Water Fired Single-Effect Chillers and Chiller-Heaters
Guide Specifications
5,10,20,30 and 50 RT
S-Series Water Fired Single Effect
Absorption Chiller / Chiller-Heater
- 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.°F/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.