- General
Description
The Contractor shall
furnish and install ___ (Qty) Yazaki model WFC-S ___ Water Fired,
Single-Effect, Absorption Chiller(s) / Chiller-Heater(s) as shown on the
drawings and in accordance with these specifications.
- Chiller-Heater Operating Conditions
|
MODEL |
ITEM |
SPECIFICATIONS |
|
COOLING |
HEATING |
|
WFC-S |
*Capacity (MBH) |
|
|
|
Chilled/Hot Water |
*Inlet
temperature (oF) |
|
|
|
*Outlet temperature (oF) |
|
|
| Flow (gpm) |
|
|
|
Pressure loss (psi) |
|
|
|
Heat Medium |
*Heat input
(MBH) |
|
|
|
*Inlet temperature (oF) |
|
|
| *Outlet
temperature (oF) |
|
|
|
Flow (gpm) |
|
|
| Pressure
loss (psi) |
|
|
|
Cooling Water |
*Heat rejection (MBH) |
|
|
| *Inlet
temperature (oF) |
|
|
|
*Oulet temperature (oF) |
|
|
| Flow (gpm) |
|
|
|
Pressure loss (psi) |
|
|
|
Electrical |
Power supply |
208V, 60Hz, 3ph |
|
Consumption (W) |
|
|
| * Refer to
the product brochure for specifications |
|
Notes: 1. |
MBH
= Btu/hr x 1000 |
2.
|
Performance based on Japanese Refrigeration and Air
Conditioning Industry standards with minimum fouling factor of 0.0005
ft2.h.ºF/Btu in the evaporator, condenser and absorber
water circuits. |
- Construction
Each absorption
chiller shall be manufactured in accordance with JIS B8622 (Japanese
Industrial Standard). The chiller shall be a modular, single shell,
hermetic design using lithium bromide as the absorbent and water as the
refrigerant. The main components of the absorption chiller shall
comprise a generator, heated by hot water at 158°F to 203°F, an evaporator
for chilled water or hot water and a water cooled absorber/condenser.
Leak testing, charging with solution and inhibitor, and performance
testing of the absorption chiller shall be completed at the factory prior
to shipment. All cold and hot surfaces shall be insulated.
The generator, absorber,
condenser and evaporator shall be formed in circular bundles with
multi-pass circuits and designed to accommodate thermal expansion and
contraction during normal service. Heat exchangers for chilled/hot water,
cooling water and heat medium shall be suitable for a maximum working
pressure of 85 psig. Evaporator tubing shall be externally enhanced
to increase heat transfer. The generator tubes shall be stainless steel
and all other tubes shall be copper. Steel ring trays with drippers shall
rely upon gravity to uniformly distribute liquid refrigerant and solution
over the evaporator, absorber and generator tube bundles. A plate type
solution heat exchanger, constructed from stainless steel, shall be an
integral component for enhancing the absorption cycle efficiency.
Each absorption chiller
shall undergo a series of factory tests to ensure that the vacuum section
is leak tight and meets the manufacturer’s strict quality control
standards. The chiller-heater shall be covered with a helium charged bell
and the vacuum section shall be evacuated to 0.02 micron Hg absolute. The
leakage rate measured by a helium mass spectrometer shall not exceed 5 x
10-10 atm.cc/sec.
When the absorption
chiller functions as a chiller-heater, a motorized cooling/heating
changeover valve shall be factory installed and controlled by a HEAT-COOL
selection switch on the chiller control panel or from a remote switch. The
position of the changeover valve shall not change in the event of a power
failure.
The chiller shall be
equipped with one hermetic sealed pump assembly to circulate dilute
solution in the absorption cycle.
Solution shall
automatically drain under gravity from the generator and absorber whenever
the cooling cycle is discontinued during normal operation or by a power
failure. Crystallization in the generator, caused by abnormal (low or
high) heat medium inlet temperatures or power failure, shall be prevented
by allowing solution to drain out of the generator under gravity whenever
the solution pump stops.
