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HEAT TRANSFER WITH LAMINAR FLOW IN CONCENTRIC ANNULI WITH CONSTANT AND ARBITRARY VARIABLE AXIAL WALL TEMPERATURE

Technical Report ·
DOI:https://doi.org/10.2172/4809736· OSTI ID:4809736

An analysis has been performed to determine the heat transfer characteristics for laminar forced-convection flow in a concentric annulus with prescribed surface temperatures. Three distinct problems were considered: (a) wall temperature prescribed at both the inside and outside wall; (b) inside wall temperature prescribed and the outside wall insulated; and (c) inside wall insulated and outside wall temperature prescribed. The solution for temperature distribution was similar to that obtained by Graetz for laminar heat convection in a pipe with uniform wall temperature. Expressions are presented for heat flux, mixing cup temperature, and Nusselt number as a function of downstream position. Eigenvalues and eigenfunctions were computed for values of the ratio of the inside to the outside radii for the boundary conditions. Mixing cup temperatures, local and fully developed Nusselt numbers, and thermal entry lengths are presented graphically. The solution of Problem (a) was extended to the situation in which the temperatures of the inside and outside walls of the annulus are not equal. By utilizing the method of superposition and the solutions already obtained for Problem (a), the temperature distributions were determined. By way of illustration, heat fluxes were calculated for several values of the temperature ratio (T/sub wi/-T/sub 0/)/(T /sub w0/-T/sub 0/). Results wer e generalized to apply to the situation of arbitrary longitudinal variation of the wall temperatures of the annulus. As an illustration of the method, an extension is explicitly given for a linear increase of all temperature with axial distance. (auth)

Research Organization:
Argonne National Lab., Ill.
DOE Contract Number:
W-31109-ENG-38
NSA Number:
NSA-16-008861
OSTI ID:
4809736
Report Number(s):
ANL-6441
Country of Publication:
United States
Language:
English