Thermal Analysis of the One-Stage Melting Converter and Related Equipment for Vitrification of High-Level Radioactive Wastes

2002 ◽  
Author(s):  
L. S. Pioro ◽  
I. L. Pioro ◽  
K. E. P’yanykh
Keyword(s):  
Heat Transfer ◽  
Thermal Analysis ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Heat Removal ◽  
Radioactive Wastes ◽  
Two Phase ◽  
Melt Temperature ◽  
One Stage ◽  
High Level

One-stage melting-converter method for the vitrification of high-level radioactive wastes (HLRAW) was developed and investigated. This method includes the concentration (evaporation), calcination, and vitrification of the HLRAW in one-stage process inside a melting converter. Converter consists of a water-cooled conical metal melting chamber. Capacity for the saturated salty solution is 200 l/h and the capacity for the glass-HLRAW mixture is about 100 kg/h. Calculations showed that at a melt temperature of 1150°C, a cooling-water temperature of 20°C and a thickness of the melt lining of 15 mm the heat flux through the walls is about 75 kW/m2 and wall temperature is about 55°C. Thermal analysis showed that at the burner heat transfer rate of 460 kW the heat transfer rate for heating and melting of the charge is 20 kW, the heat transfer rate for evaporation of water from the solution is 100 kW, and the heat losses are 240 kW. Therefore, a thermal efficiency of the converter is about 26%. To keep a melt lining on the vault of converter and around a burner nozzle the special design two-phase closed thermosyphons are used. Design and heat transfer characteristics of these thermosyphons are discussed. Calculations have been made for heat removal of the melted glass and fissionable nuclides poured into the metal containers during first 500 hours.

Numerical Research on Heat Transfer Characteristics Analysis of Two Particles in Supercritical Water

2021 ◽  
Author(s):  
Xiaoyu Li ◽  
Zhenqun Wu ◽  
Huibo Wang ◽  
Hui Jin
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Phase Flow ◽  
Heat Transfer Characteristics ◽  
Particle Cluster ◽  
Two Phase ◽  
Transfer Characteristics

Abstract In the supercritical water (SCW)-particle two-phase flow of fluidized bed, the particles that make up the particle cluster interact with each other through fluid, and it will affect the flow and heat transfer. However, due to the complex properties of SCW, the research on particle cluster is lacking, especially in terms of heat transfer. This research takes two particles as an example to study the heat transfer characteristics between SCW and another particle when one particle exists. This research uses the distance and angle between the two particles as the influencing factors to study the average heat transfer rate and local heat transfer rate. In this research, it is found that the effect is obvious when L/D = 1.1. When L = 1.1D, the temperature field and the flow field will partially overlap. The overlap of the temperature field will weaken the heat transfer between SCW and the particle. The overlap of the flow field has an enhanced effect on the heat transfer between SCW and the particle. The heat transfer between SCW and particles is simultaneously affected by these two effects, especially local heat transfer rate. In addition, this research also found that as the SCW temperature decreases, the thermal conductivity and specific heat of SCW increases, which enhances the heat transfer between SCW and the particles. This research is of great significance for studying the heat transfer characteristics of SCW-particle two-phase flow in fluidized bed.

Numerical simulation of water/alumina nanofluid mixed convection in square lid-driven cavity

2019 ◽  
Vol 30 (5) ◽  
pp. 2781-2807
Author(s):  
Davood Toghraie ◽  
Ehsan Shirani
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Mixed Convection ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Richardson Number ◽  
Hartmann Number ◽  
Two Phase ◽  
Content Type ◽  
Driven Cavity

Purpose The purpose of this paper is to investigate the mixed convection of a two-phase water–aluminum oxide nanofluid in a cavity under a uniform magnetic field. Design/methodology/approach The upper wall of the cavity is cold and the lower wall is warm. The effects of different values of Richardson number, Hartmann number, cavitation length and solid nanoparticles concentration on the flow and temperature field and heat transfer rate were evaluated. In this paper, the heat flux was assumed to be constant of 10 (W/m2) and the Reynolds number was assumed to be constant of 300 and the Hartmann number and the volume fraction of solid nanoparticles varied from 0 to 60 and 0 to 0.06, respectively. The Richardson number was considered to be 0.1, 1 and 5. Aspect ratios were 1, 1.5 and 2. Findings Comparison of the results of this paper with the results of the numerical and experimental studies of other researchers showed a good correlation. The results were presented in the form of velocity and temperature profiles, stream and isotherm lines and Nusselt numbers. The results showed that by increasing the Hartmann number, the heat transfer rate decreases. An increase from 0 to 20 in Hartmann number results in a 20 per cent decrease in Nusselt numbers, and by increasing the Hartmann number from 20 to 40, a 16 per cent decrease is observed in Nusselt number. Accordingly, it is inferred that by increasing the Hartmann number, the reduction in the Nusselt number is decreased. As the Richardson number increased, the heat transfer rate and, consequently, the Nusselt number increased. Therefore, an increase in the Richardson number results in an increase of the Nusselt number, that is, an increase in Richardson number from 0.1 to 1 and from 1 to 5 results in 37 and 47 per cent increase in Nusselt number, respectively. Originality/value Even though there have been numerous investigations conducted on convection in cavities under various configurations and boundary conditions, relatively few studies are conducted for the case of nanofluid mixed convection in square lid-driven cavity under the effect of magnetic field using two-phase model.

