period two
Absorption Chiller Types
notes
| condenser | low-temperature |
| generator |
| |
| evaporator | |
absorber
| high-temperature | Figure 31 |
| generator |
| |
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).
| high- | | refrigerant vapor | condensed |
| | | | refrigerant |
| temperature | | | | |
| refrigerant | |
| generator | condenser |
| vapor |
| | |
| | | | low-temperature | |
| | | | generator | |
Figure 32
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
