Guide Specification Smardt water Cooled Chillers
Guide Specification – Smardt Water Cooled Chillers
GENERAL
1.1 SUMMARY
Section includes design, performance criteria, refrigerants, controls, and installation requirements for water-cooled centrifugal chillers.
1.2 REFERENCES
Comply with the following codes and standards:
AHRI 550/590
ANSI/ASHRAE 15
ASME Section VIII
ETL Listed
ANSI UL 1995
CSA C22.2 No. 236(Canada)
MEPS(Australia)
1.3 SUBMITTALS
Submittals shall include the following:
A. Dimensioned plan and elevation drawings, including required service clearances and location of all field piping and electrical connections.
B. Electrical and water quality requirements during operation, standby and shutdown.
C. Control system diagram showing points for field interface and connection to external BMS systems. Drawings shall show field and factory wiring.
D. Installation and Operating Manuals.
E. Manufacturers certified performance data as per AHRI at full load and IPLV or NPLV.
1.4 QUALITY ASSURANCE
A. Regulatory Requirements: Comply with the standards in Section 1.2.
1.5 DELIVERY AND HANDLING
A. Chillers shall be delivered to the job site completely assembled (unless otherwise specified).
B. Comply with the manufacturer’s instructions for transporting and rigging.
1.6 WARRANTY and MAINTENANCE
A. The chiller manufacturer’s warranty shall be for a period of one year from date of equipment start up or 18 months from the date of shipment, whichever occurs first.
B. The warranty shall include parts and labor costs for the repair or replacement of parts found to be defective in material or workmanship.
C. Maintenance of the chiller equipment, while under warranty is mandatory and shall be the responsibility of the purchaser unless supplied by the manufacturer.
Optional:
1. 2-5 year chiller and compressor parts and labor warranty.
2. Refrigerant warranty
PRODUCTS
2.1 ACCEPTABLE MANUFACTURERS
A. Smardt Inc.
B. Approved Equal. Note approved equal does not automatically imply the alternate product matches this specification, functionality or delivered quality.
2.2 PRODUCT DESCRIPTION
A. Provide and install as shown on the plans a factory assembled water-cooled packaged chiller.
B. Each unit shall include one or more Turbocor, magnetic bearing, and variable-speed centrifugal compressors. Integrated variable frequency drive shall operate with inlet guide vanes. Chillers shall operate with HCF-134a refrigerant not subject to phase-out by the Montreal Protocol and the U.S. EPA Phase-out schedule.
C. The evaporator, condenser, and expansion valve shall be configured to operate as a single refrigerant
circuit unless otherwise specified. The chiller unit compressors shall be designed for mechanical and electrical isolation to facilitate service and removal.
2.3 DESIGN REQUIREMENTS
A. Unit shall consist of one or more magnetic bearing, oil-free centrifugal compressors with integrated variable frequency drive, refrigerant flooded evaporator, water cooled condenser and operating controls with equipment protection.
B. Performance: Refer to schedule for specific operating conditions. When utilizing Turbocor model TT300 compressors chiller shall be capable of stable operation down to 20 tons. When utilizing TT350 the chiller shall be capable of stable operation down to 35 tons. With TT400 compressors, the chiller shall be capable of stable operation down to 40 tons. While using model TT500 compressors the chiller shall be capable of stable operation down to 60 tons. All these ratings measured at standard AHRI entering condenser water temperatures and without utilizing hot gas bypass.
C. Acoustics: Sound pressure for the unit shall not exceed the following specified levels, and be less than 81 dBA, measured at 1 meter (3.28 feet). Sound data shall be measured according to AHRI Standard 575-87.
D. Chiller shall be equipped for single-point power connection.
E. Evaporator shall be designed to allow for the flow rate to be reduced to the rate of 1 gpm per ton without entering laminar flow to allow for variable chilled water flow and facilitate chilled water pump energy savings. The chiller shall be able to operate in a stable fashion at this condition for at least 8 hours continuously independent of condenser water flow rate or condenser water temperature relief.
