A heat exchanger is the heart of any thermal or refrigeration
system, and hence its proper design is of paramount importance
to industry. Modelling is an economical and efficient way to
design a thermal system (and hence a heat exchanger) and
predict its performance without conducting detailed time
intensive and costly physical experiments. Although the
physics of two 'generic' modelling techniques, namely LMTD
and NTU-e, is well covered in the basic heat transfer text
books, applying these techniques can be quite an involved
process in some difficult situations, such as complex heat
exchanger geometries, one or both streams undergoing phase
change or moisture removal from an air stream, heat exchanger
experiencing a 'pinch point' etc. In some situations, models can
also become quite sophisticated and use more advanced
techniques, where a heat exchanger involving two-phase is
modelled following a segment, zone by zone or an elemental
approach. An elemental method is intensive but can be
comprehensive and accurate. This paper reviews some of these
modelling fundamentals for a two-phase heat exchanger, and
presents two novel examples of heat exchangers that were
optimised for their energy efficient use in domestic
refrigerators. These were well received by the industry.
Paper presented at the 7th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Turkey, 19-21July, 2010.