scholarly journals Role of Rotating Cylinder toward Mixed Convection inside a Wavy Heated Cavity via Two-Phase Nanofluid Concept

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1138 ◽  
Author(s):  
Ammar I. Alsabery ◽  
Mohammad Ghalambaz ◽  
Taher Armaghani ◽  
Ali Chamkha ◽  
Ishak Hashim ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Volume Fraction ◽  
Rotating Cylinder ◽  
Alumina Nanoparticles ◽  
Optimum Number ◽  
Two Phase ◽  
Rotation Direction

The mixed convection two-phase flow and heat transfer of nanofluids were addressed within a wavy wall enclosure containing a solid rotating cylinder. The annulus area between the cylinder and the enclosure was filled with water-alumina nanofluid. Buongiorno’s model was applied to assess the local distribution of nanoparticles in the host fluid. The governing equations for the mass conservation of nanofluid, nanoparticles, and energy conservation in the nanofluid and the rotating cylinder were carried out and converted to a non-dimensional pattern. The finite element technique was utilized for solving the equations numerically. The influence of the undulations, Richardson number, the volume fraction of nanoparticles, rotation direction, and the size of the rotating cylinder were examined on the streamlines, heat transfer rate, and the distribution of nanoparticles. The Brownian motion and thermophoresis forces induced a notable distribution of nanoparticles in the enclosure. The best heat transfer rate was observed for 3% volume fraction of alumina nanoparticles. The optimum number of undulations for the best heat transfer rate depends on the rotation direction of the cylinder. In the case of counterclockwise rotation of the cylinder, a single undulation leads to the best heat transfer rate for nanoparticles volume fraction about 3%. The increase of undulations number traps more nanoparticles near the wavy surface.

scholarly journals EFFECT OF OIL ON HEAT TRANSFER OF MIXED REFRIGERANT BOILING IN EVAPORATOR TUBES IN REFRIGERATION MACNINES

2019 ◽  
pp. 88-93
Author(s):  
Alexey Vasilievich Ezhov ◽  
Sergey Sergeevich Ivanov ◽  
Aleksandr Bukin ◽  
Vladimir Grigorievich Bukin
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Flow Boiling ◽  
Working Fluid ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Pipe Length ◽  
Heat Transfer Coefficients

The paper presents the results of an experimental study of the effect of oil on the heat transfer rate at boiling of mixed refrigerant R406A. Since the air conditioning system is not a pure refrigerant, but a mixture of oil with a concentration of up to 8%, such an amount of oil affects both hydrodynamics and heat exchange in the evaporators. The experimental work covers the entire range of regime parameters typical for these systems. There is shown the process of changing oil concentration in the pipe, as the working fluid boils, proving that most of the oil pipe does not impair the heat exchange in the course of two-phase flow boiling. Different modes of refrigerant R406A boiling dynamics have been defined, and each mode is given a quantitative assessment in terms of the effects of the oil and explaining of this effect on the fluid flow and heat transfer based on visual observations and the experiment results. The main factor of the effect is the freon-oil foam, which increases the proportion of the wetted surface in the wave and stratified modes and the heat transfer rate to 30%. A comparison of the heat transfer coefficients both in the cross section and along the pipe length has been performed, showing that the maximum change in heat transfer occurs in the upper part of the surface due to developing a dry wall on it and wetting it with freon-oil foam. A comparison of the heat transfer rate of pure refrigerant R406A has been done; the presence of oil in it shows that the effect of oil is complex and ambiguous. Calculation and criterion dependences for calculation of heat transfer coefficients in different modes have been proposed.