F. Condenser shall be designed to allow for the flow rate to be reduced to 1.5 gpm per ton without entering laminar flow to allow for variable condenser water flow and facilitate condenser water pump energy savings. The chiller shall be able to operate in a stable fashion at this condition for at least 8 hours continuously independent of chiller water flow rate or condenser water temperature relief.
G. Minimum entering condenser water temperature shall be 12°F above leaving chilled water temperature.
Chiller shall be able to operate in these conditions for at least 8 hours continuously to provide condenser water relief and allow compressor energy savings. Chiller shall be able to vary the condenser water temperature to the minimum condition independently of condenser water flow rate and chilled water flow rate.
H. Each compressor shall be electrically and mechanically isolated so that if a compressor fails or needs service it can be serviced or removed from the chiller without disabling the other compressors or the chiller. The chiller shall be able to operate with the remaining compressors with (1) or more compressors removed.
I. All chillers greater than 400 tons in capacity shall have at least (3) compressor to provide for redundancy and capacity turndown flexibility.J. All chillers with (2) compressors or less shall be equipped with a load balancing valve for capacity control and supply chilled temperature stability.
J.All chillers equipped with (3) or more compressors model TT350 or T500 shall be equipped with equipped with individual compressors staging valves to channel discharge gas from the outlet of the compressor to the evaporator in order for the ramp up during a high pressure ratio application.
K.Refrigerant charge Requirements:
|Chiller Capacity |Max Refrigerant Charge |
|150 Tons |531 lbs |
|250 - 290 Tons |695 lbs |
|350 Tons |851 lbs |
|420 Tons |1011 lbs |
|550 Tons |1206 lbs |
|700 Tons |1422 lbs |
|800 Tons |1880 lbs |
|900 Tons |2327 lbs |
|1000 - 1200 Tons |2529 lbs |
Optional:
1. Multiple point power connection, single point is standard
2. Low profile designs with side by side or staggered evaporator and condenser design based on the capacity.
2.4 CHILLER COMPONENTS
A. Compressors:
1. Compressors shall be of semi-hermetic centrifugal design and operate oil-free with 2 or more compressors or have N+1 redundant chiller, Two-stages of compression, magnetic bearings, movable inlet guide vanes and integrated variable frequency drive system. Options: Dual circuits with split shells are available depending on the application
2. Automatically positioned and controlled inlet guide vanes shall operate with compressor speed controls.
3. The compressor shall be capable of coming to a controlled stop in the event of a power failure. The unit shall be capable of initializing an automatic restart in the case of power failure.
4. Each compressor shall have integrated microprocessor control capable of capacity and safety control.
5. Each compressor shall be installed with individual suction, discharge and motor cooling refrigerant line isolation valves. Chillers without discharge line isolation valves that rely on non return valves in discharge line for compressor removal shall not be accepted.
6. Refrigerant Discharge line shall has a combination of shut off and check valve, Blank seal are not acceptable.
7.Guide Vanes: Modulating with factory mounted electric operator, suitable for capacity reduction down to fifteen (15) percent of specified load without hot gas bypass. Option: 10% of the specified load without hot gas bypass depends on the compressor model.
8.If compressor driver motor uses antifriction bearing with an oil lubricating system, the chiller manufacturer must provide a 20 year warranty of the compressor bearings as well as all preventive maintenance for a period of 20 years. In addition, chillers containing oil must include a 10 year warranty on all systems components and labor. All costs associated with annual oil and oil filter changes plus oil analysis for the whole life cycle of the machine should be at manufacturer expense.
9. If the compressors contain an atmospheric shaft seal, the chiller manufacturer must provide a 20 year warranty of the shaft seal as well as all preventive maintenance for a period of 20 years. In addition, the manufacturer must provide a 20 year refrigerant replacement warranty for losses due to a failure of the shaft seal.
Optional:
1. EMI filters installed for each compressor.
B. Prime Mover:
1. Permanent-magnet, synchronous hermetically sealed motor of sufficient size to effectively provide compressor horsepower requirements. Motor shall include soft-start capabilities with an inrush current of no more than 2 amps (TT300 models) and 4 amps (TT400 models). Motor shall be liquid refrigerant cooled with internal thermal overload protection devices embedded in the winding of each phase.
