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TRG-TRC011-EN 27
period two
Absorption Chiller Types
notes
Direct-Fired Chiller
The indirect-fired absorption chillers discussed previously use steam or a hot
liquid (such as water) as the energy source. In contrast, the high-temperature
generator of a direct-fired absorption chiller uses the heat released by the
combustion of a fossil fuel to boil off the refrigerant vapor.
Common fuels used to fire the burner in the high-temperature generator are
natural gas, number 2 fuel oil, or liquid petroleum (LP). Additionally,
combination burners are available that can be switched from one fuel to
another. Typical COPs for direct-fired, double-effect chillers are 0.9 to 1.1 (based
on the higher heating value, or HHV, of the fuel).
The example direct-fired chiller shown here employs the reverse-series flow
cycle. In the high-temperature generator, the intermediate solution absorbs
heat that is generated by the combustion process. Similar to the indirect-fired,
double-effect chiller, this transfer of heat causes the refrigerant to boil and
condenser
condenser
high
high
-
-
temperature
temperature
generator
generator
evaporator
evaporator
absorber
absorber
low
low
-
-
temperature
temperature
generator
generator
Figure 31
refrigerant
refrigerant
vapor
vapor
refrigerant vapor
refrigerant vapor
condensed
condensed
refrigerant
refrigerant
high
high
-
-
temperature
temperature
generator
generator
low
low
-
-
temperature
temperature
generator
generator
condenser
condenser
Figure 32