Mechanisms of Heat Transfer Enhancement of Gas–Solid Fluidized Bed: Estimation of Direct Contact Heat Exchange From Heat Transfer Surface to Fluidized Particles Using an Optical Visualization Technique

1995 ◽  
Vol 117 (1) ◽  
pp. 104-112 ◽  
Author(s):  
Y. Kurosaki ◽  
I. Satoh ◽  
T. Ishize
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Fluidized Bed ◽  
Flow Rate ◽  
Direct Contact ◽  
Heat Transfer Surface ◽  
Heat Transfer Tube ◽  
Transfer Tube ◽  
Contact Frequency ◽  
Fluidized Particles

This paper deals with mechanisms of heat transfer in a gas–solid fluidized bed. Heat transfer due to heat exchange by direct contact from a heat transfer tube immersed in the bed to fluidized particles was studied by means of visualization of contact of the fluidized particles to the heat transfer surface. The results show that the duration of contact of fluidized particles was almost uniform over the tube circumference and was hardly affected by the flow rate of fluidizing gas. On the other hand, the contact frequency between the particles and heat transfer tube was evidently influenced by the gas flow rate and particles diameter, as well as the location on the tube circumference. Using the visualized results, the amount of heat conducted to fluidized particles during the contact was estimated. This result showed that unsteady heat conduction to the fluidized particles plays an important role in the heat transfer, especially at the condition of incipient fluidization.

Experiment and Analysis on Isolation Condenser Simulator Using Pressurized Steam

2020 ◽  
Author(s):  
Kosuke Ono ◽  
Yasunori Yamamoto ◽  
Masayoshi Mori ◽  
Tetsuya Takada
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Void Fraction ◽  
Flow Rate ◽  
Nuclear Power ◽  
Natural Circulation ◽  
Heat Removal ◽  
Condensation Process ◽  
Heat Transfer Tube ◽  
Transfer Tube

Abstract Isolation condensers (ICs) are important passive cooling systems in BWRs. After the Fukushima Daiichi Nuclear Power Station accident, concerns if the IC was able to restart with the inflow of hydrogen were arose. Because ICs lose heat removal ability when non-condensable gas inflow occurs, accurate evaluation of the effect is necessary. To develop analysis methods, as an initial stage, experiments and analyses considering only high-pressure steam and water were conducted. The experiment was done by an isolation condenser simulator which contains an accumulator with heaters inside, and a heat transfer tube. From the experiment, all steam was condensed at the heat transfer tube and the approximate position of complete condensation was confirmed from the temperature distribution and the observation. The experiment provided data such as temperature distribution, natural circulation flow rate, and pressure to compare with the analysis. The analyses were conducted for 4 cases of void fraction values at the heat transfer tube inlet and found that it has a high sensitivity to condensation. The reason is estimated to be the difference in inflow velocity that strongly depends on the void fraction even if the mass flow rate is constant. And the initial condition of the liquid film also affected condensation process. Heat removal at the section before the heat transfer tube should be considered to adjust void fraction at the inlet of heat transfer tube.

scholarly journals Development Progress on the Atmospheric Fluidized Bed Coal Combustor for Cogeneration Gas Turbine System for Industrial Cogeneration Plants

1980 ◽  
Vol 102 (2) ◽  
pp. 292-296 ◽  
Author(s):  
R. S. Holcomb
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Fluidized Bed ◽  
Conceptual Design ◽  
Gas Turbines ◽  
Test System ◽  
Department Of Energy ◽  
Heat Transfer Tube ◽  
Transfer Tube ◽  
Exhaust Heat

The Atmospheric Fluidized Bed Coal Combustor Program will develop the technology for a fluidized bed coal combustion system to provide a source of high temperature air for process heating and power generation with gas turbines in industrial plants. The gas turbine has the advantages of a higher ratio of electric power output to exhaust heat load and a higher exhaust temperature than do steam turbines in cogeneration applications. The program is directed toward systems in the size range of 5 to 50 MW(e) and is sponsored by the Department of Energy. A study of industrial energy use has been completed that indicates a large potential market for gas turbine cogeneration systems. Conceptual design studies have been done for typical industrial’ installations, and some of these results are presented. The conceptual design of a 300 kW(e) test unit has been completed. A number of furnace design firms have been invited to submit their own designs for a 1500 kW(t) (5 × 106 Btu/hr) combustor, from which a final selection will be made. The design of the balance of the test system will proceed in parallel with the combustor design. An engineering design study has been completed by AiResearch Division of Garrett Corporation in which the modifications required to adapt an existing AiResearch 831-200 gas turbine to this cycle for both open and closed cycle operation were determined. Development and testing have been conducted in the areas of fluidization, heat transfer, tube corrosion and coal feeding. Results from heat transfer, tube corrosion, and coal feeding tests are presented.

Effect of Surface Heat Exchange Intensifier Geometry on Heat Transfer Tube Strength

2019 ◽  
Vol 62 (3) ◽  
pp. 373-380
Author(s):  
I. A. Popov ◽  
A. V. Shchelchkov ◽  
R. A. Aksyanov ◽  
A. N. Skrypnik ◽  
S. A. Isaev
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Surface Heat ◽  
Heat Transfer Tube ◽  
Transfer Tube ◽  
Surface Heat Exchange ◽  
Effect Of Surface

scholarly journals TESTS OF FLAT HYDROTURBINE ROTATING A HEAT EXCHANGE TUBE

2020 ◽  
Vol 2020 (1) ◽  
pp. 11-12
Author(s):  
Aleksey Bal'chugov ◽  
Borislav Kustov ◽  
Natal'ya Kustova
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Rotational Speed ◽  
Hydraulic Turbine ◽  
Vertical Tube ◽  
Heat Transfer Tube ◽  
Laboratory Bench ◽  
Transfer Tube ◽  
Heat Exchange Tube

Tests of a flat-blade hydraulic turbine designed to rotate a heat transfer tube at a laboratory bench have been performed. The dependence of the rotational speed of a hydraulic turbine in a vertical tube on the flow of water is determined.

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