2. Compressor motor and chiller unit shall include variable-frequency speed controls to match cooling load demand to compressor speed and inlet guide vane position.
3. Each compressor shall be equipped with a 5% impedance AC line reactor and individual disconnect or circuit breaker
4. Option: Having a minimum short circuit withstand rating of 65,000 or 100,000 amps with shunt trip
C. Evaporator:
1. Evaporator shall be shell-and-tube type and have separate shells. Heat exchangers shall be designed, constructed, tested and stamped according to the requirements of the ASME Code, Section VIII Code Case 1518-5. They shall have a copper wall of 0.025 in. wall thickness. In the evaporator, refrigerant shall be in the shell and water inside the tubes. The water sides shall be designed for a minimum of 145 psig. Evaporator shall be designed for 30%Turn down ratio on flow rate. The water connections for the evaporator and condenser shall be grooved suitable for Victaulic couplings or flanged. Vents and drains shall be provided. The refrigerant side of each vessel shall bear the ASME Code stamp, code case section VII. Vessels shall pass a test pressure of 1.1 times the working pressure but not less than 100 psig. Provide intermediate tube supports spaced to enable equal liquid and gas flow across multiple compressor suction ports. The evaporator water connections shall also be equipped with right-hand or left-hand connection, interchangeable.
2. The evaporator shall be provided with spring loaded reseating-type pressure relief valves according to ASHRAE-15. Rupture disks are not acceptable.
3. A perforated plate designed for vapor disengagement shall be installed inside the evaporator above the tubing to assure effective liquid droplet removal to prevent liquid damage to compressors and equalized suction pressure across evaporators with multiple compressors.
4. Tubes shall be individually replaceable and have internally and externally enhanced surfaces designed for refrigeration duty. Tubes shall have smooth full tube wall landings at the tube-sheet ends and at intermediate tube supports. Tubes shall be mechanically roller expanded into steel tube sheets containing a minimum of three concentric grooves.
5. Minimum evaporator exiting water temperature shall be 38°F, unless otherwise specified.
6. Provide factor-mounted and wired, thermal dispersion switches water flow switches on evaporator to prevent unit operation with no water flow
Optional:
1. Available in 0.028 in and 0.035 in. wall thicknesses.
2. Wall available in 90-10 cupro-nickel.
3. Marine water boxes.
4. Corrosion protection coating of water boxes and tubesheets. Corrosion protection treatment shall be based on TAFA arc sprayed aluminum method capable of providing effective long term corrosion protection. Metallized coating serves as sacrificial anode to prevent corrosion of the steel even where the coating coverage is incomplete or suffers mechanical damage.
Coating methods with epoxy coat only shall not be accepted.
5. Water side vessel design for 300 psi operation.
6. Double insulation, 1 1/2 inch, on evaporator, water boxes, suction piping, and compressor end-bell.
C. Condenser:
1. Condenser shall be shell-and-tube type and have separate shells. Heat exchangers shall be designed, constructed, tested and stamped according to the requirements of the ASME Code, Section VIII Code Case 1518-5. They shall have a copper wall of 0.025 in. wall. In the condenser, refrigerant shall be in the shell and water inside the tubes. The water sides shall be designed for a minimum of 145 psig or as specified. The water connections for the evaporator and condenser shall be grooved suitable for Victaulic couplings or flanged. Vents and drains shall be provided. The refrigerant side of each vessel shall bear the ASME Code stamp, code case section VII. Vessels shall pass a test pressure of 1.1 times the working pressure but not less than 100 psig. Provide intermediate tube supports spaced to enable equal liquid and gas flow across multiple compressor suction ports. The condenser water connections shall also be equipped with right-hand or left-hand connection, interchangeable. Condenser vessel shall be designed for variable flow rate at a minimum turn down ratio of 30%
2. The condenser shall be provided with dual relief valves equipped with a transfer valve so one valve can be removed for testing or replacement without loss of refrigerant or removal of refrigerant from the vessel. Rupture disks are not acceptable.
