The control volume approach is used for solving the differential equation system. The flow field parameters are calculated using the algorithm SIMPLE. For the iterative solution of linear algebraic equations, Gauss-Seidel method with under-relaxation is used. The numerical calculation results are obtained for the flow hydrodynamic parameters of the gas-liquid medium at cooling the high-temperature metal cylinder by taking into account vaporization. The values of temperatures, flow velocities, and vapour distribution in the computational domain are determined. The variation intensity of the metal cylinder surface temperature depending on the gas-liquid flow velocity is analyzed.

Influence of sliding surface roughness and oil temperature on piston ring pack operation of an automotive IC engine

In the paper a comprehensive model of a piston ring pack motion on an oil film has been presented. The local oil film thickness can be compared to height of the combined roughness of sliding surfaces of piston rings and cylinder liner. Equations describing the mixed lubrication problem based on the empirical mathematical model formulated in works of Patir, Cheng and Greenwood, Tripp have been combined and used in this paper. The developed model takes the following phenomena into account: hydrodynamic and contact forces, spring and gas forces acting on piston rings. The rings motion concerning low and high temperature of cylinder surface has been compared. These results concern cases of hydrodynamic and mixed lubrication. Changes of oil wetted area and contact zone of piston rings have been shown. In addition the oil film thickness distribution along cylinder liner and all the forces acting on piston rings have been analysed and discussed. The results have been presented in form of relevant diagrams. The developed model and software can be utilized for optimization of piston rings design.

Numerical simulation and experimental investigation on suction heating of a BOG compressor

One of the key components of a liquefied natural gas (LNG) receiving terminal is the boil-off gas (BOG) compressor, which is used to pump out the BOG from the LNG storage tank to ensure safety in the transportation and receiving systems. Owing to the ultra-low suction temperature, the heat exchange between the intake gas and the cylinder, piston, and cylinder cover cannot be ignored as in normal conditions. This paper presents an investigation focusing on suction heating of the BOG compressor. A finite element model with dynamic mesh was established to simulate the suction process. At the same time, a performance test rig was built to study the characteristics of the BOG compressor under low suction temperature conditions and verify the numerical model. Consequently, the results of the simulation were in good agreement with experimental results. Both results implied that the temperature of cylinder surface increased starting from the cylinder cover to the crankcase. In addition, at lower suction temperature, the temperature difference between various points on the cylinder surface and cylinder cover was much larger than that at higher suction temperature. With increasing suction temperature, the temperature coefficient increased markedly, and the difference between gas temperatures at the beginning and end of the suction process, as well as the compressor flow rate, decreased significantly; however, the volumetric efficiency increased first and then decreased. Furthermore, the temperature coefficient clearly increased when the compressor rotational speed increased from 250rpm to 3000rpm, and it decreased from 0.81 to 0.66 as the pressure ratio increased from 3.0 to 6.0.

Fiber-Optic Surface Temperature Sensor Based on Modal Interference

Spatially-integrated surface temperature sensing is highly useful when it comes to controlling processes, detecting hazardous conditions or monitoring the health and safety of equipment and people. Fiber-optic sensing based on modal interference has shown great sensitivity to temperature variation, by means of cost-effective image-processing of few-mode interference patterns. New developments in the field of sensor configuration, as described in this paper, include an innovative cooling and heating phase discrimination functionality and more precise measurements, based entirely on the image processing of interference patterns. The proposed technique was applied to the measurement of the integrated surface temperature of a hollow cylinder and compared with a conventional measurement system, consisting of an infrared camera and precision temperature probe. As a result, the optical technique is in line with the reference system. Compared with conventional surface temperature probes, the optical technique has the following advantages: low heat capacity temperature measurement errors, easier spatial deployment, and replacement of multiple angle infrared camera shooting and the continuous monitoring of surfaces that are not visually accessible.

Numerical investigation of effect of the position of the cylinder on solidification in a rectangular cavity

In the present study, it is aimed to calculate the effect of ice formation on different cylinder geometries placed in a rectangular cavity filled with water. For this aim Fluent package program was used to solve the flow domain numerically and temperature distribution and ice formation depending on time were illustrated. Water temperature in the cavity and cylinder surface temperature were assumed as 4, 8 and −10 °C respectively and firstly temperature distribution, velocity vector, liquid fraction and ratio of Ai/Ac (formed ice area/cross sectional area of cylinder) were determined for cylinders with different placement in fixed volume.

