Thermoanemometric measurements of the pulsations of the heat-transfer coefficient in a fluidized bed
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The heat transfer from surface may in general be enhanced by increasing the heat transfer coefficient between a surface and its surrounding or by increasing heat transfer area of the surface or by both. The main objective of the study and calculate the total heat transfer coefficient. Improve the heat transfer rate by using ANSYS CFD. During the CFD calculations of the flow in internally ribbed tubes. And calculated the temperature distribution and pressure inside the tube by using ansys. The model was created using CatiaV5 and meshed with Ansys, and the flow analysis is done with Ansys 19.2. The results showing that the heat transfer is increased. The enthalpy and temperature increase with flow is advancing when compare with normal boiler tube. In this study the total heat transfer rate of the pipe increase with the increase the rib height. Total heat transfer rate increase up to 7.7kw. The study show that the improvement in furnace heat transfer can be achieved by changing the internal rib design.
NTU method
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Distributor
Fluidized bed combustion
Fluidization
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Mixing is an important unit operation encountered in chemical and allied industries. Mixing can be achieved by many ways. One such way is fluidized bed. The efficiency of conventional fluidized bed is enhanced by semi- fluidized bed reactor. It is a novel type of fluid-solid contacting device. The semi fluidized bed is characterized by a fluidized bed and a fixed bed in series with single contacting vessel. Any improvement in the fluidized section of semi fluidized bed will increase overall efficiency of semi fluidized bed. This can be achieved by employing stirrer/mixing elements in fluidized section of semi fluid bed reactor. To design the semi fluidized bed as a reactor the knowledge of hydrodynamics, mass transfer, suspension characteristics and Residence time should be known. For this purpose, experiment was conducted in 0.1m internal diameter semi fluidized bed. Hydrodynamic behavior was studied and finally a correlation for pressure friction factor was derived based on the experimental results.
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The characters of a serial fluidized bed reactor, which was composed of a fast-fluidized bed, turbulent fluidized
bed and fast-fluidized bed in a cold condition were studied to resolve the problems existing in direct-chlorination of titania-en-
riched slag from the refineries in Panzhihua. The velocity of the fast-fluidized bed and concentration, flow pattern and solid resi-
dence time in turbulent fluidized bed were studied. The distribution of axial and radial concentrates of turbulent fluidized bed was
reviewed. The ability of coherence resisting in turbulent fluidized bed was studied too. The degree of scrunch which could express
the extent of coherence resisting was used to character the degree of activity in turbulent fluidized bed reactor. Results showed
that the turbulent fluidized bed has better anti-cohering ability.
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Inert
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Fluidization
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This technical report summarizes the research conducted and results obtained during the period beginning October 1, 1999 to March 31, 2000. Heat transfer characteristics study and experimental work were continued using the bench-scale CFB system with the heat transfer probe. A copper tube with thermocouples was used as the heat transfer probe which was convenient to measure the temperature changes at different locations of the bed. The heat transfer coefficient at different locations of the heat transferring surface decreases along the slides down the heat transfer surface; its temperature increase, which reducing the temperature difference between the surface of the tube and the bulk of the bed. The radial variation of heat transfer coefficients showed little increase in heat transfer coefficient near the wall. It is believed that a long heat-transferring surface is located in the core region; a boundary layer develops near the wall of the surface. This may cause clusters or streamers to form which slides down the surface. According to the results, heat transfer coefficients in the core region are not affected significantly by the location of the probe. The wall conduction resistance was eliminated and heat transfer coefficients were measured and calculated at different locations along the bed height. Heat transfer coefficients near the wall area of the bed are decreased along with the length of the probe. Heat transfer coefficient was slightly dropped when the probe was moved from the wall area to the central area of the bed.
Thermocouple
Film temperature
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Studies on roasting of sheelite concentrate have been carried out in fluidized bed to reduce its sulphur content to <5%. Initial investigations have been done using a 10 cm I.D. fluidized bed roaster and the data so generated was used for the design of a fluidized bed roaster of 50 kg/hr capacity. The experiences on roasting of sheelite concentrate with the fluid bed reactor and the methods for scale up to large size reactor are presented.
Roasting
Fluidized bed combustion
Scheelite
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The reaction principle of fluidized bed biofilm in wastewater treatment was introduced in this paper, and the fluidized bed biofilm reactors were sorted by their characteristics. It pointed out the prospect of further research and application of fluidized bed biofilm in wastewater treatment in future based on the characteristics of present technology.
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It has been studied to improve heat transfer performance by using heat transfer surfaces with various roughness. And studies have been accomplished to improve the heat transfer performance by processing a heat transfer surface or a fin having a micro size. As a result of these studies, the heat transfer tube, which is mechanically form various pins or pores, is often used in the heat transfer system. However, there is a limit to improving the heat transfer performance using only the mechanical method. Therefore, in this study, we investigated to the heat transfer performance of coating nanostructure with various shapes and patterns on the heat transfer surface. And, it has been carried out that the experiment about durability of nano-structure added adhesive. Also, after finished experiment, we have measured the contact angle and surface roughness for analyzing the change of durability. As a result of measurement of the heat transfer performance on the heat transfer surface on which the carbon nanotube nanostructure with the dot pattern is formed, the heat transfer coefficient generally increased as compared with the heat transfer surface without the nanostructure, and the increase rate of the heat transfer coefficient decreases exponentially. It was confirmed that the increase rate of the heat transfer coefficient averagely increased by 5.81% after 100 kW / m². Therefore, these results suggest that heat transfer performance can be improved by forming a nanostructure on the heat transfer surface of the heat exchanger.
Heat transfer enhancement
Fin
Enhanced heat transfer
NTU method
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