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ISSN Online: 2377-424X

International Heat Transfer Conference 12
August, 18-23, 2002, Grenoble, France

Spiral Heat Exchanger in new geometrical and thermal aspects

Get access (open in a dialog) DOI: 10.1615/IHTC12.290
6 pages

Sinopsis

The comprehensive study regarding the entrance/exit region shows that the proper line to trace the path for the channel walls at the centre of Spiral Heat Exchanger (acronym SHE) is not the Archimedean spiral as suggested till to now in literature, but the involute of the circle. In this report the main attention has been focused on a thermal theory of counter-current spiral heat exchanger which is mathematically simple and moreover, sufficiently correct from the physical and engineering point of view. Due to manufacturing difficulties almost all of such apparatuses have the open centre. For a spiral heat exchanger with the open centre the simple formula for the log mean temperature difference correction factor F is developed in the form:
F=[(1-ν2)-1 CNT -2] ln[(1+CNT2)/(1+ν2CNT 2)]. This factor depends on the dimensionless parameter CNT which is similar to the form of the NTU: CNT=kAT/√(CICII), where k means overall heat transfer coefficient, AT- peripheral surface area of apparatus without both parallel bottoms and √(CICII) geometrical mean value of heat capacity ratios CI and CII. Hotter fluid is denoted with subscript )I cooler one with subscript )II. Symbol ν denotes the ratio of the cross-section of an open centre to the cross-section of the real SHE, but without open centre. Prior, the developed theory was validated for a heat capacity rate ratio R=CI/CII that is close to one (i.e. 2/3<R<3/2). But here, by using new scale for parameter R*=R/ε2, where ε2=(1+R)/2-√R ln√R, this theory is extended to whole spectrum of the heat capacity rate ratios R (0<R<∞).