DRYING BEHAVIOR OF PEANUTS USING A ROTARY DRYER

A study was carried out to test and evaluatehigh-temperature short-time drying behavior of peanuts pods using a laboratory scale rotary dryer. The experimental work was conducted at six different levels of cylinder surface temperature 55, 65, 75, 85, 95 and 105 oC, three levels of cylinder rotational speed 3, 6 and 9 (r.p.m) and three peanut batch masses 1, 1.5 and 2 (kg/batch). The high temperature rotary drier was evaluated in terms of operating factors likewise moisture regiem, drying temperature, pods and kernels temperatures, batch mass feed, cylinder rotational speed and compatibility of experimental data to Lewis models. The optimal treatment of the high temperatur dried pods of peanuts was slected in terms of physical characteristics of microbiological quality parameters, percentages of broken, splitted, shriveled kernels, oil content of peanuts, free fatty acids and peroxide value of peanuts oil. The results show that, heating surface temperature of 65 oC, cylinder rotational speed of 6 r.p.m and pods batch mass of 1.5 kg recorded the lowest values of kernels splitting, broken and shriveling percentages. The mathematical analysis showed that, Lewis model could satisfactorily describe the drying behavior of high moisture peanuts pods.

Steady-State Modeling of Multi-Cylinder Dryers in a Corrugating Paper Machine

In this study, a steady-state model was developed to describe the paper drying process and to analyze pocket dryer conditions for a multi-cylinder fluting paper machine in Iran's Mazandaran Wood and Paper Industries. The machine has 35 cylinders grouped in three drying groups and the cylinders are heated from the inside by steam. The model is based on the mass and energy balance relationships written for fiber, air, and water in the drying section. In this research, the heat of sorption and its variations with paper temperature and humidity changes have been taken into account. Temperature and moisture variation of the paper web and cylinder surface temperature in the machine direction were predicted by the proposed model. Also, temperature and humidity of air in the drying pockets and hood exhaust were estimated by the proposed model. Moreover, the model can predict the evaporation rate and specific drying rate with sufficient accuracy in comparison with the TAPPI standard. Finally, the main modeling parameters were compared with the available operating data and the effectiveness of the developed model was verified through validations.

Constrained Large-Eddy Simulation of Compressible Flow Past a Circular Cylinder

AbstractCompressible flow past a circular cylinder at an inflow Reynolds number of 2x105is numerically investigated by using a constrained large-eddy simulation (CLES) technique. Numerical simulation with adiabatic wall boundary condition and at a free-stream Mach number of 0.75 is conducted to validate and verify the performance of the present CLES method in predicting separated flows. Some typical and characteristic physical quantities, such as the drag coefficient, the root-mean-square lift fluctuations, the Strouhal number, the pressure and skin friction distributions around the cylinder,etc.are calculated and compared with previously reported experimental data, finer-grid large-eddy simulation (LES) data and those obtained in the present LES and detached-eddy simulation (DES) on coarse grids. It turns out that CLES is superior to DES in predicting such separated flow and that CLES can mimic the intricate shock wave dynamics quite well. Then, the effects of Mach number on the flow patterns and parameters such as the pressure, skin friction and drag coefficients, and the cylinder surface temperature are studied, with Mach number varying from 0.1 to 0.95. Non-monotonic behaviors of the pressure and skin friction distributions are observed with increasing Mach number and the minimum mean separation angle occurs at a subcritical Mach number of between 0.3 and 0.5. Additionally, the wall temperature effects on the thermodynamic and aerodynamic quantities are explored in a series of simulations using isothermal wall boundary conditions at three different wall temperatures. It is found that the flow separates earlier from the cylinder surface with a longer recirculation length in the wake and a higher pressure coefficient at the rear stagnation point for higher wall temperature. Moreover, the influences of different thermal wall boundary conditions on the flow field are gradually magnified from the front stagnation point to the rear stagnation point. Moreover, the influences of different thermal wall boundary conditions on the flow field are graduallymagnified from the front stagnation point to the rear stagnation point. It is inferred that the CLES approach in its current version is a useful and effective tool for simulating wall-bounded compressible turbulent flows with massive separations.

Temperature fields across the BES III beam pipe

During the operations of the new generation Beijing Electron and Positron Collider (BEPC II) and the Beijing Spectrometer (BES III), the inner surface of the beam pipe is subjected to high radiation heat loads. Continuous high temperatures or large temperature fluctuations can cause the main drift chamber (MDC) to detect particles abnormally. Hence, a beam pipe with a cooling system was designed, and temperature fields across the beam pipe and the MDC inner cylinder were studied experimentally and by finite-element simulations. When the inlet temperatures of the cooling oil and cooling water for the central and extended beam pipes were set to 291.4K and 291.6K, respectively, results showed that the inner surface temperature of the MDC inner cylinder can be controlled within the range of 292.8–293.9K for various powers of radiation heat. This range satisfies the operating requirements of 293±2K.

