Operating instructions

GENERAL
2
These instructions are intended to acquaint
the Owner/End User with the operation and
general maintenance requirements of Yazaki
Water Fired Single-Effect Absorption Chiller or
Chiller-Heater units.
Please read ALL instructions carefully and
observe precautions. Failure to operate and
maintain this equipment in accordance with the
OPERATING INSTRUCTIONS may affect the
equipment performace and product Warranty.
If the equipment does not operate as
expected, check the Troubleshooting Guide in
these instructions BEFORE calling your
Authorized Yazaki Service Provider. This
approach will not only save cost but also avoid
any unnecessary downtime.
ABSORPTION PRINCIPLE
Yazaki absorption chillers or chiller-heaters
use a solution of lithium bromide and water,
under a vacuum, as the working fluid. Water is
the refrigerant and lithium bromide is the
absorbent. During cooling operation, refrigerant
liquid boils under the influence of a deep
vacuum in the evaporator and creates a
refrigerating effect which removes heat from the
chilled water circuit. The single-effect absorption
cycle has one generator heated by an external
source of hot water, a condenser, evaporator
and absorber. The absorber and condenser are
water cooled and heat is normally rejected
through a cooling tower.
COOLING OPERATION
Generator
When the heat medium inlet temperature
exceeds 154.4
o
F (203
o
F max.) the solution
pump forces dilute lithium bromide solution into
the generator. The solution boils vigorously
under a vacuum and droplets of concentrated
solution are carried with refrigerant vapor to the
primary separator. After separation, refrigerant
vapor flows to the condenser and concentrated
solution is precooled in the heat exchanger
before flowing to the absorber.
Condenser
In the condenser, refrigerant vapor is
condensed on the surface of the cooling coil and
latent heat, removed by the cooling water, is
rejected to a cooling tower. Refrigerant liquid
accumulates in the condenser and then passes
through an orifice into the evaporator.
Evaporator
In the evaporator, the refrigerant liquid is
exposed to a substantially deeper vacuum than
in the condenser due to the influence of the
absorber. As refrigerant liquid flows over the
surface of the evaporator coil it boils and
removes heat, equivalent to the latent heat of
the refrigerant, from the chilled water circuit. The
recirculating chilled water is cooled to 44.6
o
F
and the refrigerant vapor is attracted to the
absorber.
Absorber
A deep vacuum in the absorber is
maintained by the affinity of the concentrated
solution from the generator with the refrigerant
vapor formed in the evaporator. The refrigerant
vapor is absorbed by concentrated lithium
bromide solution flowing across the surface of
the absorber coil. Heat of condensation and
dilution are removed by the cooling water and
rejected through a cooling tower. The resulting
dilute solution is preheated in the heat exchanger
before returning to the generator where the
cycle is repeated.