Handbook of air conditioning and refrigeration / Shan K

14.20 CHAPTER FOURTEEN
Corrosion Control
of 6°F (3.3°C) in the absorber and 4°F (2.2°C) in the condenser, and the difference between the
condensing temperature and cooling water temperature leaving the condenser T con � T cl � 3°F
(1.7°C), then condensing temperature T con can be calculated as
Condensing pressure p con should be slightly lower than the boiled-off vapor pressure in the lowtemperature
generator in order to extract the vapor and be condensed in the condenser.
Many heat exchangers are typically of the shell-and-tube type. Shells are often made of mild steel
or stainless steel, and tube bundles are usually made of copper or copper-nickel alloy. Lithium bromide
is very corrosive. It attacks steel, copper, and copper alloys in the presence of air at temperatures
above 300°F (149°C). Corrosion inhibitor should be used to protect the internal components
against corrosive attacks, as specified by the manufacturer.
Rated Condition of Absorption Chiller
Minimum Performance
T con � 85 � 6 � 4 � 3 � 98�F (36.7�C)
When one selects a double-effect, direct-fired, reverse parallel flow, water-cooled absorption chiller,
the chiller’s cooling capacity must meet the required system refrigeration load. According to ARI
Standard 560, absorption chillers are rated under the following conditions:
Leaving chilled water temperature
Chilled water temperature rise
Chilled water flow rate
Entering cooling water temperature
Cooling water flow rate
Fouling factor
44°F (6.7°C)
10°F (5.6°C)
2.4 gpm/ton (0.043 L/s�kW)
85°F (29.4°C)
4.4 gpm/ton (0.079 L/s�kW)
0.00025 h�ft 2 �°F/Btu (0.000044 m 2 �C/W)
At design load, under operating conditions other than the standard rating conditions, both the cooling
capacity and the heat input should be modified.
ASHRAE/IESNA Standard 90.1-1999 mandates the minimum efficiency requirements for absorption
chillers at all capacities at rated conditions as follows:
14.7 ABSORPTION CHILLER-HEATERS
Type Minimum efficiency Efficiency as of 10/29/2001
Air-cooled, single effect 0.48 COP 0.60 COP
Water-cooled, single effect 0.60 COP 0.70 COP
Double-effect, indirect-fired 0.95 COP, 1.00 IPLV 1.00 COP, 1.05 IPLV
Double-effect, direct-fired 0.95 COP, 1.00 IPLV 1.00 COP, 1.00 IPLV
An absorption chiller-heater has nearly the same equipment and piping arrangement as those in an
absorption chiller except for some additional valves and switches. The heating cycle operation of an