Biomechanics of Surface Runoff and Soil Water Percolation

2020 ◽  
Vol 401 ◽  
pp. 36-46
Author(s):  
James Makol Madut Deng ◽  
Oluwole Daniel Makinde
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Soil Water ◽  
Heat Transfer Rate ◽  
Surface Runoff ◽  
Transfer Rate ◽  
Soil Surface ◽  
Biophysical Parameters ◽  
Two Phase ◽  
Soil Water Transport

In this study, the complex interaction of surface runoff with the biomechanics of soil water transport and heat transfer rate is theoretically investigated using a mathematical model that relies on the two phase flows of an incompressible Newtonian fluid (stormwater) within the soil (porous medium) and on the soil surface (runoff). The flow and heat transfer characteristics within the soil are determined numerically based on Darcy-Brinkman-Forchheimer model for porous medium coupled with the appropriate energy equation while analytical approach is employed to tackle the model for interacting surface runoff stormwater. The effects of various embedded biophysical parameters on the temperature distribution and stormwater transport within the soil and across the soil surface together with soil-runoff interface skin friction and Nusselt number are display graphically and discussed quantitatively. It is found that an increase in surface runoff over tightly packed soil lessens stormwater percolation rate but enhances both soil erosion and surface heat transfer rate.

Application of Mahalanobis-Taguchi system and design of experiments to reduce the field failures of splined shafts

2014 ◽  
Vol 31 (6) ◽  
pp. 681-697 ◽  
Author(s):  
Boby John
Keyword(s):  
Heat Transfer ◽  
Design Of Experiments ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Removal Rate ◽  
Heat Removal ◽  
Induction Hardening ◽  
Raw Material ◽  
Hardness Profile ◽  
Content Type

Purpose – The purpose of this paper is to develop a methodology to reduce the field failures of splined shafts. The paper also demonstrates the application of Mahalanobis-Taguchi system (MTS) for identifying the optimum hardness profile to avoid failures. Design/methodology/approach – Through the usage profile analysis and comparison between the failed and good shafts, the major reason for shaft failure was identified as hardness variation. Then MTS approach was used to identify the optimum hardness profile for the shafts. An experiment was designed with power, feed and the gap between inductor and quench ring representing the heat transfer rate, heat removal rate and the time between heat transfer and removal of induction hardening process as factors. Based on experimental results, the optimum combination factors that would reduce the variation around the optimum hardness profile were identified. Findings – The study showed that the shaft failures can be reduced by optimizing the hardness profile of the shafts rather than warning customers on overloading, changing the raw material or investing on machining operation to achieve better shaft finish. The study suggested heat transfer rate, heat removal rate and the time between heat transfer and removal had significant impact on the shaft's hardness profile. The study resulted in reducing the field failures from 0.32 to 0.029 percent. Practical implications – This study provides valuable information on how to identify optimum hardness profile using MTS methodology to reduce shaft failures and how to minimize the variation around the optimum hardness profile using design of experiments. Originality/value – To the best of author's knowledge, no study has been conducted to identify optimum hardness profile using MTS methodology. The study also provides an approach to minimize the variation around a non-linear hardness profile using design of experiments.

Effect of Loop Tilting on the Heat Transfer and Pressure Drop in Two-Phase CO2 Based Natural Circulation Loop: An Experimental Study

2020 ◽  
Vol 13 (2) ◽  
Author(s):  
L. R. Thippeswamy ◽  
Ajay Kumar Yadav
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Natural Circulation ◽  
Flow Behavior ◽  
Experimental Studies ◽  
Circulation Loop ◽  
Two Phase ◽  
Natural Circulation Loop

Abstract The natural circulation loop (NCL) is widely used where the safe and economic heat transfer device is desired. However, the instability associated with the regular change in fluid flow behavior due to the imbalance between friction and buoyant forces is a major disadvantage. One of the erudite solutions to overcome this is to tilt the entire loop by a certain angle, with an inherent penalty in heat transfer and pressure drop. In the present study, experimental studies have been carried out on two-phase carbon dioxide (CO2) based NCL, which has gained popularity because of its compactness and higher heat transfer rate. Pressure drop and heat transfer performance of the loop for various tilt angles (0 deg, 30 deg, and 45 deg) in different planes (XY and YZ planes) have been investigated. Methanol is used as the external fluid in cold and hot heat exchangers in order to maintain low operating temperature in the loop. Results show that the tilting of the loop causes a marginal drop in the heat transfer rate of two-phase CO2 based NCL. Hence, tilting of the loop could be a solution to instability problem without conceding the performance of the loop.

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