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Archives of Heat Transfer
1988, Dubrovnik, Yugoslavia

DOI: 10.1615/ICHMT.1988.20thAHT


ISBN Print: 978-0-89116-877-5

ISSN: 0899-5311

HIGH TEMPERATURE HEAT EXCHANGERS. International Symposium 1985

pages 411-412
DOI: 10.1615/ICHMT.1988.20thAHT.350
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RÉSUMÉ

At the 17th Symposium on High Temperature Heat Exchangers, 45 papers including 8 invited papers were reported in four groups: High Temperature Heat Exchanger Development, Basic Problems in High Temperature Heat Exchangers, Heat Exchangers for Future Power Plants and Industrial Applications.
The Symposium was organized to focus attention on heat and mass transfer processes associated with high temperature heat exchangers. An understanding of the processes plays an essential and important role in the rapid development of high temperature heat exchangers towards improved energy utilization and a higher efficiency of energy conservation at various power and industrial plants. In high temperature heat exchangers, gas-gas heat transfer dominates. Research and development is under way on many kinds of high temperature heat exchangers : recuperative, regenerative and direct-contact. In addition to heat transfer enhancement problems, there are several very important, basic and serious problems peculiar to high temeprature heat exchangers. These are reliability, thermal stress, thermal expansion, difficulty in scale-up and physical property variation of fluids. When discussing high temperature heat exchangers, the difference between problems encountered in heat exchangers at moderate temperatures and those at high temperatures should be clearly recognized. Heat transfer enhancement for high temperature heat exchangers, is discussed mainly in connection with radiation. In gaf-gas heat exchangers the viscosity of a gas increases with temperature and other physical properties also vary. Viscosity increase is associated with relaminarization of gas flow at high temperatures due to the decrease of the Reynolds number. This phenomenon peculiar to high temperature heat transfer is discussed. The gas radiative emissivity has been assumed to be grey so far, but radiation heat transfer problems are discussed for several channel flow cases by proposing an accurate analytical model taking into account the multi-band feature of a given gas with some numerical results. In discussion of constrictions of heat exchangers, high temperature heat exchangers have to be provided with a structure of symmetry and to fulfill the condition of a uniform outlet temperature of heated gas pipes or ducts as to avoid hot spots in the exchanger structure.

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