All external piping
connections shall be located on the same side of the absorption chiller.
Eyebolts for lifting and
anchor plates shall be supplied with the equipment.
The absorption chiller
shall be enclosed in a weatherproof cabinet and the front panel shall be
easily removed for service access.
Each absorption chiller shall be listed by Underwriters
Laboratories, Inc. as "Absorption Air Conditioning Equipment", suitable
for both indoor and outdoor installation.
- Internal Controls
Each absorption chiller
shall be supplied complete with factory wired and mounted controls located
inside a weatherproof cabinet. The following controls shall included:
a) Electronic temperature measurement of
cooling water inlet, chilled/hot water outlet, liquid refrigerant and heat
medium inlet.
b)
Solid-state controls and
pre-programmed microprocessor.
c)
Motor contactor and overload
relay for the solution pump.
d)
Control relays with dry
contacts for signaling the operation of the chilled/hot water pump,
cooling water pump, heat medium pump and heat medium 3-way bypass valve.
The control panel built into the
absorption chiller shall provide the following status lamps and manual
controls:
a)
Alarm reset.
b)
Error code display.
c)
Status lamps for Power, Run,
Stop.
d)
Status lamps for Power, Run,
Stop, Cool and Heat (chiller-heater only).
e)
Status lamp for Standby Mode
(chiller-heater only).
f)
Status lamp for Freeze
Protection.
g)
Heating and Cooling selection
switches (chiller-heater only).
h)
Start, Stop and Remote
selection switch.
A junction box shall
be provided for field connections to the power supply, low voltage control
circuits for the chilled/hot water pump, cooling water pump, cooling tower
fan, heat medium pump, heat medium 3-way bypass valve and external control
interlocks.
The
cooling and heating capacity of the absorption chiller shall be controlled
in response to the outlet chilled/hot water temperature OPENING and
CLOSING a 3-way bypass valve in the heat medium circuit.
The following abnormal operating
conditions shall safely shut-down the water fired absorption chiller:
a)
Abnormal changeover valve
position (chiller-heater only).
b)
Solution pump overload relay
tripped.
c)
Chilled / hot water pump
overload relay tripped.
d)
Cooling water pump overload
relay tripped.
e)
Cooling tower fan overload
relay tripped.
f)
Low chilled / hot water flow.
g)
Open sensor circuit.
A digital display
panel with the following functions shall be supplied with each water fired
absorption chiller to assist with troubleshooting and fault diagnosis:
a) Microprocessor Input and output
status.
b)
Temperature of all sensors.
c)
Error code history (max. 6).
d)
Cooling operating hours.
e)
Cooling and heating operating
hours (chiller-heater only).
f)
Verify control set points.
g)
Set CPU calendar and clock.
h)
Set chiller or chiller-heater
model, cooling capacity and serial number.
i)
Clear error code history.
j)
Check current and force
operation of the refrigerant control valve.
k)
Check function of solenoid
valves.
- External Controls
(Supplied by Others)
The cooling tower fan
shall be controlled by a sump thermoswitch (cooling tower switch) so that
it cycles ON at 81.5°F and OFF at 77°F respectively. If there is a
tendency for the cooling water temperature leaving the cooling tower to
fall below 75°F during normal operation, a 3-way temperature control valve
shall be installed and set to maintain the cooling water above 70°F
(minimum).
If cooling water
remains in the condenser and absorber of a chiller-heater during heating
operation and there is frequent cycling between heating and cooling
operation, the 3-way temperature control valve shall be forced open for 1
minute each time cooling operation is selected so that “hot” cooling water
is bypassed to the cooling tower sump.
Motor
contactors, overload relays, auxiliary relays and AUTO-OFF-MANUAL switches
for the chilled/hot water pump, cooling water pump, heat medium pump and
cooling tower fan shall be furnished and installed by the contractor.
The following
status/alarm outputs and remote control inputs shall be provided in the
water fired absorption chiller for field connection to an external
building energy management control system:
(a)
Heating mode status.
