Flow Circuits - Carrier 16JT Series Start Up & Operation Manual

Flow Circuits —
Figures 5 and 6 illustrate the basic flow
circuits of the 16JT absorption chiller.
The liquid to be chilled is passed through the evaporator
tube bundle and is cooled by the evaporation of refrigerant
water sprayed over the outer surface of the tubes by the re-
circulating refrigerant pump. The refrigerant vapors are drawn
into the absorber section and are absorbed by the lithium
bromide-water solution sprayed over the absorber tubes. The
heat picked up from the chilled liquid is transferred from the
absorbed vapor to cooling water flowing through the ab-
sorber tubes.
The solution in the absorber becomes diluted as it absorbs
water, and loses its ability to continue the absorption. It is
then transferred by the solution pump to the generator sec-
tions to be reconcentrated. Approximately half of the weak
(diluted) solution goes to the high-stage generator where it
is heated directly by high-pressure steam to boil out its ab-
sorbed water. This vapor passes to the low-stage generator
tubes. In the low-stage generator, the rest of the weak so-
lution is heated by the high-temperature vapor from the high-
stage generator, to boil out its absorbed water.
This water vapor from the low-stage generator solution
passes into the condenser section and condenses on tubes
containing cooling water. This is the same cooling water which
had just flowed through the absorber tubes. The condensed
high-temperature water from the low-stage generator tubes
also passes over the condenser tubes where it is
EA — Refrigerant Pump Overload Cutout
EA1 — Refrigerant Pump Overload Cutout
EA2 — Solution Pump Overload Cutout
EA3 — Solution Spray Pump Motor Overload Cutout
EA4 — Vacuum Pump Motor Overload
FA1 — Chilled Water Low-Flow Cutout
I/P — Current/Pneumatic Transducer
LC — Refrigerant Cutout Level Switches
(High, Mid, Low)
PA1 — High-Pressure Switch (High-Stage
Temperature Generator)
P1 — Compound Gage (High-Temperature
Generator)
PWS1 — Absorber Pressure Switch
*The LCD valve is physically located with the float in the high stage generator overflow box, not
where it is schematically shown in the illustration.
Fig. 5 — Typical Flow Circuits, with Data Points, Shown for 16JT080-150,080L-150L Arrangements
cooled to the condenser temperature. The combined con-
densed refrigerant liquid from the two generators now flows
back to the evaporator to begin a new refrigerant cycle.
The strong (reconcentrated) solution flows from the two
generators back to the absorber spray headers to begin a new
solution cycle. On the way, it passes through solution heat
exchangers where heat is transferred from the hot, strong so-
lution to the cooler, weak solution being pumped to the gen-
erators. Solution to and from the high-stage generator
passes through both a high-temperature heat exchanger and
a low-temperature heat exchanger. Solution to and from the
low-stage generator passes through only the low-temperature
heat exchanger, mixed with the high-stage generator solu-
tion. This heat transfer improves solution cycle efficiency by
preheating the relatively cool, weak solution before it enters
the generators, and precooling the hotter, strong solution be-
fore it enters the absorber. The efficiency is further improved
by transferring heat to the cooler, weak solution from the hot
steam condensate in the condensate drain heat exchanger and
trap.
The weak solution flowing to the generators passes through
a flow control valve which is positioned by a float in the
high-stage generator overflow box. The purpose of the valve
is to automatically maintain optimum solution flow to the
two generators at all operating conditions for maximum
efficiency.
LEGEND
SA — Pneumatic Supply Air
TA1 — Chilled-Water Low-Temperature Cutout
TA3 — Refrigerant Pump Motor Coil High-
Temperature Cutout
TA4 — Solution Pump Motor Coil High-
Temperature Cutout
TA5 — Solution High-Temperature Cutout
TC2 — Cooling Water Temperature Cutout
TIC — Chilled Water Outlet Temperature Control
TI 1-4 — Weak Solution Thermometers
TI 5-8 — Strong Solution Thermometers
TI 9-10 — Refrigerant Thermometers
6
TSW1 — Automatic Start-Stop Thermostat
TSW2 — Cycle-Guard™ Thermostat
Control Wiring
Piping Connections
Valve
NOTES:
1. Spray pump and second solution pump are lo-
cated on large sizes only.
2. Vacuum pump is optional.
3. Electric capacity control is shown.
(Pneumatic is optional.)