engleski

Local Entropy Production of the Parallel Flow and Counterflow Heat Exchanger

The paper gives an analytical dimensionless analysis of the local entropy generation and its ratio with the local exchanged heat flow rate for parallel flow and counterflow heat exchangers. The end (side) of the heat exchanger, which is the inlet of the weaker stream, is, among other, proven to be relevant variable for those local values. Elaborated algorithm provides explicit connection between entropy generation and ratio of entropy generation to local exchanged heat flow rate in dependence on the relevant dimensionless variables A/A0, π2=kA0/C1, π3=C1/C2 and πT =T1'/T2'. Value π2 vary between 1.0 and 4.0, value π3 amounts 0.0 ; 0.5 and 1.0, while 0.5 and 2.0 were taken for value πT. From obtained general equations for parallel flow and counterflow heat exchanger special cases for observed values were extracted, considering the cases where one of the streams condenses or evaporates. Given algorithm, aside the local amounts of the observed values, also gives overall amounts of the mentioned values. The results are presented by appropriate diagrams and additionally interpreted.

parallel flow and counterflow heat exchanger ; local entropy generation ; local rate of heat flow ; dimensionless analysis

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