3. Tubes shall be individually replaceable and have internally and externally enhanced surfaces designed for refrigeration duty. Tubes shall have smooth full tube wall landings at the tube-sheet ends and at intermediate tube supports. Tubes shall be mechanically roller expanded into steel tube sheets containing a minimum of three concentric grooves.
4. Provide factory-mounted and wired, thermal dispersion switches water flow switches on condenser to prevent unit operation with no water flow
Optional:
1. Available in 0.028 in and 0.035 in. wall thicknesses.
2. Wall available in 90-10 cupro-nickel.
3. Marine water boxes.
4. Corrosion protection coating of water boxes and tubesheets. Corrosion protection treatment shall be based on TAFA arc sprayed aluminum method capable of providing effective long term corrosion protection. Metallized coating serves as sacrificial anode to prevent corrosion of the steel even where the coating coverage is incomplete or suffers mechanical damage.
Coating methods with epoxy coat only shall not be accepted.
5. Water side vessel design for of 300 psi operation
6. Increased condenser water temperature for heat recovery to 125°F.
D. Liquid level controls
1. Control of refrigerant flow shall utilize a single or multiple 6,000 step electronic expansion valve (EXV), to operate within the full range from full load to the lowest loading capacity for the chiller. Fixed orifice metering devices or float controls using hot gas bypass are not acceptable. The EXV liquid line shall have a sight glass with moisture indicator and temperature sensor connected to control system for validation of sub-cooling.
2.The EXV valve shall be controlled by condenser level float control for better efficiency and to avoid compressor slugging. EXV superheat control shall not be acceptable
3. Condenser shall be provided with a capacitive type liquid level transducer with a resolution of not less than 1024 discrete steps. Transducer shall be wired to chiller control system. Condenser liquid level measurement shall be used in electronic expansion valve control algorithm with a minimum level set point to ensure adequate liquid seal is maintained in condenser to provide compressor motor cooling during operation. Condenser liquid level shall be clearly displayed on graphical operator interface in a minimum of two screens, chillers without direct level measurement are prohibited due to possible over heating damage that may occur in compressors when liquid seal is lost.
F. Chiller Controls
The controller fitted to the oil-free centrifugal chiller package shall be an embedded real time microprocessor device that utilizes control software written specifically for chiller applications. User operation shall be accomplished using a panel mounted color touch-screen interface. The status of the compressors and all system parameters including compressor alarms and temperature trends shall be viewable.
1. Chiller control system shall have the capability to store one year of operational data. No less than 60 points of information shall be sampled at a maximum of 15 minute intervals.
2. Chiller control system shall have full web based remote control capability including the capability for remote operation and software updates.
3. There shall be a backup superheat control on inlet of the compressor in order to control the EXV in the event of a failure of the primary level sensing device.
Controller features must include the following:
1. Selectable control mode – leaving chilled water, entering chilled water or suction pressure control.
2. 10.4-inch or 12 inch, 65,000 colors, touch panel operator interface operating windows XP embedded.
3. Chiller documentation shall be viewable via touch panel in pdf format.
4. Operator interface shall be capable of connecting directly to compressors via serial communication protocol and display compressor information using Turbocor compressor monitoring/ commissioning software.
5. Chiller control panel shall contain a minimum of three processors; all control functionality shall be carried out on a dedicated real time processor and data served to a remote graphical user interface via an open Ethernet protocol. Proprietary protocols between any pc based or micro based processor strictly prohibited.
6. Optional native BacNet capable via IP.
7. Chiller control shall be capable of controlling up to eight Turbocor compressors on up to eight individual refrigerant circuits serving the same chilled water stream.
8. Chiller control panel user interface shall be capable of remote control via an internet connection without the use of any third party gateway device or additional hardware or software.
9. Chiller control shall be able to operate in headless mode (no touch panel connected) and utilize standard windows XP or higher computer to display user interface via Ethernet connection.
