38 research outputs found
Falling film Ammonia Evaporators
Get PDFThis paper is a literature review and correlation of data on
falling film and spray evaporators. This type of evaporator offers
the potential advantages of improved heat-transfer coefficients and
a reduction in charge of evaporating fluid. The challenge in
reviewing papers by various authors is that the data appears in
different forms, so an attempt has been made to achieve some
uniformity in order to critically compare the data. Another
objective of this paper is to provide guidelines for how a
developer and manufacturer of this type of evaporator can improve
the performance of the model under development.
One of the important factors in achieving the maximum
improvement in evaporator performance is the proper choice of the
rate of refrigerant spray. A circulation rate that is too high
increases the refrigerant charge and also increases the pumping
power for the circulation of the refrigerant. On the other hand,
if the spray rate is too low, some areas on the tube become dry and
the heat-transfer coefficient drops off rapidly. Also, the optimum
tube placement in a falling-film evaporator may not be the same as
in a flooded ~vaporator. This paper also explores research studies
on enhanced surfaces for ammonia and the potential combination of
enhanced surfaces with the falling film concept
