Abstract:
The temperature of zeotropic mixtures does not remain constant throughout a heat exchanger. Furthermore,
Zeotropes often exhibit a nonlinear temperature-enthalpy relationship. These factors contradict some of the assumptions
made in deriving the log mean temperature difference (LMTD), which is used in computing the size of a heat exchanger
(UA). In this paper an ammonia-water mixture in a counter-flow heat exchanger will be examined as an example of a
zeotropic mixture. The actual (UA) obtained via numerical analysis will be compared to the (UA) found using (LMTD), and
representative error scales shall be developed for this purpose.
Keywords: Zeotropic mixtures, Ammonia-water, Log mean temperature difference, Heat exchanger size, Error scales,
Energy equation solver.
