NORTHERN KENTUCKY UNIVERSITY
NEW POWER PLANT
TECHNICAL SPECIFICATION
FOR
WATER CHILLER
PART 1 - GENERAL
1.1 SCOPE
- Fabricate and deliver FOB job site two electric centrifugal water chillers as specified below.
- Where the word “chiller” is used in this specification, it shall be interpreted to refer to both units being provided unless otherwise specified.
1.2 BIDS
A. The base bid shall be for two 2500 ton chillers.
B. The vendor will be selected based primarily on the chillers that provide the lowest life cycle owning and operating cost. Time basis of evaluation will be 20 years using the Modified Life Cycle Cost Analysis Calculations and the Base Bid. The energy costs of the chiller, the condenser water pump and the primary chilled water pump will be used in this analysis. This data should be entered on the Form of Proposal.
1.3 VENDOR SUGGESTED ALTERNATES
A. It is the intent of this specification to provide high quality, low maintenance equipment. The manufacturer is permitted and encouraged to provide alternates that will increase efficiency, lower price, or reduce space required. To be fully responsive, the manufacturer shall bid as specified, then list any proposed alternates with a reason for the proposed change, a technical discussion of the performance of the proposed alternate, along with the cost and schedule implications of the proposed alternate.
B. Owner may, or may not, at his sole option, consider vendor suggested alternates in determining the lowest and best bid.
1.4 CODES AND STANDARDS
A. All equipment furnished under this specification shall comply with the latest edition of the applicable standards and codes of ASHRAE, ARI, ANSI, ASME, NEC, OSHA and the Commonwealth of Kentucky.
B. Provide evidence that electrical equipment and materials meet the standards of Underwriters Laboratories, Inc. (UL). The listing mark or classification marking of UL displayed on the equipment will be accepted as evidence of such compliance.
C. Chiller shall comply with the requirements of ANSI/ASHRAE 15, Safety Code for Mechanical Refrigeration.
1.5 SUBMITTALS
A. Submit shop drawings for review by Engineer showing fabrication details, equipment configuration, dimensions, finish details, and connection details. Provide drawings of sufficient detail to indicate all components and critical dimensions. Do not release equipment for fabrication until Engineer's review is complete, resubmittals, if required, have been made, and Engineer affixes his stamp to the drawings indicating "No Exceptions Noted."
B. Engineer's review will not be a thorough review for contract compliance, and no change in the contract requirements shall be inferred from the Engineer's notations, lack of notations, or affixing of the "No Exceptions Noted" stamp to a submittal.
C. Product data shall indicate type of materials, dimensions, weights, performance, electrical characteristics, and finishes of all components. The following information shall be included with the data submitted:
1. Certified chiller performance data showing selection based on operating parameters specified.
2. Certified dimensional drawings.
3. Piping, wiring and control diagrams.
1.6 INSTALLATION, OPERATION AND MAINTENANCE DATA
At the time of delivery of the equipment to the site, submit the following information for the equipment and all component parts:
A. Complete field installation instructions.
B. Seven copies of manufacturer’s standard installation, operation, and maintenance data, which shall include copies of approved certified drawings.
C. Data from vibration analysis.
1.7 WARRANTY
Within the warranty period, the manufacturer shall promptly correct, repair, or replace components as necessary to remedy any failure or malfunction of the units, without additional cost to the Owner. Warranty shall include all required labor, parts, materials, and services. The chillers shall be warranted against any failure caused by defects in material or workmanship for 12 months from date of start-up, not to exceed 18 months from date of shipment, if chillers are accepted by owner. Warranty shall include all required labor, parts, materials, and services to remove and reinstall.
1.8 MAINTENANCE AND SERVICE
A. Five years of maintenance and service shall be included in bid. The maintenance and service time period shall start after the unit has been put into operation on a permanent basis. Maintenance and service shall be performed by the unit manufacturer or a regular service organization normally employed by the manufacturer. Maintenance shall include the replacement of all parts necessary to maintain the chiller in an operating condition that meets all of the requirements of this specification.
B. Notify the Owner at least two weeks in advance of making a regular service visit.
C. Include an additional four years of parts and labor warranty for the complete chiller assembly which includes motor alignment, complete chiller refrigerant charge, and all gaskets and o-rings. Additionally, all compressor shaft seals shall be inspected twice annually during the 5-year warranty period, and any shaft seal leaks shall be repaired at no cost to the Owner.