10. Ability to place all outputs in a manual state (hand, off, auto) via graphical user interface.
11. Alarm screen shall be capable of filtering faults into specific categories such as compressor, chiller and system faults in order to provide rapid diagnosis and separation of failure modes.
12. Variable speed cooling tower control.
13. Tower bypass valve control.
14. Ability to turn on/off duty standby chilled water pumps.
15. Ability to turn on/off duty standby condenser water pumps.
16. Ability to operate chiller isolation valves for both evaporator and condenser,
17. Multiple compressors staging algorithm shall operate at the optimized power curves of each compressor simultaneously and shall reset automatically every second during operation. Compressor staging methods that operates using simple incremental percent of demand shall not be accepted.
18. Continuous data logging for operational trending and bin analysis shall be exportable to “CSV” format. (12 months data stored).
19. Built-in stepper motor controls for EXVs
20. Controls lockup protection
21. Ramp rate control - Peak energy demand limiting algorithms.
22. Three levels of alarm safety for minimum chiller down time
23. Chiller control software shall employ an active fault avoidance algorithm to reduce chiller capacity and/or power level in the case the chiller approaches within 10% of any trip limit value such as suction pressure, discharge pressure, chiller amp limit, leaving chilled water temperature limit etc...
24. Store up to 32,000 alarm and fault events stored with date / time stamp.
25. Real time data trending viewable via Touch panel.
26. Chiller load profile charts viewable via Touch panel.
27. Chiller control graphical user interface shall be capable of displaying data in SI or I-P units without affecting control or BAS protocol units.
28. Controls shall identify within 60 seconds a compressor that is not starting or ramping properly. Upon this identification, the compressor shall be disabled, the remaining compressors shall be operated in an optimized fashion and an alarm shall be sent to alert the operator.
29. Chiller faults (14) possible conditions.
30. Each compressor alarm (9) possible conditions.
31. Each compressor fault (13) possible conditions.
32. Each compressor bearing fault (8) possible conditions.
33. Each compressor bearing fault (16) possible conditions.
34. Each compressor IGV position.
Optional:
1. BMS interface module for the interface with BacNET MSTP, BacNET IP or LonTalk FT10.
Data on Main Display Screen shall include (& shall communicate via protocol):
a) Entering and leaving chilled water temperatures.
b) Entering and leaving condenser water temperatures.
c) (7) states available
d) Active timers
e) Chiller enable status
f) Chiller water flow proof status
g) Condenser water flow proof status
h) Indication of compressor readiness
i) Indication of clearance to run
j) Chiller set point
k) Total chiller kW
l) Total chiller current input
m) Three pages of data trends with zoom functionality
n) Graphical dial indicators that clearly indicate safe and unsafe operating values
o) Graphical representation of evaporator and condenser showing gas movement when chiller is running.
p) Current alarms (announce and manual reset provision)
q) Compressor actual rpm, maximum rpm, minimum rpm
r) Compressor alarm description & fault description
s) Compressor percentage motor demand.
t) Compressor safety interlock status
u) Compressor modbus communication health status
v) Compressor suction and discharge pressures
w) Compressor suction and discharge temperatures
x) Compressor internal cooling system temperatures and status.
y) Compressor motor kW and amps.
z) Compressor pressure ratio.
EXECUTION
3.1 INSTALLATION
A. Install per manufacturer’s IOM documentation, shop drawings, and submittal documents.
B. Align chiller on foundations or mounting rails as specified on drawings.
C. Arrange piping to enable dismantling and permit head removal for tube cleaning.
D. Coordinate electrical installation with electrical contractor.
E. Coordinate controls and BMS interface with controls contractor.
F. Provide all material required for a fully operational and functional chiller.
3.2 START-UP
A. Units shall be field charged with HFC-134a refrigerant.
B. Factory Start-Up Services: Provide factory supervised start-up on-site for a minimum of two working days ensure proper operation of the equipment. During the period of start-up, the factory authorized technician shall instruct the owner’s representative in proper care and operation of the equipment.
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