Heat Exchangers
and their
Application in Geothermally Heated Structures
Heat Exchangers are devices
that transfer heat from a hot medium to a cool
medium through conduction. Heat flows naturally
from hot to cold. The heat transfer is more
efficient if the different temperature mediums
have greater contact, which is accomplished by
maximizing the surface area of contact and the
lapsed time of contact.
Heat exchangers are useful for heating a separate
fluid from the initially hot fluid. For instance,
geothermal water from wells usually contains high
levels of dissolved elements which are corrosive.
Rather than piping the mineral-rich geothermal
fluid through pipe systems, turbines, or other
machinery, the heat from the geothermal fluid can
be extracted and transferred to a second fluid,
called a binary or process fluid, using a heat
exchanger. The binary fluid that circulates
through a heating system, or other process, is a
clean, non-corrosive fluid. It can be glycol or
purified water, or some other fluid with desirable
properties like various refrigerants. For
instance, Chena Hot Springs near Fairbanks
uses 73 degree Celsius geothermal water to
heat a refrigerant fluid with a much lower
boiling temperature, enabling the resort to
produce steam power from the boiling fluid.
|
|