Fully Ceramic Composite Heat Exchanger Qualification for Advanced Combustion Chambers

2005 ◽  
Author(s):  
Clément Bouquet ◽  
Roger Fischer ◽  
Agnès Luc-Bouhali ◽  
Olivier Dessornes ◽  
Jacques Thebault ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Ceramic Composite ◽  
Combustion Chambers ◽  
Advanced Combustion ◽  
Composite Heat

Fouling of Heat Exchanger Tubes in Pulverized-Coal-Fired Combustion Chambers

2008 ◽  
Author(s):  
Efim Korytni ◽  
Yuli Berman ◽  
Boris Davidson ◽  
Miron Perelman ◽  
Roman Saveliev ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Power Plants ◽  
Ash Deposition ◽  
Axially Symmetric ◽  
Combustion Chambers ◽  
Weakly Bound ◽  
Water Steam ◽  
Overall Heat Transfer Coefficient ◽  
Utility Boilers ◽  
Ash Deposit

Fouling is a major concern in coal-fired power plants caused by fly ash deposit on the heat exchanger tubes that decreases the overall heat transfer coefficient to water-steam mixture. Fouling has been characterized by weakly bound-loose form, which may be removed by various methods, such as soot-blowing, blast, and sand blowing. We have carried out experimental and modeling work on fouling to develop a methodology by which the thermal conductivity of the ash deposit would be determined in a way similar to the fouling process prevailing in real systems. For that we used tubes identical in material, diameter and temperature to those used in many utility boilers. In the experimental work we placed a tube in an axially symmetric 50 kW furnace, and tested fouling from three coals, bituminous and sub-bituminous. We also developed a dynamic model for the prediction of the ash deposition growth and its heat resistance. Comparison of the model prediction and experimental results yielded satisfactory fit. Consequently, thermal resistance of heat exchanger tuber with ash deposit of those coals was determined.

CHARACTERISTICS AND FLOW VISUALIZATION OF A THERMOSYPHON IN MELTS INSIDE A COMPOSITE HEAT EXCHANGER TUBE

1990 ◽  
Vol 3 (4) ◽  
pp. 355-370
Author(s):  
Wen-Jei Yang ◽  
Nengli Zhang ◽  
C. P. Lee ◽  
Yuen-Sang Ho ◽  
Jeff Chiou
Keyword(s):  
Heat Exchanger ◽  
Flow Visualization ◽  
Heat Exchanger Tube ◽  
Composite Heat ◽  
Exchanger Tube

Compact Carbon-Carbon Composite Heat Exchanger

2002 ◽  
Author(s):  
M. Khairul Alam ◽  
Roland J. Watts ◽  
John Price
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
High Surface ◽  
Single Layer ◽  
Carbon Matrix ◽  
Carbon Composite ◽  
Metal Plate ◽  
Air Stream ◽  
Standard Plate ◽  
Composite Heat

Composite heat exchangers can provide significant reduction in the weight of a compact heat exchanger in comparison to metal heat transfer units. A Carbon-Carbon (C-C) composite heat exchanger core has been fabricated to study the heat transfer and friction characteristics of single layer plate-fin geometry. The plate and fins are both C-C composites, in which the carbon matrix is reinforced by high conductivity graphitic carbon fibers to improve the fin effectiveness of the heat exchanger. A heat flux is applied to the top and bottom of the heat exchanger core to heat an air stream passing through the channels. The heat transfer coefficient and the friction coefficient are determined and the experimental results are compared with data for a standard plate fin heat exchanger of similar geometry. It was determined that the C-C heat exchanger had lower Colburn heat transfer factor than a similar metal plate-fin heat exchanger; but had high surface temperature effectiveness. The friction factor of the C-C heat exchanger was slightly lower than the metal plate-fin heat exchanger.

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