Development of High-Temperature Heat Exchangers Using SIC Microchannels

Author(s):  
Merrill A Wilson ◽  
Raymond Cutler ◽  
Marc Flinders ◽  
Matt Quist ◽  
Darin Ray ◽  
...  
Author(s):  
Stefano Consonni ◽  
Ennio Macchi

Externally Fired Combined Cycles (EFCC) constitute one of the options allowing the use of “dirty” fuels like coal, biomass or waste in conjunction with modern, high efficiency gas turbines. This two-part paper discusses thermodynamic, technological and economic issues crucial to the successful realization of EFCCs. Part B discusses the cycle arrangement, its implications for the design and the cost of the high temperature heat exchangers, the effects of scale and the economic prospects. An “enhanced” configuration whereby the excess air sent to the combustor is limited to the minimum required for complete combustion can reach net LHV efficiencies above 50%, with relatively low high-temperature heat transfer surface requirements. Cost projections are hindered by the uncertainty on the cost of the high temperature heat exchangers. Estimates based on published and proprietary data collected by the authors indicate that EFCCs should be cost-competitive with IGCCs, especially at medium-low power outputs.


Author(s):  
Benedikt Hoegel ◽  
Dirk Pons ◽  
Michael Gschwendtner ◽  
Alan Tucker ◽  
Mathieu Sellier

Low-temperature heat sources such as waste heat and geothermal energy in the range from 100 ℃ to 200 ℃ are widely available and their potential is largely untapped. Stirling engines are one possibility to convert this heat to a usable power output. Much work has been done to optimise Stirling engines for high-temperature heat sources such as external combustion or concentrated solar energy but only little is known about suitable engine layouts at lower temperature differences. With the reduced temperature difference, changes become necessary not only in the heat exchangers and the regenerator but also in the operating parameters such as frequency and phase angle. This paper shows results obtained from a third-order simulation model that help to identify beneficial parameter combinations, and explains the differences of low and high-temperature engines.


Author(s):  
Q. Y. Chen ◽  
M. Zeng ◽  
D. H. Zhang ◽  
Q. W. Wang

In the present paper, the compact ceramic high temperature heat exchangers with parallel offset strip fins and inclined strip fins (inclined angle β = 0∼70°) are investigated with CFD method. The numerical simulations are carried out for high temperature (1500°C), without and with radiation heat transfer, and the periodic boundary is used in transverse direction. The fluid of high temperature side is the standard flue gas. The material of heat exchanger is SiC. NuS-G.R(with surface and gaseous radiation heat transfer) is averagely higher than NuNo.R (without radiation heat transfer) by 7% and fS-G.R is averagely higher than fNo.R by 5%. NuS-G.R(with surface and gaseous radiation heat transfer) is averagely higher than NuS.R (with only surface radiation heat transfer) by 0.8% and fS-G.R is averagely higher than fS.R by 3%. The thermal properties have significantly influence on the heat transfer and pressure drop characteristics, respectively. The heat transfer performance of the ceramic heat exchanger with inclined fins (β = 30°) is the best.


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