1.9. INSTALLATION AND STARTUP
- Provide factory certified supervision and assistance to the installing contractor for unit installation and system startup. The supervision and assistance effort shall consist of 5 eight hour days per chiller as a minimum.
- Send four technicians to manufacturer’s school to instruct them in the operation and servicing of the chiller. One course shall be given at startup and the other within the next twelve months. Courses shall be scheduled at the Owner’s convenience.
PART 2 PRODUCTS
2.1 GENERAL - CENTRIFUGAL CHILLERS
A. Chiller shall be electric motor driven centrifugal type with R-123 or R-134a refrigerant. Chiller may have single or dual compressors and may be hermetic or open drive.
B. Chiller shall be painted with durable, alkyd modified, vinyl enamel machinery paint prior to shipping.
C. Chiller shall be factory insulated. Chiller manufacturer shall provide recommendations regarding any additional insulation to be field installed.
2.2 PERFORMANCE
A. The nominal capacity of each chiller shall be 2500 tons. Evaporator shall have the capacity to cool 6000 GPM of water from 52 deg F to 42 deg F with a 0.0001 fouling factor. Basis of design for evaporator pressure drop is 13.1 feet.
B. Condenser shall have the capacity to reject heat from 85 to 95 deg F at approximately 7500 GPM with a 0.00025 fouling factor. Basis of design for condenser pressure drop is 14.9 feet.
C. Non-standard part load value (NPLV) shall not exceed 0.55 kilowatts per ton of refrigeration.
D. Chiller shall be rated in accordance with ARI 550/590, Centrifugal or Rotary Water-Chilling Packages.
- Chiller shall be factory tested in accordance with ARI 550/590 testing procedures. A three-point test shall be run. Certified test results shall be provided at 100 percent, 50 percent and 15 percent. Tests may be run with condenser water flow at 6300 GPM.
- An additional test shall be run at 25 percent load and 85 deg. F entering condenser water to show that the unit can run under these conditions without surge.
- Provide a full spectrum vibration analysis in three axes on both ends of chiller.
2.3 CONSTRUCTION
A. Chiller shall consist in general of an evaporator, condenser, single or dual compressors, compressor lubrication system(s), motor(s), motor starter(s), control panel(s) and accessories. Interconnecting refrigerant piping and wiring shall be completed at the factory.
B. Compressor(s)
1. Compressors shall be single or multiple stage centrifugal types driven by electric motor(s). The housing shall be fully accessible with vertical circular joints. The complete operating assembly shall be removable from the compressor and scroll housing. Compressor castings shall be designed for a minimum working pressure of 200 psig and hydrostatic pressure tested at a minimum of 300 psig. The rotor assembly shall consist of a heat treated alloy steel drive shaft and impeller shaft with a cast aluminum, fully shrouded impeller. The compressor shaft shall be factory aligned to the motor, and shall be checked and realigned if necessary at the job site. The impeller shall be designed for balanced thrust, and shall be dynamically balanced and overspeed tested for smooth, vibration free operation. Insert type journal bearings shall be fabricated of aluminum alloy, precision bored and axially grooved.
2. If compressors are gear driven, gears shall be internal single helical gears with crowned teeth and shall be designed so that more than one tooth is in contact at all times to provide even distribution of the compressor load. Each gear shall be individually mounted in its own journal and thrust bearings to isolate it from impeller and drive forces.
3. Lubrication oil shall be force fed to all bearings, gears, and rotating surfaces by an oil pump which operates prior to startup and continuously during operation and during coast down. A gravity fed oil reservoir shall be built into the top of the compressor to provide lubrication during coast down in the event of a power failure. An oil reservoir, separate from the compressor, shall contain a submersible oil pump and one immersion type oil heater, thermostatically controlled to remove refrigerant from the oil. Oil shall be filtered by an externally mounted replaceable cartridge oil filter equipped with service valves, and cooled by a refrigerant or water cooled oil cooler before entering the compressor. Oil piping on the driveline shall be completely factory installed and tested.
