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国际计算热科学期刊
ESCI SJR: 0.249 SNIP: 0.434 CiteScore™: 0.7

ISSN 打印: 1940-2503
ISSN 在线: 1940-2554

国际计算热科学期刊

DOI: 10.1615/ComputThermalScien.2011003072
pages 461-481

THREE-DIMENSIONAL ANALYSIS OF LARGE SHELL-AND-TUBE HEAT EXCHANGERS AT HIGH TEMPERATURES

Masato Handa
Hitachi, Ltd., Hitachi Research Laboratory, 832-2 Horiguchi, Hitachinaka-shi, Ibaraki-ken 312-0034, Japan
Kenji Yamamoto
Hitachi, Ltd., Hitachi Research Laboratory, 832-2 Horiguchi, Hitachinaka-shi, Ibaraki-ken 312-0034, Japan
Yoshio Shimogori
Babcock-Hitachi, K. K. Kure Division, 6-9 Takara-machi, Kure-shi, Hiroshima-ken, 737-8508 Japan

ABSTRACT

The distributed resistance approach has been extended to obtain surface temperature distributions around the tubes in large shell-and-tube heat exchangers at high temperatures. The tube side is discretized in a different manner while following the existing shell-side models of flow resistance, convective heat transfer, and turbulence. The tube side is divided into small straight parts and they are further discretized in their circumferential directions as well as in their axial ones. To reduce the computational time and memory, convective and radiative heat fluxes are not calculated directly on each discretized surface; rather, each of them is calculated on the representative surface in which the discretized surfaces are lumped differently depending on convection or radiation. The discrete transfer method (DTM) is adopted to calculate radiation. To implement DTM properly a new algorithm of ray tracing is developed. For the example application, the heat recovery area in a coal fired boiler is taken. As the emissivity of the heat exchanger at high temperatures increases, a large increased temperature variation around the tube is observed. The simulated results of the global heat absorption and local temperature distributions exhibit good agreement with the measured data. The paths of the radiation beams onto the tube are investigated and the influence range of radiation is clarified. The treatment of the influence range in a past numerical study of a utility boiler is also discussed.