Comparison of Surface Heat-Transfer Coefficient of GCr15 Steel Quenched by Clear Water and Nitrogen-Spray Water

In order to simulate the thermal stresses, thermal strains and residual stresses of steel during quenching by numerical means, it is necessary to obtain an accurate boundary condition of temperature field. The explicit finite difference method, nonlinear estimate method and the experimental relation between temperature and time during water and nitrogen-spray water quenching have been used to solve the inverse problem of heat conduction. The relations between surface heat-transfer coefficient in water and nitrogen-spray water quenching and surface temperature of cylinder have been given. In numerical calculation, the thermal physical properties of material were treated as the function of temperature. The results show that the relations between surface heat-transfer coefficient and surface temperature are non-linear during water and nitrogen-spray water quenching, the heat-transfer coefficient is bigger when water quenching than when nitrogen-spray water before 580°C, the heat-transfer coefficient is smaller when water quenching than when nitrogen-spray water after 400°C. The results of calculation coincided with the results of experiment. This method can effectively determine the surface heat-transfer coefficient during water and nitrogen-spray water quenching.

Comparison of Surface Heat-Transfer Coefficient of GCr15 Steel Quenched by Clear Water and Nitrogen-Spray Water

In order to simulate the thermal stresses, thermal strains and residual stresses of steel during quenching by numerical means, it is necessary to obtain an accurate boundary condition of temperature field. The explicit finite difference method, nonlinear estimate method and the experimental relation between temperature and time during water and nitrogen-spray water quenching have been used to solve the inverse problem of heat conduction. The relations between surface heat-transfer coefficient in water and nitrogen-spray water quenching and surface temperature of cylinder have been given. In numerical calculation, the thermal physical properties of material were treated as the function of temperature. The results show that the relations between surface heat-transfer coefficient and surface temperature are non-linear during water and nitrogen-spray water quenching, the heat-transfer coefficient is bigger when water quenching than when nitrogen-spray water before 580°C, the heat-transfer coefficient is smaller when water quenching than when nitrogen-spray water after 400°C. The results of calculation coincided with the results of experiment. This method can effectively determine the surface heat-transfer coefficient during water and nitrogen-spray water quenching.

Forced Convection Heat Transfer around Heated Inclined Cylinder

and numerical investigations are conducted to study heat transfer coefficient around cylindrical shape bluff body subjected to constant heat flux at its outer surface and cooled by air steam flowing around it. The study covered positioning the cylinder in vertical, horizontal and 45o inclined angle with respect to the free air stream, with its axis in horizontal position parallel to the flow and Reynolds numbers ranging (8,900 - 48,000) for vertical, inclined and horizontal positions. Numerical approach is realized by conducting mathematical model of the problem and solving it numerically using a CFD Code FLUENT 6.3.26 after describing the mesh model using the Gambit 2.2.30. Three dimensional Cartesian coordinate system is considered in this study. The studied geometry is generated by using GAMBIT with dimensions of rectangular box L=127mm, W=130mm and H=129mm. The dimensions of heated cylinder is set identical to the experimental test H=90mm and R=17mm. Proper assumptions are based to solve the governed equations. The experiments are based on air as cooling fluid to investigate heat transfer coefficient around the heated cylinder. Constant heat flux is generated on the surface of the cylinder using proper electrical heater. The heat flux around the cylinder equal (5217, 5201 and 5284 W/m2) for vertical, inclined and horizontal positions respectively. Air flow is ensured around the heated cylinder at different velocities using proper test rig. Local heat transfer coefficients around the cylinder are investigated based on the heat flux measured value and the temperature differences between local cylinder surface temperature and the air stream temperature measured by thermocouples, and standard Pitot-static tube with curved junction (N.P.L standard) was used to measure air free stream velocity. The conducted comparison between the recent experimental results and those obtained from previous work showed reliable agreement. Where maximum error obtained from this comparison was 6.4% for vertical position.

Finite Element Modeling of Induction Heating on Easy-Open-End Dies

Through the magnetic-thermal coupling of ANSYS, the finite element modeling (FEM) of induction heating of the easy-open-end die was completed and the distribution of the dies temperature was determined. Simulation results showed that the dies cylinder surface temperature was high and close to the center was low with a small difference in temperature of about 3°C. Both simulation and experiment results demonstrated the benefits of using induction heating which could guarantee rapid and even heating. This result meant that the dies height varies evenly and was easy to be controlled. The results supplied a strong theoretical foundation for the project of real-time control easy-open-ends notch height.

Eulerian simulation of subcooled boiling flow in straight and curved annuli

In this study, two types of water flow, turbulent single-phase flow and low-pressure subcooled boiling flow, in straight and curved horizontal annuli are investigated numerically. The control volume technique is used for discretizing governing equations, the SIMPLEC algorithm for pressure-velocity coupling, and the shear stress transport k-ω model for turbulent flow. A three-dimensional two-fluid model is used for the subcooled boiling flow, the results of which are compared with those of the single-phase flow. The available water boiling experiment results at low pressure are used to validate the numerical results and were found to have good agreement. The inner cylinder surface temperature of the curved annulus in almost all angles is less than that of the straight annulus in both single-phase and subcooled boiling flow. The maxmum and minimum temperatures in the curved annulus occur at defferent points compared to straight annulus ones due to effects of the centrifugal force.

