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Mean temperature difference: A reappraisal
Author(s) -
Gardner Karl,
Taborek Jerry
Publication year - 1977
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690230602
Subject(s) - baffle , heat exchanger , thermodynamics , mechanics , constant (computer programming) , mixing (physics) , mathematics , heat transfer coefficient , stratification (seeds) , mean radiant temperature , heat transfer , chemistry , physics , computer science , geology , seed dormancy , germination , botany , quantum mechanics , dormancy , biology , programming language , oceanography , climate change
The derivation of the mean temperature difference in heat exchangers is based on a number of assumptions or idealizations, the most important ones being that the heat transfer coefficient is constant throughout the exchanger; that the temperature of either fluid is constant over any cross section of its nominal path, that is, complete mixing, no stratification or bypassing; and that an additional assumption for shell and tube exchangers, which has not always been fully recognized, is that within one baffle crossing the shell fluid temperature change is small with respect to its overall change, (that is, number of baffles is large). In actual exchangers, any of the above assumptions are frequently subject to various degrees of invalidation. This paper examines the effects of deviating from the first two assumptions and presents a new solution to the third.