FORM 155.32-ICOM2.EN.UL
SECTION 2 - PRODUCT DESCRIPTION
ISSUE DATE:1/10/2018
JOHNSON CONTROLS
17
HOW IT WORKS (DIRECT FIRED UNITS)
The double effect (direct fired) absorption chiller-heater uses water as the refrigerant and LiBr as the absorbent. The vapor
pressure of the LiBr solution is lower than the vapor pressure of the refrigerant. The vapor pressure of the LiBr solution is
directly related to the amount of refrigerant (water) present in the solution with the LiBr salt and the solution temperature.
Figure 2 -
Two Step Direct Fired Absorption Chiller-Heater Cycle Diagram
(Cooling Mode)
NOTE: Temperatures and pressures on this graphic are representative; actual values may differ.
EVAPORATOR
Liquid refrigerant enters the evaporator and is distributed over the top of the tube bundle. As the refrigerant droplets cover the
outside surface of the tubes, the heat from the returning chilled water passing through the tubes causes the refrigerant to flash
from a liquid to a vapor. The temperature at which this happens depends on the evaporator shell pressure which is dictated by
the absorber section of the chiller-heater. The refrigerant vapor passes through the mist eliminators and into the absorber
section of the chiller-heater. As the liquid refrigerant passes down through the bundle of evaporator tubes, the refrigerant
gradually vaporizes. The refrigerant remaining in a liquid state at the bottom drains into the refrigerant tank and is pumped back
up to the top of the tube bundle where the process is repeated.
P11
63
SH1
VH
M
63G P13
V8
VK
SV3
VJ
Pilot Piping
Main Piping
LG4
Condenser
Low Temp.
Generator
LD19981_UL
V24
Evaporator
(Upper)
Absorber
(Upper)
Absorber
(Lower)
Evaporator
(Lower)
95
˚
F
86
˚
F
44
˚
F
53.6
˚
F
Low Temp.
Generator Drain
Heat Exchanger
High
Temp.
Heat
Exchanger
High Temp.
Generator
Exhaust
Gas Outlet
Gas Inlet
Control
Motor
Low Temp.
Heat
Exchanger
Solution
Circulation
Pump
Solution
Spray Pump
Chilled Water
Cooling Water
Refrigerant
Diluted Solution
Concentrated Solution
Cooling
Water
Outlet
Cooling
Water Inlet
Chilled
Water
Outlet
Chilled
Water Inlet