Article ID Journal Published Year Pages File Type
6588412 Chemical Engineering Science 2018 6 Pages PDF
Abstract
In most heat transfer applications, knowledge of the viscosity variation is important. Thus viscosity correction factors have been researched and proposed for almost a century. One of the most successful relations was reported by Sieder-Tate in 1936, which has been widely used in engineering analysis and design. In this study, we have improved on the Sieder-Tate relation, following a classical theoretical analysis of the thermal boundary layer. An exact solution to the viscosity correction factor was obtained which shows that the Sieder-Tate correction factor over-predicts the heat transfer coefficient in the case of cold wall (cooling) and does not hold properly for hot wall (heating). We have found that a relation of μ∞μw0.254 (in case of cooling) and μ∞μw0.087 in the case of heating is better than the Sieder-Tate factor of μ∞μw0.14 (uniformly applied to both the heating and cooling cases). Here μ∞ and μw are the bulk and wall viscosity coefficients respectively. The theoretical analysis also shows that the above correction factors are limited to small values of lnμwμ∞ (for cold wall) and lnμ∞μw (for hot wall). However a general solution has been obtained and the correlation developed by Petukhov (1970) closely matches the exact solution for the case of cold wall cooling of a fluid.
Related Topics
Physical Sciences and Engineering Chemical Engineering Chemical Engineering (General)
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