Theortical and Exprimental Study of Forced Convection Heat Transfer from a Horizontal Cylinder Embeded in Porous Medium

Theoretical and experimental study of heat transfer by forced convection from the cylinder in cross flow embedded in a saturated porous media was carried out. The theoretical part of the work includes the derivation of the governing momentum and energy equation by using Darcy flow model. The two equations are solved by finite difference method with constant cylinder surface temperature, with a Peclet numbers ranged between (1< Pe

Enhancement of nucleate pool boiling heat transfer to dilute binary mixtures using endothermic chemical reactions around the smoothed horizontal cylinder

Experimental studies on enhancing the pool boiling heat transfer coefficient of binary dilute mixtures of water/glycerol, water/MEG (Mono-ethylene glycol) and water/DEG (di-ethylene glycol) have been carried out. Some particular endothermic chemical reactions related to ammonium salts were used to enhance the pool boiling heat transfer coefficient, simultaneously with occurrence of pool boiling heat transfer. Accordingly, 100 g of Ammonium nitrate, ammonium perborate and Ammonium sulfate were selected to dissolve into mixtures. High and extreme solution enthalpies of each of these ammonium salt powders are employed to reduce the surface temperature around the horizontal cylinder locally. Results demonstrated that presence of ammonium salts into the mixtures deteriorates the surface temperature of cylinder and as the result, higher pool boiling heat transfer coefficient is reported for tested solutions. Results are also reported and compared for different ammonium salts to find the influence of inducing different enthalpies of solution on pool boiling heat transfer coefficient. Obtained results also indicated that presence of endothermic reaction besides the pool boiling heat transfer enhances the heat transfer coefficients in comparison with nucleate pool boiling phenomenon solely.

G060031 二重円管内密度成層中での自然対流熱伝達に及ぼす管径と初期温度の影響

The effects of the inner cylinder diameter and the initial temperature of a stably stratified fluid were experimentally investigated on free convection heat transfer between coaxial cylinders. The stratified layer was formed using a sucrose aqueous solution, and was heated from the outer cylinder (70mm I.D.) at constant heat flux and cooled from the inner cylinder (50.8mm or 15mm O.D.) at constant temperature. The experiment was conducted for the initial temperature of the fluid T_0 equal to or greater than the surface temperature of the inner cylinder T_c. As a result it has been found that the initial temperature of the fluid affects the heat transfer and growth of the convection layers in the early stage of heating. As for the effects of the inner cylinder diameter, the onset of the free convection occurs earlier and thereby the heat transfer is affected with increasing the diameter of the inner cylinder, because of a decrease of the distance between the heating and cooling surfaces.

Experimental and Theoretical Study of Natural Convection Heat Transfer between Two Inclined Concentric Cylinders Filled with Porous Media

Porous media have considerable importance in improvement of heat transfer and storage. This research includes an experimental and theoretical study of transient and steady state natural convection heat transfer between two inclined concentric cylinders filled with a porous medium, under condition of applying uniform heat flux on the inner cylinder and constant outer surface temperature for the outer cylinder. Glass beads was used as porous medium , the study shows that the heat dissipated ability in the inner cylinder is function of Rayligh number , and the Nusselt number increase is directly proportional with the increase in Rayligh number in the steady state .Fluent program was used to show the heat dissipation and the flow lines inside the gap between the two cylinders in the horizontal and inclined situation, the experimental results show that the nature of the heat distribution depends greatly on Rayligh number, and the angle of inclination of the cylinders. An experimental relationship between Nu&amp;Ra was obtained under the study conditions

Experimental and Theoretical Study of Natural Convection Heat Transfer between Two Inclined Concentric Cylinders Filled With Porous Media

Porous media have considerable importance in improvement of heat transfer and storage. This research includes an experimental and theoretical study of transient and steady state natural convection heat transfer between two inclined concentric cylinders filled with a porous medium, under condition of applying uniform heat flux on the inner cylinder and constant outer surface temperature for the outer cylinder. Glass beads was used as porous medium , the study shows that the heat dissipated ability in the inner cylinder is function of Rayligh number , and the Nusselt number increase is directly proportional with the increase in Rayligh number in the steady state . Fluent program was used to show the heat dissipation and the flow lines inside the gap between the two cylinders in the horizontal and inclined situation, the experimental results show that the nature of the heat distribution depends greatly on Rayligh number, and the angle of inclination of the cylinders. An experimental relationship between Nu&Ra was obtained under the study conditions.