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ABS-PRC001-EN8
Application
Considerations
General
General
The Horizon single-stage steam-fired or
hot water absorption chiller is designed
to provide 40°F to 60°F [4.4°C to 15.6°C]
chilled water, for comfort or process
cooling applications, within all three
market segments – commercial,
industrial and institutional. They are
most-often used where an economic
analysis of fuel costs versus electrical
rates indicates an operating cost
advantage.
In many process applications, they can
be utilized to convert excess heat energy
to provide chilled water for process or
comfort applications.
Operating Limits
Trane single-stage absorption chillers
operate with nominal 12 psig [0.83 bar]
steam or nominal 270°F [132°C] hot
water. In all applications, superheat
should be limited so steam temperature
does not exceed 340°F [171°C].
Waterflows that are within the limits
indicated on the appropriate selection
table will ensure tube water velocities
not exceeding 10 feet per second
[3.05 m/sec] in copper tubes and 11 feet
per second [3.35 m/sec] in cupronickel
tubes. Changes in condenser water
temperature should not exceed
1°F per minute in the range from 75°F to
95°F [23.9°C to 35°C].
Sound and Vibration
Absorption units are well-suited for
areas where low sound levels are
required. The Trane Horizon single-stage
steam absorption chiller will operate
under normal load conditions at less
than 85 dBA sound pressure level.
During operation there is no vibration of
any components that could be
damaging to the chiller or that could
transmit objectionable sound or
vibration to the building.
Chiller Installation
The following should be considered
when installing an absorption chiller:
• Rigging and service clearances
• Foundation support
• Chiller isolation for sound/vibration
reduction
• Condensate handling
• Steam supply control
• Condenser-water temperature control
• Chilled-water flow control
• Chilled- and condenser-water flow limit
• Generator hot-water application
Cooling-Tower Water Flow
The ARI standard gpm/ton for single-
stage absorption chillers is 3.6, however,
lower flow through the condenser and
absorber section will present an
opportunity for a smaller tower, smaller
piping, and smaller condenser pump.
For more information on lower flows in
the cooling tower water circuit, refer to
the appropriate Trane engineering
bulletin, available from your local Trane
representative.
Water Treatment
The use of untreated or improperly
treated water may result in scaling,
erosion, and corrosion, algae or slime. It
is recommended that the services of a
qualified water-treatment specialist be
used to determine what treatment, if
any, is advisable. The Trane Company
assumes no responsibility for the results
of untreated or improperly treated water.
Combination Systems
Peak energy savings can be achieved
when using a combination of electric
chillers and absorption chillers for air
conditioning loads. The absorption
chiller is used to shave seasonal, billable
peak-power demands during summer
operation, and the electric chiller is run
below the allowed demand limit,
reducing costly demand charges. Trane
offers both electric chillers and
absorption chillers with the unit control
panel (UCP2) as standard. Although the
chillers have different features and
modes of operation, the chiller control
panel looks and acts the same when
used with any chiller model. Each
control panel is programmed to monitor
the particular chiller for which it was
designed, however, maintenance and
service personnel only need to become
familiar with one control panel.
Combined with a Trane Tracer
®
system, a
chiller plant has almost unlimited
operational flexibility, and all equipment
is supplied from a single source.
Multiple Machine Installations
The Trane absorption machine can be
applied to series or parallel chilled-water
flow, depending upon the design
requirement. The arrangement that is
best for an individual system should be
based on an analysis of system water
and temperature rise requirements,
system and machine pressure-drop
characteristics, and installation cost.
Parallel flow allows minimum chilled-
water pressure drop through the
machines. However, with one machine
“off,” it is not usually possible to
maintain the design chilled-water
temperature unless one machine is
isolated with shut off valves and the
chilled-water flow decreased.
Series flow permits design chilled-water
temperature at light loads with one
machine “off.” However, at all operating
conditions, the chilled-water pressure
drop through the machine is high.
Accurate chilled-water temperatures can
be maintained on individual machines
between 100 percent and 10 percent of
nominal chiller load, which allows for a
wide range of control options. Each
chiller has a stand-alone control system
to manage the desired water
temperature, and also the ability to
receive remote commands to support
various system demands from a control
center. This versatility of control makes
the management of more than one
machine relatively easy.