(b)
Cooling mode status.
(c)
Chiller operating status.
(d)
General fault alarm.
(e)
Remote COOLING mode selection
(chiller-heater only).
(f)
Remote HEATING mode selection
(chiller-heater only).
(g)
Remote RUN selection.
(h)
Remote STOP selection.
- Interlocks
The thermal overload
relays for the chilled/hot water pump, cooling water pump and cooling
tower fan shall be interlocked with the chiller controls via normally
closed contacts on auxiliary relays. In the event of a pump overload, the
auxiliary relay contact shall open and shutdown the chiller.
- Installation
The absorption
chiller shall be installed on a level surface. Shims shall be placed under
the absorption chiller frame to adjust the level of the upper vessel for
longitudinal and transverse alignment.
The absorption
chiller shall be installed in a location where there is access to all side
and top panels. A minimum of 40 inches clearance shall be provided
in front of the equipment. The piping configuration shall allow
clear access to the absorption chiller for service.
Thermowells or
temperature test points, similar to P/T plugs, shall be installed on the
inlet and outlet water piping to the absorption chiller.
Balancing valves
shall be installed in all external water circuits to adjust the flow
within the following tolerances:
a) 80 - 120 % of rated
chilled/hot water flow.
b)
100 - 120 % of rated cooling
water flow.
c)
30 - 120 % of rated heat
medium flow.
A fused disconnect switch shall be
furnished and installed in the power supply circuit to each absorption
chiller unit.
The water quality in
the chilled/hot water, cooling water, and heat medium circuits shall not
exceed the following limits:
ITEM
|
CHILLED/ HOT WATER |
HEAT MEDIUM |
COOLING WATER |
MAKE-UP WATER |
|
Standard |
pH (at 77°F) |
6.8 - 8.0 |
7.0 – 8.0 |
6.5 ‑ 8.2 |
6.8 - 8.0 |
|
Conductivity (mS/cm at 77°F) |
400 |
300 |
800 |
300 |
|
Chloride ion (Cl- ppm) |
50 |
30 |
200 |
50 |
|
Sulfate ion (SO42-
ppm) |
50 |
30 |
200 |
50 |
|
M-alkalinity (CaCO3 ppm) |
50 |
50 |
100 |
50 |
|
Total hardness (CaCO3 ppm) |
70 |
70 |
*200 |
70 |
|
Calcium hardness (CaCO3 ppm) |
50 |
50 |
150 |
50 |
|
Ionic silica (SiO2 ppm) |
30 |
30 |
50 |
30 |
|
Reference |
Total iron (Fe ppm) |
1.0 |
1.0 |
1.0 |
0.3 |
|
Copper (Cu ppm) |
1.0 |
1.0 |
0.3 |
0.1 |
|
Sulfide ion (S2- ppm) |
N.D. |
N.D. |
N.D. |
N.D. |
|
Ammonium ion (NH4+
ppm) |
1.0 |
0.1 |
1.0 |
0.1 |
|
Residual chlorine (Cl ppm) |
0.3 |
0.1 |
0.3 |
0.3 |
|
Free carbon dioxide (CO2 ppm) |
4.0 |
0.4 |
4.0 |
4.0 |
|
Ryzner stability index |
- |
- |
6.0 - 7.0 |
- |
N.D.= Not Detectable
*
Maximum total hardness of make-up water shall not exceed 70 ppm when bleed
off is the only method used to control water quality.
- Start-up
The manufacturer or their authorized service
provider shall startup and provide routine maintenance on the water fired
single-effect absorption chiller. The Contractor shall provide personnel
familiar with the system design and controls to assist during start-up.
Installation and Operating Instructions
shall be provided with the absorption chiller.
The warranty
on each water fired single-effect absorption chiller shall commence on the
date of initial startup and continue for a period of one year, not to
exceed two years from the date of manufacture, and shall include parts and
a limited labor allowance.