C. Evaporator
1. The evaporator shall be the flooded shell and tube type. Chillers using R-134a shall be designed for 180 psig working pressure on the refrigerant side, and tested at 270 psig. The shell shall be fabricated from rolled carbon steel plate with fusion welded seams. Provide carbon steel tube sheets, drilled to accommodate the tubes, and intermediate tube supports spaced no more than four feet apart. Two liquid level sight glasses shall be located on the side of the shell to aid in determining proper refrigerant charge unless other means are provided. For chillers using R-134a, the refrigerant side shall be designed, tested and stamped in accordance with ASME Boiler and Pressure Vessel Code, Section VIII, Division 1.
2. Tubes shall be high efficiency, externally and internally enhanced type. Each tube shall be roller expanded into tube sheets providing a leak proof seal. Tubes shall be 0.028 inch thick, copper alloy, and individually replaceable. Water velocity through the tubes shall not exceed 12 feet per second.
3. The evaporators shall each have two refrigerant relief devices sized to meet the requirements of ANSI/ASHRAE 15 Safety Code for Mechanical Refrigeration.
4. Water boxes with connections to external piping shall be marine type. Water boxes without connections to external piping shall be standard type. Connections to external piping shall be ANSI Class 150 raised face flanges. Water boxes shall be designed for 150 psig design working pressure and be tested at 225 psig. Plugged ¾ in. vent and drain connections shall be provided in each water box. Provide factory mounted gantries or davits for accessing both sides of the evaporator.
D. Refrigerant Condenser
1. The refrigerant condenser shall be the shell and tube type. Chillers using R-134a shall be designed for 180 psig working pressure on the refrigerant side, and tested at 270 psig. The shell shall be fabricated from rolled carbon steel plate with fusion welded seams. Provide carbon steel tube sheets, drilled to accommodate the tubes, and intermediate tube supports spaced no more than four feet apart. For chillers using R-134a the refrigerant side shall be designed, tested and stamped in accordance with ASME Boiler and Pressure Vessel Code, Section VIII, Division 1.
2. Tubes shall be high efficiency, externally and internally enhanced type. Each tube shall be roller expanded into tube sheets providing a leakproof seal. Tubes shall be 0.028 inch thick, copper alloy and shall be individually replaceable. Water velocity through the tubes shall not exceed 12 feet per second.
3. Water boxes with connections to external piping shall be marine type. Water boxes without connections to external piping shall be standard type. Connections to external piping shall be ANSI Class 150 raised face flanges. Water boxes shall be designed for 150 psig design working pressure and be tested at 225 psig. Plugged ¾ in. vent and drain connections shall be provided in each water box. Provide factory mounted gantries or davits for accessing both sides of the condenser.
E. Refrigerant Flow Control
1. Refrigerant flow to the evaporator shall be controlled to maintain proper refrigerant level in the condenser and evaporator. This shall optimize unit performance at varying load and temperature conditions. Fixed orifices may be used.
F. Purge System: For refrigerants with vapor pressure less than 14.7 psig when machine is operating, provide purge system connected to main refrigeration system. When in operation, purge system shall function to automatically remove air, water vapor, and non-condensable gases from refrigeration system and to condense, separate, and return to system any refrigerant present therein.
1. Purge system shall utilize a separate compressor that operates independently of the chiller. No external cooling water shall be required. Purge system shall be complete with all necessary operating and safety devices and with oil separators if required by manufacturer. Excess purge alarm shall be included to automatically lock out the purge system if excessive purging is detected. An operator override of the lockout shall be provided.
2. As part of the purge system, provide activated carbon canister on the purge system exhaust to limit refrigerant emissions to 0.002 pounds of refrigerant lost per pound of dry air.
G. Compressor motor(s) shall be 4.16 kV, 60 Hz, 3 phase, 3 wire, two pole, squirrel cage induction type. Two pressure lubricated bearings shall support the rotating assembly.
H. Starters
1. Provide motor starters for compressor(s), lube oil pump and purge pump, complete with transformer for 115 volt operation of motors and electric controls.
2. The compressor starters shall be across-the-line 5 kV class and shall conform with the following:
a. NEMA-1 construction.
b. The starter assembly for a chiller shall consist of two starters factory assembled as a single unit. The assembly shall be constructed with a 1200 amp copper main cross-bus.
c. An option for stacked (two high) starters will be considered, however, they must be fully compatible with Cutler-Hammer Amp-Gard.
d. The starter assembly for one chiller shall not be dependent on being attached to the starter assembly for another chiller.