Size matters: selecting the
right heat exchanger
for your thermal processing
needs
By Matt Hale, International Sales and Marketing Director, HRS Heat Exchangers
hermal processing is an
essential part of many
production processes and
many manufacturers will
be using a heat exchanger
to carry out their thermal
processing requirements. Yet, with such
a variety of applications possible, it’s
important that you select the right heat
exchanger for your individual requirement.
T
Know your process
There are a number of types of heat
exchanger on the market: plate, tubular,
corrugated tube, scraped surface, etc.
Each is suited to a particular application,
so think carefully about your process,
including the nature of the material/s
to be heated or cooled, the objective of
the process and any restrictions of the
environment where the heat exchanger
is to be used. The driving force for heat
transfer is the difference in temperature
between the two substances (in most
cases fluids) and this heat transfer will be
influenced by the type of heat exchanger.
One size does not fit all
Once the correct type of exchanger has
been chosen, processors must then make
sure that the model supplied is correctly
sized for the job. In other words, that it
offers the right amount of heat transfer for
the fluid/s being treated at the throughput
required. The heat exchanger must have
a large enough heat transfer area for the
specified fluids and their specified inlet
and outlet temperatures. Most calculations
should also factor in variables such as
whether the heat exchanger operates
using counter-flow or parallel flow.
116
PECM Issue 27
Breaking down barriers
Another important factor controlling
heat transfer is the resistance to heat flow
through the various ‘layers’ that form a
barrier between the two fluids. One way
to prevent the build-up of these layers is
to increase the speed at which the fluid
passes through the heat exchanger so that
turbulence is formed and the boundary
layer breaks away from the surface of the
tube. Another option is to scrape barrier
layers away in a scraped-surface heat
exchanger.
State of the art calculations
As with any kind of science, the
mathematics and understanding of
thermal dynamics is continuing to evolve
and improve, although much of the
science used for heat exchanger design is
up to 80 years old. It is therefore important
to choose a supplier which utilises the
latest understanding of thermodynamics
in order to design heat exchangers
which provide the very best levels of
performance.
www.hrs-heatexchangers.com